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Sample records for carbonic anhydrase ca

  1. Expression of a novel carbonic anhydrase, CA XIII, in normal and neoplastic colorectal mucosa

    International Nuclear Information System (INIS)

    Carbonic anhydrase (CA) isozymes may have an important role in cancer development. Some isozymes control pH homeostasis in tumors that appears to modulate the behaviour of cancer cells. CA XIII is the newest member of the CA gene family. It is a cytosolic isozyme which is expressed in a number of normal tissues. The present study was designed to investigate CA XIII expression in prospectively collected colorectal tumor samples. Both neoplastic and normal tissue specimens were obtained from the same patients. The analyses were performed using CA XIII-specific antibodies and an immunohistochemical staining method. For comparison, the tissue sections were immunostained for other cytosolic isozymes, CA I and II. The results indicated that the expression of CA XIII is down-regulated in tumor cells compared to the normal tissue. The lowest signal was detected in carcinoma samples. This pattern of expression was quite parallel for CA I and II. The down-regulation of cytosolic CA I, II and XIII in colorectal cancer may result from reduced levels of a common transcription factor or loss of closely linked CA1, CA2 and CA13 alleles on chromosome 8. Their possible role as tumor suppressors should be further evaluated

  2. Expression of a novel carbonic anhydrase, CA XIII, in normal and neoplastic colorectal mucosa

    Directory of Open Access Journals (Sweden)

    Saarnio Juha

    2005-04-01

    Full Text Available Abstract Background Carbonic anhydrase (CA isozymes may have an important role in cancer development. Some isozymes control pH homeostasis in tumors that appears to modulate the behaviour of cancer cells. CA XIII is the newest member of the CA gene family. It is a cytosolic isozyme which is expressed in a number of normal tissues. The present study was designed to investigate CA XIII expression in prospectively collected colorectal tumor samples. Methods Both neoplastic and normal tissue specimens were obtained from the same patients. The analyses were performed using CA XIII-specific antibodies and an immunohistochemical staining method. For comparison, the tissue sections were immunostained for other cytosolic isozymes, CA I and II. Results The results indicated that the expression of CA XIII is down-regulated in tumor cells compared to the normal tissue. The lowest signal was detected in carcinoma samples. This pattern of expression was quite parallel for CA I and II. Conclusion The down-regulation of cytosolic CA I, II and XIII in colorectal cancer may result from reduced levels of a common transcription factor or loss of closely linked CA1, CA2 and CA13 alleles on chromosome 8. Their possible role as tumor suppressors should be further evaluated.

  3. Membrane Specific Carbonic Anhydrase (CA-IV) Expression in Bovine Lung: The Effects of Alcoholic and Non-Alcoholic Drinks

    OpenAIRE

    DEMİR, Nazan; NADAROĞLU, Hayrunnisa

    2002-01-01

    Carbonic anhydrase (CA) (carbonate hydrolyase: E. C. 4.2.1.1) from bovine lung was purified by a new method and characterized. The purification level was 4306-fold. The optimum temperature for maximum enzyme activity was 37.5°C. The optimum pH was 7.4, varying between 3.5 and 10.0. SDS-polyacryamide gel electrophoresis (3-10% discontinuous SDS-PAGE) showed two distinct bands for CA-IV. The molecular weights of the enzymes were found to be approximately 54.000 and 29.000, respectively. ...

  4. The human carbonic anhydrase isoenzymes I and II (hCA I and II) inhibition effects of trimethoxyindane derivatives.

    Science.gov (United States)

    Taslimi, Parham; Gulcin, Ilhami; Ozgeris, Bunyamin; Goksu, Suleyman; Tumer, Ferhan; Alwasel, Saleh H; Supuran, Claudiu T

    2016-01-01

    Carbonic anhydrases (CAs, EC 4.2.1.1) had six genetically distinct families described to date in various organisms. There are 16 known CA isoforms in humans. Human CA isoenzymes I and II (hCA I and hCA II) are ubiquitous cytosolic isoforms. Acetylcholine esterase (AChE. EC 3.1.1.7) is a hydrolase that hydrolyzes the neurotransmitter acetylcholine relaying the signal from the nerve. In this study, some trimethoxyindane derivatives were investigated as inhibitors against the cytosolic hCA I and II isoenzymes, and AChE enzyme. Both hCA isozymes were inhibited by trimethoxyindane derivatives in the low nanomolar range. These compounds were good hCA I inhibitors (Kis in the range of 1.66-4.14 nM) and hCA II inhibitors (Kis of 1.37-3.12 nM) and perfect AChE inhibitors (Kis in the range of 1.87-7.53 nM) compared to acetazolamide as CA inhibitor (Ki: 6.76 nM for hCA I and Ki: 5.85 nM for hCA II) and Tacrine as AChE inhibitor (Ki: 7.64 nM). PMID:25697270

  5. The Cellular Physiology of Carbonic Anhydrases

    Directory of Open Access Journals (Sweden)

    Breton S

    2001-07-01

    Full Text Available Carbonic anhydrases are zinc metalloenzymes that catalyze the reversible hydration of CO(2 to form HCO(3(- and protons according to the following reaction: CO(2 + H(2O = H(2CO(3 = HCO(3(- + H(+. The first reaction is catalyzed by carbonic anhydrase and the second reaction occurs instantaneously. The carbonic anhydrase (CA gene family includes ten enzymatically active members, which are major players in many physiological processes, including renal and male reproductive tract acidification, bone resorption, respiration, gluconeogenesis, signal transduction, and formation of gastric acid. The newly identified CA IX (previously called MN and CA XII are related to cell proliferation and oncogenesis. Carbonic anhydrase isozymes have different kinetic properties and they are present in various tissues and in various cell compartments. CA I, II, III and VII are cytoplasmic, CA V is mitochondrial, and CA VI is present in salivary secretions. CA IV, IX, XII and XIV are membrane proteins: CA IV is a glycosyl-phosphatidylinositol-anchored protein, and CA IX, XII and XIV are transmembrane proteins. The present work will focus on the roles of CA II and CA IV in transepithelial proton secretion and bicarbonate reabsorption processes. The localization of these isoforms in selected epithelia that are involved in net acid/base transport, such as kidney proximal tubules and collecting ducts, and tubules from the male reproductive tract will be reviewed.

  6. Sulfonamide inhibition studies of the α-carbonic anhydrase from the gammaproteobacterium Thiomicrospira crunogena XCL-2, TcruCA.

    Science.gov (United States)

    Vullo, Daniela; Bhatt, Avni; Mahon, Brian P; McKenna, Robert; Supuran, Claudiu T

    2016-01-15

    We report a sulfonamide/sulfamate inhibition study of the α-carbonic anhydrase (CA, EC 4.2.1.1) present in the gammaproteobacterium Thiomicrospira crunogena XCL-2, a mesophilic hydrothermal vent-isolate organism, TcruCA. As Thiomicrospira crunogena is one of thousands of marine organisms that uses CA for metabolic regulation, the effect of sulfonamide inhibition has been considered. Sulfonamide-based drugs have been widely used in a variety of antibiotics, and bioelimination of these compounds results in exposure of these compounds to marine life. The enzyme was highly inhibited, with Ki values ranging from 2.5 to 40.7nM by a variety of sulfonamides including acetazolamide, methazolamide, ethoxzolamide, dichlorophenamide, dorzolamide, brinzolamide, benzolamide and benzenesulfonamides incorporating 4-hydroxyalkyl moieties. Less effective inhibitors were topiramate, zonisamide, celecoxib, saccharin and hydrochlorothiazide as well as simple benzenesulfonamides incorporating amino, halogeno, alkyl, aminoalkyl and other moieties in the ortho- or para-positions of the aromatic ring (Kis of 202-933nM). The active site interactions between TcruCA and three clinically-used CA inhibitors, acetazolamide (Diamox®), dorzolamide (Trusopt®), and brinzolamide (Azopt®) are studied using molecular docking to provide insight into the reported Ki values. Comparison between various enzymes belonging to this family may also bring interesting hints in these fascinating phenomena. PMID:26691758

  7. Heterocyclic compounds as carbonic anhydrase inhibitor.

    Science.gov (United States)

    Husain, Asif; Madhesia, Diwakar

    2012-12-01

    The carbonic anhydrases (CAs, EC 4.2.1.1) constitute interesting targets for the design of pharmacological agents useful in the treatment or prevention of a variety of disorders such as, glaucoma, acid-base disequilibria, epilepsy, and other neuromuscular diseases, altitude sickness, edema, and obesity. A quite new and unexpected application of the CA inhibitors (CAIs) is with regard to their potential use in the management (imaging and treatment) of hypoxic tumors. A series of sulfonamides, including some clinically used derivatives like acetazolamide, methazolamide, ethoxzolamide, dichlorophenamide, dorzolamide, brinzolamide, benzolamide, and sulpiride, or indisulam, a compound in clinical development as antitumor drug, as well as the sulfamate antiepileptic drug topiramate have been reported to inhibit various human carbonic anhydrase isozyme. Various heterocyclic sulfonamides have been reported in this review with their potency to inhibit different carbonic anhydrases isozymes. PMID:21981003

  8. Inhibitory Effect of Furosemide on Carbonic Anhydrase

    Institute of Scientific and Technical Information of China (English)

    CUI Jianli; ZHAO Tongjin; JIANG Yan; ZHOU Haimeng

    2006-01-01

    This study investigated the inhibitory effect of a high efficiency diuretic, furosemide, on carbonic anhydrase (CA). First, comparing the inhibitory effect of acetazolamide, a low efficiency diuretic, on CA, shows that furosemide or acetazolamide can quickly make CA inactive when its concentration is close to the enzyme concentration, different from the usual inhibitory kinetics in which the concentration of the inhibitor is far higher than the enzyme concentration. Secondly, the reaction of the enzyme indicates that the inhibitory effect of furosemide or acetazolamide on carbonic anhydrase is quickly reversible. Finally, the degree of the inhibitory effect of furosemide and of acetazolamide on CA are compared. The results show that furosemide inhibits CA less than acetazolamide.

  9. Accelerating Mineral Carbonation Using Carbonic Anhydrase.

    Science.gov (United States)

    Power, Ian M; Harrison, Anna L; Dipple, Gregory M

    2016-03-01

    Carbonic anhydrase (CA) enzymes have gained considerable attention for their potential use in carbon dioxide (CO2) capture technologies because they are able to catalyze rapidly the interconversion of aqueous CO2 and bicarbonate. However, there are challenges for widespread implementation including the need to develop mineralization process routes for permanent carbon storage. Mineral carbonation of highly reactive feedstocks may be limited by the supply rate of CO2. This rate limitation can be directly addressed by incorporating enzyme-catalyzed CO2 hydration. This study examined the effects of bovine carbonic anhydrase (BCA) and CO2-rich gas streams on the carbonation rate of brucite [Mg(OH)2], a highly reactive mineral. Alkaline brucite slurries were amended with BCA and supplied with 10% CO2 gas while aqueous chemistry and solids were monitored throughout the experiments (hours to days). In comparison to controls, brucite carbonation using BCA was accelerated by up to 240%. Nesquehonite [MgCO3·3H2O] precipitation limited the accumulation of hydrated CO2 species, apparently preventing BCA from catalyzing the dehydration reaction. Geochemical models reproduce observed reaction progress in all experiments, revealing a linear correlation between CO2 uptake and carbonation rate. Data demonstrates that carbonation in BCA-amended reactors remained limited by CO2 supply, implying further acceleration is possible. PMID:26829491

  10. Common genetic denominators for Ca++-based skeleton in Metazoa: role of osteoclast-stimulating factor and of carbonic anhydrase in a calcareous sponge.

    Directory of Open Access Journals (Sweden)

    Werner E G Müller

    Full Text Available Calcium-based matrices serve predominantly as inorganic, hard skeletal systems in Metazoa from calcareous sponges [phylum Porifera; class Calcarea] to proto- and deuterostomian multicellular animals. The calcareous sponges form their skeletal elements, the spicules, from amorphous calcium carbonate (ACC. Treatment of spicules from Sycon raphanus with sodium hypochlorite (NaOCl results in the disintegration of the ACC in those skeletal elements. Until now a distinct protein/enzyme involved in ACC metabolism could not been identified in those animals. We applied the technique of phage display combinatorial libraries to identify oligopeptides that bind to NaOCl-treated spicules: those oligopeptides allowed us to detect proteins that bind to those spicules. Two molecules have been identified, the (putative enzyme carbonic anhydrase and the (putative osteoclast-stimulating factor (OSTF, that are involved in the catabolism of ACC. The complete cDNAs were isolated and the recombinant proteins were prepared to raise antibodies. In turn, immunofluorescence staining of tissue slices and qPCR analyses have been performed. The data show that sponges, cultivated under standard condition (10 mM CaCl(2 show low levels of transcripts/proteins for carbonic anhydrase or OSTF, compared to those animals that had been cultivated under Ca(2+-depletion condition (1 mM CaCl(2. Our data identify with the carbonic anhydrase and the OSTF the first two molecules which remain conserved in cells, potentially involved in Ca-based skeletal dissolution, from sponges (sclerocytes to human (osteoclast.

  11. Coral Carbonic Anhydrases: Regulation by Ocean Acidification

    Science.gov (United States)

    Zoccola, Didier; Innocenti, Alessio; Bertucci, Anthony; Tambutté, Eric; Supuran, Claudiu T.; Tambutté, Sylvie

    2016-01-01

    Global change is a major threat to the oceans, as it implies temperature increase and acidification. Ocean acidification (OA) involving decreasing pH and changes in seawater carbonate chemistry challenges the capacity of corals to form their skeletons. Despite the large number of studies that have investigated how rates of calcification respond to ocean acidification scenarios, comparatively few studies tackle how ocean acidification impacts the physiological mechanisms that drive calcification itself. The aim of our paper was to determine how the carbonic anhydrases, which play a major role in calcification, are potentially regulated by ocean acidification. For this we measured the effect of pH on enzyme activity of two carbonic anhydrase isoforms that have been previously characterized in the scleractinian coral Stylophora pistillata. In addition we looked at gene expression of these enzymes in vivo. For both isoforms, our results show (1) a change in gene expression under OA (2) an effect of OA and temperature on carbonic anhydrase activity. We suggest that temperature increase could counterbalance the effect of OA on enzyme activity. Finally we point out that caution must, thus, be taken when interpreting transcriptomic data on carbonic anhydrases in ocean acidification and temperature stress experiments, as the effect of these stressors on the physiological function of CA will depend both on gene expression and enzyme activity. PMID:27271641

  12. Coral Carbonic Anhydrases: Regulation by Ocean Acidification.

    Science.gov (United States)

    Zoccola, Didier; Innocenti, Alessio; Bertucci, Anthony; Tambutté, Eric; Supuran, Claudiu T; Tambutté, Sylvie

    2016-01-01

    Global change is a major threat to the oceans, as it implies temperature increase and acidification. Ocean acidification (OA) involving decreasing pH and changes in seawater carbonate chemistry challenges the capacity of corals to form their skeletons. Despite the large number of studies that have investigated how rates of calcification respond to ocean acidification scenarios, comparatively few studies tackle how ocean acidification impacts the physiological mechanisms that drive calcification itself. The aim of our paper was to determine how the carbonic anhydrases, which play a major role in calcification, are potentially regulated by ocean acidification. For this we measured the effect of pH on enzyme activity of two carbonic anhydrase isoforms that have been previously characterized in the scleractinian coral Stylophora pistillata. In addition we looked at gene expression of these enzymes in vivo. For both isoforms, our results show (1) a change in gene expression under OA (2) an effect of OA and temperature on carbonic anhydrase activity. We suggest that temperature increase could counterbalance the effect of OA on enzyme activity. Finally we point out that caution must, thus, be taken when interpreting transcriptomic data on carbonic anhydrases in ocean acidification and temperature stress experiments, as the effect of these stressors on the physiological function of CA will depend both on gene expression and enzyme activity.

  13. Coral Carbonic Anhydrases: Regulation by Ocean Acidification

    Directory of Open Access Journals (Sweden)

    Didier Zoccola

    2016-06-01

    Full Text Available Global change is a major threat to the oceans, as it implies temperature increase and acidification. Ocean acidification (OA involving decreasing pH and changes in seawater carbonate chemistry challenges the capacity of corals to form their skeletons. Despite the large number of studies that have investigated how rates of calcification respond to ocean acidification scenarios, comparatively few studies tackle how ocean acidification impacts the physiological mechanisms that drive calcification itself. The aim of our paper was to determine how the carbonic anhydrases, which play a major role in calcification, are potentially regulated by ocean acidification. For this we measured the effect of pH on enzyme activity of two carbonic anhydrase isoforms that have been previously characterized in the scleractinian coral Stylophora pistillata. In addition we looked at gene expression of these enzymes in vivo. For both isoforms, our results show (1 a change in gene expression under OA (2 an effect of OA and temperature on carbonic anhydrase activity. We suggest that temperature increase could counterbalance the effect of OA on enzyme activity. Finally we point out that caution must, thus, be taken when interpreting transcriptomic data on carbonic anhydrases in ocean acidification and temperature stress experiments, as the effect of these stressors on the physiological function of CA will depend both on gene expression and enzyme activity.

  14. Coral Carbonic Anhydrases: Regulation by Ocean Acidification.

    Science.gov (United States)

    Zoccola, Didier; Innocenti, Alessio; Bertucci, Anthony; Tambutté, Eric; Supuran, Claudiu T; Tambutté, Sylvie

    2016-01-01

    Global change is a major threat to the oceans, as it implies temperature increase and acidification. Ocean acidification (OA) involving decreasing pH and changes in seawater carbonate chemistry challenges the capacity of corals to form their skeletons. Despite the large number of studies that have investigated how rates of calcification respond to ocean acidification scenarios, comparatively few studies tackle how ocean acidification impacts the physiological mechanisms that drive calcification itself. The aim of our paper was to determine how the carbonic anhydrases, which play a major role in calcification, are potentially regulated by ocean acidification. For this we measured the effect of pH on enzyme activity of two carbonic anhydrase isoforms that have been previously characterized in the scleractinian coral Stylophora pistillata. In addition we looked at gene expression of these enzymes in vivo. For both isoforms, our results show (1) a change in gene expression under OA (2) an effect of OA and temperature on carbonic anhydrase activity. We suggest that temperature increase could counterbalance the effect of OA on enzyme activity. Finally we point out that caution must, thus, be taken when interpreting transcriptomic data on carbonic anhydrases in ocean acidification and temperature stress experiments, as the effect of these stressors on the physiological function of CA will depend both on gene expression and enzyme activity. PMID:27271641

  15. Non-Classical Inhibition of Carbonic Anhydrase

    Science.gov (United States)

    Lomelino, Carrie L.; Supuran, Claudiu T.; McKenna, Robert

    2016-01-01

    Specific isoforms from the carbonic anhydrase (CA) family of zinc metalloenzymes have been associated with a variety of diseases. Isoform-specific carbonic anhydrase inhibitors (CAIs) are therefore a major focus of attention for specific disease treatments. Classical CAIs, primarily sulfonamide-based compounds and their bioisosteres, are examined as antiglaucoma, antiepileptic, antiobesity, antineuropathic pain and anticancer compounds. However, many sulfonamide compounds inhibit all CA isoforms nonspecifically, diluting drug effectiveness and causing undesired side effects due to off-target inhibition. In addition, a small but significant percentage of the general population cannot be treated with sulfonamide-based compounds due to a sulfa allergy. Therefore, CAIs must be developed that are not only isoform specific, but also non-classical, i.e. not based on sulfonamides, sulfamates, or sulfamides. This review covers the classes of non-classical CAIs and the recent advances in the development of isoform-specific inhibitors based on phenols, polyamines, coumarins and their derivatives. PMID:27438828

  16. Carbonic anhydrase inhibitors drug design.

    Science.gov (United States)

    McKenna, Robert; Supuran, Claudiu T

    2014-01-01

    Inhibition of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1) has pharmacologic applications in the field of antiglaucoma, anticonvulsant, antiobesity, and anticancer agents but is also emerging for designing anti-infectives (antifungal and antibacterial agents) with a novel mechanism of action. As a consequence, the drug design of CA inhibitors (CAIs) is a very dynamic field. Sulfonamides and their isosteres (sulfamates/sulfamides) constitute the main class of CAIs which bind to the metal ion in the enzyme active site. Recently the dithiocarbamates, possessing a similar mechanism of action, were reported as a new class of inhibitors. Other families of CAIs possess a distinct mechanism of action: phenols, polyamines, some carboxylates, and sulfocoumarins anchor to the zinc-coordinated water molecule. Coumarins and five/six-membered lactones are prodrug inhibitors, binding in hydrolyzed form at the entrance of the active site cavity. Novel drug design strategies have been reported principally based on the tail approach for obtaining all these types of CAIs, which exploit more external binding regions within the enzyme active site (in addition to coordination to the metal ion), leading thus to isoform-selective compounds. Sugar-based tails as well as click chemistry were the most fruitful developments of the tail approach. Promising compounds that inhibit CAs from bacterial and fungal pathogens, of the dithiocarbamate, phenol and carboxylate types have also been reported. PMID:24146385

  17. Genomic organization of the human gene (CA5) and pseudogene for mitochondrial carbonic anhydrase V and their localization to chromosomes 16q and 16p

    Energy Technology Data Exchange (ETDEWEB)

    Nagao, Yoshiro; Sly, W.S.; Batanian, J.R. [St. Louis Univ. School of Medicine, MO (United States)] [and others

    1995-08-10

    Carbonic anhydrase V (CA V) is expressed in mitochondrial matrix in liver and several other tissues. It is of interest for its putative roles in providing bicarbonate to carbamoyl phosphate synthetase for ureagenesis and to pyruvate carboxylase for gluconeogenesis and its possible importance in explaining certain inherited metabolic disorders with hyperammonemia and hypoglycemia. Following the recent characterization of the cDNA for human CA V, we report the isolation of the human gene from two {lambda} genomic libraries and its characterization. The CA V gene (CA5) is approximately 50 kb long and contains 7 exons and 6 introns. The exon-intron boundaries are found in positions identical to those determined for the previously described CA II, CA III, and CA VII genes. Like the CA VII gene, CA5 does not contain typical TATA and CAAT promoter elements in the 5{prime} flanking region but does contain a TTTAA sequence 147 nucleotides upstream of the initiation codon. CA5 also contains a 12-bp GT-rich segment beginning 13 bp downstream of the polyadenylation signal in the 3{prime} untranslated region of exon 7. FISH analysis allowed CA5 to be assigned to chromosome 16q24.3. An unprocessed pseudogene containing sequence homologous to exons 3-7 and introns 3-6 was also isolated and was assigned by FISH analysis to chromosome 16p11.2-p12. 22 refs., 4 figs., 1 tab.

  18. Microwave assisted synthesis of novel acridine-acetazolamide conjugates and investigation of their inhibition effects on human carbonic anhydrase isoforms hCA I, II, IV and VII.

    Science.gov (United States)

    Ulus, Ramazan; Aday, Burak; Tanç, Muhammet; Supuran, Claudiu T; Kaya, Muharrem

    2016-08-15

    4-Amino-N-(5-sulfamoyl-1,3,4-thiadiazol-2-yl)benzamide was condensed with cyclic-1,3-diketones (dimedone and cyclohexane-1,3-dione) and aromatic aldehydes under microwave irradiation, leading to a series of acridine-acetazolamide conjugates. The new compounds were investigated as inhibitors of carbonic anhydrases (CA, EC 4.2.1.1), and more precisely cytosolic isoforms hCA I, II, VII and membrane-bound one hCA IV. All investigated isoforms were inhibited in low micromolar and nanomolar range by the new compounds. hCA IV and VII were inhibited with KIs in the range of 29.7-708.8nM (hCA IV), and of 1.3-90.7nM (hCA VII). For hCA I and II the KIs were in the range of 6.7-335.2nM (hCA I) and of 0.5-55.4nM (hCA II). The structure-activity relationships (SAR) for the inhibition of these isoforms with the acridine-acetazolamide conjugates reported here were delineated. PMID:27298005

  19. The most recently discovered carbonic anhydrase, CA XV, is expressed in the thick ascending limb of Henle and in the collecting ducts of mouse kidney.

    Directory of Open Access Journals (Sweden)

    Sina Saari

    Full Text Available BACKGROUND: Carbonic anhydrases (CAs are key enzymes for physiological pH regulation, including the process of urine acidification. Previous studies have identified seven cytosolic or membrane-bound CA isozymes in the kidney. Recently, we showed by in situ hybridization that the mRNA for the most novel CA isozyme, CA XV, is present in the renal cortex. CA XV is a unique isozyme among mammalian CAs, because it has become a pseudogene in primates even though expressed in several other species. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we raised a polyclonal antibody against recombinant mouse CA XV that was produced in a baculovirus/insect cell expression system, and the antibody was used for immunohistochemical analysis in different mouse tissues. Positive immunoreactions were found only in the kidney, where the enzyme showed a very limited distribution pattern. Parallel immunostaining experiments with several other anti-CA sera indicated that CA XV is mainly expressed in the thick ascending limb of Henle and collecting ducts, and the reactions were most prominent in the cortex and outer medulla. CONCLUSION/SIGNIFICANCE: Although other studies have proposed a role for CA XV in cell proliferation, its tightly limited distribution may point to a specialized function in the regulation of acid-base homeostasis.

  20. Carbonic Anhydrase II Deficiency in a Saudi Woman

    OpenAIRE

    Alhuzaim, Omar N; Almohareb, Ohoud M; Safiya M. Sherbeeni

    2015-01-01

    OBJECTIVE Carbonic anhydrase (CA) II deficiency is a rare autosomal recessive disorder caused by mutation in the CA II gene that leads to osteopetrosis, renal tubular acidosis (RTA), and cerebral calcification. Our aim is to present a patient with the classic triad of CA II deficiency syndrome to enhance the awareness about this rare syndrome. METHODS We describe the clinical and radiological findings of a Saudi woman patient with CA II deficiency syndrome. RESULTS A Saudi woman in her 20s pr...

  1. The impact of hydroquinone on acetylcholine esterase and certain human carbonic anhydrase isoenzymes (hCA I, II, IX, and XII).

    Science.gov (United States)

    Scozzafava, Andrea; Kalın, Pınar; Supuran, Claudiu T; Gülçin, İlhami; Alwasel, Saleh H

    2015-12-01

    Carbonic anhydrases (CAs) are widespread and the most studied members of a great family of metalloenzymes in higher vertebrates including humans. CAs were investigated for their inhibition of all of the catalytically active mammalian isozymes of the Zn(2+)-containing CA, (CA, EC 4.2.1.1). On the other hand, acetylcholinesterase (AChE. EC 3.1.1.7), a serine protease, is responsible for ACh hydrolysis and plays a fundamental role in impulse transmission by terminating the action of the neurotransmitter ACh at the cholinergic synapses and neuromuscular junction. In the present study, the inhibition effect of the hydroquinone (benzene-1,4-diol) on AChE activity was evaluated and effectively inhibited AChE with Ki of 1.22 nM. Also, hydroquinone strongly inhibited some human cytosolic CA isoenzymes (hCA I and II) and tumour-associated transmembrane isoforms (hCA IX, and XII), with Kis in the range between micromolar (415.81 μM) and nanomolar (706.79 nM). The best inhibition was observed in cytosolic CA II. PMID:25586344

  2. Natural products that inhibit carbonic anhydrase.

    Science.gov (United States)

    Poulsen, Sally-Ann; Davis, Rohan A

    2014-01-01

    The chemical diversity, binding specificity and propensity to interact with biological targets has inspired many researchers to utilize natural products as molecular probes. Almost all reported carbonic anhydrase inhibitors comprise a zinc binding group in their structure of which the primary sulfonamide moiety (-SO2NH2) is the foremost example and to a lesser extent the primary sulfamate (-O-SO2NH2) and sulfamide (-NH-SO2NH2) groups. Natural products that comprise these zinc binding groups in their structure are however rare and relatively few natural products have been explored as a source for novel carbonic anhydrase inhibitors. This chapter will highlight the recent and growing interest in carbonic anhydrase inhibitors sourced from nature, demonstrating that natural product chemical space presents a rich source of potential alternate chemotypes for the discovery of novel drug-like carbonic anhydrase inhibitors. PMID:24146386

  3. Carbonic Anhydrases and Their Biotechnological Applications

    Directory of Open Access Journals (Sweden)

    Robert McKenna

    2013-08-01

    Full Text Available The carbonic anhydrases (CAs are mostly zinc-containing metalloenzymes which catalyze the reversible hydration/dehydration of carbon dioxide/bicarbonate. The CAs have been extensively studied because of their broad physiological importance in all kingdoms of life and clinical relevance as drug targets. In particular, human CA isoform II (HCA II has a catalytic efficiency of 108 M−1 s−1, approaching the diffusion limit. The high catalytic rate, relatively simple procedure of expression and purification, relative stability and extensive biophysical studies of HCA II has made it an exciting candidate to be incorporated into various biomedical applications such as artificial lungs, biosensors and CO2 sequestration systems, among others. This review highlights the current state of these applications, lists their advantages and limitations, and discusses their future development.

  4. Carbonic anhydrases as targets for medicinal chemistry.

    Science.gov (United States)

    Supuran, Claudiu T; Scozzafava, Andrea

    2007-07-01

    Carbonic anhydrases (CAs, EC 4.2.1.1) are zinc enzymes acting as efficient catalysts for the reversible hydration of carbon dioxide to bicarbonate. 16 different alpha-CA isoforms were isolated in mammals, where they play crucial physiological roles. Some of them are cytosolic (CA I, CA II, CA III, CA VII, CA XIII), others are membrane-bound (CA IV, CA IX, CA XII, CA XIV and CA XV), CA VA and CA VB are mitochondrial, and CA VI is secreted in saliva and milk. Three acatalytic forms are also known, the CA related proteins (CARP), CARP VIII, CARP X and CARP XI. Representatives of the beta-delta-CA family are highly abundant in plants, diatoms, eubacteria and archaea. The catalytic mechanism of the alpha-CAs is understood in detail: the active site consists of a Zn(II) ion co-ordinated by three histidine residues and a water molecule/hydroxide ion. The latter is the active species, acting as a potent nucleophile. For beta- and gamma-CAs, the zinc hydroxide mechanism is valid too, although at least some beta-class enzymes do not have water directly coordinated to the metal ion. CAs are inhibited primarily by two classes of compounds: the metal complexing anions and the sulfonamides/sulfamates/sulfamides possessing the general formula RXSO(2)NH(2) (R=aryl; hetaryl; perhaloalkyl; X=nothing, O or NH). Several important physiological and physio-pathological functions are played by CAs present in organisms all over the phylogenetic tree, related to respiration and transport of CO(2)/bicarbonate between metabolizing tissues and the lungs, pH and CO(2) homeostasis, electrolyte secretion in a variety of tissues/organs, biosynthetic reactions, such as the gluconeogenesis and ureagenesis among others (in animals), CO(2) fixation (in plants and algae), etc. The presence of these ubiquitous enzymes in so many tissues and in so different isoforms represents an attractive goal for the design of inhibitors with biomedical applications. Indeed, CA inhibitors are clinically used as

  5. Enzymes for carbon sequestration: neutron crystallographic studies of carbonic anhydrase

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, S. Z., E-mail: zfisher@lanl.gov; Kovalevsky, A. Y. [Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Domsic, J. [Department of Biochemistry and Molecular Biology, PO Box 100245, University of Florida, Gainesville, FL 32610 (United States); Mustyakimov, M. [Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Silverman, D. N. [Department of Pharmacology and Therapeutics, PO Box 100267, University of Florida, Gainesville, FL 32610 (United States); McKenna, R. [Department of Biochemistry and Molecular Biology, PO Box 100245, University of Florida, Gainesville, FL 32610 (United States); Langan, P. [Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2010-11-01

    The first neutron crystal structure of carbonic anhydrase is presented. The structure reveals interesting and unexpected features of the active site that affect catalysis. Carbonic anhydrase (CA) is a ubiquitous metalloenzyme that catalyzes the reversible hydration of CO{sub 2} to form HCO{sub 3}{sup −} and H{sup +} using a Zn–hydroxide mechanism. The first part of catalysis involves CO{sub 2} hydration, while the second part deals with removing the excess proton that is formed during the first step. Proton transfer (PT) is thought to occur through a well ordered hydrogen-bonded network of waters that stretches from the metal center of CA to an internal proton shuttle, His64. These waters are oriented and ordered through a series of hydrogen-bonding interactions to hydrophilic residues that line the active site of CA. Neutron studies were conducted on wild-type human CA isoform II (HCA II) in order to better understand the nature and the orientation of the Zn-bound solvent (ZS), the charged state and conformation of His64, the hydrogen-bonding patterns and orientations of the water molecules that mediate PT and the ionization of hydrophilic residues in the active site that interact with the water network. Several interesting and unexpected features in the active site were observed which have implications for how PT proceeds in CA.

  6. Close association of carbonic anhydrase (CA2a & CA15a, Na+/H+ exchanger (Nhe3b, and ammonia transporter Rhcg1 in zebrafish ionocytes responsible for Na+ uptake

    Directory of Open Access Journals (Sweden)

    Yusuke eIto

    2013-04-01

    Full Text Available Freshwater fishes actively absorb salt from their environment to tolerate low salinities. We previously reported that vacuolar-type H+-ATPase/mitochondrion-rich cells (H-MRCs on the skin epithelium of zebrafish larvae (Danio rerio are primary sites for Na+ uptake. In this study, in an attempt to clarify the mechanism for the Na+ uptake, we performed a systematic analysis of gene expression patterns of zebrafish carbonic anhydrase (CA isoforms and found that, of 12 CA isoforms, CA2a and CA15a are highly expressed in H-MRCs at larval stages. The ca2a and ca15a mRNA expression were salinity-dependent; they were up-regulated in 0.03 mM Na+ water whereas ca15a but not ca2a was down-regulated in 70 mM Na+ water. Immunohistochemistry demonstrated cytoplasmic distribution of CA2a and apical membrane localization of CA15a. Furthermore, cell-surface immunofluorescence staining revealed external surface localization of CA15a. Depletion of either CA2a or CA15a expression by Morphorino antisense oligonucleotides resulted in a significant decrease in Na+ accumulation in H-MRCs. An in situ proximity ligation assay demonstrated a very close association of CA2a, CA15a, Na+/H+ exchanger 3b (Nhe3b, and Rhcg1 ammonia transporter in H-MRC. Our findings suggest that CA2a, CA15a, and Rhcg1 play a key role in Na+ uptake under freshwater conditions by forming a transport metabolon with Nhe3b.

  7. The history and rationale of using carbonic anhydrase inhibitors in the treatment of peptic ulcers. In memoriam Ioan Puşcaş (1932-2015).

    Science.gov (United States)

    Buzás, György M; Supuran, Claudiu T

    2016-08-01

    Carbonic anhydrase (CA, EC 4.2.1.1) inhibitors (CAIs) started to be used in the treatment of peptic ulcers in the 1970s, and for more than two decades, a group led by Ioan Puşcaş used them for this purpose, assuming that by inhibiting the gastric mucosa CA isoforms, hydrochloric acid secretion is decreased. Although acetazolamide and other sulfonamide CAIs are indeed effective in healing ulcers, the inhibition of CA isoforms in other organs than the stomach led to a number of serious side effects which made this treatment obsolete when the histamine H2 receptor antagonists and the proton pump inhibitors became available. Decades later, in 2002, it has been discovered that Helicobacter pylori, the bacterial pathogen responsible for gastric ulcers and cancers, encodes for two CAs, one belonging to the α-class and the other one to the β-class of these enzymes. These enzymes are crucial for the life cycle of the bacterium and its acclimation within the highly acidic environment of the stomach. Inhibition of the two bacterial CAs with sulfonamides such as acetazolamide, a low-nanomolar H. pylori CAI, is lethal for the pathogen, which explains why these compounds were clinically efficient as anti-ulcer drugs. Thus, the approach promoted by Ioan Puşcaş for treating this disease was a good one although the rationale behind it was wrong. In this review, we present a historical overview of the sulfonamide CAIs as anti-ulcer agents, in memoriam of the scientist who was in the first line of this research trend. PMID:26108882

  8. The history and rationale of using carbonic anhydrase inhibitors in the treatment of peptic ulcers. In memoriam Ioan Puşcaş (1932-2015).

    Science.gov (United States)

    Buzás, György M; Supuran, Claudiu T

    2016-08-01

    Carbonic anhydrase (CA, EC 4.2.1.1) inhibitors (CAIs) started to be used in the treatment of peptic ulcers in the 1970s, and for more than two decades, a group led by Ioan Puşcaş used them for this purpose, assuming that by inhibiting the gastric mucosa CA isoforms, hydrochloric acid secretion is decreased. Although acetazolamide and other sulfonamide CAIs are indeed effective in healing ulcers, the inhibition of CA isoforms in other organs than the stomach led to a number of serious side effects which made this treatment obsolete when the histamine H2 receptor antagonists and the proton pump inhibitors became available. Decades later, in 2002, it has been discovered that Helicobacter pylori, the bacterial pathogen responsible for gastric ulcers and cancers, encodes for two CAs, one belonging to the α-class and the other one to the β-class of these enzymes. These enzymes are crucial for the life cycle of the bacterium and its acclimation within the highly acidic environment of the stomach. Inhibition of the two bacterial CAs with sulfonamides such as acetazolamide, a low-nanomolar H. pylori CAI, is lethal for the pathogen, which explains why these compounds were clinically efficient as anti-ulcer drugs. Thus, the approach promoted by Ioan Puşcaş for treating this disease was a good one although the rationale behind it was wrong. In this review, we present a historical overview of the sulfonamide CAIs as anti-ulcer agents, in memoriam of the scientist who was in the first line of this research trend.

  9. Expression and characterization of a recombinant psychrophilic γ-carbonic anhydrase (NcoCA) identified in the genome of the Antarctic cyanobacteria belonging to the genus Nostoc.

    Science.gov (United States)

    De Luca, Viviana; Del Prete, Sonia; Vullo, Daniela; Carginale, Vincenzo; Di Fonzo, Pietro; Osman, Sameh M; AlOthman, Zeid; Supuran, Claudiu T; Capasso, Clemente

    2016-10-01

    Carbonic anhydrases (CAs, EC 4.2.1.1) catalyze the CO2 hydration/dehydration reversible reaction: CO2 + H2O ⇄ [Formula: see text] + H(+). Living organisms encode for at least six distinct genetic families of such catalyst, the α-, β-, γ-, δ-, ζ- and η-CAs. The main function of the CAs is to quickly process the CO2 derived by metabolic processes in order to regulate acid-base homeostasis, connected to the production of protons (H(+)) and bicarbonate. Few data are available in the literature on Antarctic CAs and most of the scientific information regards CAs isolated from mammals or prokaryotes (as well as other mesophilic sources). It is of great interest to study the biochemical behavior of such catalysts identified in organism living in the Antarctic sea where temperatures average -1.9 °C all year round. The enzymes isolated from Antarctic organisms represent a useful tool to study the relations among structure, stability and function of proteins in organisms adapted to living at constantly low temperatures. In the present paper, we report in detail the cloning, purification, and physico-chemical properties of NcoCA, a γ-CA isolated from the Antarctic cyanobacterium Nostoc commune. This enzyme showed a higher catalytic efficiency at lower temperatures compared to mesophilic counterparts belonging to α-, β-, γ-classes, as well as a limited stability at moderate temperatures. PMID:26226178

  10. Expression and characterization of a recombinant psychrophilic γ-carbonic anhydrase (NcoCA) identified in the genome of the Antarctic cyanobacteria belonging to the genus Nostoc.

    Science.gov (United States)

    De Luca, Viviana; Del Prete, Sonia; Vullo, Daniela; Carginale, Vincenzo; Di Fonzo, Pietro; Osman, Sameh M; AlOthman, Zeid; Supuran, Claudiu T; Capasso, Clemente

    2016-10-01

    Carbonic anhydrases (CAs, EC 4.2.1.1) catalyze the CO2 hydration/dehydration reversible reaction: CO2 + H2O ⇄ [Formula: see text] + H(+). Living organisms encode for at least six distinct genetic families of such catalyst, the α-, β-, γ-, δ-, ζ- and η-CAs. The main function of the CAs is to quickly process the CO2 derived by metabolic processes in order to regulate acid-base homeostasis, connected to the production of protons (H(+)) and bicarbonate. Few data are available in the literature on Antarctic CAs and most of the scientific information regards CAs isolated from mammals or prokaryotes (as well as other mesophilic sources). It is of great interest to study the biochemical behavior of such catalysts identified in organism living in the Antarctic sea where temperatures average -1.9 °C all year round. The enzymes isolated from Antarctic organisms represent a useful tool to study the relations among structure, stability and function of proteins in organisms adapted to living at constantly low temperatures. In the present paper, we report in detail the cloning, purification, and physico-chemical properties of NcoCA, a γ-CA isolated from the Antarctic cyanobacterium Nostoc commune. This enzyme showed a higher catalytic efficiency at lower temperatures compared to mesophilic counterparts belonging to α-, β-, γ-classes, as well as a limited stability at moderate temperatures.

  11. Thermostable Carbonic Anhydrases in Biotechnological Applications

    Directory of Open Access Journals (Sweden)

    Anna Di Fiore

    2015-07-01

    Full Text Available Carbonic anhydrases are ubiquitous metallo-enzymes which catalyze the reversible hydration of carbon dioxide in bicarbonate ions and protons. Recent years have seen an increasing interest in the utilization of these enzymes in CO2 capture and storage processes. However, since this use is greatly limited by the harsh conditions required in these processes, the employment of thermostable enzymes, both those isolated by thermophilic organisms and those obtained by protein engineering techniques, represents an interesting possibility. In this review we will provide an extensive description of the thermostable carbonic anhydrases so far reported and the main processes in which these enzymes have found an application.

  12. Structure and function of carbonic anhydrases.

    Science.gov (United States)

    Supuran, Claudiu T

    2016-07-15

    Carbonic anhydrases (CAs, EC 4.2.1.1) catalyse the interconversion between CO2 and bicarbonate as well as other hydrolytic reactions. Among the six genetic families known to date, the α-, β-, γ-, δ-, ζ- and η-CAs, detailed kinetic and X-ray crystallographic studies have allowed a deep understanding of the structure-function relationship in this superfamily of proteins. A metal hydroxide nucleophilic species of the enzyme, and a unique active site architecture, with half of it hydrophilic and the opposing part hydrophobic, allow these enzymes to act as some of the most effective catalysts known in Nature. The CA activation and inhibition mechanisms are also known in detail, with a large number of new inhibitor classes being described in the last years. Apart from the zinc binders, some classes of inhibitors anchor to the metal ion coordinated nucleophile, others occlude the entrance of the active site cavity and more recently, compounds binding outside the active site were described. CA inhibition has therapeutic applications for drugs acting as diuretics, antiepileptics, antiglaucoma, antiobesity and antitumour agents. Targeting such enzymes from pathogens may lead to novel anti-infectives. Successful structure-based drug design campaigns allowed the discovery of highly isoform selective CA inhibitors (CAIs), which may lead to a new generation of drugs targeting these widespread enzymes. The use of CAs in CO2 capture processes for mitigating the global temperature rise has also been investigated more recently. PMID:27407171

  13. How many carbonic anhydrase inhibition mechanisms exist?

    Science.gov (United States)

    Supuran, Claudiu T

    2016-01-01

    Six genetic families of the enzyme carbonic anhydrase (CA, EC 4.2.1.1) were described to date. Inhibition of CAs has pharmacologic applications in the field of antiglaucoma, anticonvulsant, anticancer, and anti-infective agents. New classes of CA inhibitors (CAIs) were described in the last decade with enzyme inhibition mechanisms differing considerably from the classical inhibitors of the sulfonamide or anion type. Five different CA inhibition mechanisms are known: (i) the zinc binders coordinate to the catalytically crucial Zn(II) ion from the enzyme active site, with the metal in tetrahedral or trigonal bipyramidal geometries. Sulfonamides and their isosters, most anions, dithiocarbamates and their isosters, carboxylates, and hydroxamates bind in this way; (ii) inhibitors that anchor to the zinc-coordinated water molecule/hydroxide ion (phenols, carboxylates, polyamines, 2-thioxocoumarins, sulfocoumarins); (iii) inhibitors which occlude the entrance to the active site cavity (coumarins and their isosters), this binding site coinciding with that where CA activators bind; (iv) compounds which bind out of the active site cavity (a carboxylic acid derivative was seen to inhibit CA in this manner), and (v) compounds for which the inhibition mechanism is not known, among which the secondary/tertiary sulfonamides as well as imatinib/nilotinib are the most investigated examples. As CAIs are used clinically in many pathologies, with a sulfonamide inhibitor (SLC-0111) in Phase I clinical trials for the management of metastatic solid tumors, this review updates the recent findings in the field which may be useful for a structure-based drug design approach of more selective/potent modulators of the activity of these enzymes. PMID:26619898

  14. Carbonic anhydrase IX in early-stage non-small cell lung cancer.

    NARCIS (Netherlands)

    Kim, S.; Rabbani, Z.N.; Vollmer, R.T.; Schreiber, E.G.; Oosterwijk, E.; Dewhirst, M.W.; Vujaskovic, Z.; Kelley, M.J.

    2004-01-01

    PURPOSE: Tumor hypoxia is associated with poor prognosis and increased tumor aggressiveness. Carbonic anhydrase (CA) IX, an endogenous marker for tumor hypoxia, catalyzes the hydration of carbon dioxide into carbonic acid and contributes to the pH regulation of tumor cells. Therefore, CA IX might al

  15. Hyperkalaemia induced by carbonic anhydrase inhibitor.

    OpenAIRE

    Wakabayashi, Y.

    1991-01-01

    An 81-year-old man developed hyperkalaemic and hyperchloraemic metabolic acidosis following treatment with a carbonic anhydrase inhibitor for his glaucoma. He had mild renal failure and selective aldosterone deficiency was confirmed. In this case the treatment did not lead to hypokalaemia because of the limited potassium secretory capacity in the renal tubules from selective aldosterone deficiency; rather, it may have led to hyperkalaemia because metabolic acidosis induced by the carbonic anh...

  16. Thermostable Carbonic Anhydrases in Biotechnological Applications

    OpenAIRE

    Anna Di Fiore; Vincenzo Alterio; Simona M. Monti; Giuseppina De Simone; Katia D'Ambrosio

    2015-01-01

    Carbonic anhydrases are ubiquitous metallo-enzymes which catalyze the reversible hydration of carbon dioxide in bicarbonate ions and protons. Recent years have seen an increasing interest in the utilization of these enzymes in CO2 capture and storage processes. However, since this use is greatly limited by the harsh conditions required in these processes, the employment of thermostable enzymes, both those isolated by thermophilic organisms and those obtained by protein engineering techniques,...

  17. Future Perspective in Carbonic Anhydrase Inhibitors and its Drugs

    Directory of Open Access Journals (Sweden)

    S.Petchimuthu

    2013-09-01

    Full Text Available Through this review it is contemplated that carbonic anhydrase inhibitors, were a traditional drugs of choice for the treatment of glaucoma with a myriad of side effects and inadequate topical effectiveness, may be formulated into a topically effective agent by utilizing various newer formulation approaches of ocular drug delivery. Even though the carbonic anhydrase inhibitor, acetazolamide (ACZ has a poor solubility and penetration power (BCS Class IV, various studies mentioned in the review indicate that it is possible to successfully formulate topically effective ACZ by using:(i High concentration of the drug, (ii Surfactant gel preparations of ACZ, (iii ACZ loaded into liposomes, (iv Cyclodextrins to increase the solubility and hence bioavailability of ACZ, and Viscolyzers and other polymers either alone or in combination with cyclodextrins. With the advent of newer topical carbonic anhydrase inhibitors (CAIs like dorzolamide and brinzolamide, a localized effect with fewer side effects is expected.But whenever absorbed systemically, a similar range of adverse effects (attributable to sulphonamides may occur upon use. Furthermore, oral ACZ is reported to be more physiologically effective than 2% dorzolamide hydrochloridead ministered topically, even though in isolated tissues dorzolamide appears to be the most active as it shows the lowest IC50 values for CA-II and CA-IV. Hence, there exists considerable scope for the development of more/equally effective and inexpensive topically effective formulations of ACZ. The use of various formulation technologies discussed in this review can provide a fresh impetus to research in this area.

  18. Evolution of carbonic anhydrase in C4 plants.

    Science.gov (United States)

    Ludwig, Martha

    2016-06-01

    During the evolution of C4 photosynthesis, the intracellular location with most carbonic anhydrase (CA) activity has changed. In Flaveria, the loss of the sequence encoding a chloroplast transit peptide from an ancestral C3 CA ortholog confined the C4 isoform to the mesophyll cell cytosol. Recent studies indicate that sequence elements and histone modifications controlling the expression of C4-associated CAs were likely present in the C3 ancestral chromatin, enabling the evolution of the C4 pathway. Almost complete abolishment of maize CA activity yields no obvious phenotype at ambient CO2 levels. This contrasts with results for Flaveria CA mutants, and has opened discussion on the role of CA in the C4 carbon concentrating mechanism.

  19. The effects of some bromophenols on human carbonic anhydrase isoenzymes.

    Science.gov (United States)

    Taslimi, Parham; Gülçin, İlhami; Öztaşkın, Necla; Çetinkaya, Yasin; Göksu, Süleyman; Alwasel, Saleh H; Supuran, Claudiu T

    2016-08-01

    Carbonic anhydrases (CAs, EC 4.2.1.1), which are involved in a variety of physiological and pathological processes, are ubiquitous metalloenzymes mainly catalyzing the reversible hydration of carbon dioxide (CO2) to bicarbonate ([Formula: see text]) and proton (H(+)). In this study, a dozen of bromophenol derivatives (1-12) were evaluated as metalloenzyme CA (EC 4.2.1.1) inhibitors against the human carbonic anhydrase isoenzymes I and II (hCA I and II). Cytosolic hCA I and II isoenzymes were effectively inhibited by bromophenol derivatives (1-12) with Kis in the low nanomolar range of 1.85 ± 0.58 to 5.04 ± 1.46 nM against hCA I and in the range of 2.01 ± 0.52 to 2.94 ± 1.31 nM against hCA II, respectively. PMID:26133541

  20. Legionella pneumophila Carbonic Anhydrases: Underexplored Antibacterial Drug Targets

    OpenAIRE

    Supuran, Claudiu T.

    2016-01-01

    Carbonic anhydrases (CAs, EC 4.2.1.1) are metalloenzymes which catalyze the hydration of carbon dioxide to bicarbonate and protons. Many pathogenic bacteria encode such enzymes belonging to the α-, β-, and/or γ-CA families. In the last decade, enzymes from some of these pathogens, including Legionella pneumophila, have been cloned and characterized in detail. These enzymes were shown to be efficient catalysts for CO2 hydration, with kcat values in the range of (3.4–8.3) × 105 s−1 and kcat/KM ...

  1. Molecular and biochemical characterization of carbonic anhydrases of Paracoccidioides

    Science.gov (United States)

    Tomazett, Mariana Vieira; Zanoelo, Fabiana Fonseca; Bailão, Elisa Flávia Cardoso; Bailão, Alexandre Melo; Borges, Clayton Luiz; Soares, Célia Maria de Almeida

    2016-01-01

    Abstract Carbonic anhydrases (CA) belong to the family of zinc metalloenzymes that catalyze the reversible hydration of carbon dioxide to bicarbonate. In the present work, we characterized the cDNAs of four Paracoccidioides CAs (CA1, CA2, CA3, and CA4). In the presence of CO2, there was not a significant increase in fungal ca1, ca2 and ca4 gene expression. The ca1 transcript was induced during the mycelium-to-yeast transition, while ca2 and ca4 gene expression was much higher in yeast cells, when compared to mycelium and mycelium-to-yeast transition. The ca1 transcript was induced in yeast cells recovered directly from liver and spleen of infected mice, while transcripts for ca2 and ca4 were down-regulated. Recombinant CA1 (rCA1) and CA4 (rCA4), with 33 kDa and 32 kDa respectively, were obtained from bacteria. The enzymes rCA1 (β-class) and rCA4 (α-class) were characterized regarding pH, temperature, ions and amino acids addition influence. Both enzymes were stable at pHs 7.5-8.5 and temperatures of 30-35 °C. The enzymes were dramatically inhibited by Hg+2 and activated by Zn+2, while only rCA4 was stimulated by Fe2+. Among the amino acids tested (all in L configuration), arginine, lysine, tryptophan and histidine enhanced residual activity of rCA1 and rCA4. PMID:27560991

  2. Carbonic anhydrase 5 regulates acid-base homeostasis in zebrafish.

    Directory of Open Access Journals (Sweden)

    Ruben Postel

    Full Text Available The regulation of the acid-base balance in cells is essential for proper cellular homeostasis. Disturbed acid-base balance directly affects cellular physiology, which often results in various pathological conditions. In every living organism, the protein family of carbonic anhydrases regulate a broad variety of homeostatic processes. Here we describe the identification, mapping and cloning of a zebrafish carbonic anhydrase 5 (ca5 mutation, collapse of fins (cof, which causes initially a collapse of the medial fins followed by necrosis and rapid degeneration of the embryo. These phenotypical characteristics can be mimicked in wild-type embryos by acetazolamide treatment, suggesting that CA5 activity in zebrafish is essential for a proper development. In addition we show that CA5 regulates acid-base balance during embryonic development, since lowering the pH can compensate for the loss of CA5 activity. Identification of selective modulators of CA5 activity could have a major impact on the development of new therapeutics involved in the treatment of a variety of disorders.

  3. Electropolymerized carbonic anhydrase immobilization for carbon dioxide capture.

    Science.gov (United States)

    Merle, Geraldine; Fradette, Sylvie; Madore, Eric; Barralet, Jake E

    2014-06-17

    Biomimetic carbonation carried out with carbonic anhydrase (CA) in CO2-absorbing solutions, such as methyldiethanolamine (MDEA), is one approach that has been developed to accelerate the capture of CO2. However, there are several practical issues, such as high cost and limited enzyme stability, that need to be overcome. In this study, the capacity of CA immobilization on a porous solid support was studied to improve the instability in the tertiary amine solvent. We have shown that a 63% porosity macroporous carbon foam support makes separation and reuse facile and allows for an efficient supply and presentation of CO2 to an aqueous solvent and the enzyme catalytic center. These enzymatic supports conserved 40% of their initial activity after 42 days at 70 °C in an amine solvent, whereas the free enzyme shows no activity after 1 h in the same conditions. In this work, we have overcome the technical barrier associated with the recovery of the biocatalyst after operation, and most of all, these electropolymerized enzymatic supports have shown a remarkable increase of thermal stability in an amine-based CO2 sequestration solvent. PMID:24856780

  4. Bortezomib inhibits bacterial and fungal β-carbonic anhydrases.

    Science.gov (United States)

    Supuran, Claudiu T

    2016-09-15

    Inhibition of the β-carbonic anhydrases (CAs, EC 4.2.1.1) from pathogenic fungi (Cryptococcus neoformans, Candida albicans, Candida glabrata, Malassezia globosa) and bacteria (three isoforms from Mycobacterium tuberculosis, Rv3273, Rv1284 and Rv3588), as well from the insect Drosophila melanogaster (DmeCA) and the plant Flaveria bidentis (FbiCA1) with the boronic acid peptidomimetic proteosome inhibitor bortezomib was investigated. Bortezomib was a micromolar inhibitor of all these enzymes, with KIs ranging between 1.12 and 11.30μM. Based on recent crystallographic data it is hypothesized that the B(OH)2 moiety of the inhibitor is directly coordinated to the zinc ion from the enzyme active site. The class of boronic acids, an under-investigated type of CA inhibitors, may lead to the development of anti-infectives with a novel mechanism of action, based on the pathogenic organisms CA inhibition. PMID:27469982

  5. Capsaicin: A Potent Inhibitor of Carbonic Anhydrase Isoenzymes

    Directory of Open Access Journals (Sweden)

    Betul Arabaci

    2014-07-01

    Full Text Available Carbonic anhydrase (CA, EC 4.2.1.1 is a zinc containing metalloenzyme that catalyzes the rapid and reversible conversion of carbon dioxide (CO2 and water (H2O into a proton (H+ and bicarbonate (HCO3– ion. On the other hand, capsaicin is the main component in hot chili peppers and is used extensively used in spices, food additives and drugs; it is responsible for their spicy flavor and pungent taste. There are sixteen known CA isoforms in humans. Human CA isoenzymes I, and II (hCA I and hCA II are ubiquitous cytosolic isoforms. In this study, the inhibition properties of capsaicin against the slow cytosolic isoform hCA I, and the ubiquitous and dominant rapid cytosolic isozymes hCA II were studied. Both CA isozymes were inhibited by capsaicin in the micromolar range. This naturally bioactive compound has a Ki of 696.15 µM against hCA I, and of 208.37 µM against hCA II.

  6. Human carbonic anhydrase II as a host for piano-stool complexes bearing a sulfonamide anchor.

    Science.gov (United States)

    Monnard, Fabien W; Heinisch, Tillmann; Nogueira, Elisa S; Schirmer, Tilman; Ward, Thomas R

    2011-08-01

    d(6)-piano-stool complexes bearing an arylsulfonamide anchor display sub-micromolar affinity towards human Carbonic Anhydrase II (hCA II). The 1.3 Å resolution X-ray crystal structure of [(η(6)-C(6)Me(6))Ru(bispy 3)Cl](+)⊂ hCA II highlights the nature of the host-guest interactions. PMID:21706094

  7. IgM natural autoantibodies against bromelain-treated mouse red blood cells recognise carbonic anhydrase.

    Science.gov (United States)

    Jonusys, A M; Cox, K O; Steele, E J

    1991-01-01

    Carbonic anhydrase (CA) from mouse erythrocyte membranes is recognised as an autoantigen in Western blotting experiments with FUB 1, a murine IgM monoclonal antibody that binds both phosphatidylcholine and bromelain-treated mouse red blood cells (BrMRBC). Serum from mice stimulated with lipopolysaccharide (LPS-serum) also recognises CA. From SDS-PAGE, and blotting experiments with whole mouse erythrocytes, we found two closely spaced glycoprotein bands in the 30 kD region that reacted with both FUB 1 and LPS-serum. One of the molecular weight markers, bovine carbonic anhydrase which is of a molecular weight of about 30 kD, electrophoresed in the same 30 kD region also reacted with these antibodies. Carbonic anhydrases from a range of mammalian species were found to be crossreactive with FUB 1 and LPS-serum by Western blotting, whereas human glycophorin A and human asialoglycophorin were not recognised by the antibodies. FUB 1 specifically recognises both native and denatured bovine carbonic anhydrase in ELISA assays. The serological identity of the determinants of CA and BrMRBC was confirmed by specific absorption of both FUB 1 and LPS-serum with BrMRBC and normal mouse erythrocytes. We propose that a native autoantigenic epitope on erythrocytes may be revealed by the proteolytic action of bromelain and that this determinant is associated, at least in part, with carbonic anhydrase.

  8. N-Nitrosulfonamides: A new chemotype for carbonic anhydrase inhibition.

    Science.gov (United States)

    Nocentini, Alessio; Vullo, Daniela; Bartolucci, Gianluca; Supuran, Claudiu T

    2016-08-15

    A series of N(1)-substituted aromatic sulfonamides was obtained by applying a selective sulfonamide nitration synthetic strategy leading to Ar-SO2NHNO2 derivatives which were investigated as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors. Two human (h) hCA isoforms, the cytosolic hCA II and the transmembrane hCA IX, in addition to the fungal enzyme from Malassezia globosa, MgCA, were included in the study. Most of the new compounds reported selectively inhibited hCA IX over hCA II and at the same time showed effective MgCA inhibitory properties, with KIs ranging between 0.22 and 8.09μM. The N-nitro sulfonamides are a new chemotype with CA inhibitory effects. As hCA IX was recently validated as antitumor/antimetastatic drug target, its selective inhibition could be exploited for interesting biomedical applications. Moreover, due to the effective MgCAs inhibitory properties of the N-nitro sulfonamides, of considerable interest in the cosmetics field as potential anti-dandruff agents, the N-nitro sulfonamides may be considered as interesting leads for the design of more efficient compounds targeting fungal enzymes. PMID:27290692

  9. Discovery of a new family of carbonic anhydrases in the malaria pathogen Plasmodium falciparum--the η-carbonic anhydrases.

    Science.gov (United States)

    Del Prete, Sonia; Vullo, Daniela; Fisher, Gillian M; Andrews, Katherine T; Poulsen, Sally-Ann; Capasso, Clemente; Supuran, Claudiu T

    2014-09-15

    The genome of the protozoan parasite Plasmodium falciparum, the causative agent of the most lethal type of human malaria, contains a single gene annotated as encoding a carbonic anhydrase (CAs, EC 4.2.1.1) thought to belong to the α-class, PfCA. Here we demonstrate the kinetic properties of PfCA for the CO2 hydration reaction, as well as an inhibition study of this enzyme with inorganic and complex anions and other molecules known to interact with zinc proteins, including sulfamide, sulfamic acid, and phenylboronic/arsonic acids, detecting several low micromolar inhibitors. A closer examination of the sequence of this and the CAs from other Plasmodium spp., as well as a phylogenetic analysis, revealed that these protozoa encode for a yet undisclosed, new genetic family of CAs termed the η-CA class. The main features of the η-CAs are described in this report. PMID:25168745

  10. Carbonic Anhydrase and Metalloderivatives: A Bioinorganic Chemistry Study

    Science.gov (United States)

    McQuate, Robert S.

    1977-01-01

    Discusses selected bioinorganic aspects of carbonic anhydrase and describes experiments that will reinforce the students' understanding of the presence and essential role that metal ions have in some biological systems. (SL)

  11. Carbonic anhydrase isozymes Ⅸ and Ⅻ in gastric tumors

    Institute of Scientific and Technical Information of China (English)

    Mari Leppilampi; Juha Saarnio; Tuomo J. Karttunen; Jyrki Kivel(a); Silvia Pastorekov(a); Jaromir Pastorek; Abdul Waheed; William S. Sly; Seppo Parkkila

    2003-01-01

    AIM: To systematically study the expression of carbonic anhydrase (CA) isowmes Ⅸ and Ⅻ in gastric tumors.METHODS: We analyzed a representative series of specimens from non-neoplastic gastric mucosa and from various dysplastic and neoplastic gastric lesions for the expression of CA IX and XII. Immunohistochemical staining was performed using isozyme-specific antibodies and biotinstreptavidin complex method.RESULTS: CA IX was highly expressed in the normal gastric mucosa and remained positive in many gastric tumors. In adenomas, CA IX expression significantly decreased towards the high grade dysplasia. However, the expression resumed back to the normal level in well differentiated adenocarcinomas,while it again declined in carcinomas with less differentiation.In comparison, CA Ⅻ showed no or weak immunoreaction in the normal gastric mucosa and was slightly increased in tumors.CONCLUSION: These results demonstrate that CA Ⅸexpression is sustained in several types of gastric tumors.The variations observed in the CA Ⅸ levels support the concept that gastric adenomas and carcinomas are distinct entities and do not represent progressive steps of a single pathway.

  12. Future Perspective in Carbonic Anhydrase Inhibitors and its Drugs

    OpenAIRE

    S.Petchimuthu; Dr. N. Narayanan

    2013-01-01

    Through this review it is contemplated that carbonic anhydrase inhibitors, were a traditional drugs of choice for the treatment of glaucoma with a myriad of side effects and inadequate topical effectiveness, may be formulated into a topically effective agent by utilizing various newer formulation approaches of ocular drug delivery. Even though the carbonic anhydrase inhibitor, acetazolamide (ACZ) has a poor solubility and penetration power (BCS Class IV), various studies mentioned in the revi...

  13. Carbonic anhydrase activity in the red blood cells of sea level and high altitude natives.

    Science.gov (United States)

    Gamboa, J; Caceda, R; Gamboa, A; Monge-C, C

    2000-01-01

    Red blood cell carbonic anhydrase (CA) activity has not been studied in high altitude natives. Because CA is an intraerythocytic enzyme and high altitude natives are polycythemic, it is important to know if the activity of CA per red cell volume is different from that of their sea level counterparts. Blood was collected from healthy subjects living in Lima (150m) and from twelve subjects from Cerro de Pasco (4330m), and hematocrit and carbonic anhydrase activity were measured. As expected, the high altitude natives had significantly higher hematocrits than the sea level controls (p = 0.0002). No difference in the CA activity per milliliter of red cells was found between the two populations. There was no correlation between the hematocrit and CA activity.

  14. Dithiocarbamates Strongly Inhibit Carbonic Anhydrases and Show Antiglaucoma Action in Vivo

    OpenAIRE

    Carta, Fabrizio; Aggarwal, Mayank; Maresca, Alfonso; Scozzafava, Andrea; McKenna, Robert; Masini, Emanuela; Supuran, Claudiu T.

    2012-01-01

    A series of dithiocarbamates was prepared by reaction of primary/secondary amines with carbon disulfide in the presence of bases. These compounds were tested for the inhibition of 4 human (h) isoforms of the zinc enzyme carbonic anhydrase, CA (EC 4.2.1.1), hCA I, II, IX and XII, involved in pathologies such as glaucoma (CA II and XII) or cancer (CA IX). Several low nanomolar inhibitors targeting these CAs were detected. X-ray crystal structure of hCA II adduct with morpholine dithiocarbamate ...

  15. Carbonic anhydrases in normal gastrointestinal tract and gastrointestinal tumours

    Institute of Scientific and Technical Information of China (English)

    Antti J. Kivel(a); Jyrki Kivel(a); Juha Saarnio; Seppo Parkkila

    2005-01-01

    Carbonic anhydrases (CAs) catalyse the hydration of CO2to bicarbonate at physiological pH. This chemical interconversion is crucial since HCO3- is the substrate for several biosynthetic reactions. This review is focused on the distribution and role of CA isoenzymes in both normal and pathological gastrointestinal (GI) tract tissues. It has been known for many years that CAs are widely present in the GI tract and play important roles in several physiological functions such as production of saliva, gastric acid, bile, and pancreatic juice as well as in absorption of salt and water in intestine. New information suggests that these enzymes participate in several processes that were not envisioned earlier. Especially, the recent reports on plasma membranebound isoenzymes Ⅸ and Ⅻ have raised considerable interest since they were reported to participate in cancer invasion and spread. They are induced by tumour hypoxia and may also play a role in von Hippel-Lindau (VHL)-mediated carcinogenesis.

  16. Carbonic anhydrase mediated carbon dioxide sequestration: promises, challenges and future prospects.

    Science.gov (United States)

    Yadav, Raju R; Krishnamurthi, Kannan; Mudliar, Sandeep N; Devi, S Saravana; Naoghare, Pravin K; Bafana, Amit; Chakrabarti, Tapan

    2014-06-01

    Anthropogenic activities have substantially increased the level of greenhouse gases (GHGs) in the atmosphere and are contributing significantly to the global warming. Carbon dioxide (CO2 ) is one of the major GHGs which plays a key role in the climate change. Various approaches and methodologies are under investigation to address CO2 capture and sequestration worldwide. Carbonic anhydrase (CA) mediated CO2 sequestration is one of the promising options. Therefore, the present review elaborates recent developments in CA, its immobilization and bioreactor methodologies towards CO2 sequestration using the CA enzyme. The promises and challenges associated with the efficient utilization of CA for CO2 sequestration and scale up from flask to lab-scale bioreactor are critically discussed. Finally, the current review also recommends the possible future needs and directions to utilize CA for CO2 sequestration. PMID:24740638

  17. Dithiocarbamates: a new class of carbonic anhydrase inhibitors. Crystallographic and kinetic investigations.

    OpenAIRE

    Carta, Fabrizio; Aggarwal, Mayank; Maresca, Alfonso; Scozzafava, Andrea; McKenna, Robert; Supuran, Claudiu T.

    2012-01-01

    The zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1) is inhibited by several classes of zinc-binders (sulfonamides, sulfamates, and sulfamides) as well as by compounds which do not interact with the metal ion (phenols, polyamines and coumarins). Here we report a new class of potent CA inhibitors which bind the zinc ion: the dithiocarbamates (DTCs). They coordinate to the zinc ion from the enzyme active site in monodentate manner and establish many favorable interactions with amino acid residue...

  18. Carbonic anhydrases are upstream regulators of CO2-controlled stomatal movements in guard cells

    KAUST Repository

    Hu, Honghong

    2009-12-13

    The continuing rise in atmospheric CO2 causes stomatal pores in leaves to close and thus globally affects CO2 influx into plants, water use efficiency and leaf heat stress. However, the CO2-binding proteins that control this response remain unknown. Moreover, which cell type responds to CO2, mesophyll or guard cells, and whether photosynthesis mediates this response are matters of debate. We demonstrate that Arabidopsis thaliana double-mutant plants in the beta-carbonic anhydrases betaCA1 and betaCA4 show impaired CO2-regulation of stomatal movements and increased stomatal density, but retain functional abscisic-acid and blue-light responses. betaCA-mediated CO2-triggered stomatal movements are not, in first-order, linked to whole leaf photosynthesis and can function in guard cells. Furthermore, guard cell betaca-overexpressing plants exhibit instantaneous enhanced water use efficiency. Guard cell expression of mammalian alphaCAII complements the reduced sensitivity of ca1 ca4 plants, showing that carbonic anhydrase-mediated catalysis is an important mechanism for betaCA-mediated CO2-induced stomatal closure and patch clamp analyses indicate that CO2/HCO3- transfers the signal to anion channel regulation. These findings, together with ht1-2 (ref. 9) epistasis analysis demonstrate that carbonic anhydrases function early in the CO2 signalling pathway, which controls gas-exchange between plants and the atmosphere.

  19. Relationship among Photosys- tem Ⅱ carbonic anhydrase, extrinsic polypeptides and manganese cluster

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Effects of Photosystem Ⅱ (PS Ⅱ) extrinsic poly- peptides of oxygen-evolving complex and manganese clusters on PSⅡ carbonic anhydrase (CA) were studied with spinach PSⅡ membranes. The result supported that membrane-bound CA is located in the donor side of PSⅡ. The extrinsic polypeptides played an important role of maintaining CA activity. After removing manganese clusters, oxygen evolution activity was inhibited, but PSⅡ-CA activity was unchanged. It was concluded that CA activity is independent of the presence of manganese clusters, and was not directly correlated with oxygen evolution activity.

  20. Targeting carbonic anhydrase to treat diabetic retinopathy: Emerging evidences and encouraging results

    Energy Technology Data Exchange (ETDEWEB)

    Weiwei, Zhang [Department of Endocrinology and Metabolism, HuaShan Hospital, Institute of Endocrinology and Diabetology, Shanghai Medical College, Fudan University, No. 12 Wulumuqi Road, Shanghai 200040 (China); Hu, Renming, E-mail: taylorzww@gmail.com [Department of Endocrinology and Metabolism, HuaShan Hospital, Institute of Endocrinology and Diabetology, Shanghai Medical College, Fudan University, No. 12 Wulumuqi Road, Shanghai 200040 (China)

    2009-12-18

    Diabetic retinopathy (DR) is the leading cause of vision loss among working-age populations in developed countries. Current treatment options are limited to tight glycemic, blood pressure control and destructive laser surgery. Carbonic anhydrases (CAs) are a group of enzymes involving in the rapid conversion of carbon dioxide to bicarbonate and protons. Emerging evidences reveal CA inhibitors hold the promise for the treatment of DR. This article summarizes encouraging results from clinical and animal studies, and reviews the possible mechanisms.

  1. Targeting carbonic anhydrase to treat diabetic retinopathy: Emerging evidences and encouraging results

    International Nuclear Information System (INIS)

    Diabetic retinopathy (DR) is the leading cause of vision loss among working-age populations in developed countries. Current treatment options are limited to tight glycemic, blood pressure control and destructive laser surgery. Carbonic anhydrases (CAs) are a group of enzymes involving in the rapid conversion of carbon dioxide to bicarbonate and protons. Emerging evidences reveal CA inhibitors hold the promise for the treatment of DR. This article summarizes encouraging results from clinical and animal studies, and reviews the possible mechanisms.

  2. Carbonic Anhydrase: In the Driver's Seat for Bicarbonate Transport

    Directory of Open Access Journals (Sweden)

    Sterling D

    2001-07-01

    Full Text Available Carbonic anhydrases are a widely expressed family of enzymes that catalyze the reversible reaction: CO(2 + H(2O = HCO(3(- + H(+. These enzymes therefore both produce HCO(3(- for transport across membranes and consume HCO(3(- that has been transported across membranes. Thus these enzymes could be expected to have a key role in driving the transport of HCO(3(- across cells and epithelial layers. Plasma membrane anion exchange proteins (AE transport chloride and bicarbonate across most mammalian membranes in a one-for-one exchange reaction and act as a model for our understanding of HCO(3(- transport processes. Recently it was shown that AE1, found in erythrocytes and kidney, binds carbonic anhydrase II (CAII via the cytosolic C-terminal tail of AE1. To examine the physiological consequences of the interaction between CAII and AE1, we characterized Cl(-/HCO(3(- exchange activity in transfected HEK293 cells. Treatment of AE1-transfected cells with acetazolamide, a CAII inhibitor, almost fully inhibited anion exchange activity, indicating that endogenous CAII activity is essential for transport. Further experiments to examine the role of the AE1/CAII interaction will include measurements of the transport activity of AE1 following mutation of the CAII binding site. In a second approach a functionally inactive CA mutant, V143Y, will be co-expressed with AE1 in HEK293 cells. Since over expression of V143Y CAII would displace endogenous wild-type CAII from AE1, a loss of transport activity would be observed if binding to the AE1 C-terminus is required for transport.

  3. A magnificent enzyme superfamily: carbonic anhydrases, their purification and characterization.

    Science.gov (United States)

    Ozensoy Guler, Ozen; Capasso, Clemente; Supuran, Claudiu T

    2016-10-01

    In this paper, we reviewed the purification and characterization methods of the α-carbonic anhydrase (CA, EC 4.2.1.1) class. Six genetic families (α-, β-, γ-, δ-, ζ- and η-CAs) all know to date, all encoding such enzymes in organisms widely distributed over the phylogenetic tree. Starting from the manuscripts published in the 1930s on the isolation and purification of α-CAs from blood and other tissues, and ending with the recent discovery of the last genetic family in protozoa, the η-CAs, considered for long time an α-CA, we present historically the numerous and different procedures which were employed for obtaining these catalysts in pure form. α-CAs possess important application in medicine (as many human α-CA isoforms are drug targets) as well as biotechnological processes, in which the enzymes are ultimately used for CO2 capture in order to mitigate the global warming effects due to greenhouse gases. Recently, it was discovered an involvement of CAs in cancerogenesis as well as infection caused by pathogenic agents such as bacteria, fungi and protozoa. Inhibition studies of CAs identified in the genome of the aforementioned organisms might lead to the discovery of innovative drugs with a novel mechanism of action. PMID:26118417

  4. Glaucoma and the applications of carbonic anhydrase inhibitors.

    Science.gov (United States)

    Scozzafava, Andrea; Supuran, Claudiu T

    2014-01-01

    Inhibition of carbonic anhydrase (CA, EC 4.2.1.1) has pharmacologic applications in the treatment of glaucoma, a disease affecting a large number of people and characterized by an elevated intraocular pressure (IOP). At least three isoforms, CA II, IV and XII are targeted by the sulfonamide inhibitors, some of which are clinically used drugs. Acetazolamide, methazolamide and dichlorophenamide are first generation CA inhibitors (CAIs) still used as systemic drugs for the management of this disease. Dorzolamide and brinzolamide represent the second generation inhibitors, being used topically, as eye drops, with less side effects compared to the first generation drugs. Third generation inhibitors have been developed by using the tail approach, but they did not reach the clinics yet. The most promising such derivatives are the sulfonamides incorporating either tails with nitric oxide releasing moieties or hybrid drugs possessing prostaglandin (PG) F agonist moieties in their molecules. Recently, the dithiocarbamates have also been described as CAIs possessing IOP lowering effects in animal models of glaucoma. CAIs are used alone or in combination with other drugs such as adrenergic agonist/antagonists, or PG analogs, being an important component of the antiglaucoma drugs armamentarium. PMID:24146387

  5. New natural product carbonic anhydrase inhibitors incorporating phenol moieties.

    Science.gov (United States)

    Karioti, Anastasia; Ceruso, Mariangela; Carta, Fabrizio; Bilia, Anna-Rita; Supuran, Claudiu T

    2015-11-15

    Carbonic anhydrases (CAs, EC 4.2.1.1) catalyze the fundamental reaction of CO2 hydration in all living organisms, being actively involved in the regulation of a plethora of patho/physiological conditions. They represent a typical example of enzyme convergent evolution, as six genetically unrelated families of such enzymes were described so far. The need to find selective CA inhibitors (CAIs) triggered the investigation of natural product libraries, which proved to be a valid source of agents with such an activity, as demonstrated for the phenols, polyamines and coumarins. Herein we report an in vitro inhibition study of human (h) CA isoforms hCAs I, II, IV, VII and XII with a panel of natural polyphenols including flavones, flavonols, flavanones, flavanols, isoflavones and depsides, some of which extracted from Quercus ilex and Salvia miltiorrhiza. Several of the investigated derivatives showed interesting inhibition activity and selectivities for inhibiting some important isoforms over the off-target ones hCA I and II.

  6. Legionella pneumophila Carbonic Anhydrases: Underexplored Antibacterial Drug Targets.

    Science.gov (United States)

    Supuran, Claudiu T

    2016-01-01

    Carbonic anhydrases (CAs, EC 4.2.1.1) are metalloenzymes which catalyze the hydration of carbon dioxide to bicarbonate and protons. Many pathogenic bacteria encode such enzymes belonging to the α-, β-, and/or γ-CA families. In the last decade, enzymes from some of these pathogens, including Legionella pneumophila, have been cloned and characterized in detail. These enzymes were shown to be efficient catalysts for CO₂ hydration, with kcat values in the range of (3.4-8.3) × 10⁵ s(-1) and kcat/KM values of (4.7-8.5) × 10⁷ M(-1)·s(-1). In vitro inhibition studies with various classes of inhibitors, such as anions, sulfonamides and sulfamates, were also reported for the two β-CAs from this pathogen, LpCA1 and LpCA2. Inorganic anions were millimolar inhibitors, whereas diethyldithiocarbamate, sulfamate, sulfamide, phenylboronic acid, and phenylarsonic acid were micromolar ones. The best LpCA1 inhibitors were aminobenzolamide and structurally similar sulfonylated aromatic sulfonamides, as well as acetazolamide and ethoxzolamide (KIs in the range of 40.3-90.5 nM). The best LpCA2 inhibitors belonged to the same class of sulfonylated sulfonamides, together with acetazolamide, methazolamide, and dichlorophenamide (KIs in the range of 25.2-88.5 nM). Considering such preliminary results, the two bacterial CAs from this pathogen represent promising yet underexplored targets for obtaining antibacterials devoid of the resistance problems common to most of the clinically used antibiotics, but further studies are needed to validate them in vivo as drug targets. PMID:27322334

  7. Legionella pneumophila Carbonic Anhydrases: Underexplored Antibacterial Drug Targets

    Directory of Open Access Journals (Sweden)

    Claudiu T. Supuran

    2016-06-01

    Full Text Available Carbonic anhydrases (CAs, EC 4.2.1.1 are metalloenzymes which catalyze the hydration of carbon dioxide to bicarbonate and protons. Many pathogenic bacteria encode such enzymes belonging to the α-, β-, and/or γ-CA families. In the last decade, enzymes from some of these pathogens, including Legionella pneumophila, have been cloned and characterized in detail. These enzymes were shown to be efficient catalysts for CO2 hydration, with kcat values in the range of (3.4–8.3 × 105 s−1 and kcat/KM values of (4.7–8.5 × 107 M−1·s−1. In vitro inhibition studies with various classes of inhibitors, such as anions, sulfonamides and sulfamates, were also reported for the two β-CAs from this pathogen, LpCA1 and LpCA2. Inorganic anions were millimolar inhibitors, whereas diethyldithiocarbamate, sulfamate, sulfamide, phenylboronic acid, and phenylarsonic acid were micromolar ones. The best LpCA1 inhibitors were aminobenzolamide and structurally similar sulfonylated aromatic sulfonamides, as well as acetazolamide and ethoxzolamide (KIs in the range of 40.3–90.5 nM. The best LpCA2 inhibitors belonged to the same class of sulfonylated sulfonamides, together with acetazolamide, methazolamide, and dichlorophenamide (KIs in the range of 25.2–88.5 nM. Considering such preliminary results, the two bacterial CAs from this pathogen represent promising yet underexplored targets for obtaining antibacterials devoid of the resistance problems common to most of the clinically used antibiotics, but further studies are needed to validate them in vivo as drug targets.

  8. Carbonic Anhydrase II Deficiency in a Saudi Woman

    Science.gov (United States)

    Alhuzaim, Omar N; Almohareb, Ohoud M; Sherbeeni, Safiya M

    2015-01-01

    OBJECTIVE Carbonic anhydrase (CA) II deficiency is a rare autosomal recessive disorder caused by mutation in the CA II gene that leads to osteopetrosis, renal tubular acidosis (RTA), and cerebral calcification. Our aim is to present a patient with the classic triad of CA II deficiency syndrome to enhance the awareness about this rare syndrome. METHODS We describe the clinical and radiological findings of a Saudi woman patient with CA II deficiency syndrome. RESULTS A Saudi woman in her 20s presented to our hospital for evaluation of increased bone density. She was known to have delayed developmental milestone with growth retardation and poor scholastic performance. She had multiple fragile fractures started at the age of 15 involving the lower extremities. A physical examination revealed dysmorphic features and intellectual disability with intelligence quotient (IQ) of 36. The initial blood workup showed a picture of distal RTA with hypokalemia, and the radiological imaging confirmed the presence of osteopetrosis and multiple kidney stones. The combination of osteopetrosis with RTA raised the possibility of CA II deficiency. Therefore, computed tomography (CT) of the brain was done and showed intracranial calcification involving the basal ganglia. She was started on potassium chloride and sodium bicarbonate. In addition, she underwent right-sided percutaneous nephrolithotripsy. Her DNA analysis came to show a sequence variant c.232+1G>A, which was detected in both of the CA II genes (homozygous). CONCLUSION Early recognition of the disease is a key, as an early appropriate treatment institution is essential in order to prevent further complications. PMID:25674028

  9. Ethylene bis-imidazoles are highly potent and selective activators for isozymes VA and VII of carbonic anhydrase, with a potential nootropic effect

    OpenAIRE

    Draghici, Bogdan; Vullo, Daniela; Akocak, Suleyman; Walker, Ellen A; Supuran, Claudiu T.; Ilies, Marc A.

    2014-01-01

    A series of ethylene bis-imidazoles was synthesized via a novel microwave-mediated synthesis. Biological testing on eight isozymes of carbonic anhydrase (CA) present in the human brain revealed compounds with nanomolar potency against CA VA and CA VII, also displaying excellent selectivity against other CA isozymes present in this organ.

  10. Structural Basis for the Inhibition of Helicobacter pylori α-Carbonic Anhydrase by Sulfonamides.

    Directory of Open Access Journals (Sweden)

    Joyanta K Modak

    Full Text Available Periplasmic α-carbonic anhydrase of Helicobacter pylori (HpαCA, an oncogenic bacterium in the human stomach, is essential for its acclimation to low pH. It catalyses the conversion of carbon dioxide to bicarbonate using Zn(II as the cofactor. In H. pylori, Neisseria spp., Brucella suis and Streptococcus pneumoniae this enzyme is the target for sulfonamide antibacterial agents. We present structural analysis correlated with inhibition data, on the complexes of HpαCA with two pharmacological inhibitors of human carbonic anhydrases, acetazolamide and methazolamide. This analysis reveals that two sulfonamide oxygen atoms of the inhibitors are positioned proximal to the putative location of the oxygens of the CO2 substrate in the Michaelis complex, whilst the zinc-coordinating sulfonamide nitrogen occupies the position of the catalytic water molecule. The structures are consistent with acetazolamide acting as site-directed, nanomolar inhibitors of the enzyme by mimicking its reaction transition state. Additionally, inhibitor binding provides insights into the channel for substrate entry and product exit. This analysis has implications for the structure-based design of inhibitors of bacterial carbonic anhydrases.

  11. New selective carbonic anhydrase IX inhibitors: synthesis and pharmacological evaluation of diarylpyrazole-benzenesulfonamides.

    Science.gov (United States)

    Rogez-Florent, Tiphaine; Meignan, Samuel; Foulon, Catherine; Six, Perrine; Gros, Abigaëlle; Bal-Mahieu, Christine; Supuran, Claudiu T; Scozzafava, Andrea; Frédérick, Raphaël; Masereel, Bernard; Depreux, Patrick; Lansiaux, Amélie; Goossens, Jean-François; Gluszok, Sébastien; Goossens, Laurence

    2013-03-15

    Carbonic anhydrase (CA) IX expression is increased upon hypoxia and has been proposed as a therapeutic target since it has been associated with poor prognosis, tumor progression and pH regulation. We report the synthesis and the pharmacological evaluation of a new class of human carbonic anhydrase (hCA) inhibitors, 4-(5-aryl-2-hydroxymethyl-pyrazol-1-yl)-benzenesulfonamides. A molecular modeling study was conducted in order to simulate the binding mode of this new family of enzyme inhibitors within the active site of hCA IX. Pharmacological studies revealed high hCA IX inhibitory potency in the parameters nanomolar range. This study showed that the position of sulfonamide group in meta of the 1-phenylpyrazole increase a selectivity hCA IX versus hCA II of our compounds. An in vitro antiproliferative screening has been performed on the breast cancer MDA-MB-231 cell using doxorubicin as cytotoxic agent and in presence of selected CA IX inhibitor. The results shown that the cytotoxic efficiency of doxorubicin in an hypoxic environment, expressed in IC50 value, is restored at 20% level with 1μM CA IX inhibitor. PMID:23168081

  12. Xanthates and trithiocarbonates strongly inhibit carbonic anhydrases and show antiglaucoma effects in vivo.

    Science.gov (United States)

    Carta, Fabrizio; Akdemir, Atilla; Scozzafava, Andrea; Masini, Emanuela; Supuran, Claudiu T

    2013-06-13

    Dithiocarbamates (DTCs) were recently discovered as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors. A series of xanthates and a trithiocarbonate, structurally related to the DTCs, were prepared by reaction of alcohols/thiols with carbon disulfide in the presence of bases. These compounds were tested for the inhibition of four human (h) isoforms, hCA I, II, IX, and XII, involved in pathologies such as glaucoma (CA II and XII) or cancer (CA IX). Several low nanomolar xanthate/trithiocarbonate inhibitors targeting these CAs were detected. A docking study of some xanthates within the CA II active site showed that these compounds bind in a similar manner with the dithiocarbamates, coordinating monodentately to the Zn(II) ion from the enzyme active site. Several xanthates showed potent intraocular pressure lowering activity in two animal models of glaucoma via the topical administration. Xanthates and thioxanthates represent two novel, promising classes of CA inhibitors. PMID:23647428

  13. Carnosine inhibits carbonic anhydrase IX-mediated extracellular acidosis and suppresses growth of HeLa tumor xenografts

    OpenAIRE

    Ditte, Zuzana; Ditte, Peter; Labudova, Martina; Simko, Veronika; Iuliano, Filippo; Zatovicova, Miriam; Csaderova, Lucia; Pastorekova, Silvia; Pastorek, Jaromir

    2014-01-01

    Background Carbonic anhydrase IX (CA IX) is a transmembrane enzyme that is present in many types of solid tumors. Expression of CA IX is driven predominantly by the hypoxia-inducible factor (HIF) pathway and helps to maintain intracellular pH homeostasis under hypoxic conditions, resulting in acidification of the tumor microenvironment. Carnosine (β-alanyl-L-histidine) is an anti-tumorigenic agent that inhibits the proliferation of cancer cells. In this study, we investigated the role of CA I...

  14. Evolution of the mammary capillary network and carbonic anhydrase activity throughout lactation and during somatotropin treatment in goats

    DEFF Research Database (Denmark)

    Nielsen, Mette Benedicte Olaf; Cvek, Katarina; Dahlborn, Kristina

    2010-01-01

    During the normal course of lactation, mammary metabolic activity and blood flow are closely correlated. Six lactating goats were used in this experiment to test the hypothesis that the capillary network and the capillary enzyme, carbonic anhydrase (CA; EC 4.2.1.1) are important regulatory factors...

  15. Modulation of the initial mineralization process of SaOS-2 cells by carbonic anhydrase activators and polyphosphate.

    Science.gov (United States)

    Wang, Xiaohong; Schröder, Heinz C; Schlossmacher, Ute; Neufurth, Meik; Feng, Qingling; Diehl-Seifert, Bärbel; Müller, Werner E G

    2014-05-01

    Ca-phosphate/hydroxyapatite (HA) crystals constitute the mineral matrix of vertebrate bones, while Ca-carbonate is the predominant mineral of many invertebrates, like mollusks. Recent results suggest that CaCO₃ is also synthesized during early bone formation. We demonstrate that carbonic anhydrase-driven CaCO₃ formation in vitro is activated by organic extracts from the demosponge Suberites domuncula as well as by quinolinic acid, one component isolated from these extracts. Further results revealed that the stimulatory effect of bicarbonate (HCO₃ (-)) ions on mineralization of osteoblast-like SaOS-2 cells is strongly enhanced if the cells are exposed to inorganic polyphosphate (polyP), a linear polymer of phosphate linked by energy-rich phosphodiester bonds. The effect of polyP, administered as polyP (Ca²⁺ salt), on HA formation was found to be amplified by addition of the carbonic anhydrase-activating sponge extract or quinolinic acid. Our results support the assumption that CaCO₃ deposits, acting as bio-seeds for Ca-carbonated phosphate formation, are formed as an intermediate during HA mineralization and that the carbonic anhydrase-mediated formation of those deposits is under a positive-negative feedback control by bone alkaline phosphatase-dependent polyP metabolism, offering new targets for therapy of bone diseases/defects. PMID:24374859

  16. A new peptide ligand for targeting human carbonic anhydrase IX, identified through the phage display technology.

    Directory of Open Access Journals (Sweden)

    Vasileios Askoxylakis

    Full Text Available UNLABELLED: Carbonic anhydrase IX (CAIX is a transmembrane enzyme found to be overexpressed in various tumors and associated with tumor hypoxia. Ligands binding this target may be used to visualize hypoxia, tumor manifestation or treat tumors by endoradiotherapy. METHODS: Phage display was performed with a 12 amino acid phage display library by panning against a recombinant extracellular domain of human carbonic anhydrase IX. The identified peptide CaIX-P1 was chemically synthesized and tested in vitro on various cell lines and in vivo in Balb/c nu/nu mice carrying subcutaneously transplanted tumors. Binding, kinetic and competition studies were performed on the CAIX positive human renal cell carcinoma cell line SKRC 52, the CAIX negative human renal cell carcinoma cell line CaKi 2, the human colorectal carcinoma cell line HCT 116 and on human umbilical vein endothelial cells (HUVEC. Organ distribution studies were carried out in mice, carrying SKRC 52 tumors. RNA expression of CAIX in HCT 116 and HUVEC cells was investigated by quantitative real time PCR. RESULTS: In vitro binding experiments of (125I-labeled-CaIX-P1 revealed an increased uptake of the radioligand in the CAIX positive renal cell carcinoma cell line SKRC 52. Binding of the radioligand in the colorectal carcinoma cell line HCT 116 increased with increasing cell density and correlated with the mRNA expression of CAIX. Radioligand uptake was inhibited up to 90% by the unlabeled CaIX-P1 peptide, but not by the negative control peptide octreotide at the same concentration. No binding was demonstrated in CAIX negative CaKi 2 and HUVEC cells. Organ distribution studies revealed a higher accumulation in SKRC 52 tumors than in heart, spleen, liver, muscle, intestinum and brain, but a lower uptake compared to blood and kidney. CONCLUSIONS: These data indicate that CaIX-P1 is a promising candidate for the development of new ligands targeting human carbonic anhydrase IX.

  17. Effects of carbonic anhydrase inhibition on ventilation-perfusion matching in the dog lung.

    OpenAIRE

    Swenson, E.R.; Robertson, H T; Hlastala, M P

    1993-01-01

    Lung carbonic anhydrase (CA) permits rapid pH responses when changes in regional ventilation or perfusion alter airway and alveolar PCO2. These pH changes affect airway and vascular resistances and lung compliance to optimize the balance of regional ventilation (VA) and perfusion (Q) in the lung. To test the hypothesis that these or other CA-dependent mechanisms contribute to VA/Q matching, we administered acetazolamide (25 mg/kg intravenously) to six anesthetized and paralyzed dogs and measu...

  18. Design, synthesis, and evaluation of NO-donor containing carbonic anhydrase inhibitors to lower intraocular pressure.

    Science.gov (United States)

    Huang, Qinhua; Rui, Eugene Y; Cobbs, Morena; Dinh, Dac M; Gukasyan, Hovhannes J; Lafontaine, Jennifer A; Mehta, Saurabh; Patterson, Brian D; Rewolinski, David A; Richardson, Paul F; Edwards, Martin P

    2015-03-26

    The antiglaucoma drugs dorzolamide (1) and brinzolamide (2) lower intraocular pressure (IOP) by inhibiting the carbonic anhydrase (CA) enzyme to reduce aqueous humor production. The introduction of a nitric oxide (NO) donor into the alkyl side chain of dorzolamide (1) and brinzolamide (2) has led to the discovery of NO-dorzolamide 3a and NO-brinzolamide 4a, which could lower IOP through two mechanisms: CA inhibition to decrease aqueous humor secretion (reduce inflow) and NO release to increase aqueous humor drainage (increase outflow). Compounds 3a and 4a have shown improved efficacy of lowering IOP in both rabbits and monkeys compared to brinzolamide (2). PMID:25728019

  19. Structural analysis of inhibitor binding to human carbonic anhydrase II.

    OpenAIRE

    Boriack-Sjodin, P. A.; Zeitlin, S; Chen, H H; Crenshaw, L.; Gross, S.; Dantanarayana, A.; P. Delgado; May, J. A.; Dean, T.; Christianson, D. W.

    1998-01-01

    X-ray crystal structures of carbonic anhydrase II (CAII) complexed with sulfonamide inhibitors illuminate the structural determinants of high affinity binding in the nanomolar regime. The primary binding interaction is the coordination of a primary sulfonamide group to the active site zinc ion. Secondary interactions fine-tune tight binding in regions of the active site cavity >5 A away from zinc, and this work highlights three such features: (1) advantageous conformational restraints of a bi...

  20. Strong topical steroid, NSAID, and carbonic anhydrase inhibitor cocktail for treatment of cystoid macular edema

    Directory of Open Access Journals (Sweden)

    Asahi MG

    2015-12-01

    Full Text Available Masumi G Asahi, Gabriela L Bobarnac Dogaru, Spencer M Onishi, Ron P GallemoreRetina Macula Institute, Torrance, CA, USA Purpose: To report the combination cocktail of strong steroid, non-steroidal anti-inflammatory drug (NSAID, and carbonic anhydrase inhibitor drops for treatment of cystoid macular edema. Methods: This is a retrospective case series of patients with cystoid macular edema managed with a topical combination of strong steroid (difluprednate, NSAID, and carbonic anhydrase inhibitor drops. The patients were followed with optical coherence tomography and fluorescein angiography. Results: In our six cases, resolution of the cystic edema with improvement in visual acuity was achieved with the use of a combination cocktail of drops. Leakage on fluorescein angiography and cystic edema on optical coherence tomography both responded to treatment with the topical cocktail of drops. Conclusion: A topical cocktail of strong steroid, NSAID, and carbonic anhydrase inhibitor drops are effective for managing cystoid macular edema. Further studies comparing this combination with more invasive treatments should be undertaken to determine the efficacy of this cocktail over other treatment options. Keywords: birdshot chorioretinopathy, diabetic macular edema, retinal vein occlusion

  1. Screening and docking studies of natural phenolic inhibitors of carbonic anhydrase

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Carbonic anhydrase Ⅱ (CAⅡ) is an important enzyme complex with Zn2+,which is involved in many physiological and pathological processes, such as calcification, glaucoma and tumorigenicity. In order to search for novel inhibitors of CAⅡ, inhibition assay of carbonic anhydrase Ⅱ was performed, by which seven natural phenolic compounds, including four phenolics (grifolin, 4-O-methyl-grifolic acid, grifolic acid, and isovanillic acid) and three flavones (eriodictyol, quercetin and puerin A), showed in-hibitory activities against CAⅡ with IC50s in the range of 6.37-71.73 μmol/L. Grifolic acid is the most active one with IC50 of 6.37 μmol/L. These seven phenolic compounds were proved to be novel natural carbonic anhydrase Ⅱ inhibitors, which were obtained in flexible docking study with GOLD 3.0 soft-ware. Results indicated that the aliphatic chain and polar groups of hydroxyl and carboxyl are impor-tant to their inhibitory activities, providing a new insight into study on CA Ⅱ potent inhibitors.

  2. Cadmium-Containing Carbonic Anhydrase CDCA1 in Marine Diatom Thalassiosira weissflogii

    Directory of Open Access Journals (Sweden)

    Vincenzo Alterio

    2015-03-01

    Full Text Available The Carbon Concentration Mechanism (CCM allows phytoplakton species to accumulate the dissolved inorganic carbon (DIC necessary for an efficient photosynthesis even under carbon dioxide limitation. In this mechanism of primary importance for diatoms, a key role is played by carbonic anhydrase (CA enzymes which catalyze the reversible hydration of CO2, thus taking part in the acquisition of inorganic carbon for photosynthesis. A novel CA, named CDCA1, has been recently discovered in the marine diatom Thalassiosira weissflogii. CDCA1 is a cambialistic enzyme since it naturally uses Cd2+ as catalytic metal ion, but if necessary can spontaneously exchange Cd2+ to Zn2+. Here, the biochemical and structural features of CDCA1 enzyme will be presented together with its putative biotechnological applications for the detection of metal ions in seawaters.

  3. Catalase, carbonic anhydrase and xanthine oxidase activities in patients with mycosis fungoides.

    Science.gov (United States)

    Cengiz, Fatma Pelin; Beyaztas, Serap; Gokce, Basak; Arslan, Oktay; Guler, Ozen Ozensoy

    2015-04-01

    Mycosis fungoides (MF) is the most common form of cutaneous T-cell lymphoma. In several studies the relationship between catalase (CAT), human cytosolic carbonic anhydrases (CA; hCA-I and hCA-II) and xanthine oxidase (XO) enzyme activities have been investigated in various types of cancers but carbonic anhydrase, catalase and xanthine oxidase activities in patients with MF have not been previously reported. Therefore, in this preliminary study we aim to investigate CAT, CA and XO activities in patients with MF. This study enrolled 32 patients with MF and 26 healthy controls. According to the results, CA and CAT activities were significantly lower in patients with mycosis fungoides than controls (p < 0.001) (p < 0.001). There was no significant difference in XO activity between patient and control group (p = 0.601). Within these findings, we believe these enzyme activity levels might be a potentially important finding as an additional diagnostic biochemical tool for MF.

  4. Engineering de novo disulfide bond in bacterial α-type carbonic anhydrase for thermostable carbon sequestration

    Science.gov (United States)

    Jo, Byung Hoon; Park, Tae Yoon; Park, Hyun June; Yeon, Young Joo; Yoo, Young Je; Cha, Hyung Joon

    2016-01-01

    Exploiting carbonic anhydrase (CA), an enzyme that rapidly catalyzes carbon dioxide hydration, is an attractive biomimetic route for carbon sequestration due to its environmental compatibility and potential economic viability. However, the industrial applications of CA are strongly hampered by the unstable nature of enzymes. In this work, we introduced in silico designed, de novo disulfide bond in a bacterial α-type CA to enhance thermostability. Three variants were selected and expressed in Escherichia coli with an additional disulfide bridge. One of the variants showed great enhancement in terms of both kinetic and thermodynamic stabilities. This improvement could be attributed to the loss of conformational entropy of the unfolded state, showing increased rigidity. The variant showed an upward-shifted optimal temperature and appeared to be thermoactivated, which compensated for the lowered activity at 25 °C. Collectively, the variant constructed by the rapid and effective de novo disulfide engineering can be used as an efficient biocatalyst for carbon sequestration under high temperature conditions. PMID:27385052

  5. Engineering de novo disulfide bond in bacterial α-type carbonic anhydrase for thermostable carbon sequestration

    Science.gov (United States)

    Jo, Byung Hoon; Park, Tae Yoon; Park, Hyun June; Yeon, Young Joo; Yoo, Young Je; Cha, Hyung Joon

    2016-07-01

    Exploiting carbonic anhydrase (CA), an enzyme that rapidly catalyzes carbon dioxide hydration, is an attractive biomimetic route for carbon sequestration due to its environmental compatibility and potential economic viability. However, the industrial applications of CA are strongly hampered by the unstable nature of enzymes. In this work, we introduced in silico designed, de novo disulfide bond in a bacterial α-type CA to enhance thermostability. Three variants were selected and expressed in Escherichia coli with an additional disulfide bridge. One of the variants showed great enhancement in terms of both kinetic and thermodynamic stabilities. This improvement could be attributed to the loss of conformational entropy of the unfolded state, showing increased rigidity. The variant showed an upward-shifted optimal temperature and appeared to be thermoactivated, which compensated for the lowered activity at 25 °C. Collectively, the variant constructed by the rapid and effective de novo disulfide engineering can be used as an efficient biocatalyst for carbon sequestration under high temperature conditions.

  6. Structural study of interaction between brinzolamide and dorzolamide inhibition of human carbonic anhydrases.

    Science.gov (United States)

    Pinard, Melissa A; Boone, Christopher D; Rife, Brittany D; Supuran, Claudiu T; McKenna, Robert

    2013-11-15

    Carbonic anhydrases (CAs, EC 4.2.1.1) are metalloenzymes that catalyze the reversible hydration of carbon dioxide and bicarbonate. Their pivotal role in metabolism, ubiquitous nature, and multiple isoforms (CA I-XIV) has made CAs an attractive drug target in clinical applications. The usefulness of CA inhibitors (CAIs) in the treatment of glaucoma and epilepsy are well documented. In addition several isoforms of CAs (namely, CA IX) also serve as biological markers for certain tumors, and therefore they have the potential for useful applications in the treatment of cancer. This is a structural study on the binding interactions of the widely used CA inhibitory drugs brinzolamide (marketed as Azopt®) and dorzolamide (marketed as Trusopt®) with CA II and a CA IX-mimic, which was created via site-directed mutagenesis of CA II cDNA such that the active site resembles that of CA IX. Also the inhibition of CA II and CA IX and molecular docking reveal brinzolamide to be a more potent inhibitor among the other catalytically active CA isoforms compared to dorzolamide. The structures show that the tail end of the sulfonamide inhibitor is critical in forming stabilizing interactions that influence tight binding; therefore, for future drug design it is the tail moiety that will ultimately determine isoform specificity. PMID:24090602

  7. Increased levels of carbonic anhydrase II in the developing Down syndrome brain.

    Science.gov (United States)

    Palminiello, Sonia; Kida, Elizabeth; Kaur, Kulbir; Walus, Marius; Wisniewski, Krystyna E; Wierzba-Bobrowicz, Teresa; Rabe, Ausma; Albertini, Giorgio; Golabek, Adam A

    2008-01-23

    By using a proteomic approach, we found increased levels of carbonic anhydrase II (CA II) in the brain of Ts65Dn mice, a mouse model for Down syndrome (DS). Further immunoblot analyses showed that the levels of CA II are increased not only in the brain of adult Ts65Dn mice but also in the brain of infants and young children with DS. Cellular localization of the enzyme in human brain, predominantly in the oligodendroglia and primitive vessels in fetal brain and in the oligodendroglia and some GABAergic neurons postnatally, was similar in DS subjects and controls. Given the role of CA II in regulation of electrolyte and water balance and pH homeostasis, up-regulation of CA II may reflect a compensatory mechanism mobilized in response to structural/functional abnormalities in the developing DS brain. However, this up-regulation may also have an unfavorable effect by increasing susceptibility to seizures of children with DS.

  8. Heavy metal ion inhibition studies of human, sheep and fish α-carbonic anhydrases.

    Science.gov (United States)

    Demirdağ, Ramazan; Yerlikaya, Emrah; Şentürk, Murat; Küfrevioğlu, Ö İrfan; Supuran, Claudiu T

    2013-04-01

    Carbonic anhydrases (CAs, EC 4.2.1.1) were purified from sheep kidney (sCA IV), from the liver of the teleost fish Dicentrarchus labrax (dCA) and from human erythrocytes (hCA I and hCA II). The purification procedure consisted of a single step affinity chromatography on Sepharose 4B-tyrosine-sulfanilamide. The kinetic parameters of these enzymes were determined for their esterase activity with 4-nitrophenyl acetate as substrate. The following metal ions, Pb(2+), Co(2+), Hg(2+), Cd(2+), Zn(2+), Se(2+), Cu(2+), Al(3+) and Mn(3+) showed inhibitory effects on these enzymes. The tested metal ions inhibited these CAs competitively in the low milimolar/submillimolar range. The susceptibility to various cations inhibitors differs significantly between these vertebrate α-CAs and is probably due to their binding to His64 or the histidine cluster. PMID:22145795

  9. Density functional theory study of proton transfer in carbonic anhydrase

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lidong; XIE Daiqian

    2005-01-01

    Proton transfer in carbonic anhydrase II has been studied at the B3LYP/6-31G(D) level. The active site model consists of the zinc ion, four histidine residues, two threonine residues, and three water molecules. Our calculations showed that the proton of the zinc-bound water molecule could be transferred to the nearest water molecule and an intermediate containing H3O+ is then formed. The intermediate is only 1.3 kJ·mol-1 above the reactant complex, whereas the barrier height for the proton transfer is about 8.1 kJ·mol-1.

  10. Sarcoidosis patient: an unexpected reaction to carbonic anhydrase enzyme inhibitor

    OpenAIRE

    Khedr, Yahya A H; Khedr, Abdulla H

    2013-01-01

    Ocular diseases are very common in many of the systemic diseases such as sarcoidosis, and may sometimes be the presenting symptom of the disease. In this case report, we present an unusual reaction of the sarcoid granuloma to carbonic anhydrase enzyme inhibitors (CAIs), which was encountered in a patient with ocular sarcoidosis. This observation was taken after a 2-week interval between a CT scan orbits and an MRI orbits which showed a decrease in size from 4×3×4 cm to 2.5×2.5×2 cm, respectiv...

  11. Human secreted carbonic anhydrase: cDNA cloning, nucleotide sequence, and hybridization histochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Aldred, P.; Fu, Ping; Barrett, G.; Penschow, J.D.; Wright, R.D.; Coghlan, J.P.; Fernley, R.T. (The Howard Florey Institute of Experimental Physiology and Medicine, Parkville, Victoria (Australia))

    1991-01-01

    Complementary DNA clones coding for the human secreted carbonic anhydrase isozyme (CAVI) have been isolated and their nucleotide sequences determined. These clones identify a 1.45-kb mRNA that is present in high levels in parotid submandibular salivary glands but absent in other tissues such as the sublingual gland, kidney, liver, and prostate gland. Hybridization histochemistry of human salivary glands shows mRNA for CA VI located in the acinar cells of these glands. The cDNA clones encode a protein of 308 amino acids that includes a 17 amino acid leader sequence typical of secreted proteins. The mature protein has 291 amino acids compared to 259 or 260 for the cytoplasmic isozymes, with most of the extra amino acids present as a carboxyl terminal extension. In comparison, sheep CA VI has a 45 amino acid extension. Overall the human CA VI protein has a sequence identity of 35 {percent} with human CA II, while residues involved in the active site of the enzymes have been conserved. The human and sheep secreted carbonic anhydrases have a sequence identity of 72 {percent}. This includes the two cysteine residues that are known to be involved in an intramolecular disulfide bond in the sheep CA VI. The enzyme is known to be glycosylated and three potential N-glycosylation sites (Asn-X-Thr/Ser) have been identified. Two of these are known to be glycosylated in sheep CA VI. Southern analysis of human DNA indicates that there is only one gene coding for CA VI.

  12. Optic nerve oxygen tension in pigs and the effect of carbonic anhydrase inhibitors

    DEFF Research Database (Denmark)

    Stefánsson, E; Jensen, P K; Eysteinsson, T;

    1999-01-01

    To evaluate how the oxygen tension of the optic nerve (ONP(O)2) is affected by the administration of the carbonic anhydrase inhibitors dorzolamide and acetazolamide and by alterations in oxygen and carbon dioxide in the breathing mixture....

  13. Carbonic Anhydrase: An Efficient Enzyme with Possible Global Implications

    Directory of Open Access Journals (Sweden)

    Christopher D. Boone

    2013-01-01

    Full Text Available As the global atmospheric emissions of carbon dioxide (CO2 and other greenhouse gases continue to grow to record-setting levels, so do the demands for an efficient and inexpensive carbon sequestration system. Concurrently, the first-world dependence on crude oil and natural gas provokes concerns for long-term availability and emphasizes the need for alternative fuel sources. At the forefront of both of these research areas are a family of enzymes known as the carbonic anhydrases (CAs, which reversibly catalyze the hydration of CO2 into bicarbonate. CAs are among the fastest enzymes known, which have a maximum catalytic efficiency approaching the diffusion limit of 108 M−1s−1. As such, CAs are being utilized in various industrial and research settings to help lower CO2 atmospheric emissions and promote biofuel production. This review will highlight some of the recent accomplishments in these areas along with a discussion on their current limitations.

  14. Carbonic anhydrase activity in isolated chloroplasts of chlamydomonas reinhardtii

    International Nuclear Information System (INIS)

    In a new assay of carbonic anhydrase, NaH14CO3 solution at the bottom of a sealed vessel releases 14CO3 which diffuses to the top of the vessel to be assimilated by actively photosynthesizing Chlamydomonas cells. The assay is initiated by illuminating cells and stopped by turning the light off and killing the cells with acid. Enzyme activity was estimated from acid stable radioactivity above the uncatalyzed background level. With bovine carbonic anhydrase, 1.5 Wilbur Anderson Unit (WAU) can be consistantly measured at 5-6 fold above background. Sonicated whole cells of air adapted wild type (+)gave 741.1 ± 12.4 WAU/mg chl. Intact washed cells of mixotrophically grown wall-less mutant CWD(-) and a high CO2 requiring wall-less double mutant CIA-3/CW15 (-) gave 7.1 ± 1.9 and 2.8 ± 7.8 WAU/mg chl respectively. Chloroplasts isolated from CWD and CIA-3/CW15 and subsequently disrupted gave 64.0 ± 14.7 and 2.8 ± 3.2 WAU/mg chl respectively. Chloroplast sonicate from another wall-less mutant CW15(-) gave activity comparable to CWD. Thus on a chlorophyll basis, enzyme activity in chloroplasts from mixotrophically grown cells is about 1/10th of the level found in air adapted wild type cells. CIA-3 seems to lack this activity

  15. Comparison of amino and epoxy functionalized SBA-15 used for carbonic anhydrase immobilization.

    Science.gov (United States)

    Fei, Xiaoyao; Chen, Shaoyun; Liu, Dai; Huang, Chunjie; Zhang, Yongchun

    2016-09-01

    Two functionalized SBA-15 [amine-functionalized SBA-15 (AFS) and epoxy-functionalized SBA-15 (GFS)] with different types of functional groups were synthesized by a hydrothermal process and post functionalized with 3-aminopropyltriethoxysilane (APTES) and 3-glycidyloxypropyltrimethoxysilane (GPTMS), respectively. They were used for the immobilization of carbonic anhydrase (CA). The physicochemical properties of the functionalized SBA-15 were characterized by X-ray powder diffraction (XRD), N2 adsorption-desorption, (13)C, (29)Si solid-state nuclear magnetic resonance (NMR) spectroscopy, and scanning electron microscopy (SEM). Before and after CA was immobilized on AFS and GFS, the effects of temperature and pH value on the enzyme activity, storage stability, and reusability were investigated using para-nitrophenyl acetate (p-NPA) assay. CA/GFS showed a better performance with respect to storage stability and reusability than CA/AFS. Moreover, the amount of CaCO3 precipitated over CA/AFS was less than that precipitated over CA/GFS, which was almost equal to that precipitated over the free CA. The results indicate that the epoxy group is a more suitable functional group for covalent bonding with CA than the amino group, and GFS is a promising support for CA immobilization. PMID:27215831

  16. Carbonic anhydrase XII expression is associated with histologic grade of cervical cancer and superior radiotherapy outcome

    International Nuclear Information System (INIS)

    To investigate whether expression of carbonic anhydrase XII (CA12) is associated with histologic grade of the tumors and radiotherapy outcomes of the patients with invasive cervical cancer. CA12 expression was examined by immunohistochemical stains in cervical cancer tissues from 183 radiotherapy patients. Histological grading was classified as well (WD), moderately (MD) or poorly differentiated (PD). Oligonucleotide microarray experiment was performed using seven cervical cancer samples to examine differentially expressed genes between WD and PD cervical cancers. The association between CA12 and histological grade was analyzed by chi-square test. CA12 and histological grades were analyzed individually and as combined CA12 and histologic grade categories for effects on survival outcome. Immunohistochemical expression of CA12 was highly associated with the histologic grade of cervical cancer. Lack of CA12 expression was associated with PD histology, with an odds ratio of 3.9 (P = 0.01). Microarray analysis showed a fourfold reduction in CA12 gene expression in PD tumors. CA12 expression was marginally associated with superior disease-free survival. Application of the new combined categories resulted in further discrimination of the prognosis of patients with moderate and poorly differentiated tumor grade. Our study indicates that CA12 may be used as a novel prognostic marker in combination with histologic grade of the tumors

  17. Optic nerve oxygen tension in pigs and the effect of carbonic anhydrase inhibitors

    DEFF Research Database (Denmark)

    Stefánsson, E; Jensen, P K; Eysteinsson, T;

    1999-01-01

    To evaluate how the oxygen tension of the optic nerve (ONP(O)2) is affected by the administration of the carbonic anhydrase inhibitors dorzolamide and acetazolamide and by alterations in oxygen and carbon dioxide in the breathing mixture.......To evaluate how the oxygen tension of the optic nerve (ONP(O)2) is affected by the administration of the carbonic anhydrase inhibitors dorzolamide and acetazolamide and by alterations in oxygen and carbon dioxide in the breathing mixture....

  18. Carbon dioxide capture using Escherichia coli expressing carbonic anhydrase in a foam bioreactor.

    Science.gov (United States)

    Watson, Stuart K; Han, Zhenlin; Su, Wei Wen; Deshusses, Marc A; Kan, Eunsung

    2016-12-01

    The present study reports CO2 capture and conversion to bicarbonate using Escherichia coli expressing carbonic anhydrase (CA) on its cell surface in a novel foam bioreactor. The very large gas-liquid interfacial area in the foam bioreactor promoted rapid CO2 absorption while the CO2 in the aqueous phase was subsequently converted to bicarbonate ions by the CA. CO2 gas removal in air was investigated at various conditions such as gas velocity, cell density and CO2 inlet concentration. Regimes for kinetic and mass transfer limitations were defined. Very high removal rates of CO2 were observed: 9570 g CO2 m(-3) bioreactor h(-1) and a CO2 removal efficiency of 93% at 4% inlet CO2 when the gas retention time was 24 s, and cell concentration was 4 gdw L(-1). These performances are superior to earlier reports of experimental bioreactors using CA for CO2 capture. Overall, this bioreactor system has significant potential as an alternative CO2 capture technology.

  19. Characterization of carbonic anhydrase XIII in the erythrocytes of the Burmese python, Python molurus bivittatus.

    Science.gov (United States)

    Esbaugh, A J; Secor, S M; Grosell, M

    2015-09-01

    Carbonic anhydrase (CA) is one of the most abundant proteins found in vertebrate erythrocytes with the majority of species expressing a low activity CA I and high activity CA II. However, several phylogenetic gaps remain in our understanding of the expansion of cytoplasmic CA in vertebrate erythrocytes. In particular, very little is known about isoforms from reptiles. The current study sought to characterize the erythrocyte isoforms from two squamate species, Python molurus and Nerodia rhombifer, which was combined with information from recent genome projects to address this important phylogenetic gap. Obtained sequences grouped closely with CA XIII in phylogenetic analyses. CA II mRNA transcripts were also found in erythrocytes, but found at less than half the levels of CA XIII. Structural analysis suggested similar biochemical activity as the respective mammalian isoforms, with CA XIII being a low activity isoform. Biochemical characterization verified that the majority of CA activity in the erythrocytes was due to a high activity CA II-like isoform; however, titration with copper supported the presence of two CA pools. The CA II-like pool accounted for 90 % of the total activity. To assess potential disparate roles of these isoforms a feeding stress was used to up-regulate CO2 excretion pathways. Significant up-regulation of CA II and the anion exchanger was observed; CA XIII was strongly down-regulated. While these results do not provide insight into the role of CA XIII in the erythrocytes, they do suggest that the presence of two isoforms is not simply a case of physiological redundancy.

  20. Synthesis and inhibition potency of novel ureido benzenesulfonamides incorporating GABA as tumor-associated carbonic anhydrase IX and XII inhibitors.

    Science.gov (United States)

    Ceruso, Mariangela; Antel, Sabrina; Scozzafava, Andrea; Supuran, Claudiu T

    2016-01-01

    New ureido benzenesulfonamides incorporating a GABA moiety as a linker between the ureido and the sulfonamide functionalities were synthesized and their inhibition potency determined against both the predominant cytosolic (hCA I and II) and the transmembrane tumor-associated (hCA IX and XII) isoforms of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). The majority of these compounds were medium potency inhibitors of the cytosolic isoform hCA I and effective hCA II inhibitors, whereas they showed strong inhibition of the two transmembrane tumor-associated isoforms hCA IX and XII, with KIs in nanomolar range. Only one derivative had a good selectivity for inhibition of the tumor-associated hCA IX target isoform over the cytosolic and physiologically dominant off-target hCA I and II, being thus a potential tool to develop new anticancer agents. PMID:25792500

  1. Benzenesulfonamides incorporating bulky aromatic/heterocyclic tails with potent carbonic anhydrase inhibitory activity.

    Science.gov (United States)

    Bozdag, Murat; Alafeefy, Ahmed M; Vullo, Daniela; Carta, Fabrizio; Dedeoglu, Nurcan; Al-Tamimi, Abdul-Malek S; Al-Jaber, Nabila A; Scozzafava, Andrea; Supuran, Claudiu T

    2015-12-15

    Three series of sulfonamides incorporating long, bulky tails were obtained by applying synthetic strategies in which substituted anthranilic acids, quinazolines and aromatic sulfonamides have been used as starting materials. They incorporate long, bulky diamide-, 4-oxoquinazoline-3-yl- or quinazoline-4-yl moieties in their molecules, and were investigated for the inhibition of four physiologically relevant carbonic anhydrase (CA, EC 4.2.1.1) isoforms, the cytosolic human (h) hCA I and II, as well as the transmembrane hCA IX and XII. Most of the new sulfonamides showed excellent inhibitory effects against the four isoforms, with KIs of 7.6-322nM against hCA I, of 0.06-85.4nM against hCA II; of 6.7-152nM against hCA IX and of 0.49-237nM against hCA XII; respectively. However no relevant isoform-selective behavior has been observed for any of them, although hCA II and XII, isoforms involved in glaucoma-genesis were the most inhibited ones. The structure-activity relationship for inhibiting the four CAs with these derivatives is discussed in detail. PMID:26639945

  2. Transmembrane carbonic anhydrase isozymes IX and XII in the female mouse reproductive organs

    Directory of Open Access Journals (Sweden)

    Tomas Eija

    2004-10-01

    Full Text Available Abstract Background Carbonic anhydrase (CA classically catalyses the reversible hydration of dissolved CO2 to form bicarbonate ions and protons. The twelve active CA isozymes are thought to regulate a variety of cellular functions including several processes in the reproductive systems. Methods The present study was designed to investigate the expression of transmembrane CAs, CA IX and XII, in the mouse uterus, ovary and placenta. The expression of CA IX and XII was examined by immunoperoxidase staining method and western blotting. CA II and XIII served as positive controls since they are known to be present in the mouse reproductive tract. Results The data of our study indicated that CA XII is expressed in the mouse endometrium. Only very faint signal was observed in the corpus luteum of the ovary and the placenta remained mainly negative. CA IX showed weak reaction in the endometrial epithelium, while it was completely absent in the ovary and placenta. Conclusion The conservation of CA XII expression in both mouse and human endometrium suggests a role for this isozyme in reproductive physiology.

  3. Carbonic anhydrase in Escherichia coli. A product of the cyn operon.

    Science.gov (United States)

    Guilloton, M B; Korte, J J; Lamblin, A F; Fuchs, J A; Anderson, P M

    1992-02-25

    The product of the cynT gene of the cyn operon in Escherichia coli has been identified as a carbonic anhydrase. The cyn operon also includes the gene cynS, encoding the enzyme cyanase. Cyanase catalyzes the reaction of cyanate with bicarbonate to give ammonia and carbon dioxide. The carbonic anhydrase was isolated from an Escherichia coli strain overexpressing the cynT gene and characterized. The purified enzyme was shown to contain 1 Zn2+/subunit (24 kDa) and was found to behave as an oligomer in solution; the presence of bicarbonate resulted in partial dissociation of the oligomeric enzyme. The kinetic properties of the enzyme are similar to those of carbonic anhydrases from other species, including inhibition by sulfonamides and cyanate. The amino acid sequence shows a high degree of identity with the sequences of two plant carbonic anhydrases. but not with animal and algal carbonic anhydrases. Since carbon dioxide formed in the bicarbonate-dependent decomposition of cyanate diffuses out of the cell faster than it would be hydrated to bicarbonate, the apparent function of the induced carbonic anhydrase is to catalyze hydration of carbon dioxide and thus prevent depletion of cellular bicarbonate.

  4. The role of carbonic anhydrase in C4 photosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Studer, Anthony [Life Sciences Research Foundation, Baltimore, MD (United States)

    2015-10-01

    Current pressures on the global food supply have accelerated the urgency for a second green revolution using novel and sustainable approaches to increase crop yield and efficiency. This proposal outlines experiments to address fundamental questions regarding the biology of C4 photosynthesis, the method of carbon fixation utilized by the most productive food, feed and bioenergy crops. Carbonic anhydrase (CA) has been implicated in multiple cellular functions including nitrogen metabolism, water use efficiency, and photosynthesis. CA catalyzes the first dedicated step in C4 photosynthesis, the hydration of CO2 into bicarbonate, and is potentially rate limiting in C4 grasses. Using insertional mutagenesis, we have generated CA mutants in maize, and propose the characterization of these mutants using phenotypic, physiological, and transcriptomic profiling to assay the plant’s response to altered CA activity. In addition, florescent protein tagging experiments will be employed to study the subcellular localization of CA paralogs, providing critical data for modeling carbon fixation in C4 plants. Finally, I propose parallel experiments in Setaria viridis to explore its relevance as model C4 grass. Using a multifaceted approach, this proposal addresses important questions in basic biology, as well as the need for translation research in response to looming global food challenges.

  5. Carbonic anhydrase III regulates peroxisome proliferator-activated receptor-{gamma}2

    Energy Technology Data Exchange (ETDEWEB)

    Mitterberger, Maria C. [Cell Metabolism and Differentiation Research Group, Institute for Biomedical Aging Research of the Austrian Academy of Sciences, 6020 Innsbruck (Austria); Kim, Geumsoo [Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-8012 (United States); Rostek, Ursula [Cell Metabolism and Differentiation Research Group, Institute for Biomedical Aging Research of the Austrian Academy of Sciences, 6020 Innsbruck (Austria); Levine, Rodney L. [Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-8012 (United States); Zwerschke, Werner, E-mail: werner.zwerschke@oeaw.ac.at [Cell Metabolism and Differentiation Research Group, Institute for Biomedical Aging Research of the Austrian Academy of Sciences, 6020 Innsbruck (Austria)

    2012-05-01

    Carbonic anhydrase III (CAIII) is an isoenzyme of the CA family. Because of its low specific anhydrase activity, physiological functions in addition to hydrating CO{sub 2} have been proposed. CAIII expression is highly induced in adipogenesis and CAIII is the most abundant protein in adipose tissues. The function of CAIII in both preadipocytes and adipocytes is however unknown. In the present study we demonstrate that adipogenesis is greatly increased in mouse embryonic fibroblasts (MEFs) from CAIII knockout (KO) mice, as demonstrated by a greater than 10-fold increase in the induction of fatty acid-binding protein-4 (FABP4) and increased triglyceride formation in CAIII{sup -/-} MEFs compared with CAIII{sup +/+} cells. To address the underlying mechanism, we investigated the expression of the two adipogenic key regulators, peroxisome proliferator-activated receptor-{gamma}2 (PPAR{gamma}2) and CCAAT/enhancer binding protein-{alpha}. We found a considerable (approximately 1000-fold) increase in the PPAR{gamma}2 expression in the CAIII{sup -/-} MEFs. Furthermore, RNAi-mediated knockdown of endogenous CAIII in NIH 3T3-L1 preadipocytes resulted in a significant increase in the induction of PPAR{gamma}2 and FABP4. When both CAIII and PPAR{gamma}2 were knocked down, FABP4 was not induced. We conclude that down-regulation of CAIII in preadipocytes enhances adipogenesis and that CAIII is a regulator of adipogenic differentiation which acts at the level of PPAR{gamma}2 gene expression. -- Highlights: Black-Right-Pointing-Pointer We discover a novel function of Carbonic anhydrase III (CAIII). Black-Right-Pointing-Pointer We show that CAIII is a regulator of adipogenesis. Black-Right-Pointing-Pointer We demonstrate that CAIII acts at the level of PPAR{gamma}2 gene expression. Black-Right-Pointing-Pointer Our data contribute to a better understanding of the role of CAIII in fat tissue.

  6. Research progress of carbon dioxide capture by using carbonic anhydrase%碳酸酐酶用于二氧化碳捕集的研究进展

    Institute of Scientific and Technical Information of China (English)

    王静

    2012-01-01

    碳酸酐酶(CA)可以加速捕集化石燃料燃烧产生的二氧化碳,从而降低CO2的排放量.主要介绍了CA的来源、活性、稳定性及作用.分析了使用新型生物方法对二氧化碳进行捕集和储存的优缺点,并对下一步的工作进行了展望.%It has been demonstrated that carbonic anhydrase has the potential of accelerating of carbon dioxide capture from fossil fuel and reduce the discharge of carbon dioxide. The source, activity, stability and functions of carbonic anhydrase are mainly presented. In addition, the advantages and disadvantages of using new biological for carbon dioxide capture and storage are discussed and analyzed, and the further study is prospected.

  7. Dithiocarbamates with potent inhibitory activity against the Saccharomyces cerevisiae β-carbonic anhydrase.

    Science.gov (United States)

    Bozdag, Murat; Carta, Fabrizio; Vullo, Daniela; Isik, Semra; AlOthman, Zeid; Osman, Sameh M; Scozzafava, Andrea; Supuran, Claudiu T

    2016-01-01

    Dithiocarbamates (DTCs) prepared from primary or secondary amines, which incorporated amino/hydroxyl-alkyl, mono-/bicyclic aliphatic/heterocyclic rings based on the quinuclidine, piperidine, hydroxy-/carboxy-/amino-substituted piperidine, morpholine and piperazine scaffolds, were investigated for the inhibition of α- and β-carbonic anhydrases (CAs, EC 4.2.1.1) of pharmacologic relevance, such as the human (h) isoform hCA I and II, as well as the Saccharomyces cerevisiae β-CA, scCA. The yeast and its β-CA were shown earlier to be useful models of pathogenic fungal infections. The DTCs investigated here were medium potency hCA I inhibitors (K(I)s of 66.5-910 nM), were more effective as hCA II inhibitors (K(I)s of 8.9-107 nM) and some of them showed excellent, low nanomolar activity against the yeast enzyme, with inhibition constants ranging between 6.4 and 259 nM. The detailed structure activity relationship for inhibition of the yeast and human enzymes is discussed. Several of the investigated DTCs showed excellent selectivity ratios for inhibiting the yeast over the human cytosolic CA isoforms. PMID:25669351

  8. Sulfonamide inhibition studies of the δ-carbonic anhydrase from the diatom Thalassiosira weissflogii.

    Science.gov (United States)

    Vullo, Daniela; Del Prete, Sonia; Osman, Sameh M; De Luca, Viviana; Scozzafava, Andrea; Alothman, Zeid; Supuran, Claudiu T; Capasso, Clemente

    2014-01-01

    The δ-carbonic anhydrase (CA, EC 4.2.1.1) TweCA from the marine diatom Thalassiosira weissflogii has recently been cloned, purified and its activity/inhibition with anions investigated. Here we report the first sulfonamide/sulfamate inhibition study of a δ-class CA. Among the 40 such compounds investigated so far, 3-bromosulfanilamide, acetazolamide, ethoxzolamide, dorzolamide and brinzolamide were the most effective TweCA inhibitors detected, with KIs of 49.6-118nM. Many simple aromatic sulfonamides as well as dichlorophenamide, benzolamide, topiramate, zonisamide, indisulam and valdecoxib were medium potency inhibitors, (KIs of 375-897nM). Saccharin and hydrochlorothiazide were ineffective inhibitors of the δ-class enzyme, with KIs of 4.27-9.20μM. The inhibition profile of the δ-CA is very different from that of α-, β- and γ-CAs from different organisms. Although no X-ray crystal structure of this enzyme is available, we hypothesize that as for other CA classes, the sulfonamides inhibit the enzymatic activity by binding to the Zn(II) ion from the δ-CA active site. PMID:24314394

  9. Sulfonamide inhibition studies of the η-class carbonic anhydrase from the malaria pathogen Plasmodium falciparum.

    Science.gov (United States)

    Vullo, Daniela; Del Prete, Sonia; Fisher, Gillian M; Andrews, Katherine T; Poulsen, Sally-Ann; Capasso, Clemente; Supuran, Claudiu T

    2015-02-01

    The η-carbonic anhydrases (CAs, EC 4.2.1.1) were recently discovered as the sixth genetic class of this metalloenzyme superfamily, and are so far known only in protozoa, including various Plasmodium species, the causative agents of malaria. We report here an inhibition study of the η-CA from Plasmodium falciparum (PfCA) against a panel of sulfonamides and one sulfamate compound, some of which are clinically used. The strongest inhibitors identified were ethoxzolamide and sulthiame, with KIs of 131-132 nM, followed by acetazolamide, methazolamide and hydrochlorothiazide (KIs of 153-198 nM). Brinzolamide, topiramate, zonisamide, indisulam, valdecoxib and celecoxib also showed significant inhibitory action against PfCA, with KIs ranging from 217 to 308 nM. An interesting observation was that the more efficient PfCA inhibitors are representative of several scaffolds and chemical classes, including benzene sulfonamides, monocyclic/bicyclic heterocyclic sulfonamides and compounds with a more complex scaffold (i.e., the sugar sulfamate derivative, topiramate, and the coxibs, celecoxib and valdecoxib). A comprehensive inhibition study of small molecules for η-CAs is needed as a first step towards assessing PfCA as a druggable target. The present work identifies the first known η-CA inhibitors and provides a platform for the development of next generation novel PfCA inhibitors. PMID:25533402

  10. /sup 35/Cl and /sup 81/Br nuclear magnetic resonance studies of carbonic anhydrase

    Energy Technology Data Exchange (ETDEWEB)

    Ward, R.L.

    1979-02-01

    /sup 35/Cl NMR studies substantiated the binding of Cl/sup -/ to the Zn(II) of carbonic anhydrase. Zinc-free carbonic anhydrase was prepared and it exhibited essentially no effect on the Cl/sup -/ line width. The net Cl/sup -/ line width increased with temperature. /sup 81/Br NMR was quite similar to /sup 35/Cl in that its relaxation is dominated by quadrupolar interactions.

  11. Carbonic anhydrase inhibition increases retinal oxygen tension and dilates retinal vessels

    DEFF Research Database (Denmark)

    Pedersen, Daniella Bach; Koch Jensen, Peter; la Cour, Morten;

    2005-01-01

    Carbonic anhydrase inhibitors (CAIs) increase blood flow in the brain and probably also in the optic nerve and retina. Additionally they elevate the oxygen tension in the optic nerve in the pig. We propose that they also raise the oxygen tension in the retina. We studied the oxygen tension in the...... pig retina and optic nerve before and after dorzolamide injection. Also the retinal vessel diameters during carbonic anhydrase inhibition were studied....

  12. Carbonic anhydrase immobilized on hollow fiber membranes using glutaraldehyde activated chitosan for artificial lung applications

    OpenAIRE

    Kimmel, J. D.; Arazawa, D. T.; Ye, S.-H.; Shankarraman, V; Wagner, W. R.; Federspiel, W. J.

    2013-01-01

    Extracorporeal CO2 removal from circulating blood is a promising therapeutic modality for the treatment of acute respiratory failure. The enzyme carbonic anhydrase accelerates CO2 removal within gas exchange devices by locally catalyzing HCO3− into gaseous CO2 within the blood. In this work, we covalently immobilized carbonic anhydrase on the surface of polypropylene hollow fiber membranes using glutaraldehyde activated chitosan tethering to amplify the density of reactive amine functional gr...

  13. Carbonic anhydrase inhibition increases retinal oxygen tension and dilates retinal vessels

    DEFF Research Database (Denmark)

    Pedersen, Daniella Bach; Koch Jensen, Peter; la Cour, Morten;

    2005-01-01

    Carbonic anhydrase inhibitors (CAIs) increase blood flow in the brain and probably also in the optic nerve and retina. Additionally they elevate the oxygen tension in the optic nerve in the pig. We propose that they also raise the oxygen tension in the retina. We studied the oxygen tension in the...... in the pig retina and optic nerve before and after dorzolamide injection. Also the retinal vessel diameters during carbonic anhydrase inhibition were studied....

  14. Carbonic anhydrase activators: gold nanoparticles coated with derivatized histamine, histidine, and carnosine show enhanced activatory effects on several mammalian isoforms.

    Science.gov (United States)

    Saada, Mohamed-Chiheb; Montero, Jean-Louis; Vullo, Daniela; Scozzafava, Andrea; Winum, Jean-Yves; Supuran, Claudiu T

    2011-03-10

    Lipoic acid moieties were attached to amine or amino acids showing activating properties against the zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1). The obtained lipoic acid conjugates of histamine, L-histidine methyl ester, and L-carnosine methyl ester were attached to gold nanoparticles (NPs) by reaction with Au(III) salts in reducing conditions. The CA activators (CAAs)-coated NPs showed low nanomolar activation (K(A)s of 1-9 nM) of relevant cytosolic, membrane-bound, mitochondrial, and transmembrane CA isoforms, such as CA I, II, IV, VA, VII, and XIV. These NPs also effectively activated CAs ex vivo, in whole blood experiments, with an increase of 200-280% of the CA activity. This is the first example of enzyme activation with nanoparticles and may lead to biomedical applications for conditions in which the CA activity is diminished, such as aging, Alzheimer's disease, or CA deficiency syndrome. PMID:21291238

  15. The extremo-α-carbonic anhydrase from the thermophilic bacterium Sulfurihydrogenibium azorense is highly inhibited by sulfonamides.

    Science.gov (United States)

    Vullo, Daniela; De Luca, Viviana; Scozzafava, Andrea; Carginale, Vincenzo; Rossi, Mosè; Supuran, Claudiu T; Capasso, Clemente

    2013-08-01

    The α-carbonic anhydrase (CA, EC 4.2.1.1) from the newly discovered extremophilic bacterium Sulfurihydrogenibium azorense (SazCA) is the most effective CA known to date. Here we investigated the inhibition profile of this enzyme with a series of aromatic and heterocyclic sulfonamides, and one sulfamate. Many clinically used sulfonamides, such as acetazolamide, methazolamide, ethoxzolamide, dichlorophenamide, dorzolamide, brinzolamide, topiramate, celecoxib and sulpiride were low nanomolar/subnanomolar SazCA inhibitors (KIs in the range of 0.9-10.8 nM) whereas simple aromatic derivatives were less effective as SazCA inhibitors. The inhibition profile of SazCA is slightly different from that of the related enzyme from S. yellostonense (SspCA), investigated earlier by our groups. PMID:23777827

  16. Linking Carbonic Anhydrase Abundance and Diversity in Soils to Ecological Function

    Science.gov (United States)

    Pang, E.; Meredith, L. K.; Welander, P. V.

    2015-12-01

    Carbonic anhydrase (CA) is an ancient enzyme widespread among bacteria, archaea, and eukarya that catalyzes the following reaction: CO2 + H2O ⇌ HCO3- + H+. Its functions are critical for key cellular processes such as concentrating CO2 for autotrophic growth, pH regulation, and pathogen survival in hosts. Currently, there are six known CA classes (α, β, γ, δ, η, ζ) arising from several distinct evolutionary lineages. CA are widespread in sequenced genomes, with many organisms containing multiple classes of CA or multiple CA of the same class. Soils host rich microbial communities with diverse and important ecological functions, but the diversity and abundance of CA in soils has not been explored. CA appears to play an important, but poorly understood, role in some biogeochemical cycles such as those of CO2 and its oxygen isotope composition and also carbonyl sulfide (COS), which are potential tracers in predictive carbon cycle models. Recognizing the prevalence and functional significance of CA in soils, we used a combined bioinformatics and molecular biology approach to address fundamental questions regarding the abundance, diversity, and function of CA in soils. To characterize the abundance and diversity of the different CA classes in soils, we analyzed existing soil metagenomic and metatranscriptomic data from the DOE Joint Genome Institute databases. Out of the six classes of CA, we only found the α, β, and γ classes to be present in soils, with the β class being the most abundant. We also looked at genomes of sequenced soil microorganisms to learn what combination of CA classes they contain, from which we can begin to predict the physiological role of CA. To characterize the functional roles of the different CA classes in soils, we collected soil samples from a variety of biomes with diverse chemical and physical properties and quantified the rate of two CA-mediated processes: soil uptake of COS and acceleration of the oxygen isotope exchange

  17. Discovery of potent carbonic anhydrase and acetylcholine esterase inhibitors: novel sulfamoylcarbamates and sulfamides derived from acetophenones.

    Science.gov (United States)

    Akıncıoğlu, Akın; Akıncıoğlu, Hülya; Gülçin, İlhami; Durdagi, Serdar; Supuran, Claudiu T; Göksu, Süleyman

    2015-07-01

    In this study, several novel sulfamides were synthesized and evaluated for their acetylcholine esterase (AChE) and human carbonic anhydrase I, and II isoenzymes (hCA I and II) inhibition profiles. Reductive amination of methoxyacetophenones was used for the synthesis of amines. Amines were converted to sulfamoylcarbamates with chlorosulfonyl isocyanate (CSI) in the presence of BnOH. Pd-C catalyzed hydrogenolysis of sulfamoylcarbamates afforded sulfamides. These novel compounds were good inhibitors of the cytosolic hCA I, and hCA II with Ki values in the range of 45.9±8.9-687.5±84.3 pM for hCA I, and 48.80±8.2-672.2±71.9pM for hCA II. The inhibitory effects of the synthesized novel compounds on AChE were also investigated. The Ki values of these compounds were in the range of 4.52±0.61-38.28±6.84pM for AChE. These results show that hCA I, II, and AChE were effectively inhibited by the novel sulfamoylcarbamates 17-21 and sulfamide derivatives 22-26. All investigated compounds were docked within the active sites of the corresponding enzymes revealing the reasons of the effective inhibitory activity. PMID:25921269

  18. Influence of pesticide exposure on carbonic anhydrase II from sheep stomach.

    Science.gov (United States)

    Kılınç, Namık; İşgör, Mehmet Mustafa; Şengül, Bülent; Beydemir, Şükrü

    2015-09-01

    Carbonic anhydrase (CA) is a widely distributed enzyme and has a crucial role in the cells, tissues and organs of living organisms. It is found that CA-II is one of the most abundant CA isoenzymes in the gastrointestinal system. It plays an important role in the gastric acid secretion in stomach. In this study, we purified CA-II isoenzyme from sheep stomach with a 615.2 purification fold, 78% purification yield and 5562.02 specific activity. Moreover, the in vitro effects of some commonly used pesticides including chlorpyrifos, cypermethrin, dichlorvos, glyphosate isopropylamine and lambda cyhalomethrin on the enzyme activity were investigated. Of these compounds, glyphosate isopropylamine and dichlorvos showed an inhibition on CA-II esterase activity. They have IC50 values of 0.155 µM and 2.690 µM and Ki values of 0.329 µM and 3.654 µM, respectively. Both glyphosate isopropylamine and dichlorvos inhibited CA-II isoenzyme in a noncompetitive manner.

  19. Inhibition of hypoxia-inducible carbonic anhydrase-IX enhances hexokinase II inhibitor-induced hepatocellular carcinoma cell apoptosis

    OpenAIRE

    Yu, Su-jong; Yoon, Jung-Hwan; Lee, Jeong-Hoon; Myung, Sun-jung; Jang, Eun-sun; Kwak, Min-Sun; Cho, Eun-Ju; Jang, Ja-June; Kim, Yoon-jun; Lee, Hyo-Suk

    2011-01-01

    Aim: The hypoxic condition within large or infiltrative hypovascular tumors produces intracellular acidification, which could activate many signaling pathways and augment cancer cell growth and invasion. Carbonic anhydrase-IX (CA-IX) is an enzyme lowering pH. This study is to examine whether hypoxia induces CA-IX in hepatocellular carcinoma (HCC) cells, and to evaluate its clinical implication in HCC patients. Methods: Human HCC cell lines (Huh-7 and HepG2 cells) were used, and cell growth wa...

  20. Role of Carbonic Anhydrase as an Activator in Carbonate Rock Dissolution and Its Implication for Atmospheric CO2 Sink

    Institute of Scientific and Technical Information of China (English)

    刘再华

    2001-01-01

    The conversion of CO2 into H+ and is a relatively slow reaction. Hence, its kinetics may be rate determining in carbonate rock dissolution. Carbonic anhydrase (CA), which is widespread in nature, was used to catalyze the CO2 conversion process in dissolution experiments of limestone and dolomite. It was found that the rate of dissolution increases by a factor of about 10 after the addition of CA at a high CO2 partial pressure (Pco2) for limestone and about 3 at low Pco2 for dolomite. This shows that reappraisal is necessary for the importance of chemical weathering (including carbonate rock dissolution and silicate weathering) in the atmospheric CO2 sink and the mysterious missing sink in carbon cycling. It is doubtless that previous studies of weathering underestimated weathering rates due to the ignorance of CA as an activator in weathering, thus the contribution of weathering to the atmospheric CO2 sink is also underestimated. This finding also shows the need to examine the situ distribution and activity of CA in different waters and to investigate the role of CA in weathering.``

  1. Carbonic Anhydrases in Cnidarians: Novel Perspectives from the Octocorallian Corallium rubrum.

    Science.gov (United States)

    Le Goff, Carine; Ganot, Philippe; Zoccola, Didier; Caminiti-Segonds, Natacha; Allemand, Denis; Tambutté, Sylvie

    2016-01-01

    Although the ability to elaborate calcium carbonate biominerals was apparently gained independently during animal evolution, members of the alpha carbonic anhydrases (α-CAs) family, which catalyze the interconversion of CO2 into HCO3-, are involved in the biomineralization process across metazoans. In the Mediterranean red coral Corallium rubrum, inhibition studies suggest an essential role of CAs in the synthesis of two biominerals produced in this octocoral, the axial skeleton and the sclerites. Hitherto no molecular characterization of these enzymes was available. In the present study we determined the complete set of α-CAs in C. rubrum by data mining the genome and transcriptome, and measured their differential gene expression between calcifying and non-calcifying tissues. We identified six isozymes (CruCA1-6), one cytosolic and five secreted/membrane-bound among which one lacked two of the three zinc-binding histidines and was so referred to as a carbonic anhydrase related protein (CARP). One secreted isozyme (CruCA4) showed specific expression both by qPCR and western-blot in the calcifying tissues, suggesting its involvement in biomineralization. Moreover, phylogenetic analyses of α-CAs, identified in six representative cnidarians with complete genome, support an independent recruitment of α-CAs for biomineralization within anthozoans. Finally, characterization of cnidarian CARPs highlighted two families: the monophyletic cytosolic CARPs, and the polyphyletic secreted CARPs harboring a cnidarian specific cysteine disulfide bridge. Alignment of the cytosolic CARPs revealed an evolutionary conserved R-H-Q motif in place of the characteristic zinc-binding H-H-H necessary for the catalytic function of α-CAs. PMID:27513959

  2. Novel sulfonamide bearing coumarin scaffolds as selective inhibitors of tumor associated carbonic anhydrase isoforms IX and XII.

    Science.gov (United States)

    Chandak, Navneet; Ceruso, Mariangela; Supuran, Claudiu T; Sharma, Pawan K

    2016-07-01

    Four novel scaffolds consisting of total 24 compounds (1a-1o, 2a-2c, 3a-3c and 4a-4c) bearing aromatic sulfonamide and coumarin moieties connected through various linkers were synthesized in order to synergize the inhibition potential of both the moieties against four selected human carbonic anhydrase isoforms (hCA I, II, IX & XII). All compounds were found to be potent inhibitors of tumor associated hCA IX & XII while at the same time required large amounts to inhibit off-targeted housekeeping hCA I & II. Selectivity was more pronounced against hCA II over I, and hCA XII over IX. Results were compared with antitumor drug acetazolamide. One derivative 2b of series 2 was found to be a better selective inhibitor of hCA IX and XII. PMID:27137360

  3. Indomethacin lowers optic nerve oxygen tension and reduces the effect of carbonic anhydrase inhibition and carbon dioxide breathing

    DEFF Research Database (Denmark)

    Pedersen, D B; Eysteinsson, T; Stefánsson, E;

    2004-01-01

    Prostaglandins are important in blood flow regulation. Carbon dioxide (CO(2)) breathing and carbonic anhydrase inhibition increase the oxygen tension in the retina and optic nerve. To study the mechanism of this effect and the role of cyclo-oxygenase in the regulation of optic nerve oxygen tension...... (ONPO(2)), the authors investigated how indomethacin affects ONPO(2) and the ONPO(2) increases caused by CO(2) breathing and carbonic anhydrase inhibition in the pig....

  4. Sulfonamide inhibition studies of the γ-carbonic anhydrase from the Antarctic cyanobacterium Nostoc commune.

    Science.gov (United States)

    Vullo, Daniela; De Luca, Viviana; Del Prete, Sonia; Carginale, Vincenzo; Scozzafava, Andrea; Capasso, Clemente; Supuran, Claudiu T

    2015-04-15

    A carbonic anhydrase (CA, EC 4.2.1.1) belonging to the γ-class has been cloned, purified and characterized from the Antarctic cyanobacterium Nostoc commune. The enzyme showed a good catalytic activity for the physiologic reaction (hydration of carbon dioxide to bicarbonate and a proton) with the following kinetic parameters, kcat of 9.5×10(5)s(-1) and kcat/KM of 8.3×10(7)M(-1)s(-1), being the γ-CA with the highest catalytic activity described so far. A range of aromatic/heterocyclic sulfonamides and one sulfamate were investigated as inhibitors of the new enzyme, denominated here NcoCA. The best NcoCA inhibitors were some sulfonylated sulfanilamide derivatives possessing elongated molecules, aminobenzolamide, acetazolamide, benzolamide, dorzolamide, brinzolamide and topiramate, which showed inhibition constants in the range of 40.3-92.3nM. As 1,5-bisphosphate carboxylase/oxygenase (RubisCO) and γ-CAs are closely associated in carboxysomes of cyanobacteria for enhancing the affinity of RubisCO for CO2 and the efficiency of photosynthesis, investigation of this new enzyme and its affinity for modulators of its activity may bring new insights in these crucial processes. PMID:25773015

  5. Innovative molecular diagnosis of Trichinella species based on β-carbonic anhydrase genomic sequence.

    Science.gov (United States)

    Zolfaghari Emameh, Reza; Kuuslahti, Marianne; Näreaho, Anu; Sukura, Antti; Parkkila, Seppo

    2016-03-01

    Trichinellosis is a helminthic infection where different species of Trichinella nematodes are the causative agents. Several molecular assays have been designed to aid diagnostics of trichinellosis. These assays are mostly complex and expensive. The genomes of Trichinella species contain certain parasite-specific genes, which can be detected by polymerase chain reaction (PCR) methods. We selected β-carbonic anhydrase (β-CA) gene as a target, because it is present in many parasites genomes but absent in vertebrates. We developed a novel β-CA gene-based method for detection of Trichinella larvae in biological samples. We first identified a β-CA protein sequence from Trichinella spiralis by bioinformatic tools using β-CAs from Caenorhabditis elegans and Drosophila melanogaster. Thereafter, 16 sets of designed primers were tested to detect β-CA genomic sequences from three species of Trichinella, including T. spiralis, Trichinella pseudospiralis and Trichinella nativa. Among all 16 sets of designed primers, the primer set No. 2 efficiently amplified β-CA genomic sequences from T. spiralis, T. pseudospiralis and T. nativa without any false-positive amplicons from other parasite samples including Toxoplasma gondii, Toxocara cati and Parascaris equorum. This robust and straightforward method could be useful for meat inspection in slaughterhouses, quality control by food authorities and medical laboratories. PMID:26639312

  6. Coumarin or benzoxazinone based novel carbonic anhydrase inhibitors: synthesis, molecular docking and anticonvulsant studies.

    Science.gov (United States)

    Karataş, Mert Olgun; Uslu, Harun; Sarı, Suat; Alagöz, Mehmet Abdullah; Karakurt, Arzu; Alıcı, Bülent; Bilen, Cigdem; Yavuz, Emre; Gencer, Nahit; Arslan, Oktay

    2016-10-01

    Among many others, coumarin derivatives are known to show human carbonic anhydrase (hCA) inhibitory activity. Since hCA inhibition is one of the underlying mechanisms that account for the activities of some antiepileptic drugs (AEDs), hCA inhibitors are expected to have anti-seizure properties. There are also several studies reporting compounds with an imidazole and/or benzimidazole moiety which exert these pharmacological properties. In this study, we prepared fifteen novel coumarin-bearing imidazolium and benzimidazolium chloride, nine novel benzoxazinone-bearing imidazolium and benzimidazolium chloride derivatives and evaluated their hCA inhibitory activities and along with fourteen previously synthesized derivatives we scanned their anticonvulsant effects. As all compounds inhibited purified hCA isoforms I and II, some of them also proved protective against Maximal electroshock seizure (MES) and ScMet induced seizures in mice. Molecular docking studies with selected coumarin derivatives have revealed that these compounds bind to the active pocket of the enzyme in a similar fashion to that previously described for coumarin derivatives.

  7. Alkyl sulfonic acide hydrazides: Synthesis, characterization, computational studies and anticancer, antibacterial, anticarbonic anhydrase II (hCA II) activities

    Science.gov (United States)

    O. Ozdemir, Ummuhan; İlbiz, Firdevs; Balaban Gunduzalp, Ayla; Ozbek, Neslihan; Karagoz Genç, Zuhal; Hamurcu, Fatma; Tekin, Suat

    2015-11-01

    Methane sulfonic acide hydrazide, CH3SO2NHNH2 (1), ethane sulfonic acide hydrazide, CH3CH2SO2NHNH2 (2), propane sulfonic acide hydrazide, CH3CH2CH2SO2NHNH2 (3) and butane sulfonic acide hydrazide, CH3CH2CH2CH2SO2NHNH2 (4) have been synthesized as homologous series and characterized by using elemental analysis, spectrophotometric methods (1H-13C NMR, FT-IR, LC-MS). In order to gain insight into the structure of the compounds, we have performed computational studies by using 6-311G(d, p) functional in which B3LYP functional were implemented. The geometry of the sulfonic acide hydrazides were optimized at the DFT method with Gaussian 09 program package. A conformational analysis of compounds were performed by using NMR theoretical calculations with DFT/B3LYP/6-311++G(2d, 2p) level of theory by applying the (GIAO) approach. The anticancer activities of these compounds on MCF-7 human breast cancer cell line investigated by comparing IC50 values. The antibacterial activities of synthesized compounds were studied against Gram positive bacteria; Staphylococcus aureus ATCC 6538, Bacillus subtilis ATCC 6633, Bacillus cereus NRRL-B-3711, Enterococcus faecalis ATCC 29212 and Gram negative bacteria; Escherichia coli ATCC 11230, Pseudomonas aeruginosa ATCC 15442, Klebsiella pneumonia ATCC 70063 by using the disc diffusion method. The inhibition activities of these compounds on carbonic anhydrase II enzyme (hCA II) have been investigated by comparing IC50 and Ki values. The biological activity screening shows that butane sulfonic acide hydrazide (4) has more activity than the others against tested breast cancer cell lines MCF-7, Gram negative/Gram positive bacteria and carbonic anhydrase II (hCA II) isoenzyme.

  8. Increased oxidation-related glutathionylation and carbonic anhydrase activity in endometriosis.

    Science.gov (United States)

    Andrisani, Alessandra; Donà, Gabriella; Brunati, Anna Maria; Clari, Giulio; Armanini, Decio; Ragazzi, Eugenio; Ambrosini, Guido; Bordin, Luciana

    2014-06-01

    This study examined the possible involvement of carbonic anhydrase activation in response to an endometriosis-related increase in oxidative stress. Peripheral blood samples obtained from 27 healthy controls and 30 endometriosis patients, classified as having endometriosis by histological examination of surgical specimens, were analysed by multiple immunoassay and carbonic anhydrase activity assay. Red blood cells (RBC) were analysed for glutathionylated protein (GSSP) content in the membrane, total glutathione (GSH) in the cytosol and carbonic anhydrase concentration and activity. In association with a membrane increase of GSSP and a cytosolic decrease of GSH content in endometriosis patients, carbonic anhydrase significantly increased (P < 0.0001) both monomerization and activity compared with controls. This oxidation-induced activation of carbonic anhydrase was positively and significantly correlated with the GSH content of RBC (r = 0.9735, P < 0.001) and with the amount of the 30-kDa monomer of carbonic anhydrase (r = 0.9750, P < 0.001). Because carbonic anhydrase activation is implied in many physiological and biochemical processes linked to pathologies such as glaucoma, hypertension, obesity and infections, carbonic anhydrase activity should be closely monitored in endometriosis. These data open promising working perspectives for diagnosis and treatment of endometriosis and hopefully of other oxidative stress-related diseases. Endometriosis is a chronic disease associated with infertility and local inflammatory response, which is thought to spread rapidly throughout the body as a systemic subclinical inflammation. One of the causes in the pathogenesis/evolution of endometriosis is oxidative stress, which occurs when reactive oxygen species are produced faster than the endogenous antioxidant defence systems can neutralize them. Once produced, reactive oxygen species can alter the morphological and functional properties of endothelial cells, including

  9. Non-destructive measurement of carbonic anhydrase activity and the oxygen isotope composition of soil water

    Science.gov (United States)

    Jones, Sam; Sauze, Joana; Ogée, Jérôme; Wohl, Steven; Bosc, Alexandre; Wingate, Lisa

    2016-04-01

    Carbonic anhydrases are a group of metalloenzymes that catalyse the hydration of aqueous carbon dioxide (CO2). The expression of carbonic anhydrase by bacteria, archaea and eukarya has been linked to a variety of important biological processes including pH regulation, substrate supply and biomineralisation. As oxygen isotopes are exchanged between CO2 and water during hydration, the presence of carbonic anhydrase in plants and soil organisms also influences the oxygen isotope budget of atmospheric CO2. Leaf and soil water pools have distinct oxygen isotope compositions, owing to differences in pool sizes and evaporation rates, which are imparted on CO2during hydration. These differences in the isotopic signature of CO2 interacting with leaves and soil can be used to partition the contribution of photosynthesis and soil respiration to net terrestrial CO2 exchange. However, this relies on our knowledge of soil carbonic anhydrase activity and currently, the prevalence and function of these enzymes in soils is poorly understood. Isotopic approaches used to estimate soil carbonic anhydrase activity typically involve the inversion of models describing the oxygen isotope composition of CO2 fluxes to solve for the apparent, potentially catalysed, rate of oxygen exchange during hydration. This requires information about the composition of CO2 in isotopic equilibrium with soil water obtained from destructive, depth-resolved soil water sampling. This can represent a significant challenge in data collection given the considerable potential for spatial and temporal variability in the isotopic composition of soil water and limited a priori information with respect to the appropriate sampling resolution and depth. We investigated whether we could circumvent this requirement by constraining carbonic anhydrase activity and the composition of soil water in isotopic equilibrium with CO2 by solving simultaneously the mass balance for two soil CO2 steady states differing only in the

  10. Characterization of the first beta-class carbonic anhydrase from an arthropod (Drosophila melanogaster and phylogenetic analysis of beta-class carbonic anhydrases in invertebrates

    Directory of Open Access Journals (Sweden)

    Niederhauser Barbara

    2010-07-01

    Full Text Available Abstract Background The β-carbonic anhydrase (CA, EC 4.2.1.1 enzymes have been reported in a variety of organisms, but their existence in animals has been unclear. The purpose of the present study was to perform extensive sequence analysis to show that the β-CAs are present in invertebrates and to clone and characterize a member of this enzyme family from a representative model organism of the animal kingdom, e.g., Drosophila melanogaster. Results The novel β-CA gene, here named DmBCA, was identified from FlyBase, and its orthologs were searched and reconstructed from sequence databases, confirming the presence of β-CA sequences in 55 metazoan species. The corresponding recombinant enzyme was produced in Sf9 insect cells, purified, kinetically characterized, and its inhibition was investigated with a series of simple, inorganic anions. Holoenzyme molecular mass was defined by dynamic light scattering analysis and gel filtration, and the results suggested that the holoenzyme is a dimer. Double immunostaining confirmed predictions based on sequence analysis and localized DmBCA protein to mitochondria. The enzyme showed high CO2 hydratase activity, with a kcat of 9.5 × 105 s-1 and a kcat/KM of 1.1 × 108 M-1s-1. DmBCA was appreciably inhibited by the clinically-used sulfonamide acetazolamide, with an inhibition constant of 49 nM. It was moderately inhibited by halides, pseudohalides, hydrogen sulfide, bisulfite and sulfate (KI values of 0.67 - 1.36 mM and more potently by sulfamide (KI of 0.15 mM. Bicarbonate, nitrate, nitrite and phenylarsonic/boronic acids were much weaker inhibitors (KIs of 26.9 - 43.7 mM. Conclusions The Drosophila β-CA represents a highly active mitochondrial enzyme that is a potential model enzyme for anti-parasitic drug development.

  11. Characterization of carbonic anhydrase II from Chlorella vulgaris in bio-CO2 capture.

    Science.gov (United States)

    Li, Li; Fu, Ming-Lai; Zhao, Yong-Hao; Zhu, Yun-Tian

    2012-11-01

    Carbonic anhydrase II (CA II) can catalyze the reversible hydration reaction of CO(2) at a maximum of 1.4 × 10(6) molecules of CO(2) per second. The crude intracellular enzyme extract containing CA II was derived from Chlorella vulgaris. A successful CO(2) capture experiment with the presence of calcium had been conducted on the premise that the temperature was conditioned at a scope of 30-40 °C, that the biocatalyst-nurtured algal growth period lasted 3 days, and that pH ranged from7.5 to 8.5. Ions of K(+), Na(+), Ca(2+), Co(2+), Cu(2+), Fe(3+), Mg(2+), Mn(2+), and Zn(2+) at 0.01, 0.1, and 0.5 M were found to exhibit no more than 30 % inhibition on the residual activity of the biocatalyst. It is reasonable to expect that calcification catalyzed by microalgae presents an alternative to geological carbon capture and sequestration through a chain of fundamental researches carried on under the guidance of sequestration technology. PMID:22821342

  12. Enzyme-accelerated and structure-guided crystallization of calcium carbonate: role of the carbonic anhydrase in the homologous system.

    Science.gov (United States)

    Müller, Werner E G; Schlossmacher, Ute; Schröder, Heinz C; Lieberwirth, Ingo; Glasser, Gunnar; Korzhev, Michael; Neufurth, Meik; Wang, Xiaohong

    2014-01-01

    The calcareous spicules from sponges, e.g. from Sycon raphanus, are composed of almost pure calcium carbonate. In order to elucidate the formation of those structural skeletal elements, the function of the enzyme carbonic anhydrase (CA), isolated from this species, during the in vitro calcium carbonate-based spicule formation, was investigated. It is shown that the recombinant sponge CA substantially accelerates calcium carbonate formation in the in vitro diffusion assay. A stoichiometric calculation revealed that the turnover rate of the sponge CA during the calcification process amounts to 25 CO2s(-1) × molecule CA(-1). During this enzymatically driven process, initially pat-like particles are formed that are subsequently transformed to rhomboid/rhombohedroid crystals with a dimension of ~50 μm. The CA-catalyzed particles are smaller than those which are formed in the absence of the enzyme. The Martens hardness of the particles formed is ~4 GPa, a value which had been determined for other biogenic calcites. This conclusion is corroborated by energy-dispersive X-ray spectroscopy, which revealed that the particles synthesized are composed predominantly of the elements calcium, oxygen and carbon. Surprising was the finding, obtained by light and scanning electron microscopy, that the newly formed calcitic crystals associate with the calcareous spicules from S. raphanus in a highly ordered manner; the calcitic crystals almost perfectly arrange in an array orientation along the two opposing planes of the spicules, leaving the other two plane arrays uncovered. It is concluded that the CA is a key enzyme controlling the calcium carbonate biomineralization process, which directs the newly formed particles to existing calcareous spicular structures. It is expected that with the given tools new bioinspired materials can be fabricated. PMID:23978410

  13. Knock-down of hypoxia-induced carbonic anhydrases IX and XII radiosensitizes tumor cells by increasing intracellular acidosis

    Directory of Open Access Journals (Sweden)

    Jérôme eDoyen

    2013-01-01

    Full Text Available The relationship between acidosis within the tumor microenvironment and radioresistance of hypoxic tumor cells remains unclear. Previously we reported that hypoxia-induced carbonic anhydrases CAIX and CAXII constitute a robust pHi-regulating system that confers a survival advantage on hypoxic human colon carcinoma LS174Tr cells in acidic microenvironments. Here we investigate the role of acidosis, CAIX and CAXII knock-down in combination with ionizing radiation. Fibroblasts cells (-/+ CAIX and LS174Tr cells (inducible knock-down for ca9/ca12 were analyzed for cell cycle phase distribution and survival after irradiation in extracellular pHo manipulations and hypoxia (1% O2 exposure. Radiotherapy was used to target ca9/ca12-silenced LS174Tr tumors grown in nude mice. We found that diminishing the pHi-regulating capacity of fibroblasts through inhibition of NHE-1 sensitize cells to radiation-induced cell death. Secondly, the pHi-regulating function of CAIX plays a key protective role in irradiated fibroblasts in an acidic environment as accompanied by a reduced number of cells in the radiosensitive phases of the cell cycle. Thirdly, we demonstrate that irradiation of LS174Tr spheroids, silenced for either ca9 or both ca9/ca12, showed a respective 50% and 75% increase in cell death as a result of a decrease in cell number in the radioresistant S phase and a disruption of CA-mediated pHi regulation. Finally, LS174Tr tumor progression was strongly decreased when ca9/ca12 silencing was combined with irradiation in vivo. These findings highlight the combinatory use of radiotherapy with targeting of the pHi-regulating carbonic anhydrases as an anti-cancer strategy.

  14. Sulfonamide inhibition studies of the β-carbonic anhydrase from the pathogenic bacterium Vibrio cholerae.

    Science.gov (United States)

    Del Prete, Sonia; Vullo, Daniela; De Luca, Viviana; Carginale, Vincenzo; Ferraroni, Marta; Osman, Sameh M; AlOthman, Zeid; Supuran, Claudiu T; Capasso, Clemente

    2016-03-01

    The genome of the pathogenic bacterium Vibrio cholerae encodes for three carbonic anhydrases (CAs, EC 4.2.1.1) belonging to the α-, β- and γ-classes. VchCA, the α-CA from this species was investigated earlier, whereas the β-class enzyme, VchCAβ was recently cloned, characterized kinetically and its X-ray crystal structure reported by this group. Here we report an inhibition study with sulfonamides and one sulfamate of this enzyme. The best VchCAβ inhibitors were deacetylated acetazolamide and methazolamide and hydrochlorothiazide, which showed inhibition constants of 68.2-87.0nM. Other compounds, with medium potency against VchCAβ, (KIs in the range of 275-463nM), were sulfanilamide, metanilamide, sulthiame and saccharin whereas the clinically used agents such as acetazolamide, methazolamide, ethoxzolamide, dorzolamide, zonisamide and celecoxib were micromolar inhibitors (KIs in the range of 4.51-8.57μM). Identification of potent and possibly selective inhibitors of VchCA and VchCAβ over the human CA isoforms, may lead to pharmacological tools useful for understanding the physiological role(s) of this under-investigated enzymes. PMID:26850377

  15. Sulfonamide inhibition studies of the β-carbonic anhydrase from the pathogenic bacterium Vibrio cholerae.

    Science.gov (United States)

    Del Prete, Sonia; Vullo, Daniela; De Luca, Viviana; Carginale, Vincenzo; Ferraroni, Marta; Osman, Sameh M; AlOthman, Zeid; Supuran, Claudiu T; Capasso, Clemente

    2016-03-01

    The genome of the pathogenic bacterium Vibrio cholerae encodes for three carbonic anhydrases (CAs, EC 4.2.1.1) belonging to the α-, β- and γ-classes. VchCA, the α-CA from this species was investigated earlier, whereas the β-class enzyme, VchCAβ was recently cloned, characterized kinetically and its X-ray crystal structure reported by this group. Here we report an inhibition study with sulfonamides and one sulfamate of this enzyme. The best VchCAβ inhibitors were deacetylated acetazolamide and methazolamide and hydrochlorothiazide, which showed inhibition constants of 68.2-87.0nM. Other compounds, with medium potency against VchCAβ, (KIs in the range of 275-463nM), were sulfanilamide, metanilamide, sulthiame and saccharin whereas the clinically used agents such as acetazolamide, methazolamide, ethoxzolamide, dorzolamide, zonisamide and celecoxib were micromolar inhibitors (KIs in the range of 4.51-8.57μM). Identification of potent and possibly selective inhibitors of VchCA and VchCAβ over the human CA isoforms, may lead to pharmacological tools useful for understanding the physiological role(s) of this under-investigated enzymes.

  16. Catecholamine-induced vasoconstriction is sensitive to carbonic anhydrase I activation

    Directory of Open Access Journals (Sweden)

    Puscas I.

    2001-01-01

    Full Text Available We studied the relationship between alpha- and beta-adrenergic agonists and the activity of carbonic anhydrase I and II in erythrocyte, clinical and vessel studies. Kinetic studies were performed. Adrenergic agonists increased erythrocyte carbonic anhydrase as follows: adrenaline by 75%, noradrenaline by 68%, isoprenaline by 55%, and orciprenaline by 62%. The kinetic data indicated a non-competitive mechanism of action. In clinical studies carbonic anhydrase I from erythrocytes increased by 87% after noradrenaline administration, by 71% after orciprenaline and by 82% after isoprenaline. The increase in carbonic anhydrase I paralleled the increase in blood pressure. Similar results were obtained in vessel studies on piglet vascular smooth muscle. We believe that adrenergic agonists may have a dual mechanism of action: the first one consists of a catecholamine action on its receptor with the formation of a stimulus-receptor complex. The second mechanism proposed completes the first one. By this second component of the mechanism, the same stimulus directly acts on the carbonic anhydrase I isozyme (that might be functionally coupled with adrenergic receptors, so that its activation ensures an adequate pH for stimulus-receptor coupling for signal transduction into the cell, resulting in vasoconstriction.

  17. Extraction of superoxide dismutase, catalase, and carbonic anhydrase from stroma-free red blood cell hemolysate for the preparation of the nanobiotechnological complex of polyhemoglobin-superoxide dismutase-catalase-carbonic anhydrase.

    Science.gov (United States)

    Guo, C; Gynn, M; Chang, T M S

    2015-06-01

    We report a novel method to simultaneously extract superoxide dismutase (SOD), catalase (CAT), and carbonic anhydrase (CA) from the same sample of red blood cells (RBCs). This avoids the need to use expensive commercial enzymes, thus enabling a cost-effective process for large-scale production of a nanobiotechnological polyHb-SOD-CAT-CA complex, with enhancement of all three red blood cell functions. An optimal concentration of phosphate buffer for ethanol-chloroform treatment results in good recovery of CAT, SOD, and CA after extraction. Different concentrations of the enzymes can be used to enhance the activity of polyHb-SOD-CAT-CA to 2, 4, or 6 times that of RBC.

  18. Thermodynamics of binding of Zn2+ to carbonic anhydrase inhibitors

    Science.gov (United States)

    Remko, Milan; Garaj, Vladimír

    The Becke3LYP functional of DFT theory and the two-layered ONIOM (B3LYP/6-311+G(d,p): MNDO) method were used to characterize 46 gas-phase complexes of 34 neutral and anionic ligands (H2O, CH3OH, CH3COOH, CH3CONH2, HOSO2NH2, CO2, HSO2NH2, CH3SO2NH2, CH3C(=O)NHOH, imidazole, NH2SO2NH2, anions of 4-aminobenzenesulphonamide, saccharin, 1I9L, brinzolamide, dorzolamide, acetazolamide, further HO(-), CH3O(-), CH3COO(-), CH3CONH(-), N=N=N(-), S=C=N(-), CH3C(=O)NHO(-), HOCOO(-), imidazoleN(-), phenol-O(-), HOSO2NH(-), (-)OSO2NH(-), (-)OSO2NH2, H2NSO2NH(-), HSO2NH(-), CH3SO2NH(-), and CF3SO2NH(-), respectively) with Zn2+. Proton dissociation enthalpies and Gibbs energies of acidic inhibitors in the presence of zinc were computed. Their gas-phase acidity considerably increases upon chelation. Of the bases investigated, the weakest zinc affinity is exhibited by carbon dioxide (-313.5 kJ mol-1). Deprotonated inhibitors have higher affinities for zinc than the neutral ones. Compared to the other mono-deprotonated ligands the acetohydroxamic acid anion has the highest affinity for zinc (-1872.7 kJ mol-1). The zinc affinity of the acetazolamide anion computed using the hybrid ONIOM (B3LYP/6-311+G(d,p): MNDO) method is in very good agreement with the full DFT ones and this method can be adopted to model large complexes of inhibitors with the active site of carbonic anhydrase.

  19. A physiological role for cyanate-induced carbonic anhydrase in Escherichia coli.

    OpenAIRE

    Guilloton, M B; Lamblin, A F; Kozliak, E I; Gerami-Nejad, M; Tu, C.; Silverman, D.; Anderson, P. M.; Fuchs, J A

    1993-01-01

    Cyanate induces expression of the cyn operon in Escherichia coli. The cyn operon includes the gene cynS, encoding cyanase, which catalyzes the reaction of cyanate with bicarbonate to give ammonia and carbon dioxide. A carbonic anhydrase activity was recently found to be encoded by the cynT gene, the first gene of the cyn operon; it was proposed that carbonic anhydrase prevents depletion of bicarbonate during cyanate decomposition due to loss of CO2 by diffusion out of the cell (M. B. Guilloto...

  20. Surface Engineering of Polypropylene Membranes with Carbonic Anhydrase-Loaded Mesoporous Silica Nanoparticles for Improved Carbon Dioxide Hydration.

    Science.gov (United States)

    Yong, Joel K J; Cui, Jiwei; Cho, Kwun Lun; Stevens, Geoff W; Caruso, Frank; Kentish, Sandra E

    2015-06-01

    Carbonic anhydrase (CA) is a native enzyme that facilitates the hydration of carbon dioxide into bicarbonate ions. This study reports the fabrication of thin films of active CA enzyme onto a porous membrane substrate using layer-by-layer (LbL) assembly. Deposition of multilayer films consisting of polyelectrolytes and CA was monitored by quartz crystal microgravimetry, while the enzymatic activity was assayed according to the rates of p-nitrophenylacetate (p-NPA) hydrolysis and CO2 hydration. The fabrication of the films onto a nonporous glass substrate showed CO2 hydration rates of 0.52 ± 0.09 μmol cm(-2) min(-1) per layer of bovine CA and 2.6 ± 0.7 μmol cm(-2) min(-1) per layer of a thermostable microbial CA. The fabrication of a multilayer film containing the microbial CA on a porous polypropylene membrane increased the hydration rate to 5.3 ± 0.8 μmol cm(-2) min(-1) per layer of microbial CA. The addition of mesoporous silica nanoparticles as a film layer prior to enzyme adsorption was found to increase the activity on the polypropylene membranes even further to a rate of 19 ± 4 μmol cm(-2) min(-1) per layer of microbial CA. The LbL treatment of these membranes increased the mass transfer resistance of the membrane but decreased the likelihood of membrane pore wetting. These results have potential application in the absorption of carbon dioxide from combustion flue gases into aqueous solvents using gas-liquid membrane contactors. PMID:25984966

  1. Carbonic anhydrase enzyme as a potential therapeutic target for experimental trichinellosis.

    Science.gov (United States)

    Saad, Abeer E; Ashour, Dalia S; Abou Rayia, Dina M; Bedeer, Asmaa E

    2016-06-01

    Trichinellosis is a globally distributed helminthic infection. There is a considerable interest in developing new anti-helminthic drugs affecting all the developmental stages of Trichinella. Acetazolamide (carbonic anhydrase (CA) inhibitor) involves a novel mechanism of action by inhibiting such an essential enzyme for parasite metabolism. This work aimed to study the effect of acetazolamide against different stages of T. spiralis in experimental animals. Mice were divided into three groups: group I: infected and treated with acetazolamide on day 2 post infection (P.I.), group II: infected and treated with acetazolamide on day 12 P.I., and group III: infected non-treated. From each group, small intestine and muscles were removed for histopathological and immunohistochemical studies. Also, total adult and muscle larval count were estimated. We found that acetazolamide was effective in reduction of both adult and muscle larval counts. When given early, the effect was more pronounced on the adults (62.7 %). However, the efficacy of the drug against muscle larvae was increased when given late (63 %). Improvement of the intestinal histopathological changes was observed in all the treated groups. Degeneration of encysted larvae with minimal pathologic changes of infected skeletal muscle was observed in the treated groups. Expression of matrix metalloproteinase-9 showed a statistically significant decrease in the intestinal and muscle tissues in all treated groups as compared to the control group. In conclusion, the present study revealed that acetazolamide, carbonic anhydrase inhibitor, could be a promising drug against both adults and larvae of T. spiralis. PMID:26979731

  2. Monothiocarbamates Strongly Inhibit Carbonic Anhydrases in Vitro and Possess Intraocular Pressure Lowering Activity in an Animal Model of Glaucoma.

    Science.gov (United States)

    Vullo, Daniela; Durante, Mariaconcetta; Di Leva, Francesco Saverio; Cosconati, Sandro; Masini, Emanuela; Scozzafava, Andrea; Novellino, Ettore; Supuran, Claudiu T; Carta, Fabrizio

    2016-06-23

    A series of monothiocarbamates (MTCs) were prepared from primary/secondary amines and COS as potential carbonic anhydrase (CA, EC 4.2.1.1) inhibitors, using the dithiocarbamates, the xanthates, and the trithiocarbonates as lead compounds. The MTCs effectively inhibited the pharmacologically relevant human (h) hCAs isoforms I, II, IX, and XII in vitro and showed KIs spanning between the low and medium nanomolar range. By means of a computational study, the MTC moiety binding mode on the CAs was explained. Furthermore, a selection of MTCs were evaluated in a normotensive glaucoma rabbit model for their intraocular pressure (IOP) lowering effects and showed interesting activity. PMID:27253845

  3. Carbonic anhydrase levels and internal lacunar CO/sub 2/ concentrations in aquatic macrophytes

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, C.I.

    1979-01-01

    Carbonic anhydrase levels were examined in a variety of aquatic macrophytes from different habitats. In general, carbonic anhydrase levels increased across the habitat gradient such that activities were low in submersed aquatic macrophytes and high in emergent macrophytes with floating-leaved and free-floating plants exhibiting intermediate activities. Internal lacunar CO/sub 2/ concentrations were analyzed in relation to carbonic anhydrase activities. There was no correlation between these two parameters. Internal CO/sub 2/ concentrations ranged from low to high in submersed macrophytes, but were low in floating-leaved and emergent macrophytes. The observed internal CO/sub 2/ concentrations are discussed in relation to the individual morphologies of the plants and the environments in which they occurred.

  4. Carbonic anhydrase-related protein XI: structure of the gene in the greater false vampire bat (Megaderma lyra) compared with human and domestic pig.

    Science.gov (United States)

    Porter, Calvin A; Hewett-Emmett, David; Tashian, Richard E

    2013-06-01

    Carbonic anhydrase-related protein XI (CA-RP XI) is a member of the α-carbonic anhydrase family (encoded by the gene CA-11), which has lost features of the active site required for enzymatic activity. Using PCR, we amplified CA-11 from genomic DNA of the bat Megaderma lyra. To elucidate the gene structure, we sequenced PCR products and compared their sequences with genomic and mRNA sequences known from human and domestic pig. We identified and sequenced eight introns in the bat CA-11. Five introns (introns 3-7) are located in identical or similar positions in other members of the vertebrate α-carbonic anhydrase gene family. Two 5' introns and one 3' intron are located in the regions of little or no sequence similarity with other members of the gene family. The low sequence similarity and additional introns suggest a separate evolutionary origin for the 5' and 3' portions of the CA-RP XI gene. PMID:23417223

  5. Activity and stability of immobilized carbonic anhydrase for promoting CO2 absorption into a carbonate solution for post-combustion CO2 capture

    Science.gov (United States)

    Zhang, S.; Zhang, Z.; Lu, Y.; Rostam-Abadi, M.; Jones, A.

    2011-01-01

    An Integrated Vacuum Carbonate Absorption Process (IVCAP) currently under development could significantly reduce the energy consumed when capturing CO2 from the flue gases of coal-fired power plants. The biocatalyst carbonic anhydrase (CA) has been found to effectively promote the absorption of CO2 into the potassium carbonate solution that would be used in the IVCAP. Two CA enzymes were immobilized onto three selected support materials having different pore structures. The thermal stability of the immobilized CA enzymes was significantly greater than their free counterparts. For example, the immobilized enzymes retained at least 60% of their initial activities after 90days at 50??C compared to about 30% for their free counterparts under the same conditions. The immobilized CA also had significantly improved resistance to concentrations of sulfate (0.4M), nitrate (0.05M) and chloride (0.3M) typically found in flue gas scrubbing liquids than their free counterparts. ?? 2011 Elsevier Ltd.

  6. Synthesis and Evaluation of New Phthalazine Urea and Thiourea Derivatives as Carbonic Anhydrase Inhibitors

    Directory of Open Access Journals (Sweden)

    Nurcan Berber

    2013-01-01

    Full Text Available A new series of phthalazine substituted urea and thiourea derivatives were synthesized, and their inhibitory effects on the activity of purified human carbonic anhydrases (hCAs I and II were evaluated. 2H-Indazolo[2,1-b]phthalazine-trione derivative (1 was prepared with 4-nitrobenzaldehyde, dimedone, and phthalhydrazide in the presence of TFA in DMF, and nitro group was reduced to amine derivative (2 with SnCl2·2H2O. The compound was reacted with isocyanates and isothiocyanates to get the final products (3a–p. The results showed that all the synthesized compounds inhibited the CA isoenzymes activity. 3a (IC50 = 6.40 µM for hCA I and 6.13 µM for hCA II has the most inhibitory effect. The synthesized compounds are very bulky to be able to bind near the zinc ion, and they much more probably bind as the coumarin derivatives.

  7. Indazole, Pyrazole, and Oxazole Derivatives Targeting Nitric Oxide Synthases and Carbonic Anhydrases.

    Science.gov (United States)

    Maccallini, Cristina; Di Matteo, Mauro; Vullo, Daniela; Ammazzalorso, Alessandra; Carradori, Simone; De Filippis, Barbara; Fantacuzzi, Marialuigia; Giampietro, Letizia; Pandolfi, Assunta; Supuran, Claudiu T; Amoroso, Rosa

    2016-08-19

    Nitric oxide (NO) is an essential endogenous mediator with a physiological role in the central nervous system as neurotransmitter and neuromodulator. A growing number of studies have demonstrated that abnormal nitrergic signaling is a crucial event in the development of neurodegeneration. In particular, the uncontrolled production of NO by neuronal nitric oxide synthase (nNOS) is observed in several neurodegenerative diseases. Moreover, it is well recognized that specific isoforms of human carbonic anhydrase (hCA) physiologically modulate crucial pathways of signal processing and that low expression of CA affects cognition, leading to mental retardation, Alzheimer's disease, and aging-related cognitive impairments. In light of this, dual agents that are able to target both NOS (inhibition) and CA (activation) could be useful drug candidates for the treatment of Alzheimer's disease, aging, and other neurodegenerative diseases. In the present work, we show the design, synthesis, and in vitro biological evaluation of new nitrogen-based heterocyclic compounds. Among the tested molecules, 2-amino-3-(4-hydroxyphenyl)-N-(1H-indazol-5-yl)propanamide hydrochloride (10 b) was revealed to be a potent dual agent, able to act as a selective nNOS inhibitor and activator of the hCA I isoform. PMID:27377568

  8. Anion inhibition studies of the β-carbonic anhydrase from the pathogenic bacterium Vibrio cholerae.

    Science.gov (United States)

    Vullo, Daniela; Del Prete, Sonia; De Luca, Viviana; Carginale, Vincenzo; Ferraroni, Marta; Dedeoglu, Nurcan; Osman, Sameh M; AlOthman, Zeid; Capasso, Clemente; Supuran, Claudiu T

    2016-03-01

    The genome of the pathogenic bacterium Vibrio cholerae encodes for three carbonic anhydrases (CAs, EC 4.2.1.1) belonging to the α-, β- and γ-classes. Here we report and anion inhibition study of the β-CA, VchCAβ with anions and other small molecules which inhibit metalloenzymes. The best VchCAβ anion inhibitors were sulfamide, sulfamate, phenylboronic acid and phenylarsonic acid, which showed KIs in the range of 54-86μM. Diethyldithiocarbonate was also an effective VchCAβ inhibitor, with an inhibition constant of 0.73mM. The halides, cyanate, thiocyanate, cyanide, bicarbonate, carbonate, nitrate, nitrite, stannate, selenate, tellurate, divanadate, tetraborate, perrhenate, perruthenate, peroxydisulfate, selenocyanide, trithiocarbonate, and fluorosulfonate showed affinity in the low millimolar range, with KIs of 2.3-9.5mM. Identification of selective inhibitors of VchCAβ (over the human CA isoforms) may lead to pharmacological tools useful for understanding the physiological role(s) of this under-investigated enzyme. PMID:26853167

  9. Anion inhibition profiles of the complete domain of the η-carbonic anhydrase from Plasmodium falciparum.

    Science.gov (United States)

    Del Prete, Sonia; Vullo, Daniela; De Luca, Viviana; Carginale, Vincenzo; di Fonzo, Pietro; Osman, Sameh M; AlOthman, Zeid; Supuran, Claudiu T; Capasso, Clemente

    2016-09-15

    We have cloned, purified and investigated the catalytic activity and anion inhibition profiles of a full catalytic domain (358 amino acid residues) carbonic anhydrase (CA, EC 4.2.1.1) from Plasmodium falciparum, PfCAdom, an enzyme belonging to the η-CA class and identified in the genome of the malaria-producing protozoa. A truncated such enzyme, PfCA1, containing 235 residues was investigated earlier for its catalytic and inhibition profiles. The two enzymes were efficient catalysts for CO2 hydration: PfCAdom showed a kcat of 3.8×10(5)s(-1) and kcat/Km of 7.2×10(7)M(-1)×s(-1), whereas PfCA showed a lower activity compared to PfCAdom, with a kcat of 1.4×10(5)s(-1) and kcat/Km of 5.4×10(6)M(-1)×s(-1). PfCAdom was generally less inhibited by most anions and small molecules compared to PfCA1. The best PfCAdom inhibitors were sulfamide, sulfamic acid, phenylboronic acid and phenylarsonic acid, which showed KIs in the range of 9-68μM, followed by bicarbonate, hydrogensulfide, stannate and N,N-diethyldithiocarbamate, which were submillimolar inhibitors, with KIs in the range of 0.53-0.97mM. Malaria parasites CA inhibition was proposed as a new strategy to develop antimalarial drugs, with a novel mechanism of action. PMID:27480028

  10. Structural insight into activity enhancement and inhibition of H64A carbonic anhydrase II by imidazoles

    Directory of Open Access Journals (Sweden)

    Mayank Aggarwal

    2014-03-01

    Full Text Available Human carbonic anhydrases (CAs are zinc metalloenzymes that catalyze the hydration and dehydration of CO2 and HCO3−, respectively. The reaction follows a ping-pong mechanism, in which the rate-limiting step is the transfer of a proton from the zinc-bound solvent (OH−/H2O in/out of the active site via His64, which is widely believed to be the proton-shuttling residue. The decreased catalytic activity (∼20-fold lower with respect to the wild type of a variant of CA II in which His64 is replaced with Ala (H64A CA II can be enhanced by exogenous proton donors/acceptors, usually derivatives of imidazoles and pyridines, to almost the wild-type level. X-ray crystal structures of H64A CA II in complex with four imidazole derivatives (imidazole, 1-methylimidazole, 2-methylimidazole and 4-methylimidazole have been determined and reveal multiple binding sites. Two of these imidazole binding sites have been identified that mimic the positions of the `in' and `out' rotamers of His64 in wild-type CA II, while another directly inhibits catalysis by displacing the zinc-bound solvent. The data presented here not only corroborate the importance of the imidazole side chain of His64 in proton transfer during CA catalysis, but also provide a complete structural understanding of the mechanism by which imidazoles enhance (and inhibit when used at higher concentrations the activity of H64A CA II.

  11. Sclerostin regulates release of bone mineral by osteocytes by induction of carbonic anhydrase 2.

    Science.gov (United States)

    Kogawa, Masakazu; Wijenayaka, Asiri R; Ormsby, Renee T; Thomas, Gethin P; Anderson, Paul H; Bonewald, Lynda F; Findlay, David M; Atkins, Gerald J

    2013-12-01

    The osteocyte product sclerostin is emerging as an important paracrine regulator of bone mass. It has recently been shown that osteocyte production of receptor activator of NF-κB ligand (RANKL) is important in osteoclastic bone resorption, and we reported that exogenous treatment of osteocytes with sclerostin can increase RANKL-mediated osteoclast activity. There is good evidence that osteocytes can themselves liberate mineral from bone in a process known as osteocytic osteolysis. In the current study, we investigated sclerostin-stimulated mineral dissolution by human primary osteocyte-like cells (hOCy) and mouse MLO-Y4 cells. We found that sclerostin upregulated osteocyte expression of carbonic anhydrase 2 (CA2/Car2), cathepsin K (CTSK/Ctsk), and tartrate-resistant acid phosphatase (ACP5/Acp5). Because acidification of the extracellular matrix is a critical step in the release of mineral from bone, we further examined the regulation by sclerostin of CA2. Sclerostin stimulated CA2 mRNA and protein expression in hOCy and in MLO-Y4 cells. Sclerostin induced a decrease in intracellular pH (pHi) in both cell types as well as a decrease in extracellular pH (pHo) and the release of calcium ions from mineralized substrate. These effects were reversed in the co-presence of the carbonic anhydrase inhibitor, acetozolamide. Car2-siRNA knockdown in MLO-Y4 cells significantly inhibited the ability of sclerostin to both reduce the pHo and release calcium from a mineralized substrate. Knockdown in MLO-Y4 cells of each of the putative sclerostin receptors, Lrp4, Lrp5 and Lrp6, using siRNA, inhibited the sclerostin induction of Car2, Catk and Acp5 mRNA, as well as pHo and calcium release. Consistent with this activity of sclerostin resulting in osteocytic osteolysis, human trabecular bone samples treated ex vivo with recombinant human sclerostin for 7 days exhibited an increased osteocyte lacunar area, an effect that was reversed by the co-addition of acetozolamide. These findings

  12. Structures of murine carbonic anhydrase IV and human carbonic anhydrase II complexed with brinzolamide: molecular basis of isozyme-drug discrimination.

    OpenAIRE

    Stams, T.; Y. Chen; Boriack-Sjodin, P. A.; Hurt, J. D.; Liao, J; May, J. A.; Dean, T.; Laipis, P; Silverman, D. N.; Christianson, D. W.

    1998-01-01

    Carbonic anhydrase IV (CAIV) is a membrane-associated enzyme anchored to plasma membrane surfaces by a phosphatidylinositol glycan linkage. We have determined the 2.8-angstroms resolution crystal structure of a truncated, soluble form of recombinant murine CAIV. We have also determined the structure of its complex with a drug used for glaucoma therapy, the sulfonamide inhibitor brinzolamide (Azopt). The overall structure of murine CAIV is generally similar to that of human CAIV; however, some...

  13. Effects of carbonyl sulfide (COS) and carbonic anhydrase on stomatal conductance

    Science.gov (United States)

    Yakir, D.; Stimler, K.; Berry, J. A.

    2011-12-01

    The potential use of COS as tracer of the gross, one-way, CO2 flux into plants is based on its co-diffusion with CO2 into leaves without outflux stimulated research on COS-CO2 interactions during leaf gas exchange. We carried out gas exchange measurements of COS and CO2 in 22 plant species representing deciduous and evergreen trees, grasses, and shrubs, under a range of light intensities and ambient COS concentrations, using mid IR laser spectroscopy. A narrow range in the normalized ratio of the net uptake rates of COS (As) and CO2 (Ac; As/Ac*[CO2]/[COS]) was observed, with a mean value of 1.61±0.26. These results reflect the dominance of stomatal conductance over both COS and CO2 uptake, imposing a relatively constant ratio between the two fluxes (except under low light conditions when CO2, but not COS, metabolism is light limited). A relatively constant ratio under common ambient conditions will facilitate the application of COS as a tracer of gross photosynthesis from leaf to global scales. However, its effect on stomatal conductance may require a special attention. Increasing COS concentrations between 250 and 2800 pmol mol-1 (enveloping atmospheric levels) seems to stimulate stomatal conductance. We examined the stimulation of conductance by COS in a range of species and show that there is a large variation with some species showing almost no response while others are highly responsive (up to doubling stomatal conductance). Using C3 and C4 plants with antisense lines abolishing carbonic anhydrase activity, we show that the activity of this enzyme is essential for both the uptake of COS and the enhancement of stomatal conductance by COS. Since carbonic anhydrase catalyzes the conversion of COS to CO2 and H2S it seems likely that the stomata are responding to H2S produced in the mesophyll. In all natural species examined the uptake of COS and CO2 were highly correlated, and there was no relationship between the sensitivity of stomata and the rate of COS uptake

  14. DNA cloning, characterization, and inhibition studies of an α-carbonic anhydrase from the pathogenic bacterium Vibrio cholerae.

    Science.gov (United States)

    Del Prete, Sonia; Isik, Semra; Vullo, Daniela; De Luca, Viviana; Carginale, Vincenzo; Scozzafava, Andrea; Supuran, Claudiu T; Capasso, Clemente

    2012-12-13

    We have cloned, purified, and characterized an α-carbonic anhydrase (CA, EC 4.2.1.1) from the human pathogenic bacterium Vibrio cholerae, VchCA. The new enzyme has significant catalytic activity, and an inhibition study with sulfonamides and sulfamates led to the detection of a large number of low nanomolar inhibitors, among which are methazolamide, acetazolamide, ethoxzolamide, dorzolamide, brinzolamide, benzolamide, and indisulam (KI values in the range 0.69-8.1 nM). As bicarbonate is a virulence factor of this bacterium and since ethoxzolamide was shown to inhibit the in vivo virulence, we propose that VchCA may be a target for antibiotic development, exploiting a mechanism of action rarely considered until now. PMID:23181552

  15. Carboxysomal carbonic anhydrases: Structure and role in microbial CO2 fixation

    Energy Technology Data Exchange (ETDEWEB)

    Cannon, Gordon C.; Heinhorst, Sabine; Kerfeld, Cheryl A.

    2010-06-23

    Cyanobacteria and some chemoautotrophic bacteria are able to grow in environments with limiting CO2 concentrations by employing a CO2-concentrating mechanism (CCM) that allows them to accumulate inorganic carbon in their cytoplasm to concentrations several orders of magnitude higher than that on the outside. The final step of this process takes place in polyhedral protein microcompartments known as carboxysomes, which contain the majority of the CO2-fixing enzyme, RubisCO. The efficiency of CO2 fixation by the sequestered RubisCO is enhanced by co-localization with a specialized carbonic anhydrase that catalyzes dehydration of the cytoplasmic bicarbonate and ensures saturation of RubisCO with its substrate, CO2. There are two genetically distinct carboxysome types that differ in their protein composition and in the carbonic anhydrase(s) they employ. Here we review the existing information concerning the genomics, structure and enzymology of these uniquely adapted carbonic anhydrases, which are of fundamental importance in the global carbon cycle.

  16. Synthesis and carbonic anhydrase inhibitory properties of amino acid - coumarin/quinolinone conjugates incorporating glycine, alanine and phenylalanine moieties.

    Science.gov (United States)

    Küçükbay, F Zehra; Küçükbay, Hasan; Tanc, Muhammet; Supuran, Claudiu T

    2016-12-01

    N-Protected amino acids (Gly, Ala and Phe) were reacted with amino substituted coumarin and quinolinone derivatives, leading to the corresponding N-protected amino acid-coumarin/quinolinone conjugates. The carbonic anhydrase (CA, EC 4.2.1.1) inhibitory activity of the new compounds was assessed against various human (h) isoforms, such as hCA I, hCA II, hCA IV and hCA XII. The quinolinone conjugates were inactive as enzyme inhibitors, whereas the coumarins were ineffective hCA I/II inhibitors (KIs > 50 μM) but were submicromolar hCA IV and XII inhibitors, with inhibition constants ranging between 92 nM and 1.19 μM for hCA IV, and between 0.11 and 0.79 μM for hCA XII. These coumarin derivatives, as many others reported earlier, thus show an interesting selective inhibitory profile for the membrane-bound over the cytosolic CA isoforms.

  17. Identification of two carbonic anhydrases in the mantle of the European Abalone Haliotis tuberculata (Gastropoda, Haliotidae): phylogenetic implications.

    Science.gov (United States)

    LE Roy, Nathalie; Marie, Benjamin; Gaume, Béatrice; Guichard, Nathalie; Delgado, Sidney; Zanella-Cléon, Isabelle; Becchi, Michel; Auzoux-Bordenave, Stéphanie; Sire, Jean-Yves; Marin, Frédéric

    2012-07-01

    Carbonic anhydrases (CAs) represent a diversified family of metalloenzymes that reversibly catalyze the hydration of carbon dioxide. They are involved in a wide range of functions, among which is the formation of CaCO(3) skeletons in metazoans. In the shell-forming mantle tissues of mollusks, the location of the CA catalytic activity is elusive and gives birth to contradicting views. In the present paper, using the European abalone Haliotis tuberculata, a key model gastropod in biomineralization studies, we identified and characterized two CAs (htCA1 and htCA2) that are specific of the shell-forming mantle tissue. We analyzed them in a phylogenetic context. Combining various approaches, including proteomics, activity tests, and in silico analyses, we showed that htCA1 is secreted but is not incorporated in the organic matrix of the abalone shell and that htCA2 is transmembrane. Together with previous studies dealing with molluskan CAs, our findings suggest two possible modes of action for shell mineralization: the first mode applies to, for example, the bivalves Unio pictorum and Pinctada fucata, and involves a true CA activity in their shell matrix; the second mode corresponds to, for example, the European abalone, and does not include CA activity in the shell matrix. Our work provides new insight on the diversity of the extracellular macromolecular tools used for shell biomineralization study in mollusks.

  18. Complexes With Biologically Active Ligands. Part 4. Coordination Compounds of Chlorothiazide With Transition Metal Ions Behave as Strong Carbonic Anhydrase Inhibitors

    OpenAIRE

    Supuran, Claudiu T.

    1996-01-01

    Complexes of the diuretic benzothiadiazine derivative chlorothiazide (6-chloro-7-sulfamoyl- 1,2,4-benzothiadiazine-1,1-dioxide) with V(IV); Fe(II); Co(II); Ni(II); Cu(II), Ag(I) and U(VI) were prepared and characterized by elemental analysis, spectroscopic, thermogravimetric, magnetic and conductimetric measurements. The complexes behave as effective inhibitors for two isozymes (I and II) of carbonic anhydrase (CA).

  19. Immunocytochemical localization of carbonic anhydrase in the pseudobranch tissue of the rainbow trout Oncorhynchus mykiss

    Institute of Scientific and Technical Information of China (English)

    S. M. RAHIM; A. G. MAZLAN; K. D. SIMON; J. P. DELAUNOY; P. LAURENT

    2014-01-01

    本文题目:虹鳟假鳃组织中的碳酸酐酶免疫细胞化学定位Immunocytochemical localization of carbonic anhydrase in the pseudobranch tissue of the rainbow trout Oncorhynchus mykiss研究目的:假腮的功能早已引起科学家兴趣,但还有待阐明。本文通过研究硬骨鱼类品种虹鳟鱼(Oncorhynchus mykiss)的假腮碳酸酐酶的免疫定位,来探讨假腮碳酸酐酶的生理功能。研究方法:免疫组织化学染色技术。重要结论:免疫组化结果显示碳酸酐酶分布在假腮细胞中,更精确地说是在其细胞顶端分布。细胞基底端、管状系统、毛细血管和柱细胞均无免疫染色。免疫细胞化学定位进一步验证了这些结果,并显示一部分是细胞质碳酸酐酶,其余的与细胞膜结构连接。此外,腔隙层未显示出免疫过氧化物酶的活性。本研究揭示了假腮碳酸酐酶的功能与细胞外介质有关,碳酸酐酶能干预传入神经纤维刺激机制。%Pseudobranch function has long interested scientists, but its role has yet to be elucidated. Several studies have suggested that pseudobranchs serve respiratory, osmoregulatory, and sensory functions. This work investigated the immunolocalization of pseudobranch carbonic anhydrase (CA) in the teleost fish species rainbow trout (Oncor-hynchus mykiss) to clarify its physiological function. CA was purified from rainbow trout gil s O. mykiss and specific antibodies were raised. Immunoblotting between tissue homogenates of pseudobranch and gil CA antibodies showed specific immunostaining with only one band corresponding to CA in the pseudobranch homogenate. Results of im-munohistochemical technique revealed that CA was distributed within pseudobranch cells and more precisely in the apical parts (anti-vascular) of cells. The basal (vascular) parts of cells, tubular system, blood capillaries, and pillar cells were not immunostained. Immunocytochemistry confirmed these results and

  20. Fluorescent sulfonamide carbonic anhydrase inhibitors incorporating 1,2,3-triazole moieties: Kinetic and X-ray crystallographic studies.

    Science.gov (United States)

    Carta, Fabrizio; Ferraroni, Marta; Scozzafava, Andrea; Supuran, Claudiu T

    2016-01-15

    Fluorescent sulfonamide carbonic anhydrase (CA, EC 4.2.1.1) inhibitors (CAIs) were essential for demonstrating the role played by the tumor-associated isoform CA IX in acidification of tumors, cancer progression towards metastasis and for the development of imaging and therapeutic strategies for the management of hypoxic tumors which overexpress CA IX. However, the presently available such compounds are poorly water soluble which limits their use. Here we report new fluorescent sulfonamides 7, 8 and 10 with increased water solubility. The new derivatives showed poor hCA I inhibitory properties, but were effective inhibitors against the hCA II (KIs of 366-127 nM), CA IX (KIs of 8.1-36.9 nM), CA XII (KIs of 4.1-20.5 nM) and CA XIV (KIs of 12.8-53.6 nM). A high resolution X-ray crystal structure of one of these compounds bound to hCA II revealed the factors associated with the good inhibitory properties. Furthermore, this compound showed a three-fold increase of water solubility compared to a similar derivative devoid of the triazole moiety, making it an interesting candidate for ex vivo/in vivo studies. PMID:26682703

  1. Characterization of an Alpha Type Carbonic Anhydrase from Paracentrotus lividus Sea Urchin Embryos.

    Science.gov (United States)

    Karakostis, Konstantinos; Costa, Caterina; Zito, Francesca; Brümmer, Franz; Matranga, Valeria

    2016-06-01

    Carbonic anhydrases (CA) are zinc metalloenzymes that catalyze the reversible hydration of carbon dioxide to bicarbonate. In the sea urchin, CA has a role in the formation of the calcitic skeleton during embryo development. Here, we report a newly identified mRNA sequence from embryos of the sea urchin Paracentrotus lividus, referred to as Pl-can. The complete coding sequence was identified with the aid of both EST databases and experimental procedures. Pl-CAN is a 447 aa-long protein, with an estimated molecular mass of 48.5 kDa and an isoelectric point of 6.83. The in silico study of functional domains showed, in addition to the alpha type CA-specific domain, the presence of an unexpected glycine-rich region at the N-terminal of the molecule. This is not found in any other species described so far, but probably it is restricted to the sea urchins. The phylogenetic analysis indicated that Pl-CAN is evolutionarily closer to human among chordates than to other species. The putative role(s) of the identified domains is discussed. The Pl-can temporal and spatial expression profiles, analyzed throughout embryo development by comparative qPCR and whole-mount in situ hybridization (WMISH), showed that Pl-can mRNA is specifically expressed in the primary mesenchyme cells (PMC) of the embryo and levels increase along with the growth of the embryonic skeleton, reaching a peak at the pluteus stage. A recombinant fusion protein was produced in E. coli and used to raise specific antibodies in mice recognized the endogenous Pl-CAN by Western blot in embryo extracts from gastrula and pluteus. PMID:27230618

  2. Variable involvement of the perivascular retinal tissue in carbonic anhydrase inhibitor induced relaxation of porcine retinal arterioles in vitro

    DEFF Research Database (Denmark)

    Kehler, Anne Katrine; Holmgaard, Kim; Hessellund, Anders;

    2007-01-01

    PURPOSE: Inhibition of carbonic anhydrase in the eye is an important treatment modality for reducing the intraocular pressure in glaucoma. However, evidence suggests that carbonic anhydrase inhibition also exerts a relaxing effect on the vessels in the optic nerve, and it has been suggested......, and the vasodilating effect of acetazolamide almost disappeared. CONCLUSIONS: A further elucidation of the mechanisms of action of carbonic anhydrase-induced dilation of retinal arterioles may contribute to a better understanding of the regulation of retinal blood flow. The perivascular retinal tissue may play...... a significant role in diameter control of retinal arterioles. Udgivelsesdato: 2007-Oct...

  3. Expression and Activity of Carbonic Anhydrase IX Is Associated With Metabolic Dysfunction in MDA-MB-231 Breast Cancer Cells

    OpenAIRE

    Ying LI; Wang, Hai; Oosterwijk, Egbert; Tu, Chingkuang; Shiverick, Kathleen T.; Silverman, David N.; Frost, Susan C.

    2009-01-01

    The expression of carbonic anhydrase IX (CAIX), a marker for hypoxic tumors, is correlated with poor prognosis in breast cancer patients. We show herein that the MDA-MB-231 cells, a “triple-negative,” basal B line, express exclusively CAIX, while a luminal cell line (T47D) expresses carbonic anhydrase XII (CAXII). CAIX expression in the basal B cells is both density-and hypoxia-dependent and is correlated with carbonic anhydrase activity. Evidence is provided that CAIX contributes to extracel...

  4. Biochemical and developmental characterization of carbonic anhydrase II from chicken erythrocytes

    Directory of Open Access Journals (Sweden)

    Orito Kensuke

    2011-03-01

    Full Text Available Abstract Background Carbonic anhydrase (CA of the chicken has attracted attention for a long time because it has an important role in the eggshell formation. The developmental profile of CA-II isozyme levels in chicken erythrocytes has not been determined or reported. Furthermore, the relations with CA-II in erythrocyte and egg production are not discussed. In the present study, we isolated CA-II from erythrocytes of chickens and determined age-related changes of CA-II levels in erythrocytes. Methods Chicken CA-II was purified by a combination of column chromatography. The levels of CA-II in the hemolysate of the chicken were determined using the ELISA system in blood samples from 279 female chickens, ages 1 to 93 weeks, 69 male chickens, ages 3 to 59 weeks and 52 weeks female Araucana-chickens. Results The mean concentration of CA-II in hemolysate from 1-week-old female was 50.8 ± 11.9 mg/g of Hb. The mean levels of CA-II in 25-week-old (188.1 ± 82.6 mg/g of Hb, 31-week-old (193.6 ± 69.7 mg/g of Hb and 49-week-old (203.8 ± 123.5 mg/g of Hb female-chickens showed the highest level of CA-II. The levels of CA-II in female WL-chickens significantly decreased at 63 week (139.0 ± 19.3 mg/g of Hb. The levels of CA-II in female WL-chicken did not change from week 63 until week 93.The mean level of CA-II in hemolysate of 3-week-old male WL-chickens was 78.3 ± 20.7 mg/g of Hb. The levels of CA-II in male WL-chickens did not show changes in the week 3 to week 59 timeframe. The mean level of CA-II in 53-week-old female Araucana-chickens was 23.4 ± 1.78 mg/g of Hb. These levels of CA-II were about 11% of those of 49-week-old female WL-chickens. Simple linear regression analysis showed significant associations between the level of CA-II and egg laying rate from 16 week-old at 63 week-old WL-chicken (p Conclusions Developmental changes and sexual differences of CA-II concentration in WL-chicken erythrocytes were observed. The concentration of CA-II in

  5. Metal Complexes of 1,3,4-Thiadiazole-2,5-Disulfonamide are Strong Dual Carbonic Anhydrase Inhibitors, although the Ligand Possesses very Weak such Properties

    Science.gov (United States)

    Supuran, Claudiu T.

    1995-01-01

    Coordination compounds of Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) with 1,3,4-thiadiazole-2,5-disulfonamide as ligand were synthesized and characterized by IR and UV spectroscopy, conductimetry and thermogravimetry. The parent ligand is a very weak carbonic anhydrase (CA) inhibitor, although it constituted the lead for developing important classes of diuretics. The complex derivatives behave as much stronger CA inhibitors, with IC50 values around 10−8M against isozyme CA II, and 10−7 M against isozyme CAI. PMID:18472784

  6. Metal Complexes of 1,3,4-Thiadiazole-2,5-Disulfonamide are Strong Dual Carbonic Anhydrase Inhibitors, although the Ligand Possesses very Weak such Properties.

    Science.gov (United States)

    Supuran, C T

    1995-01-01

    Coordination compounds of Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) with 1,3,4-thiadiazole-2,5-disulfonamide as ligand were synthesized and characterized by IR and UV spectroscopy, conductimetry and thermogravimetry. The parent ligand is a very weak carbonic anhydrase (CA) inhibitor, although it constituted the lead for developing important classes of diuretics. The complex derivatives behave as much stronger CA inhibitors, with IC(50) values around 10(-8)M against isozyme CA II, and 10(-7) M against isozyme CAI.

  7. Cloning, expression, purification and sulfonamide inhibition profile of the complete domain of the η-carbonic anhydrase from Plasmodium falciparum.

    Science.gov (United States)

    Del Prete, Sonia; Vullo, Daniela; De Luca, Viviana; Carginale, Vincenzo; Osman, Sameh M; AlOthman, Zeid; Supuran, Claudiu T; Capasso, Clemente

    2016-09-01

    We report the cloning, purification and characterization of the full domain of carbonic anhydrase (CA, EC 4.2.1.1) from Plasmodium falciparum, which incorporates 358 amino acid residues (from 181 to 538, in the sequence of this 600 amino acid long protein), called PfCAdom. The enzyme, which belongs to the η-CA class showed the following kinetic parameters: kcat of 3.8×10(5)s(-1) and kcat/Km of 7.2×10(7)M(-1)×s(-1), being 13.3 times more effective as a catalyst compared to the truncated form PfCA. PfCAdom is more effective than the human (h) isoform hCA I, being around 50% less effective compared to hCA II, one of the most catalytically efficient enzymes known so far. Intriguingly, the sulfonamides CA inhibitors generally showed much weaker inhibitory activity against PfCAdom compared to PfCA, prompting us to hypothesize that the 69 amino acid residues insertion present in the active site of this η-CA is crucial for the active site architecture. The best sulfonamide inhibitors for PfCAdom were acetazolamide, methazolamide, metanilamide and sulfanilamide, with KIs in the range of 366-808nM. PMID:27485387

  8. Expression of proteins encoded by the Escherichia coli cyn operon: carbon dioxide-enhanced degradation of carbonic anhydrase.

    Science.gov (United States)

    Kozliak, E I; Guilloton, M B; Gerami-Nejad, M; Fuchs, J A; Anderson, P M

    1994-09-01

    Cyanase catalyzes the reaction of cyanate with bicarbonate to give 2CO2. The cynS gene encoding cyanase, together with the cynT gene for carbonic anhydrase, is part of the cyn operon, the expression of which is induced in Escherichia coli by cyanate. The physiological role of carbonic anhydrase is to prevent depletion of cellular bicarbonate during cyanate decomposition due to loss of CO2 (M.B. Guilloton, A.F. Lamblin, E. I. Kozliak, M. Gerami-Nejad, C. Tu, D. Silverman, P.M. Anderson, and J.A. Fuchs, J. Bacteriol. 175:1443-1451, 1993). A delta cynT mutant strain was extremely sensitive to inhibition of growth by cyanate and did not catalyze decomposition of cyanate (even though an active cyanase was expressed) when grown at a low pCO2 (in air) but had a Cyn+ phenotype at a high pCO2. Here the expression of these two enzymes in this unusual system for cyanate degradation was characterized in more detail. Both enzymes were found to be located in the cytosol and to be present at approximately equal levels in the presence of cyanate. A delta cynT mutant strain could be complemented with high levels of expressed human carbonic anhydrase II; however, the mutant defect was not completely abolished, perhaps because the E. coli carbonic anhydrase is significantly less susceptible to inhibition by cyanate than mammalian carbonic anhydrases. The induced E. coli carbonic anhydrase appears to be particularly adapted to its function in cyanate degradation. Active cyanase remained in cells grown in the presence of either low or high pCO2 after the inducer cyanate was depleted; in contrast, carbonic anhydrase protein was degraded very rapidly (minutes) at a high pCO2 but much more slowly (hours) at a low pCO2. A physiological significance of these observations is suggested by the observation that expression of carbonic anhydrase at a high pCO2 decreased the growth rate.

  9. Synthesis of a new series of dithiocarbamates with effective human carbonic anhydrase inhibitory activity and antiglaucoma action.

    Science.gov (United States)

    Bozdag, Murat; Carta, Fabrizio; Vullo, Daniela; Akdemir, Atilla; Isik, Semra; Lanzi, Cecilia; Scozzafava, Andrea; Masini, Emanuela; Supuran, Claudiu T

    2015-05-15

    A new series of dithiocarbamates (DTCs) was prepared from primary/secondary amines incorporating amino/hydroxyl-alkyl, mono- and bicyclic aliphatic ring systems based on the quinuclidine, piperidine, hydroxy-/carboxy-/amino-substituted piperidine, morpholine and piperazine scaffolds, and carbon disulfide. The compounds were investigated for the inhibition of four mammalian α-carbonic anhydrases (CAs, EC 4.2.1.1) of pharmacologic relevance, that is, the human (h) hCA I, II, IX and XII, drug targets for antiglaucoma (hCA II and XII) or antitumor (hCA IX/XII) agents. The compounds were moderate or inefficient hCA I inhibitors (off-target isoform for both applications), efficiently inhibited hCA II, whereas some of them were low nanomolar/subnanomolar hCA IX/XII inhibitors. One DTC showed excellent intraocular pressure (IOP) lowering properties in an animal model of glaucoma, with a two times better efficiency compared to the clinically used sulfonamide dorzolamide. PMID:25846066

  10. Epidermal carbonic anhydrase activity and exoskeletal metal content during the molting cycle of the blue crab, Callinectes sapidus.

    Science.gov (United States)

    Calhoun, Stacy; Zou, Enmin

    2016-03-01

    During the crustacean molting cycle, the exoskeleton is first mineralized in postmolt and intermolt and then presumably demineralized in premolt in order for epidermal retraction to occur. The mineralization process calls for divalent metal ions, such as Ca(2+) and Mg(2+) , and bicarbonate ions whereas protons are necessary for dissolution of carbonate salts. Carbonic anhydrase (CA) has been suggested to be involved in exoskeletal mineralization by providing bicarbonate ions through catalyzing the reaction of carbon dioxide hydration. However, results of earlier studies on the role of epidermal CA in metal incorporation in crustacean exoskeleton are not consistent. This study was aimed to provide further evidence to support the notion that epidermal CA is involved in exoskeletal mineralization using the blue crab, Callinectes sapidus (Rathbun 1896), as the model crustacean. Significant increases first in calcium and magnesium then in manganese post-ecdysis indicate significant metal deposition during postmolt and intermolt. Significant positive correlation between calcium or magnesium content and epidermal CA activity in postmolt and intermolt constitutes evidence that CA is involved in the mineralization of the crustacean exoskeleton. Additionally, we proposed a hypothetical model to describe the role of epidermal CA in both mineralization and demineralization of the exoskeleton based on the results of epidermal CA activity and exoskeletal metal content during the molting cycle. Furthermore, we found that the pattern of epidermal CA activity during the molting cycle of C. sapidus is similar to that of ecdysteroids reported for the same species, suggesting that epidermal CA activity may be under control of the molting hormones. PMID:26935248

  11. Phosphorylation controls the localization and activation of the lumenal carbonic anhydrase in Chlamydomonas reinhardtii.

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    Amaya Blanco-Rivero

    Full Text Available BACKGROUND: Cah3 is the only carbonic anhydrase (CA isoform located in the thylakoid lumen of Chlamydomonas reinhardtii. Previous studies demonstrated its association with the donor side of the photosystem II (PSII where it is required for the optimal function of the water oxidizing complex. However this enzyme has also been frequently proposed to perform a critical function in inorganic carbon acquisition and CO(2 fixation and all mutants lacking Cah3 exhibit very poor growth after transfer to low CO(2 conditions. RESULTS/CONCLUSIONS: In the present work we demonstrate that after transfer to low CO(2, Cah3 is phosphorylated and that phosphorylation is correlated to changes in its localization and its increase in activity. When C. reinhardtii wild-type cells were acclimated to limiting CO(2 conditions, the Cah3 activity increased about 5-6 fold. Under these conditions, there were no detectable changes in the level of the Cah3 polypeptide. The increase in activity was specifically inhibited in the presence of Staurosporine, a protein kinase inhibitor, suggesting that the Cah3 protein was post-translationally regulated via phosphorylation. Immunoprecipitation and in vitro dephosphorylation experiments confirm this hypothesis. In vivo phosphorylation analysis of thylakoid polypeptides indicates that there was a 3-fold increase in the phosphorylation signal of the Cah3 polypeptide within the first two hours after transfer to low CO(2 conditions. The increase in the phosphorylation signal was correlated with changes in the intracellular localization of the Cah3 protein. Under high CO(2 conditions, the Cah3 protein was only associated with the donor side of PSII in the stroma thylakoids. In contrast, in cells grown at limiting CO(2 the protein was partly concentrated in the thylakoids crossing the pyrenoid, which did not contain PSII and were surrounded by Rubisco molecules. SIGNIFICANCE: This is the first report of a CA being post

  12. Sulfonamide inhibition studies of the γ-carbonic anhydrase from the Antarctic bacterium Colwellia psychrerythraea.

    Science.gov (United States)

    Vullo, Daniela; De Luca, Viviana; Del Prete, Sonia; Carginale, Vincenzo; Scozzafava, Andrea; Osman, Sameh M; AlOthman, Zeid; Capasso, Clemente; Supuran, Claudiu T

    2016-02-15

    The Antarctic bacterium Colwellia psychrerythraea encodes for a γ-class carbonic anhydrase (CA, EC 4.2.1.1), which was cloned, purified and characterized. The enzyme (CpsCAγ) has a moderate catalytic activity for the physiologic reaction of CO2 hydration to bicarbonate and protons, with a k(cat) 6.0×10(5) s(-1) and a k(cat)/K(m) of 4.7×10(6) M(-1) s(-1). A series of sulfonamides and a sulfamate were investigated as inhibitors of the new enzyme. The best inhibitor was metanilamide (K(I) of 83.5 nM) followed by indisulam, valdecoxib, celecoxib, sulthiame and hydrochlorothiazide (K(I)s ranging between 343 and 491 nM). Acetazolamide, methazolamide as well as other aromatic/heterocyclic derivatives showed inhibition constants between 502 and 7660 nM. The present study may shed some more light regarding the role that γ-CAs play in the life cycle of psychrophilic bacteria as the Antarctic one investigated here, by allowing the identification of inhibitors which may be useful as pharmacologic tools.

  13. A physiological role for cyanate-induced carbonic anhydrase in Escherichia coli.

    Science.gov (United States)

    Guilloton, M B; Lamblin, A F; Kozliak, E I; Gerami-Nejad, M; Tu, C; Silverman, D; Anderson, P M; Fuchs, J A

    1993-03-01

    Cyanate induces expression of the cyn operon in Escherichia coli. The cyn operon includes the gene cynS, encoding cyanase, which catalyzes the reaction of cyanate with bicarbonate to give ammonia and carbon dioxide. A carbonic anhydrase activity was recently found to be encoded by the cynT gene, the first gene of the cyn operon; it was proposed that carbonic anhydrase prevents depletion of bicarbonate during cyanate decomposition due to loss of CO2 by diffusion out of the cell (M. B. Guilloton, J. J. Korte, A. F. Lamblin, J. A. Fuchs, and P. M. Anderson, J. Biol. Chem. 267:3731-3734, 1992). The function of the product of the third gene of this operon, cynX, is unknown. In the study reported here, the physiological roles of cynT and cynX were investigated by construction of chromosomal mutants in which each of the three genes was rendered inactive. The delta cynT chromosomal mutant expressed an active cyanase but no active carbonic anhydrase. In contrast to the wild-type strain, the growth of the delta cynT strain was inhibited by cyanate, and the mutant strain was unable to degrade cyanate and therefore could not use cyanate as the sole nitrogen source when grown at a partial CO2 pressures (pCO2) of 0.03% (air). At a high pCO2 (3%), however, the delta cynT strain behaved like the wild-type strain; it was significantly less sensitive to the toxic effects of cyanate and could degrade cyanate and use cyanate as the sole nitrogen source for growth. These results are consistent with the proposed function for carbonic anhydrase. The chromosomal mutant carrying cynS::kan expressed induced carbonic anhydrase activity but no active cyanase. The cynS::kan mutant was found to be much less sensitive to cyanate than the delta cynT mutant at a low pCO2, indicating that bicarbonate depletion due to the reaction of bicarbonate with cyanate catalyzed by cyanase is more deleterious to growth than direct inhibition by cyanate. Mutants carrying a nonfunctional cynX gene (cynX::kan and

  14. Downregulation of carbonic anhydrase IX promotes Col10a1 expression in chondrocytes.

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    Toshifumi Maruyama

    Full Text Available Carbonic anhydrase (CA IX is a transmembrane isozyme of CAs that catalyzes reversible hydration of CO(2. While it is known that CA IX is distributed in human embryonic chondrocytes, its role in chondrocyte differentiation has not been reported. In the present study, we found that Car9 mRNA and CA IX were expressed in proliferating but not hypertrophic chondrocytes. Next, we examined the role of CA IX in the expression of marker genes of chondrocyte differentiation in vitro. Introduction of Car9 siRNA to mouse primary chondrocytes obtained from costal cartilage induced the mRNA expressions of Col10a1, the gene for type X collagen α-1 chain, and Epas1, the gene for hypoxia-responsible factor-2α (HIF-2α, both of which are known to be characteristically expressed in hypertrophic chondrocytes. On the other hand, forced expression of CA IX had no effect of the proliferation of chondrocytes or the transcription of Col10a1 and Epas1, while the transcription of Col2a1 and Acan were up-regulated. Although HIF-2α has been reported to be a potent activator of Col10a1 transcription, Epas1 siRNA did not suppress Car9 siRNA-induced increment in Col10a1 expression, indicating that down-regulation of CA IX induces the expression of Col10a1 in chondrocytes in a HIF-2α-independent manner. On the other hand, cellular cAMP content was lowered by Car9 siRNA. Furthermore, the expression of Col10a1 mRNA after Car9 silencing was augmented by an inhibitor of protein kinase A, and suppressed by an inhibitor for phosphodiesterase as well as a brominated analog of cAMP. While these results suggest a possible involvement of cAMP-dependent pathway, at least in part, in induction of Col10a1 expression by down-regulation of Car9, more detailed study is required to clarify the role of CA IX in regulation of Col10a1 expression in chondrocytes.

  15. Significance of different carbon forms and carbonic anhydrase activity in monitoring and prediction of algal blooms in the urban section of Jialing River, Chongqing, China.

    Science.gov (United States)

    Nie, Yudong; Zhang, Zhi; Shen, Qian; Gao, Wenjin; Li, Yingfan

    2016-05-18

    The Three Gorges Dam is one of the largest hydroelectric power plants worldwide; its reservoir was preliminarily impounded in 2003 and finally impounded to 175 m in 2012. The impoundment caused some environmental problems, such as algal blooms. Carbonic anhydrase (CA) is an important biocatalyst in the carbon utilization by algae and plays an important role in algal blooms. CA has received considerable attention for its role in red tides in oceans, but less investigation has been focused on its role in algal blooms in fresh water. In this study, the seasonal variation of water quality parameters, different carbon forms, carbonic anhydrase activity (CAA), and the algal cell density of four sampling sites in the urban section of the Jialing River were investigated from November 1, 2013 to October 31, 2014. Results indicated that CAA exhibited a positive correlation with dissoluble organic carbon (DOC), pH, and temperature, but a negative correlation with CO2 and dissoluble inorganic carbon (DIC). Algal cell density exhibited a positive correlation with flow velocity (V), pH, particulate organic carbon (POC), and CAA, a negative correlation with CO2, and a negative partial correlation with DIC. The relationship between CAA and algal cell density for the entire year can be described as cells = 23.278CAA - 42.666POC + 139.547pH - 1057.106. The algal bloom prediction model for the key control period can be described as cells = -45.895CAA + 776.103V- 29.523DOC + 14.219PIC + 35.060POC + 19.181 (2 weeks in advance) and cells = 69.200CAA + 203.213V + 4.184CO2 + 38.911DOC + 40.770POC - 189.567 (4 weeks in advance). The findings in this study demonstrate that the carbon utilization by algae is conducted by CA and provide a new method of monitoring algal cell density and predicting algal blooms. PMID:27142237

  16. Structural elucidation of the hormonal inhibition mechanism of the bile acid cholate on human carbonic anhydrase II

    Energy Technology Data Exchange (ETDEWEB)

    Boone, Christopher D. [University of Florida, PO Box 100267, Gainesville, FL 32610 (United States); Tu, Chingkuang [University of Florida, PO Box 100245, Gainesville, FL 32610 (United States); McKenna, Robert, E-mail: rmckenna@ufl.edu [University of Florida, PO Box 100267, Gainesville, FL 32610 (United States)

    2014-06-01

    The structure of human carbonic anhydrase II in complex with cholate has been determined to 1.54 Å resolution. Elucidation of the novel inhibition mechanism of cholate will aid in the development of a nonsulfur-containing, isoform-specific therapeutic agent. The carbonic anhydrases (CAs) are a family of mostly zinc metalloenzymes that catalyze the reversible hydration/dehydration of CO{sub 2} into bicarbonate and a proton. Human isoform CA II (HCA II) is abundant in the surface epithelial cells of the gastric mucosa, where it serves an important role in cytoprotection through bicarbonate secretion. Physiological inhibition of HCA II via the bile acids contributes to mucosal injury in ulcerogenic conditions. This study details the weak biophysical interactions associated with the binding of a primary bile acid, cholate, to HCA II. The X-ray crystallographic structure determined to 1.54 Å resolution revealed that cholate does not make any direct hydrogen-bond interactions with HCA II, but instead reconfigures the well ordered water network within the active site to promote indirect binding to the enzyme. Structural knowledge of the binding interactions of this nonsulfur-containing inhibitor with HCA II could provide the template design for high-affinity, isoform-specific therapeutic agents for a variety of diseases/pathological states, including cancer, glaucoma, epilepsy and osteoporosis.

  17. A novel library of saccharin and acesulfame derivatives as potent and selective inhibitors of carbonic anhydrase IX and XII isoforms.

    Science.gov (United States)

    Carradori, Simone; Secci, Daniela; De Monte, Celeste; Mollica, Adriano; Ceruso, Mariangela; Akdemir, Atilla; Sobolev, Anatoly P; Codispoti, Rossella; De Cosmi, Federica; Guglielmi, Paolo; Supuran, Claudiu T

    2016-03-01

    Small libraries of N-substituted saccharin and N-/O-substituted acesulfame derivatives were synthesized and tested as atypical and selective inhibitors of four different isoforms of human carbonic anhydrase (hCA I, II, IX and XII, EC 4.2.1.1). Most of them inhibited hCA XII in the low nanomolar range, hCA IX with KIs ranging between 19 and 2482nM, whereas they were poorly active against hCA II (KIs >10μM) and hCA I (KIs ranging between 318nM and 50μM). Since hCA I and II are ubiquitous off-target isoforms, whereas the cancer-related isoforms hCA IX and XII were recently validated as drug targets, these results represent an encouraging achievement in the development of new anticancer candidates. Moreover, the lack of a classical zinc binding group in the structure of these inhibitors opens innovative, yet unexplored scenarios for different mechanisms of inhibition that could explain the high inhibitory selectivity. A computational approach has been carried out to further rationalize the biological data and to characterize the binding mode of some of these inhibitors. PMID:26810710

  18. Diminished Cellular Immune Response to Carbonic Anhydrase II in Patients with Sjogren's Syndrome and Idiopathic Chronic Pancreatitis

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    Onishi S

    2004-07-01

    Full Text Available CONTEXT: A serum antibody to carbonic anhydrase II has been reported in patients with Sjögren’s syndrome and idiopathic chronic pancreatitis. OBJECTIVE: To evaluate cellular immune response to carbonic anhydrase II in patients with Sjögren’s syndrome and idiopathic chronic pancreatitis. PATIENTS: Idiopathic chronic pancreatitis (n=23, Sjögren’s syndrome (n=12, alcoholic chronic pancreatitis (n=3 and normal controls (n=13. MAIN OUTCOME MEASURES: Proliferation assay of peripheral blood mononuclear cells. RESULTS: Notable increased proliferation of the mononuclear cells upon stimulation with carbonic anhydrase II was observed in 2 patients with idiopathic chronic pancreatitis (9% and 2 patients with Sjögren’s syndrome (17% but not in patients with alcoholic chronic pancreatitis nor in normal controls. Among the four study groups, there was no significant difference in the prevalence rate of the positive proliferative responses (P=0.444. CONCLUSION: Carbonic anhydrase II may not be a major target antigen for the immunological process in the pathogenesis of Sjögren’s syndrome and idiopathic chronic pancreatitis. Serum antibody to carbonic anhydrase II may be detected in these patients as a consequence of the immune reaction against other antigens which mimic carbonic anhydrase II.

  19. [Targeting of type IV carbonic anhydrases in Capan-1 human pancreatic duct cells is concomitant of the polarization].

    Science.gov (United States)

    Mairal, A; Fanjul, M; Hollande, E

    1996-01-01

    Carbonic anhydrases II and IV play an essential role in the synthesis and secretion of HCO3- ions in pancreatic duct cells. Secretion of these ions is regulated by the CFTR (cystic fibrosis transmembrane conductance regulator) chloride channel. In the present study, the expression of carbonic anhydrases IV and their targeting to plasma membranes were examined during the growth of human pancreatic duct cells in vitro. Human cancerous pancreatic duct cells of Capan-1 cell line which polarize during their growth were used. We show that: a) these cells express carbonic anhydrases IV continuously during growth in culture, and the expression depends on the stage of growth and the conformation of the cells; b) carbonic anhydrases IV are seen in the cytoplasm in non-polarized cells, but become progressively anchored to plasma membranes as the cells polarize, being targeted to the apical membranes of polarized cells; c) the subcellular distribution of carbonic anhydrases IV indicates that these enzymes are synthetized in rough endoplasmic reticulum and then transported towards the plasma membrane using the classical secretory pathway through the Golgi apparatus. The results indicated that targeting of carbonic anhydrases IV in Capan-1 cells is linked to cellular polarization. PMID:8881572

  20. Thermodynamics of binding of a sulfonamide inhibitor to metal-mutated carbonic anhydrase as studied by affinity capillary electrophoresis.

    Science.gov (United States)

    Sato, Yosuke; Hoshino, Hitoshi; Iki, Nobuhiko

    2015-09-01

    By affinity capillary electrophoresis (ACE), the thermodynamic binding constants of a sulfonamide (SA) inhibitor to bovine carbonic anhydrase II (CA) and metal mutated variants (M-CAs) were evaluated. 1-(4-Aminosulfonylphenylazo)-2-naphthol-6,8-disulfonate was used as the SA in the electrophoretic buffer for ACE. The Scatchard analysis of the dependence of the electrophoretic mobility of native CA on the SA concentration provided the binding constant to be Kb=(2.29±0.05)×10(6) M(-1) (at pH8.4, 25°C). On the other hand, apoCA showed far smaller value [Kb=(3.76±0.14)×10(2) M(-1)], suggesting that the coordination of SA to the Zn(II) center controlled the binding thermodynamics. The ACE of M-CAs showed the same behaviors as native CA but with different Kb values. For example, Co-CA adopting the same tetrahedral coordination geometry as native CA exhibited the largest Kb value [(2.55±0.05)×10(6) M(-1)] among the M-CAs. In contrast, Mn- and Ni-CA, which adopted the octahedral coordination geometry, had Kb values that were about two orders of magnitude lower. Because the hydrophobic cavity of CA around the active center pre-organized the orientation of SA, thereby fixing the ligating NH(-) moiety to the apex of the tetrahedron supported by three basal His3 of CA, metals such as Zn and Co at the center of M-CA gave the most stable CA-SA complex. However, pre-organization was not favored for octahedral geometry. Thus, pre-organization of SA was the key to facilitating the tetrahedral coordination geometry of the Zn(II) active center of CA.

  1. In vivo imaging and quantification of carbonic anhydrase IX expression as an endogenous biomarker of tumor hypoxia.

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    Bagna Bao

    Full Text Available Carbonic anhydrase IX (CA IX is a transmembrane protein that has been shown to be greatly upregulated under conditions of hypoxia in many tumor cell lines. Tumor hypoxia is associated with impaired efficacy of cancer therapies making CA IX a valuable target for preclinical and diagnostic imaging. We have developed a quantitative in vivo optical imaging method for detection of CA IX as a marker of tumor hypoxia based on a near-infrared (NIR fluorescent derivative of the CA IX inhibitor acetazolamide (AZ. The agent (HS680 showed single digit nanomolar inhibition of CA IX as well as selectivity over other CA isoforms and demonstrated up to 25-fold upregulation of fluorescent CA IX signal in hypoxic versus normoxic cells, which could be blocked by 60%-70% with unlabeled AZ. CA IX negative cell lines (HCT-116 and MDA-MB-231, as well as a non-binding control agent on CA IX positive cells, showed low fluorescent signal under both conditions. In vivo FMT imaging showed tumor accumulation and excellent tumor definition from 6-24 hours. In vivo selectivity was confirmed by pretreatment of the mice with unlabeled AZ resulting in >65% signal inhibition. HS680 tumor signal was further upregulated >2X in tumors by maintaining tumor-bearing mice in a low oxygen (8% atmosphere. Importantly, intravenously injected HS680 signal was co-localized specifically with both CA IX antibody and pimonidazole (Pimo, and was located away from non-hypoxic regions indicated by a Hoechst stain. Thus, we have established a spatial correlation of fluorescence signal obtained by non-invasive, tomographic imaging of HS680 with regions of hypoxia and CA IX expression. These results illustrate the potential of HS680 and combined with FMT imaging to non-invasively quantify CA IX expression as a hypoxia biomarker, crucial to the study of the underlying biology of hypoxic tumors and the development and monitoring of novel anti-cancer therapies.

  2. Production, purification, and characterization of a fusion protein of carbonic anhydrase from Neisseria gonorrhoeae and cellulose binding domain from Clostridium thermocellum.

    Science.gov (United States)

    Liu, Zhu; Bartlow, Patrick; Dilmore, Robert M; Soong, Yee; Pan, Zhiwei; Koepsel, Richard; Ataai, Mohammad

    2009-01-01

    Carbon dioxide capture technologies have the potential to become an important climate change mitigation option through sequestration of gaseous CO2. A new concept for CO2 capture involves use of immobilized carbonic anhydrase (CA) that catalyzes the reversible hydration of CO2 to HCO3(-) and H+. Cost-efficient production of the enzyme and an inexpensive immobilization system are critical for development of economically feasible CA-based CO2 capture processes. An artificial, bifunctional enzyme containing CA from Neisseria gonorrhoeae and a cellulose binding domain (CBD) from Clostridium thermocellum was constructed with a His6 tag. The chimeric enzyme exhibited both CA activity and CBD binding affinity. This fusion enzyme is of particular interest due to its binding affinity for cellulose and retained CA activity, which could serve as the basis for improved technology to capture CO2 from flue gasses. PMID:19224556

  3. [Mode of action, clinical profile and relevance of carbonic anhydrase inhibitors in glaucoma therapy].

    Science.gov (United States)

    Eichhorn, M

    2013-02-01

    Since their introduction the local carbonic anhydrase inhibitors (CAH) dorzolamide and brinzolamide have become well established in the drug therapy of glaucoma. They lower intraocular pressure (IOP) by blocking specifically carbonic anhydrase in the ciliary epithelium and thereby the secretion of aqueous humor. The IOP lowering effect is comparable with that of beta-blockers, but less than that of prostaglandin agonists. Because of their specific mode of action they produce an additive pressure lowering effect with any other glaucoma drug. Therefore they are ideal for being combined with other drugs. In addition, CAH may improve perfusion of the posterior eye. Preliminary results in glaucoma patients under dorzolamide therapy suggesting a reduction in the risk of progression due to enhanced blood flow need further confirmation. PMID:23430679

  4. Expression Patterns and Subcellular Localization of Carbonic Anhydrases Are Developmentally Regulated during Tooth Formation

    OpenAIRE

    Reibring, Claes-Göran; El Shahawy, Maha; Hallberg, Kristina; Kannius-Janson, Marie; Nilsson, Jeanette; Parkkila, Seppo; Sly, William S; Waheed, Abdul; Linde, Anders; Gritli-Linde, Amel

    2014-01-01

    Carbonic anhydrases (CAs) play fundamental roles in several physiological events, and emerging evidence points at their involvement in an array of disorders, including cancer. The expression of CAs in the different cells of teeth is unknown, let alone their expression patterns during odontogenesis. As a first step towards understanding the role of CAs during odontogenesis, we used immunohistochemistry, histochemistry and in situ hybridization to reveal hitherto unknown dynamic distribution pa...

  5. Toxic Epidermal Necrolysis Induced by the Topical Carbonic Anhydrase Inhibitors Brinzolamide and Dorzolamide

    OpenAIRE

    Chun, Ji Sun; Yun, Sook Jung; Lee, Jee Bum; Kim, Seong Jin; Won, Young Ho; Lee, Seung Chul

    2008-01-01

    Brinzolamide and dorzolamide are highly specific topical carbonic anhydrase inhibitors (CAIs). They lower intraocular pressure (IOP) by reducing the rate of aqueous humour formation without serious side effects. Although systemic CAIs are the most potent medications for lowering intraocular pressure for conditions with ocular hypertension, many cases with adverse systemic reactions have been reported, including Stevens-Johnson syndrome (SJS) and Toxic epidermal necrolysis (TEN). Here, we repo...

  6. Synthesis of 4-(thiazol-2-ylamino)-benzenesulfonamides with carbonic anhydrase I, II and IX inhibitory activity and cytotoxic effects against breast cancer cell lines.

    Science.gov (United States)

    Abdel Gawad, Nagwa M; Amin, Noha H; Elsaadi, Mohammed T; Mohamed, Fatma M M; Angeli, Andrea; De Luca, Viviana; Capasso, Clemente; Supuran, Claudiu T

    2016-07-01

    A series of 4-(thiazol-2-ylamino)-benzenesulfonamides was synthesized and screened for their carbonic anhydrase (CA, EC 4.2.1.1) inhibitory and cytotoxic activity on human breast cancer cell line MCF-7. Human (h) CA isoforms I, II and IX were included in the study. The new sulfonamides showed excellent inhibition of all three isoforms, with KIs in the range of 0.84-702nM against hCA I, of 0.41-288nM against hCA II and of 5.6-29.2 against the tumor-associated hCA IX, a validated anti-tumor target, with a sulfonamide (SLC-0111) in Phase I clinical trials for the treatment of hypoxic, metastatic solid tumors overexpressing CA IX. The new compounds showed micromolar inhibition of growth efficacy against breast cancer MCF-7 cell lines. PMID:27234893

  7. Novel alkalistable α-carbonic anhydrase from the polyextremophilic bacterium Bacillus halodurans: characteristics and applicability in flue gas CO2 sequestration.

    Science.gov (United States)

    Faridi, Shazia; Satyanarayana, T

    2016-08-01

    The emissions of CO2 into the atmosphere have been constantly rising due to anthropogenic activities, which have led to global warming and climate change. Among various methods proposed for mitigating CO2 levels in the atmosphere, carbonic anhydrase (CA)-mediated carbon sequestration represents a greener and safer approach to capture and convert it into stable mineral carbonates. Despite the fact that CA is an extremely efficient metalloenzyme that catalyzes the hydration of CO2 (CO2 + H2O ↔ HCO3 (-) + H(+)) with a kcat of ∼10(6) s(-1), a thermostable, and alkalistable CA is desirable for the process to take place efficiently. The purified CA from alkaliphilic, moderately thermophilic, and halotolerant Bacillus halodurans TSLV1 (BhCA) is a homodimeric enzyme with a subunit molecular mass of ~37 kDa with stability in a broad pH range between 6.0 and 11.0. It has a moderate thermostability with a T1/2 of 24.0 ± 1.0 min at 60 °C. Based on the sensitivity of CA to specific inhibitors, BhCA is an α-CA; this has been confirmed by nucleotide/amino acid sequence analysis. This has a unique property of stimulation by SO4 (2-), and it remains unaffected by SO3 (2-), NOx, and most other components present in the flue gas. BhCA is highly efficient in accelerating the mineralization of CO2 as compared to commercial bovine carbonic anhydrase (BCA) and is also efficient in the sequestration of CO2 from the exhaust of petrol driven car, thus, a useful biocatalyst for sequestering CO2 from flue gas. PMID:27102616

  8. Transcriptome analysis and characterisation of gill-expressed carbonic anhydrase and other key osmoregulatory genes in freshwater crayfish Cherax quadricarinatus

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    Muhammad Yousuf Ali

    2015-12-01

    Full Text Available The pH and salinity balance mechanisms of crayfish are controlled by a set of transport-related genes. We identified a set of the genes from the gill transcriptome from a freshwater crayfish Cherax quadricarinatus using the Illumina NGS-sequencing technology. We identified and characterized carbonic anhydrase (CA genes and some other key genes involved in systematic acid-base balance and osmotic/ionic regulation. We also examined expression patterns of some of these genes across different sublethal pH levels [1]. A total of 72,382,710 paired-end Illumina reads were assembled into 36,128 contigs with an average length of 800 bp. About 37% of the contigs received significant BLAST hits and 22% were assigned gene ontology terms. These data will assist in further physiological-genomic studies in crayfish.

  9. Quantitative Characterization of the Interaction Space of the Mammalian Carbonic Anhydrase Isoforms I, II, VII, IX, XII, and XIV and their Inhibitors, Using the Proteochemometric Approach.

    Science.gov (United States)

    Rasti, Behnam; Karimi-Jafari, Mohammad H; Ghasemi, Jahan B

    2016-09-01

    The critical role of carbonic anhydrases in different physiological processes has put this protein family at the center of attention, challenging major diseases like glaucoma, neurological disorders such as epilepsy and Alzheimer's disease, obesity, and cancers. Many QSAR/QSPR (quantitative structure-activity/property relationship) researches have been carried out to design potent carbonic anhydrase inhibitors (CAIs); however, using inhibitors with no selectivity for different isoforms can lead to major side-effects. Given that QSAR/QSPR methods are not capable of covering multiple targets in a unified model, we have applied the proteochemometric approach to model the interaction space that governs selective inhibition of different CA isoforms by some mono-/dihydroxybenzoic acid esters. Internal and external validation methods showed that all models were reliable in terms of both validity and predictivity, whereas Y-scrambling assessed the robustness of the models. To prove the applicability of our models, we showed how structural changes of a ligand can affect the selectivity. Our models provided interesting information that can be useful for designing inhibitors with selective behavior toward isoforms of carbonic anhydrases, aiding in their selective inhibition. PMID:26990115

  10. Regulation of expression and biochemical characterization of a beta-class carbonic anhydrase from the plant growth-promoting rhizobacterium, Azospirillum brasilense Sp7.

    Science.gov (United States)

    Kaur, Simarjot; Mishra, Mukti Nath; Tripathi, Anil K

    2009-10-01

    Carbonic anhydrase (CA; [EC 4.2.1.1]) is a ubiquitous enzyme catalysing the reversible hydration of CO(2) to bicarbonate, a reaction that supports various biochemical and physiological functions. Genome analysis of Azospirillum brasilense, a nonphotosynthetic, nitrogen-fixing, rhizobacterium, revealed an ORF with homology to beta-class carbonic anhydrases (CAs). Biochemical characteristics of the beta-class CA of A. brasilense, analysed after cloning the gene (designated as bca), overexpressing in Escherichia coli and purifying the protein by affinity purification, revealed that the native recombinant enzyme is a homotetramer, inhibited by the known CA inhibitors. CA activity in A. brasilense cell extracts, reverse transcriptase (RT)-PCR and Western blot analyses showed that bca was constitutively expressed under aerobic conditions. Lower beta-galactosidase activity in A. brasilense cells harbouring bca promoter: lacZ fusion during the stationary phase or during growth on 3% CO(2) enriched air or at acidic pH indicated that the transcription of bca was downregulated by the stationary phase, elevated CO(2) levels and acidic pH conditions. These observations were also supported by RT-PCR analysis. Thus, beta-CA in A. brasilense seems to be required for scavenging CO(2) from the ambient air and the requirement of CO(2) hydration seems to be higher for the cultures growing exponentially at neutral to alkaline pH.

  11. Carbonic anhydrase IX, a hypoxia-induced catalytic component of the pH regulating machinery in tumors

    Directory of Open Access Journals (Sweden)

    Olga eSedlakova

    2014-01-01

    Full Text Available Acidic tissue microenvironment contributes to tumor progression via multiple effects including the activation of angiogenic factors and proteases, reduced cell-cell adhesion, increased migration and invasion, etc. In addition, intratumoral acidosis can influence the uptake of anticancer drugs and modulate the response of tumors to conventional therapy. Acidification of the tumor microenvironment often develops due to hypoxia-triggered oncogenic metabolism, which leads to the extensive production of lactate, protons and carbon dioxide. In order to avoid intracellular accumulation of the acidic metabolic products, which is incompatible with the survival and proliferation, tumor cells activate molecular machinery that regulates pH by driving transmembrane inside-out and outside-in ion fluxes. Carbonic anhydrase IX (CA IX is a hypoxia-induced catalytic component of the bicarbonate import arm of this machinery. Through its catalytic activity, CA IX directly participates in many acidosis-induced features of tumor phenotype as demonstrated by manipulating its expression and/or by in vitro mutagenesis. CA IX can function as a survival factor protecting tumor cells from hypoxia and acidosis, as a pro-migratory factor facilitating cell movement and invasion, as a signaling molecule transducing extracellular signals to intracellular pathways (including major signaling and metabolic cascades and converting intracellular signals to extracellular effects on adhesion, proteolysis and other processes. These functional implications of CA IX in cancer are supported by numerous clinical studies demonstrating the association of CA IX with various clinical correlates and markers of aggressive tumor behavior. Although our understanding of the many faces of CA IX is still incomplete, existing knowledge supports the view that CA IX is a biologically and clinically relevant molecule, exploitable in anticancer strategies aimed at targeting adaptive responses to hypoxia

  12. Expression patterns and subcellular localization of carbonic anhydrases are developmentally regulated during tooth formation.

    Directory of Open Access Journals (Sweden)

    Claes-Göran Reibring

    Full Text Available Carbonic anhydrases (CAs play fundamental roles in several physiological events, and emerging evidence points at their involvement in an array of disorders, including cancer. The expression of CAs in the different cells of teeth is unknown, let alone their expression patterns during odontogenesis. As a first step towards understanding the role of CAs during odontogenesis, we used immunohistochemistry, histochemistry and in situ hybridization to reveal hitherto unknown dynamic distribution patterns of eight CAs in mice. The most salient findings include expression of CAII/Car2 not only in maturation-stage ameloblasts (MA but also in the papillary layer, dental papilla mesenchyme, odontoblasts and the epithelial rests of Malassez. We uncovered that the latter form lace-like networks around incisors; hitherto these have been known to occur only in molars. All CAs studied were produced by MA, however CAIV, CAIX and CARPXI proteins were distinctly enriched in the ruffled membrane of the ruffled MA but exhibited a homogeneous distribution in smooth-ended MA. While CAIV, CAVI/Car6, CAIX, CARPXI and CAXIV were produced by all odontoblasts, CAIII distribution displayed a striking asymmetry, in that it was virtually confined to odontoblasts in the root of molars and root analog of incisors. Remarkably, from initiation until near completion of odontogenesis and in several other tissues, CAXIII localized mainly in intracellular punctae/vesicles that we show to overlap with LAMP-1- and LAMP-2-positive vesicles, suggesting that CAXIII localizes within lysosomes. We showed that expression of CAs in developing teeth is not confined to cells involved in biomineralization, pointing at their participation in other biological events. Finally, we uncovered novel sites of CA expression, including the developing brain and eye, the olfactory epithelium, melanoblasts, tongue, notochord, nucleus pulposus and sebaceous glands. Our study provides important information for

  13. Cloning, characterization and anion inhibition studies of a γ-carbonic anhydrase from the Antarctic bacterium Colwellia psychrerythraea.

    Science.gov (United States)

    De Luca, Viviana; Vullo, Daniela; Del Prete, Sonia; Carginale, Vincenzo; Osman, Sameh M; AlOthman, Zeid; Supuran, Claudiu T; Capasso, Clemente

    2016-02-15

    We have cloned, purified and characterized the γ-carbonic anhydrase (CA, EC 4.2.1.1) present in the genome of the Antarctic bacterium Colwellia psychrerythraea, which is an obligate psychrophile. The enzyme shows a significant catalytic activity for the physiologic reaction of CO2 hydration to bicarbonate and protons, with the following kinetic parameters: kcat of 6.0×10(5)s(-1) and a kcat/Km of 4.7×10(6)M(-1)×s(-1). This activity was inhibited by the sulfonamide CA inhibitor (CAI) acetazolamide, with a KI of 502nM. A range of anions was also investigated for their inhibitory action against the new enzyme CpsCA. Perchlorate, tetrafluoroborate, fluoride and bromide were not inhibitory, whereas cyanate, thiocyanate, cyanide, hydrogensulfide, carbonate and bicarbonate showed KIs in the range of 1.4-4.4mM. Diethyldithiocarbamate was a better inhibitor (KI of 0.58mM) whereas sulfamide, sulfamate, phenylboronic acid and phenylarsonic acid were the most effective inhibitors detected, with KIs ranging between 8 and 38μM. The present study may shed some more light regarding the role that γ-CAs play in the life cycle of psychrophilic bacteria as the Antarctic one investigated here. PMID:26778292

  14. Cloning, characterization and anion inhibition studies of a γ-carbonic anhydrase from the Antarctic bacterium Colwellia psychrerythraea.

    Science.gov (United States)

    De Luca, Viviana; Vullo, Daniela; Del Prete, Sonia; Carginale, Vincenzo; Osman, Sameh M; AlOthman, Zeid; Supuran, Claudiu T; Capasso, Clemente

    2016-02-15

    We have cloned, purified and characterized the γ-carbonic anhydrase (CA, EC 4.2.1.1) present in the genome of the Antarctic bacterium Colwellia psychrerythraea, which is an obligate psychrophile. The enzyme shows a significant catalytic activity for the physiologic reaction of CO2 hydration to bicarbonate and protons, with the following kinetic parameters: kcat of 6.0×10(5)s(-1) and a kcat/Km of 4.7×10(6)M(-1)×s(-1). This activity was inhibited by the sulfonamide CA inhibitor (CAI) acetazolamide, with a KI of 502nM. A range of anions was also investigated for their inhibitory action against the new enzyme CpsCA. Perchlorate, tetrafluoroborate, fluoride and bromide were not inhibitory, whereas cyanate, thiocyanate, cyanide, hydrogensulfide, carbonate and bicarbonate showed KIs in the range of 1.4-4.4mM. Diethyldithiocarbamate was a better inhibitor (KI of 0.58mM) whereas sulfamide, sulfamate, phenylboronic acid and phenylarsonic acid were the most effective inhibitors detected, with KIs ranging between 8 and 38μM. The present study may shed some more light regarding the role that γ-CAs play in the life cycle of psychrophilic bacteria as the Antarctic one investigated here.

  15. Generation of nitric oxide from nitrite by carbonic anhydrase

    DEFF Research Database (Denmark)

    Aamand, Rasmus; Dalsgaard, Thomas; Jensen, Frank B;

    2009-01-01

    bicarbonate and nitrite, we hypothesized that CA uses nitrite as a substrate to produce the potent vasodilator nitric oxide (NO) to increase local blood flow to metabolically active tissues. Here we show that CA readily reacts with nitrite to generate NO, particularly at low pH, and that the NO produced...

  16. Generation of nitric oxide from nitrite by carbonic anhydrase:

    DEFF Research Database (Denmark)

    Aamand, Rasmus; Dalsgaard, Thomas; Jensen, Frank Bo;

    2009-01-01

    bicarbonate and nitrite, we hypothesized that CA uses nitrite as a substrate to produce the potent vasodilator nitric oxide (NO) to increase local blood flow to metabolically active tissues. Here we show that CA readily reacts with nitrite to generate NO, particularly at low pH, and that the NO produced...

  17. Oxygen-18 incorporation into malic acid during nocturnal carbon dioxide fixation in crassulacean acid metabolism plants: a new approach to estimating in vivo carbonic anhydrase activity

    Energy Technology Data Exchange (ETDEWEB)

    Holtum, J.A.M.; Summons, R.; Roeske, C.A.; Comins, H.N.; O' Leary, M.H.

    1984-01-01

    Crassulacean acid metabolism (CAM) plants fix carbon dioxide at night by the carboxylation of phosphoenolpyruvate. If CO2 fixation is conducted with TC YO2, then in the absence of carbonic anhydrase, the malate formed by dark CO2 fixation should also contain high levels of carbon-13 and oxygen-18. Conversely, if carbonic anhydrase is present and highly active, oxygen exchange between CO2 and cellular H2O will occur more rapidly than carboxylation, and the ( TC) malate formed will contain little or no oxygen-18 above the natural abundance level. The presence of oxygen-18 in these molecules can be detected either by nuclear magnetic resonance or by mass spectrometry. Studies of phosphoenolpyruvate carboxylase in the presence and absence of carbonic anhydrase in vitro confirm the validity of the method. When CAM plants are studied by this method, we find that most species show incorporation of a significant amount of oxygen-18. Comparison of these results with results of isotope fractionation and gas exchange studies permits calculation of the in vivo activity of carbonic anhydrase toward HCO3 compared with that of phosphoenolpyruvate carboxylase. The ratio (carbonic anhydrase activity/phosphoenolpyruvate carboxylase activity) is species dependent and varies from a low of about 7 for Ananas comosus to values near 20 for Hoya carnosa and Bryophyllum pinnatum, 40 for Kalanchoee daigremontiana, and 100 or greater for Bryophyllum tubiflorum, Kalanchoee serrata, and Kalanchoae tomentosa. Carbonic anhydrase activity increases relative to phosphoenolpyruvate carboxylase activity at higher temperature. 37 references, 2 figures, 8 tables.

  18. Carbonic anhydrase inhibitors: Design, synthesis, kinetic, docking and molecular dynamics analysis of novel glycine and phenylalanine sulfonamide derivatives.

    Science.gov (United States)

    Fidan, İsmail; Salmas, Ramin Ekhteiari; Arslan, Mehmet; Şentürk, Murat; Durdagi, Serdar; Ekinci, Deniz; Şentürk, Esra; Coşgun, Sedat; Supuran, Claudiu T

    2015-12-01

    The inhibition of two human cytosolic carbonic anhydrase isozymes I and II, with some novel glycine and phenylalanine sulfonamide derivatives were investigated. Newly synthesized compounds G1-4 and P1-4 showed effective inhibition profiles with KI values in the range of 14.66-315μM for hCA I and of 18.31-143.8μM against hCA II, respectively. In order to investigate the binding mechanisms of these inhibitors, in silico docking studies were applied. Atomistic molecular dynamic simulations were performed for docking poses which utilize to illustrate the inhibition mechanism of used inhibitors into active site of CAII. These sulfonamide containing compounds generally were competitive inhibitors with 4-nitrophenylacetate as substrate. Some investigated compounds here showed effective hCA II inhibitory effects, in the same range as the clinically used sulfonamide, sulfanilamide or mafenide and might be used as leads for generating enzyme inhibitors possibly targeting other CA isoforms which have not been yet assayed for their interactions with such agents.

  19. Evaluation of a Carbonic Anhydrase IX-Targeted Near-Infrared Dye for Fluorescence-Guided Surgery of Hypoxic Tumors.

    Science.gov (United States)

    Lv, Peng-Cheng; Roy, Jyoti; Putt, Karson S; Low, Philip S

    2016-05-01

    Proof-of-principle studies in ovarian, lung, and brain cancer patients have shown that fluorescence-guided surgery can enable removal of otherwise undetectable malignant lesions, decrease the number of cancer-positive margins, and permit identification of disease-containing lymph nodes that would have normally evaded resection. Unfortunately, the current arsenal of tumor-targeted fluorescent dyes does not permit identification of all cancers, raising the need to design new tumor-specific fluorescent dyes to illuminate the currently undetectable cancers. In an effort to design a more universal fluorescent cancer imaging agent, we have undertaken to synthesize a fluorophore that could label all hypoxic regions of tumors. We report here the synthesis, in vitro binding, and in vivo imaging of a near-infrared (NIR) fluorescent dye that is targeted to carbonic anhydrase IX (CA IX), i.e., a widely accepted marker of hypoxic tissues. The low molecular weight NIR probe, named Hypoxyfluor, is shown to bind CA IX with high affinity and accumulate rapidly and selectively in CA IX positive tumors. Because nearly all human cancers contain hypoxic regions that express CA IX abundantly, this NIR probe should facilitate surgical resection of a wide variety of solid tumors. PMID:27043317

  20. Impacts of Elevated CO2 Concentration on Biochemical Composition,Carbonic Anhydrase, and Nitrate Reductase Activity of Freshwater Green Algae

    Institute of Scientific and Technical Information of China (English)

    Jian-Rong XIA; Kun-Shan GAO

    2005-01-01

    To investigate the biochemical response of freshwater green algae to elevated CO2 concentrations,Chlorella pyrenoidosa Chick and Chlamydomonas reinhardtii Dang cells were cultured at different CO2concentrations within the range 3-186 μmol/L and the biochemical composition, carbonic anhydrase (CA),and nitrate reductase activities of the cells were investigated. Chlorophylls (Chl), carotenoids, carbonhydrate,and protein contents were enhanced to varying extents with increasing CO2 concentration from 3-186μmol/L. The CO2 enrichment significantly increased the Chl a/Chl b ratio in Chlorella pyrenoidosa, but not in Chlamydomonas reinhardtii. The CO2 concentration had significant effects on CA and nitrate reductase activity. Elevating CO2 concentration to 186 μmol/L caused a decline in intracellular and extracellullar CA activity. Nitrate reductase activity, under either light or dark conditions, in C. reinhardtii and C. pyrenoidosa was also significantly decreased with CO2 enrichment. From this study, it can be concluded that CO2enrichment can affect biochemical composition, CA, and nitrate reductase activity, and that the biochemical response was species dependent.

  1. Evidence that an internal carbonic anhydrase is present in 5% CO2-grown and air-grown Chlamydomonas

    International Nuclear Information System (INIS)

    Inorganic carbon (C/sub i/) uptake was measured in wild-type cells of Chlamydomonas reinhardtii, and in cia-3, a mutant strain of C. reinhardtii that cannot grow with air levels of CO2. Both air-grown cells, that have a CO2 concentrating system, and 5% CO2-grown cells that do not have this system, were used. When the external pH was 5.1 or 7.3, air-grown, wild-type cells accumulated inorganic carbon (C/sub i/) and this accumulation was enhanced when the permeant carbonic anhydrase inhibitor, ethoxyzolamide, was added. When the external pH was 5.1, 5% CO2-grown cells also accumulated some C/sub i/, although not as much as air-grown cells and this accumulation was stimulated by the addition of ethoxyzolamide. At the same time, ethoxyzolamide inhibited CO2 fixation by high CO2-grown, wild-type cells at both pH 5.1 and 7.3. These observations imply that 5% CO2-grown, wild-type cells, have a physiologically important internal carbonic anhydrase, although the major carbonic anhydrase located in the periplasmic space is only present in air-grown cells. Inorganic carbon uptake by cia-3 cells supported this conclusion. This mutant strain, which is thought to lack an internal carbonic anhydrase, was unaffected by ethoxyzolamide at pH 5.1. Other physiological characteristics of cia-3 resemble those of wild-type cells that have been treated with ethoxyzolamide. It is concluded that an internal carbonic anhydrase is under different regulatory control than the periplasmic carbonic anhydrase

  2. Structural studies of β-carbonic anhydrase from the green alga Coccomyxa: inhibitor complexes with anions and acetazolamide.

    Directory of Open Access Journals (Sweden)

    Shenghua Huang

    Full Text Available The β-class carbonic anhydrases (β-CAs are widely distributed among lower eukaryotes, prokaryotes, archaea, and plants. Like all CAs, the β-enzymes catalyze an important physiological reaction, namely the interconversion between carbon dioxide and bicarbonate. In plants the enzyme plays an important role in carbon fixation and metabolism. To further explore the structure-function relationship of β-CA, we have determined the crystal structures of the photoautotroph unicellular green alga Coccomyxa β-CA in complex with five different inhibitors: acetazolamide, thiocyanate, azide, iodide, and phosphate ions. The tetrameric Coccomyxa β-CA structure is similar to other β-CAs but it has a 15 amino acid extension in the C-terminal end, which stabilizes the tetramer by strengthening the interface. Four of the five inhibitors bind in a manner similar to what is found in complexes with α-type CAs. Iodide ions, however, make contact to the zinc ion via a zinc-bound water molecule or hydroxide ion--a type of binding mode not previously observed in any CA. Binding of inhibitors to Coccomyxa β-CA is mediated by side-chain movements of the conserved residue Tyr-88, extending the width of the active site cavity with 1.5-1.8 Å. Structural analysis and comparisons with other α- and β-class members suggest a catalytic mechanism in which the movements of Tyr-88 are important for the CO(2-HCO(3(- interconversion, whereas a structurally conserved water molecule that bridges residues Tyr-88 and Gln-38, seems important for proton transfer, linking water molecules from the zinc-bound water to His-92 and buffer molecules.

  3. Structural studies of β-carbonic anhydrase from the green alga Coccomyxa: inhibitor complexes with anions and acetazolamide.

    Science.gov (United States)

    Huang, Shenghua; Hainzl, Tobias; Grundström, Christin; Forsman, Cecilia; Samuelsson, Göran; Sauer-Eriksson, A Elisabeth

    2011-01-01

    The β-class carbonic anhydrases (β-CAs) are widely distributed among lower eukaryotes, prokaryotes, archaea, and plants. Like all CAs, the β-enzymes catalyze an important physiological reaction, namely the interconversion between carbon dioxide and bicarbonate. In plants the enzyme plays an important role in carbon fixation and metabolism. To further explore the structure-function relationship of β-CA, we have determined the crystal structures of the photoautotroph unicellular green alga Coccomyxa β-CA in complex with five different inhibitors: acetazolamide, thiocyanate, azide, iodide, and phosphate ions. The tetrameric Coccomyxa β-CA structure is similar to other β-CAs but it has a 15 amino acid extension in the C-terminal end, which stabilizes the tetramer by strengthening the interface. Four of the five inhibitors bind in a manner similar to what is found in complexes with α-type CAs. Iodide ions, however, make contact to the zinc ion via a zinc-bound water molecule or hydroxide ion--a type of binding mode not previously observed in any CA. Binding of inhibitors to Coccomyxa β-CA is mediated by side-chain movements of the conserved residue Tyr-88, extending the width of the active site cavity with 1.5-1.8 Å. Structural analysis and comparisons with other α- and β-class members suggest a catalytic mechanism in which the movements of Tyr-88 are important for the CO(2)-HCO(3)(-) interconversion, whereas a structurally conserved water molecule that bridges residues Tyr-88 and Gln-38, seems important for proton transfer, linking water molecules from the zinc-bound water to His-92 and buffer molecules. PMID:22162771

  4. A sucrose-binding site provides a lead towards an isoform-specific inhibitor of the cancer-associated enzyme carbonic anhydrase IX.

    Science.gov (United States)

    Pinard, Melissa A; Aggarwal, Mayank; Mahon, Brian P; Tu, Chingkuang; McKenna, Robert

    2015-10-01

    Human carbonic anhydrase (CA; EC 4.2.1.1) isoform IX (CA IX) is an extracellular zinc metalloenzyme that catalyzes the reversible hydration of CO2 to HCO3(-), thereby playing a role in pH regulation. The majority of normal functioning cells exhibit low-level expression of CA IX. However, in cancer cells CA IX is upregulated as a consequence of a metabolic transition known as the Warburg effect. The upregulation of CA IX for cancer progression has drawn interest in it being a potential therapeutic target. CA IX is a transmembrane protein, and its purification, yield and crystallization have proven challenging to structure-based drug design, whereas the closely related cytosolic soluble isoform CA II can be expressed and crystallized with ease. Therefore, we have utilized structural alignments and site-directed mutagenesis to engineer a CA II that mimics the active site of CA IX. In this paper, the X-ray crystal structure of this CA IX mimic in complex with sucrose is presented and has been refined to a resolution of 1.5 Å, an Rcryst of 18.0% and an Rfree of 21.2%. The binding of sucrose at the entrance to the active site of the CA IX mimic, and not CA II, in a non-inhibitory mechanism provides a novel carbohydrate moiety binding site that could be further exploited to design isoform-specific inhibitors of CA IX.

  5. The selective expression of carbonic anhydrase genes of Aspergillus nidulans in response to changes in mineral nutrition and CO2 concentration.

    Science.gov (United States)

    Xiao, Leilei; Lian, Bin; Dong, Cuiling; Liu, Fanghua

    2016-02-01

    Carbonic anhydrase (CA) plays an important role in the formation and evolution of life. However, to our knowledge, there has been no report on CA isoenzyme function differentiation in fungi. Two different CA gene sequences in Aspergillus nidulans with clear genetic background provide us a favorable basis for studying function differentiation of CA isoenzymes. Heterologously expressed CA1 was used to test its weathering ability on silicate minerals and real-time quantitative PCR was used to detect expression of the CA1 and CA2 genes at different CO2 concentrations and in the presence of different potassium sources. The northern blot method was applied to confirm the result of CA1 gene expression. Heterologously expressed CA1 significantly promoted dissolution of biotite and wollastonite, and CA1 gene expression increased significantly in response to soluble K-deficiency. The northern blot test further showed that CA1 participated in K-feldspar weathering. In addition, the results showed that CA2 was primary involved in adapting to CO2 concentration change. Taken together, A. nidulans can choose different CA to meet their survival needs, which imply that some environmental microbes have evolved different CAs to adapt to changes in CO2 concentration and acquire mineral nutrition so that they can better adapt to environmental changes. Inversely, their adaption may impact mineral weathering and/or CO2 concentration, and even global change.

  6. Carbon-13 nuclear magnetic resonance as a probe of side chain orientation and mobility in carboxymethylated human carbonic anhydrase B

    NARCIS (Netherlands)

    Schoot Uiterkamp, Antonius J.M.; Armitage, Ian M.; Prestegard, James H.; Slomski, John; Coleman, Joseph E.

    1978-01-01

    13C NMR spectra of [1-13C]- and [2-13C]carboxymethyl His-200 human carbonic anhydrase B have been obtained as a function of pH and in the presence and absence of the active site Zn(II) or Cd(II) ion. Chemical shifts of the 1-13C show that the carboxyl is sensitive to two ionization processes, with a

  7. N-ethyl-N-nitrosourea-induced null mutation at the mouse Car-2 locus: An animal model for human carbonic anhydrase II deficiency syndrome

    International Nuclear Information System (INIS)

    Electrophoretic screening of (C57BL/6J x DBA/2J)F1 progeny of male mice treated with N-ethyl-N-nitrosourea revealed a mouse that lacked the paternal carbonic anhydrase II (Ca II). Breeding tests showed that this trait was heritable and due to a null mutation at the Car-2 locus on chromosome 3. Like humans with the same inherited enzyme defect, animals homozygous for the new null allele are runted and have renal tubular acidosis. However, the prominent osteopetrosis found in humans with CA II deficiency could be detected even in very old homozygous null mice. A molecular analysis of the deficient mice shows that the mutant gene is not deleted and is transcribed. The CA II protein, which is normally expressed in most tissues, could not be detected by immunodiffusion analysis in any tissues of the CA II-deficient mice, suggesting a nonsense or a missense mutation at the Car-2 locus

  8. Expression and activity of carbonic anhydrase IX is associated with metabolic dysfunction in MDA-MB-231 breast cancer cells.

    NARCIS (Netherlands)

    Li, Ying; Wang, H.; Oosterwijk, E.; Tu, C.; Shiverick, K.T.; Silverman, D.N.; Frost, S.C.

    2009-01-01

    The expression of carbonic anhydrase IX (CAIX), a marker for hypoxic tumors, is correlated with poor prognosis in breast cancer patients. We show herein that the MDA-MB-231 cells, a "triple-negative," basal B line, express exclusively CAIX, while a luminal cell line (T47D) expresses carbonic anhydra

  9. Anion and sulfonamide inhibition studies of an α-carbonic anhydrase from the Antarctic hemoglobinless fish Chionodraco hamatus.

    Science.gov (United States)

    Cincinelli, Alessandra; Martellini, Tania; Vullo, Daniela; Supuran, Claudiu T

    2015-12-01

    An α-carbonic anhydrase (CA, EC 4.2.1.1) has been purified from the Antarctic hemoglobinless fish Chionodraco hamatus (icefish). The new enzyme, denominated ChaCA, has a good catalytic activity for the physiologic CO2 hydration to bicarbonate reaction, similar to that of the low activity human isoform hCA I, with a kcat of 5.3×10(5) s(-1), and a kcat/Km of 3.7×10(7) M(-1) s(-1). The enzyme was inhibited in the submillimolar range by most inorganic anions (cyanate, thiocyanate, cyanide, bicarbonate, halides), whereas sulfamide, sulfamate, phenylboronic/phenylarsonic acids were micromolar inhibitors, with KIs in the range of 9-77 μM. Many clinically used drugs, such as acetazolamide, methazolamide, dorzolamide, brinzolamide, topiramate and benzolamide were low nanomolar inhibitors, with KIs in the range of 39.1-77.6 nM. As the physiology of CO2/bicarbonate transport or the Root effect in this Antarctic fish are poorly understood at this moment, such inhibition data may give a more detailed insight in the role that CAs play in these phenomena, by the use of inhibitors described here as physiologic tools. PMID:26525863

  10. Sulfonamide inhibition studies of the β-carbonic anhydrase from the newly discovered bacterium Enterobacter sp. B13.

    Science.gov (United States)

    Eminoğlu, Ayşenur; Vullo, Daniela; Aşık, Aycan; Çolak, Dilşat Nigar; Çanakçı, Sabriye; Beldüz, Ali Osman; Supuran, Claudiu T

    2016-04-01

    The genome of the newly identified bacterium Enterobacter sp. B13 encodes for a β-class carbonic anhydrases (CAs, EC 4.2.1.1), EspCA. This enzyme was recently cloned, and characterized kinetically by this group (J. Enzyme Inhib. Med. Chem. 2016, 31). Here we report an inhibition study with sulfonamides and sulfamates of this enzyme. The best EspCA inhibitors were some sulfanylated sulfonamides with elongated molecules, metanilamide, 4-aminoalkyl-benzenesulfonamides, acetazolamide, and deacetylated methazolamide (KIs in the range of 58.7-96.5nM). Clinically used agents such as methazolamide, ethoxzolamide, dorzolamide, brinzolamide, benzolamide, zonisamide, sulthiame, sulpiride, topiramate and valdecoxib were slightly less effective inhibitors (KIs in the range of 103-138nM). Saccharin, celecoxib, dichlorophenamide and many simple benzenesulfonamides were even less effective as EspCA inhibitors, with KIs in the range of 384-938nM. Identification of effective inhibitors of this bacterial enzyme may lead to pharmacological tools useful for understanding the physiological role(s) of the β-class CAs in bacterial pathogenicity/virulence. PMID:26920803

  11. 植物碳酸酐酶的研究进展%Progress in Research on Plant Carbonic Anhydrase

    Institute of Scientific and Technical Information of China (English)

    蒋春云; 马秀灵; 沈晓艳; 李燕; 赵彦修

    2013-01-01

    在植物组织中,碳酸酐酶(CA)催化CO2与HCO3-之间可逆的水合反应,重新固定呼吸释放的CO2并用于细胞光合作用.本文简要介绍了CA的生理机能、分类、亚细胞定位、基因功能等的研究进展,并展望了CA在提高C3植物光合效率以及CA在C3植物由C3光合类型转向C4光合类型方面的研究意义.%Carbonic anhydrase (CA) catalyses the reversible reaction between CO2 and HCO3-in plant living organisms.It can refix the respiration-released CO2 which participates in photosynthesis process.In this article we summarize the research progress in the physiological function,classification,subcellular localization and gene function of CA.And we prospect its crucial roles in increasing the photosynthetic rate in C3 plants and in the type of photosynthesis from C3 to C4.

  12. Self-healing of Early Age Cracks in Cement-based Materials by Mineralization of Carbonic Anhydrase Microorganism

    Directory of Open Access Journals (Sweden)

    Chunxiang eQian

    2015-11-01

    Full Text Available This research investigated the self-healing potential of early age cracks in cement-based materials incorporating the bacteria which can produce carbonic anhydrase. Cement-based materials specimens were pre-cracked at the age of 7, 14, 28, 60 days to study the repair ability influenced by cracking time, the width of cracks were between 0.1 and 1.0 mm to study the healing rate influenced by width of cracks. The experimental results indicated that the bacteria showed excellent repairing ability to small cracks formed at early age of 7 days, cracks below 0.4 mm was almost completely closed. The repair effect reduced with the increasing of cracking age. Cracks width influenced self-healing effectiveness significantly. The transportation of CO2 and Ca2+ controlled the self-healing process. The computer simulation analyses revealed the self-healing process and mechanism of microbiologically precipitation induced by bacteria and the depth of precipitated CaCO3 could be predicted base on valid Ca2+.

  13. Intrinsic thermodynamics of 4-substituted-2,3,5,6-tetrafluorobenzenesulfonamide binding to carbonic anhydrases by isothermal titration calorimetry.

    Science.gov (United States)

    Zubrienė, Asta; Smirnovienė, Joana; Smirnov, Alexey; Morkūnaitė, Vaida; Michailovienė, Vilma; Jachno, Jelena; Juozapaitienė, Vaida; Norvaišas, Povilas; Manakova, Elena; Gražulis, Saulius; Matulis, Daumantas

    2015-10-01

    Para substituted tetrafluorobenzenesulfonamides bind to carbonic anhydrases (CAs) extremely tightly and exhibit some of the strongest known protein-small ligand interactions, reaching an intrinsic affinity of 2 pM as determined by displacement isothermal titration calorimetry (ITC). The enthalpy and entropy of binding to five CA isoforms were measured by ITC in two buffers of different protonation enthalpies. The pKa values of compound sulfonamide groups were measured potentiometrically and spectrophotometrically, and enthalpies of protonation were measured by ITC in order to evaluate the proton linkage contributions to the observed binding thermodynamics. Intrinsic means the affinity of a sulfonamide anion for the Zn bound water form of CAs. Fluorination of the benzene ring significantly enhanced the observed affinities as it increased the fraction of deprotonated ligand while having little impact on intrinsic affinities. Intrinsic enthalpy contributions to the binding affinity were dominant over entropy and were more exothermic for CA I than for other CA isoforms. Thermodynamic measurements together with the X-ray crystallographic structures of protein-ligand complexes enabled analysis of structure-activity relationships in this enzyme ligand system.

  14. Carbonic Anhydrase VI Gene Polymorphism rs2274327 Relationship Between Salivary Parameters and Dental-Oral Health Status in Children.

    Science.gov (United States)

    Sengul, Fatih; Kilic, Munevver; Gurbuz, Taskin; Tasdemir, Sener

    2016-08-01

    The aim of this study was to research carbonic anhydrase (CA) VI one single-nucleotide polymorphism (SNP) and its potential association with dental-oral health status (dental caries, Plaque Index (PI) and Gingival Index (GI)) and salivary parameters (salivary buffering capacity, salivary flow rate (SFR)) in children. A total of 178 children were divided into two groups: non-carious (n = 70, 34 boys and 36 girls) and carious (n = 108, 47 boys and 61 girls). The clinical evaluations were performed according to the decayed, missing, and filled teeth (dmft/DMFT) index by a specialist. Clinical parameters including PI, GI, and simplified oral hygiene index (OHI-S) were recorded. Salivary pH (SpH) was measured using pH paper. Blood samples and unstimulated whole saliva were collected, and SFR was calculated. The CA VI rs2274327 polymorphism was determined by a LightSNiP assay on the realtime PCR system. The frequencies of rs2274327 were not significant between groups (p > 0.05). There was a positive correlation between OHI-S and SpH in the carious and non-carious groups (p OHI-S, PI, GI, SFR, and SpH (p > 0.05). CA VI SNP (rs2274327) had no statistically significant association with OHI-S, PI, GI, SFR, and SpH in the children.

  15. Carbonic Anhydrase VI Gene Polymorphism rs2274327 Relationship Between Salivary Parameters and Dental-Oral Health Status in Children.

    Science.gov (United States)

    Sengul, Fatih; Kilic, Munevver; Gurbuz, Taskin; Tasdemir, Sener

    2016-08-01

    The aim of this study was to research carbonic anhydrase (CA) VI one single-nucleotide polymorphism (SNP) and its potential association with dental-oral health status (dental caries, Plaque Index (PI) and Gingival Index (GI)) and salivary parameters (salivary buffering capacity, salivary flow rate (SFR)) in children. A total of 178 children were divided into two groups: non-carious (n = 70, 34 boys and 36 girls) and carious (n = 108, 47 boys and 61 girls). The clinical evaluations were performed according to the decayed, missing, and filled teeth (dmft/DMFT) index by a specialist. Clinical parameters including PI, GI, and simplified oral hygiene index (OHI-S) were recorded. Salivary pH (SpH) was measured using pH paper. Blood samples and unstimulated whole saliva were collected, and SFR was calculated. The CA VI rs2274327 polymorphism was determined by a LightSNiP assay on the realtime PCR system. The frequencies of rs2274327 were not significant between groups (p > 0.05). There was a positive correlation between OHI-S and SpH in the carious and non-carious groups (p  0.05). CA VI SNP (rs2274327) had no statistically significant association with OHI-S, PI, GI, SFR, and SpH in the children. PMID:27100223

  16. Effects of intraleaf variations in carbonic anhydrase activity and gas exchange on leaf C18OO isoflux in Zea mays.

    Science.gov (United States)

    Affek, Hagit P; Krisch, Maria J; Yakir, Dan

    2006-01-01

    Variation in the C18OO content of atmospheric CO2 (delta18Oa) can be used to distinguish photosynthesis from soil respiration, which is based on carbonic anhydrase (CA)-catalyzed 18O exchange between CO2 and 18O-enriched leaf water (delta18Ow). Here we tested the hypothesis that mean leaf delta18Ow and assimilation rates can be used to estimate whole-leaf C18OO flux (isoflux), ignoring intraleaf variations in CA activity and gas exchange parameters. We observed variations in CA activity along the leaf (> 30% decline from the leaf center toward the leaf ends), which were only partially correlated to those in delta18Ow (7 to 21 per thousand), delta18O and delta13C of leaf organic matter (25 to 30 per thousand and -12.8 to -13.2 per thousand, respectively), and substomatal CO2 concentrations (intercellular CO2 concentrations, c(i), at the leaf center were approximately 40% of those at the leaf tip). The combined effect of these variations produced a leaf-integrated isoflux that was different from that predicted based on bulk leaf values. However, because of canceling effects among the influencing parameters, isoflux overestimations were only approximately 10%. Conversely, use of measured parameters from a leaf segment could produce large errors in predicting leaf-integrated C18OO fluxes. PMID:16411935

  17. Carbonic Anhydrase as Pollution Biomarker: An Ancient Enzyme with a New Use

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    Trifone Schettino

    2012-11-01

    Full Text Available The measurement of cellular and sub-cellular responses to chemical contaminants (referred to as biomarkers in living organisms represents a recent tool in environmental monitoring. The review focuses on carbonic anhydrase, a ubiquitous metalloenzyme which plays key roles in a wide variety of physiological processes involving CO2 and HCO3−. In the last decade a number of studies have demonstrated the sensitivity of this enzyme to pollutants such as heavy metals and organic chemicals in both humans and wildlife. The review analyses these studies and discusses the potentiality of this enzyme as novel biomarker in environmental monitoring and assessment.

  18. Kinetics of Formation of Cobalt(II)- and Nickel(II) Carbonic Anhydrase.

    Science.gov (United States)

    McQuate, Robert S.; Reardon, John E.

    1978-01-01

    Discusses the kinetic behavior associated with the interaction of metal ions with apocarbonic anhydrase, focusing on the formation of two metallocarbonic anhydrase--the biochemically active Co(II) and the inactive Ni(II)derivatives. (GA)

  19. Crystal structure and kinetic studies of a tetrameric type II β-carbonic anhydrase from the pathogenic bacterium Vibrio cholerae.

    Science.gov (United States)

    Ferraroni, Marta; Del Prete, Sonia; Vullo, Daniela; Capasso, Clemente; Supuran, Claudiu T

    2015-12-01

    Carbonic anhydrase (CA) is a zinc enzyme that catalyzes the reversible conversion of carbon dioxide to bicarbonate (hydrogen carbonate) and a proton. CAs have been extensively investigated owing to their involvement in numerous physiological and pathological processes. Currently, CA inhibitors are widely used as antiglaucoma, anticancer and anti-obesity drugs and for the treatment of neurological disorders. Recently, the potential use of CA inhibitors to fight infections caused by protozoa, fungi and bacteria has emerged as a new research direction. In this article, the cloning and kinetic characterization of the β-CA from Vibrio cholerae (VchCAβ) are reported. The X-ray crystal structure of this new enzyme was solved at 1.9 Å resolution from a crystal that was perfectly merohedrally twinned, revealing a tetrameric type II β-CA with a closed active site in which the zinc is tetrahedrally coordinated to Cys42, Asp44, His98 and Cys101. The substrate bicarbonate was found bound in a noncatalytic binding pocket close to the zinc ion, as reported for a few other β-CAs, such as those from Escherichia coli and Haemophilus influenzae. At pH 8.3, the enzyme showed a significant catalytic activity for the physiological reaction of the hydration of CO2 to bicarbonate and protons, with the following kinetic parameters: a kcat of 3.34 × 10(5) s(-1) and a kcat/Km of 4.1 × 10(7) M(-1) s(-1). The new enzyme, on the other hand, was poorly inhibited by acetazolamide (Ki of 4.5 µM). As this bacterial pathogen encodes at least three CAs, an α-CA, a β-CA and a γ-CA, these enzymes probably play an important role in the life cycle and pathogenicity of Vibrio, and it cannot be excluded that interference with their activity may be exploited therapeutically to obtain antibiotics with a different mechanism of action.

  20. Gene encoding γ-carbonic anhydrase is cotranscribed with argC and induced in response to stationary phase and high CO2 in Azospirillum brasilense Sp7

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    Mishra Mukti N

    2010-07-01

    Full Text Available Abstract Background Carbonic anhydrase (CA is a ubiquitous enzyme catalyzing the reversible hydration of CO2 to bicarbonate, a reaction underlying diverse biochemical and physiological processes. Gamma class carbonic anhydrases (γ-CAs are widespread in prokaryotes but their physiological roles remain elusive. At present, only γ-CA of Methanosarcina thermophila (Cam has been shown to have CA activity. Genome analysis of a rhizobacterium Azospirillum brasilense, revealed occurrence of ORFs encoding one β-CA and two γ-CAs. Results One of the putative γ-CA encoding genes of A. brasilense was cloned and overexpressed in E. coli. Electrometric assays for CA activity of the whole cell extracts overexpressing recombinant GCA1 did not show CO2 hydration activity. Reverse transcription-PCR analysis indicated that gca1 in A. brasilense is co-transcribed with its upstream gene annotated as argC, which encodes a putative N-acetyl-γ-glutamate-phosphate reductase. 5'-RACE also demonstrated that there was no transcription start site between argC and gca1, and the transcription start site located upstream of argC transcribed both the genes (argC-gca1. Using transcriptional fusions of argC-gca1 upstream region with promoterless lacZ, we further demonstrated that gca1 upstream region did not have any promoter and its transcription occurred from a promoter located in the argC upstream region. The transcription of argC-gca1 operon was upregulated in stationary phase and at elevated CO2 atmosphere. Conclusions This study shows lack of CO2 hydration activity in a recombinant protein expressed from a gene predicted to encode a γ-carbonic anhydrase in A. brasilense although it cross reacts with anti-Cam antibody raised against a well characterized γ-CA. The organization and regulation of this gene along with the putative argC gene suggests its involvement in arginine biosynthetic pathway instead of the predicted CO2 hydration.

  1. Inhibition of hypoxia-inducible carbonic anhydrase-IX enhances hexokinase Ⅱ inhibitor-induced hepatocellular carcinoma cell apoptosis

    Institute of Scientific and Technical Information of China (English)

    Su-jong YU; Hyo-suk LEE; Jung-hwan YOON; Jeong-hoon LEE; Sun-jung MYUNG; Eun-sun JANG; Min-sun KWAK; Eun-ju CHO; Ja-june JANG; Yoon-jun KIM

    2011-01-01

    Aim: The hypoxic condition within large or infiltrative hypovascular tumors produces intracellular acidification, which could activate many signaling pathways and augment cancer cell growth and invasion. Carbonic anhydrase-Ⅸ (CA-Ⅸ) is an enzyme lowering pH. This study is to examine whether hypoxia induces CA-Ⅸ in hepatocellular carcinoma (HCC) cells, and to evaluate its clinical implication in HCC patients.Methods: Human HCC cell lines (Huh-7 and HepG2 cells) were used, and cell growth was assessed using MTS assay. CA-IX expression and apoptotic/kinase signaling were evaluated using immunoblotting. The cells were transfected with CA-Ⅸ-specific siRNA, or treated with its inhibitor 4-(2-aminoethyl) benzenesulfonamide (CAI#1), and/or the hexokinase Ⅱ inhibitor, 3-bromopyruvate (3-BP). A clinic pathological analysis of 69 patients who underwent an HCC resection was performed using a tissue array.Results: Incubation of HCC cells under hypoxia (1% 02, 5% C02, 94% N2) for 36 h significantly increased CA-IX expression level. CAI#1(400 μmol/L) or CA-IX siRNA (100 μmol/L) did not influence HCC cell growth and induce apoptosis. However, CAI#1 or CA-IX siRNA at these concentrations enhanced the apoptosis induced by 3-BP (100 μmol/L). This enhancement was attributed to increased ER stress and JNK activation, as compared with 3-BP alone. Furthermore, a clinic pathological analysis of 69 HCC patients revealed that tumor CA-Ⅸ intensity was inversely related to E-cadherin intensity.Conclusion: Inhibition of hypoxia-induced CA-Ⅸ enhances hexokinase Ⅱ inhibitor-induced HCC apoptosis. Furthermore, CA-IX expres sion profiles may have prognostic implications in HCC patients. Thus, the inhibition of CA-Ⅸ, in combination with a hexokinase Ⅱ inhibitor, may be therapeutically useful in patients with HCCs that are aggressively growing in a hypoxic environment.

  2. Zinc Transfer Kinetics of Metallothioneins and Their Fragmentswith Apo-carbonic Anhydrase

    Institute of Scientific and Technical Information of China (English)

    HUANG, Zhong-Xian; LIU, Fang; ZHENG, Qi; YU, Wen-Hao

    2001-01-01

    Tne zinc transfer reactions from Zn7-MT-I, Zn7-MT-Ⅱ, Zn4α fragment (MT-I) and Zn4-α fragment (MT-Ⅱ) to apo-carbonic anhydrase have been studied. In each reaction, no more than one zinc ion per molecule is involved in metal transfer.Zn7-MT-I and Zn7-MT-Ⅱ donate zinc to apo-carbonic anhydrase and de novo constitute it at a comparable efficiency,while Zn7-MT-Ⅱ exhibits a little faster rate. Surprisingiy,Zinc is released from Zn4-α fragment (MT-Ⅱ) with a much faster rate than from Zn4-α fragment (MT-I), whose rate is close to that of Zn7-MT-I. The reason for the difference is still unknown. Introducing complex compounds into this system may give rise to an effect on the reaction. The transfer from Zn7-MT-Ⅱ in the presence of reduced glutathione shows little difference compare to the control, suggesting that the reduced glutathione is not involved in zinc transfer process. However,glutathione disulfide does accelerate this zinc transfer reaction remarkably, indicating that the oxidative factors contribute to zinc rlease from metallothioneins.

  3. Oxygen-18 isotope of breath CO₂ linking to erythrocytes carbonic anhydrase activity: a biomarker for pre-diabetes and type 2 diabetes.

    Science.gov (United States)

    Ghosh, Chiranjit; Banik, Gourab D; Maity, Abhijit; Som, Suman; Chakraborty, Arpita; Selvan, Chitra; Ghosh, Shibendu; Chowdhury, Subhankar; Pradhan, Manik

    2015-01-01

    Carbonic anhydrase (CA), a well-characterized metalloenzyme, is associated with oxygen-18 ( (18)O)-isotopic fractionations of CO₂. To investigate how CA activity links the (18)O of breath CO₂ to pre-diabetes (PD) and type 2 diabetes (T2D) during metabolism, we studied pre- and post-dose CA activities in erythrocytes with simultaneous monitoring of (18)O/ (16)O-isotope ratios of breath CO₂ and thereafter elucidated potential metabolic pathways underlying CA alteration in the pathogenesis of T2D. Here we show that the post-dose CA activity in both T2D and PD was markedly enhanced, whereas the non-diabetic controls (NDC) exhibited a considerable reduction in post-dose CA activity when compared with their basal CA activities. However, T2D and PD exhibited isotopic enrichments of (18)O in breath CO₂, while a marked depletion of (18)O in CO₂ was manifested in NDC. Thus, the isotopic enrichments and depletions of (18)O in breath CO₂ were well correlated with the changes in CA activities for controls, PD and T2D. Our findings suggest the changes in CA activities in erythrocytes may contribute to the pathogenesis of T2D and the breath C (18)O (16)O regulated by the CA activity as a potential biomarker for non-invasive assessment of T2D, and thus may open a new method for treating T2D. PMID:25633556

  4. Oxygen-18 isotope of breath CO2 linking to erythrocytes carbonic anhydrase activity: a biomarker for pre-diabetes and type 2 diabetes

    Science.gov (United States)

    Ghosh, Chiranjit; Banik, Gourab D.; Maity, Abhijit; Som, Suman; Chakraborty, Arpita; Selvan, Chitra; Ghosh, Shibendu; Chowdhury, Subhankar; Pradhan, Manik

    2015-01-01

    Carbonic anhydrase (CA), a well-characterized metalloenzyme, is associated with oxygen-18 ( 18O)-isotopic fractionations of CO2. To investigate how CA activity links the 18O of breath CO2 to pre-diabetes (PD) and type 2 diabetes (T2D) during metabolism, we studied pre- and post-dose CA activities in erythrocytes with simultaneous monitoring of 18O/ 16O-isotope ratios of breath CO2 and thereafter elucidated potential metabolic pathways underlying CA alteration in the pathogenesis of T2D. Here we show that the post-dose CA activity in both T2D and PD was markedly enhanced, whereas the non-diabetic controls (NDC) exhibited a considerable reduction in post-dose CA activity when compared with their basal CA activities. However, T2D and PD exhibited isotopic enrichments of 18O in breath CO2, while a marked depletion of 18O in CO2 was manifested in NDC. Thus, the isotopic enrichments and depletions of 18O in breath CO2 were well correlated with the changes in CA activities for controls, PD and T2D. Our findings suggest the changes in CA activities in erythrocytes may contribute to the pathogenesis of T2D and the breath C 18O 16O regulated by the CA activity as a potential biomarker for non-invasive assessment of T2D, and thus may open a new method for treating T2D. PMID:25633556

  5. Expression of transmembrane carbonic anhydrases, CAIX and CAXII, in human development

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    Lerman Michael I

    2009-03-01

    Full Text Available Abstract Background Transmembrane CAIX and CAXII are members of the alpha carbonic anhydrase (CA family. They play a crucial role in differentiation, proliferation, and pH regulation. Expression of CAIX and CAXII proteins in tumor tissues is primarily induced by hypoxia and this is particularly true for CAIX, which is regulated by the transcription factor, hypoxia inducible factor-1 (HIF-1. Their distributions in normal adult human tissues are restricted to highly specialized cells that are not always hypoxic. The human fetus exists in a relatively hypoxic environment. We examined expression of CAIX, CAXII and HIF-1α in the developing human fetus and postnatal tissues to determine whether expression of CAIX and CAXII is exclusively regulated by HIF-1. Results The co-localization of CAIX and HIF-1α was limited to certain cell types in embryonic and early fetal tissues. Those cells comprised the primitive mesenchyma or involved chondrogenesis and skin development. Transient CAIX expression was limited to immature tissues of mesodermal origin and the skin and ependymal cells. The only tissues that persistently expressed CAIX protein were coelomic epithelium (mesothelium and its remnants, the epithelium of the stomach and biliary tree, glands and crypt cells of duodenum and small intestine, and the cells located at those sites previously identified as harboring adult stem cells in, for example, the skin and large intestine. In many instances co-localization of CAIX and HIF-1α was not evident. CAXII expression is restricted to cells involved in secretion and water absorption such as parietal cells of the stomach, acinar cells of the salivary glands and pancreas, epithelium of the large intestine, and renal tubules. Co-localization of CAXII with CAIX or HIF-1α was not observed. Conclusion The study has showed that: 1 HIF-1α and CAIX expression co- localized in many, but not all, of the embryonic and early fetal tissues; 2 There is no evidence of

  6. Optimizing lutetium 177-anti-carbonic anhydrase IX radioimmunotherapy in an intraperitoneal clear cell renal cell carcinoma xenograft model

    NARCIS (Netherlands)

    Muselaers, C.H.J.; Oosterwijk, E.; Bos, D.L.; Oyen, W.J.G.; Mulders, P.F.A.; Boerman, O.C.

    2014-01-01

    A new approach in the treatment of clear cell renal carcinoma (ccRCC) is radioimmunotherapy (RIT) using anti-carbonic anhydrase IX (CAIX) antibody G250. To investigate the potential of RIT with lutetium 177 (177Lu)-labeled G250, we conducted a protein dose escalation study and subsequently an RIT st

  7. Metabolic Effect of Estrogen Receptor Agonists on Breast Cancer Cells in the Presence or Absence of Carbonic Anhydrase Inhibitors

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    Anissa Belkaid

    2016-05-01

    Full Text Available Metabolic shift is one of the major hallmarks of cancer development. Estrogen receptor (ER activity has a profound effect on breast cancer cell growth through a number of metabolic changes driven by its effect on transcription of several enzymes, including carbonic anhydrases, Stearoyl-CoA desaturase-1, and oncogenes including HER2. Thus, estrogen receptor activators can be expected to lead to the modulation of cell metabolism in estrogen receptor positive cells. In this work we have investigated the effect of 17β-estradiol, an ER activator, and ferulic acid, a carbonic anhydrase inhibitor, as well as ER activator, in the absence and in the presence of the carbonic anhydrase inhibitor acetazolamide on the metabolism of MCF7 cells and MCF7 cells, stably transfected to express HER2 (MCF7HER2. Metabolic profiles were studied using 1D and 2D metabolomic Nuclear Magnetic Resonance (NMR experiments, combined with the identification and quantification of metabolites, and the annotation of the results in the context of biochemical pathways. Overall changes in hydrophilic metabolites were largest following treatment of MCF7 and MC7HER2 cells with 17β-estradiol. However, the carbonic anhydrase inhibitor acetazolamide had the largest effect on the profile of lipophilic metabolites.

  8. Carbonic Anhydrase and Zinc in Plant Physiology Anhidrasa Carbónica y Zinc en Fisiología Vegetal

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    Dalila Jacqueline Escudero-Almanza

    2012-03-01

    Full Text Available Carbonic anhydrase (CA (EC: 2.4.1.1 catalyzes the rapid conversion of carbon dioxide plus water into a proton and the bicarbonate ion (HCO3- that can be found in prokaryotes and higher organisms; it is represented by four different families. Carbonic anhydrase is a metalloenzyme that requires Zn as a cofactor and is involved in diverse biological processes including pH regulation, CO2 transfer, ionic exchange, respiration, CO2 photosynthetic fixation, and stomatal closure. Therefore, the review includes relevant aspects about CA morphology, oligomerization, and structural differences in the active site. On the other hand, we consider the general characteristics of Zn, its geometry, reactions, and physiology. We then consider the CA catalysis mechanism that is carried out by the metal ion and where Zn acts as a cofactor. Zinc deficiency can inhibit growth and protein synthesis, and there is evidence that it reduces the CA content in some plants, which is a relationship addressed in this review. In leaves, CA represents 20.1% of total soluble protein, while it is the second most abundant in the chloroplast after ribulose 1,5-disphosphate carboxylase/oxygenase (RuBisCO. This facilitates the supply of CO2 to the phosphoenolpyruvate carboxylase in C4 and CAM plants and RuBisCO in C3 plants.La anhidrasa carbónica (CA (EC: 4.2.1.1 cataliza la conversión rápida de dióxido de carbono más agua en un protón y el ion bicarbonato (HCO3-; la cual puede encontrarse en procariotas y en organismos superiores y está representada por cuatro familias distintas. La CA es una metaloenzima que requiere Zn como cofactor y está implicada en diversos procesos biológicos, incluyendo la regulación del pH, la transferencia de CO2, intercambio iónico, la respiración, la fijación fotosintética de CO2, y el cierre estomático. Por lo cual, la revisión incluye aspectos relevantes sobre la morfología de laAC, su oligomerización y diferencias estructurales en el

  9. Oxygen-18 incorporation into malic acid during nocturnal carbon dioxide fixation in crassulacean acid metabolism plants. A new approach to estimating in vivo carbonic anhydrase activity.

    Science.gov (United States)

    Holtum, J A; Summons, R; Roeske, C A; Comins, H N; O'Leary, M H

    1984-06-10

    Crassulacean acid metabolism (CAM) plants fix carbon dioxide at night by the carboxylation of phosphoenolpyruvate. If CO2 fixation is conducted with 13C18O2 , then in the absence of carbonic anhydrase, the malate formed by dark CO2 fixation should also contain high levels of carbon-13 and oxygen-18. Conversely, if carbonic anhydrase is present and highly active, oxygen exchange between CO2 and cellular H2O will occur more rapidly than carboxylation, and the [13C] malate formed will contain little or no oxygen-18 above the natural abundance level. The presence of oxygen-18 in these molecules can be detected either by nuclear magnetic resonance (using the oxygen-18 effect on the carbon-13 chemical shift of the carboxyl carbon) or by mass spectrometry (comparing the ions at three and five units above the molecular weight with that one unit above). Studies of phosphoenolpyruvate carboxylase in the presence and absence of carbonic anhydrase in vitro confirm the validity of the method. When CAM plants are studied by this method, we find that most species show incorporation of a significant amount of oxygen-18. Comparison of these results with results of isotope fractionation and gas exchange studies permits calculation of the in vivo activity of carbonic anhydrase toward HCO-3 compared with that of phosphoenolpyruvate carboxylase. The ratio (carbonic anhydrase activity/phosphoenolpyruvate carboxylase activity) is species dependent and varies from a low of about 7 for Ananas comosus to values near 20 for Hoya carnosa and Bryophyllum pinnatum , 40 for Kalancho ë daigremontiana , and 100 or greater for Bryophyllum tubiflorum , Kalancho ë serrata, and Kalancho ë tomentosa. Carbonic anhydrase activity increases relative to phosphoenolpyruvate carboxylase activity at higher temperature. PMID:6427227

  10. Synthesis and In Vitro Inhibition Effect of New Pyrido[2,3-d]pyrimidine Derivatives on Erythrocyte Carbonic Anhydrase I and II

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    Hilal Kuday

    2014-01-01

    Full Text Available In vitro inhibition effects of indolylchalcones and new pyrido[2,3-d]pyrimidine derivatives on purified human carbonic anhydrase I and II (hCA I and II were investigated by using CO2 as a substrate. The results showed that all compounds inhibited the hCA I and hCA II enzyme activities. Among all the synthesized compounds, 7e (IC50=6.79 µM was found to be the most active compound for hCA I inhibitory activity and 5g (IC50=7.22 µM showed the highest hCA II inhibitory activity. Structure-activity relationships study showed that indolylchalcone derivatives have higher inhibitory activities than pyrido[2,3-d]pyrimidine derivatives on hCA I and hCA II. Additionally, methyl group bonded to uracil ring increases inhibitory activities on both hCA I and hCA II.

  11. Anion inhibition profiles of α-, β- and γ-carbonic anhydrases from the pathogenic bacterium Vibrio cholerae.

    Science.gov (United States)

    Del Prete, Sonia; Vullo, Daniela; De Luca, Viviana; Carginale, Vincenzo; di Fonzo, Pietro; Osman, Sameh M; AlOthman, Zeid; Supuran, Claudiu T; Capasso, Clemente

    2016-08-15

    Among the numerous metalloenzymes known to date, carbonic anhydrase (CA, EC 4.2.1.1) was the first zinc containing one, being discovered decades ago. CA is a hydro-lyase, which catalyzes the following hydration-dehydration reaction: CO2+H2O⇋HCO3(-)+H(+). Several CA classes are presently known, including the α-, β-, γ-, δ-, ζ- and η-CAs. In prokaryotes, the existence of genes encoding CAs from at least three classes (α-, β- and γ-class) suggests that these enzymes play a key role in the physiology of these organisms. In many bacteria CAs are essential for the life cycle of microbes and their inhibition leads to growth impairment or growth defects of the pathogen. CAs thus started to be investigated in detail in bacteria, fungi and protozoa with the aim to identify antiinfectives with a novel mechanism of action. Here, we investigated the catalytic activity, biochemical properties and anion inhibition profiles of the three CAs from the bacterial pathogen Vibrio cholera, VchCA, VchCAβ and VchCAγ. The three enzymes are efficient catalysts for CO2 hydration, with kcat values ranging between (3.4-8.23)×10(5)s(-1) and kcat/KM of (4.1-7.0)×10(7)M(-1)s(-1). A set of inorganic anions and small molecules was investigated for inhibition of these enzymes. The most potent VchCAγ inhibitors were N,N-diethyldithiocarbamate, sulfamate, sulfamide, phenylboronic acid and phenylarsonic acid, with KI values ranging between 44 and 91μM. PMID:27283786

  12. Carbonic Anhydrase IX is Not a Predictor of Outcomes in Non-Metastatic Clear Cell Renal Cell Carcinoma - A Digital Analysis of Tissue Microarray

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    Marcelo Zerati

    2013-07-01

    Full Text Available Introduction The knowledge about the molecular biology of clear cell renal cell carcinoma (ccRCC is evolving, and Carbonic Anhydrase type IX (CA-IX has emerged as a potential prognostic marker in this challenging disease. However, most of the literature about CA-IX on ccRCC comes from series on metastatic cancer, with a lack of series on non-metastatic cancer. The objective is to evaluate the expression of CA-IX in a cohort of non-metastatic ccRCC, correlating with 1 overall survival, and 2 with established prognostic parameters (T stage, tumor size, Fuhrman nuclear grade, microvascular invasion and peri-renal fat invasion. Materials and Methods This is a retrospective cohort study. We evaluated 95 patients with non-metastatic clear cell renal cell carcinoma, as to the expression of CA-IX. The analyzed parameters where: overall survival (OS, TNM stage, tumor size (TS, Fuhrman nuclear grade (FNG, microvascular invasion (MVI, peri-renal fat invasion (PFI. We utilized a custom built tissue microarray, and the immunoexpression was digitally quantified using the Photoshop® software. Results: Th e mean follow-up time was 7.9 years (range 1.9 to 19.5 years. The analysis of CA-IX expression against the selected prognostic parameters showed no correlation. The results are as follows: Overall survival (p = 0.790; T stage (p = 0.179; tumor size (p = 0.143; grouped Fuhrman nuclear grade (p = 0.598; microvascular invasion (p = 0.685, and peri-renal fat invasion (p = 0.104. Conclusion Carbonic anhydrase type IX expression does not correlate with overall survival and conventional prognostic parameters in non-metastatic clear cell renal cell carcinoma.

  13. Synthesis 4-[2-(2-mercapto-4-oxo-4H-quinazolin-3-yl)-ethyl]-benzenesulfonamides with subnanomolar carbonic anhydrase II and XII inhibitory properties.

    Science.gov (United States)

    Bozdag, Murat; Alafeefy, Ahmed M; Carta, Fabrizio; Ceruso, Mariangela; Al-Tamimi, Abdul-Malek S; Al-Kahtani, Abdulla A; Alasmary, Fatmah A S; Supuran, Claudiu T

    2016-09-15

    Condensation of substituted anthranilic acids with 4-isothiocyanatoethyl-benzenesulfonamide led to series of heterocyclic benzenesulfonamides incorporating 2-mercapto-quinazolin-4-one tails. These sulfonamides were investigated as inhibitors of the human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms hCA I and II (cytosolic isozymes), as well as hCA XII (a transmembrane, tumor-associated enzyme also involved in glaucoma-genesis). The new sulfonamides acted as medium potency inhibitors of hCA I (KIs of 28.5-2954nM), being highly effective as hCA II (KIs in the range of 0.62-12.4nM) and XII (KIs of 0.54-7.11nM) inhibitors. All substitution patterns present in these compounds (e.g., halogens, methyl and methoxy moieties, in positions 6, 7 and/or 8 of the 2-mercapto-quinazolin-4-one ring) led to highly effective hCA II/XII inhibitors. These compounds should thus be of interest as preclinical candidates in pathologies in which the activity of these enzymes should be inhibited, such as glaucoma (CA II and XII as targets) or some tumors in which the activity of isoforms CA II and XII is dysregulated. PMID:27396930

  14. Conformational effects on the circular dichroism of Human Carbonic Anhydrase II: a multilevel computational study.

    Directory of Open Access Journals (Sweden)

    Tatyana G Karabencheva-Christova

    Full Text Available Circular Dichroism (CD spectroscopy is a powerful method for investigating conformational changes in proteins and therefore has numerous applications in structural and molecular biology. Here a computational investigation of the CD spectrum of the Human Carbonic Anhydrase II (HCAII, with main focus on the near-UV CD spectra of the wild-type enzyme and it seven tryptophan mutant forms, is presented and compared to experimental studies. Multilevel computational methods (Molecular Dynamics, Semiempirical Quantum Mechanics, Time-Dependent Density Functional Theory were applied in order to gain insight into the mechanisms of interaction between the aromatic chromophores within the protein environment and understand how the conformational flexibility of the protein influences these mechanisms. The analysis suggests that combining CD semi empirical calculations, crystal structures and molecular dynamics (MD could help in achieving a better agreement between the computed and experimental protein spectra and provide some unique insight into the dynamic nature of the mechanisms of chromophore interactions.

  15. Update and critical appraisal of combined timolol and carbonic anhydrase inhibitors and the effect on ocular blood flow in glaucoma patients

    Directory of Open Access Journals (Sweden)

    Adam M Moss

    2010-03-01

    Full Text Available Adam M Moss, Alon Harris, Brent Siesky, Deepam Rusia, Kathleen M Williamson, Yochai ShoshaniDepartment of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, USAAbstract: Topical hypotensive therapy with both timolol and carbonic anhydrase inhibitors has been shown to be efficacious at reducing intraocular pressure. Many prospective studies have also suggested that carbonic anhydrase inhibitors augment ocular blood flow and vascular regulation independent of their hypotensive effects. Although consistent in their findings, these studies must be cautiously interpreted due to the limitations of study design and specific blood flow imaging modalities. The purpose of this review is to appraise and critically evaluate the current body of literature investigating the effects of combined treatment with topical carbonic anhydrase inhibitors and timolol in patients with glaucoma with respect to ocular blood flow, visual function, and optic nerve head structure.Keywords: ocular blood flow, carbonic anhydrase inhibitor, timolol, glaucoma, visual function, optic nerve head

  16. Development of 3-(4-aminosulphonyl)-phenyl-2-mercapto-3H-quinazolin-4-ones as inhibitors of carbonic anhydrase isoforms involved in tumorigenesis and glaucoma.

    Science.gov (United States)

    Alafeefy, Ahmed M; Carta, Fabrizio; Ceruso, Mariangela; Al-Tamimi, Abdul-Malek S; Al-Kahtani, Abdulla A; Supuran, Claudiu T

    2016-03-15

    A series of heterocyclic benzenesulfonamides incorporating 2-mercapto-3H-quinazolin-4-one tails were prepared by condensation of substituted anthranilic acids with 4-isothiocyanato-benzenesulfonamide. These sulfonamides were investigated as inhibitors of the human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms hCA I and II (cytosolic isozymes), as well as hCA IX and XII (trans-membrane, tumor-associated enzymes). They acted as medium potency inhibitors of hCA I (KIs of 81.0-3084 nM), being highly effective as hCA II (KIs in the range of 0.25-10.8 nM), IX (KIs of 3.7-50.4 nM) and XII (KIs of 0.60-52.9 nM) inhibitors. These compounds should thus be of interest as preclinical candidates in pathologies in which the activity of these enzymes should be inhibited, such as glaucoma (CA II and XII as targets) or some tumors in which the activity of three isoforms (CA II, IX and XII) is dysregulated. PMID:26875933

  17. The alpha-carbonic anhydrase from the thermophilic bacterium Sulfurihydrogenibium yellowstonense YO3AOP1 is highly susceptible to inhibition by sulfonamides.

    Science.gov (United States)

    Vullo, Daniela; Luca, Viviana De; Scozzafava, Andrea; Carginale, Vincenzo; Rossi, Mosè; Supuran, Claudiu T; Capasso, Clemente

    2013-03-15

    The α-carbonic anhydrase (CA, EC 4.2.1.1) from the newly discovered thermophilic bacterium Sulfurihydrogenibium yellowstonense YO3AOP1 (SspCA) was investigated for its inhibition with a large series of sulfonamides and a sulfamate, the classical inhibitors of these zinc enzymes. SspCA showed an inhibition profile with these compounds very similar to that of the predominant human cytosolic isoform hCA II, and not to that of the bacterial α-CA from Helicobacter pylori. Some clinically used drugs such as acetazolamide, methazolamide, ethoxzolamide, dichlorophenamide, dorzolamide, brinzolamide, topiramate, celecoxib and sulthiame were low nanomolar SspCA/hCA II inhibitors (KIs in the range of 4.5-12.3nM) whereas simple aromatic/heterocyclic sulfonamides were less effective, micromolar inhibitors. As this highly catalytically active and thermostable enzyme may show biotechnological applications, its inhibition studies may be relevant for designing on/off systems to control its activity. PMID:22883029

  18. Production, purification, and characterization of a fusion protein of carbonic anhydrase from Neisseria gonorrhoeae and cellulose binding domain from Clostridium thermocellum

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhu [Univ. of Pittsburgh, PA (United States); Bartlow, Patrick [Univ. of Pittsburgh, PA (United States); Dilmore, Robert M. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Soong, Yee [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Pan, Zhiwei [Univ. of Pittsburgh, PA (United States); Koepsel, Richard [Univ. of Pittsburgh, PA (United States); Ataai, Mohammad [Univ. of Pittsburgh, PA (United States)

    2009-01-01

    Carbon dioxide capture technologies have the potential to become an important climate change mitigation option through sequestration of gaseous CO2, A new concept for CO2 capture involves use of immobilized carbonic anhydrase (CA) that catalyzes the reversible hydration of CO2 to HCO3- and H+. Cost-efficient production of the enzyme and an inexpensive immobilization system are critical for development of economically feasible CA-based CO2 capture processes. An artificial, bifunctional enzyme containing CA from Neisseria gonorrhoeae and a cellulose binding domain (CBD) from Clostridium thermocellum was constructed with a His6 tag. The chimeric enzyme exhibited both CA activity and CBD binding affinity. This fusion enzyme is of particular interest due to its binding affinity for cellulose and retained CA activity, which could serve as the basis for improved technology to capture CO2 from flue gasses.

  19. Amido/ureidosubstituted benzenesulfonamides-isatin conjugates as low nanomolar/subnanomolar inhibitors of the tumor-associated carbonic anhydrase isoform XII.

    Science.gov (United States)

    Eldehna, Wagdy M; Fares, Mohamed; Ceruso, Mariangela; Ghabbour, Hazem A; Abou-Seri, Sahar M; Abdel-Aziz, Hatem A; Abou El Ella, Dalal A; Supuran, Claudiu T

    2016-03-01

    By using a molecular hybridization approach, two series of amido/ureidosubstituted benzenesulfonamides incorporating substituted-isatin moieties were synthesized. The prepared derivatives were in vitro evaluated for their inhibitory activity against human carbonic anhydrase (hCA, EC 4.2.1.1) I, II (cytosolic) and IX, XII (transmembrane, tumor-associated) isoforms. All these isoforms were inhibited in variable degrees by the sulfonamides reported here. hCA I was inhibited with KIs in the range of 7.9-894 nM, hCA II in the range of 7.5-1645 nM (with one compound having a KI > 10 μM); hCA IX in the range of 5.0-240 nM, whereas hCA XII in the range of 0.47-2.83 nM. As all these isoforms are involved in various pathologies, in which their inhibition can be exploited therapeutically, the derivatives reported here may represent interesting extensions to the field of CA inhibitors of the sulfonamide type. PMID:26840366

  20. Carbonic anhydrase activity and photosynthetic rate in the tree species Paulownia tomentosa Steud. Effect of dimethylsulfoxide treatment and zinc accumulation in leaves.

    Science.gov (United States)

    Lazova, Galia N; Naidenova, Tsveta; Velinova, Katya

    2004-03-01

    The enzyme carbonic anhydrase (CA) (EC 4.2.1.1) catalyzes the reversible conversion of CO2 to HCO3- and has been shown to be involved in photosynthesis. The enzyme has been shown in animals, plants, eubacteria and viruses, but similar reports on the evidence for CA activity in tree plants does not be appear to be available. In the preliminary analyses of the work, the CA activity in leaf extracts from the tree species Paulownia tomentosa Steud. (introduced in Bulgaria) is described. A connection between CA activity and the rate of photosynthetic CO2 fixation is shown. In the second portion of the work, the effect of 10(-4) mol/L and 10(-2) mol/L dimethylsulfoxide (DMSO) on the zinc accumulation in leaves is demonstrated. It is suggested that CA activity is an indicator of the level of physiologically active zinc in leaves of P. tomentosa Steud. A connection between the process of zinc accumulation in leaves and the activity of the enzymes CA and glycolate oxidase (GO) (EC 1.1.3.1) is established. PMID:15077628

  1. Anion inhibition studies of the α-carbonic anhydrase from the protozoan pathogen Trypanosoma cruzi, the causative agent of Chagas disease.

    Science.gov (United States)

    Pan, Peiwen; Vermelho, Alane Beatriz; Scozzafava, Andrea; Parkkila, Seppo; Capasso, Clemente; Supuran, Claudiu T

    2013-08-01

    The protozoan pathogen Trypanosoma cruzi, the causative agent of Chagas disease, encodes an α-class carbonic anhydrase (CA, EC 4.2.1.1), TcCA, which was recently shown to be crucial for its life cycle. Thiols, a class of strong TcCA inhibitors, were also shown to block the growth of the pathogen in vitro. Here we report the inhibition of TcCA by inorganic and complex anions and other molecules interacting with zinc proteins, such as sulfamide, sulfamic acid, phenylboronic/arsonic acids. TcCA was inhibited in the low micromolar range by iodide, cyanate, thiocyanate, hydrogensulfide and trithiocarbonate (KIs in the range of 44-93 μM), but the best inhibitor was diethyldithiocarbamate (KI=5 μM). Sulfamide showed an inhibition constant of 120 μM, but sulfamic acid was much less effective (KI of 10.6 mM). The discovery of diethyldithiocarbamate as a low micromolar TcCA inhibitor may be useful to detect leads for developing anti-Trypanosoma agents with a diverse mechanism of action compared to clinically used drugs (benznidazole, nifurtimox) for which significant resistance emerged. PMID:23790722

  2. Estrogen and progesterone differentially regulate carbonic anhydrase II, III, IX, XII, and XIII in ovariectomized rat uteri.

    Science.gov (United States)

    Karim, Kamarulzaman; Giribabu, Nelli; Muniandy, Sekaran; Salleh, Naguib

    2016-01-01

    Changes in the uterus expression of carbonic anhydrase (CA) II, III, IX, XII, and XIII were investigated under the influence of sex-steroids in order to elucidate mechanisms underlying differential effects of these hormones on uterine pH. Uteri of ovariectomised rats receiving over three days either vehicle, estrogen, or progesterone or three days estrogen followed by three days either vehicle or progesterone were harvested. Messenger RNA (mRNA) and protein levels were quantified by real-time PCR and Western blotting, respectively. The distribution of CA isoenzymes proteins were examined by immunohistochemistry. The levels of CAII, III, XII, and XIII mRNAs and proteins were elevated while levels of CAIX mRNA and protein were reduced following progesterone-only and estrogen plus progesterone treatment, compared to the control and estrogen plus vehicle, respectively. Following estrogen treatment, expression of CAII, IX, XII, and CAXIII mRNAs and proteins were reduced, but remained at a level higher than control, except for CAIX, where its level was higher than the control and following progesterone treatment. Under progesterone-only and estrogen plus progesterone influences, high levels of CAII, III, XII, and XIII were observed in uterine lumenal and glandular epithelia and myometrium. However, a high level of CAIX was observed only under the influence of estrogen at the similar locations. In conclusion, high expression of CAII, III, XII, and XIII under the influence of progesterone and estrogen plus progesterone could result in the reduction of uterine tissue and fluid pH; however, the significance of high levels of CAIX expression under the influence of estrogen remains unclear. PMID:26709452

  3. Complexes With Biologically Active Ligands. Part 111. Synthesis and Carbonic Anhydrase Inhibitory Activity of Metal Complexes of 4,5-Disubstituted-3-Mercapto-1,2,4-Triazole Derivatives

    Science.gov (United States)

    Scozzafava, Andrea; Cavazza, Christine; Saramet, Ioana; Briganti, Fabrizio; Banciu, Mircea D.

    1998-01-01

    Complexes containing five 4,5-disubstituted-3-mercapto-1,2,4-triazoles and Zn(II), Hg(II) and Cu(I) were synthesized and characterized by standard procedures (elemental analysis; IR, electronic and NMR spectroscopy, conductimetry and TG analysis). Both the thione as well as the thiolate forms of the ligands were evidenced to interact with the metal ions in the prepared complexes. The original mercaptans and their metal complexes behave as inhibitors of three carbonic anhydrase (CA) isozymes, CA I, II and IV, but did not lower intraocular pressure in rabbits in animal models of glaucoma. PMID:18475819

  4. Complexes with biologically active ligands. Part 11. Synthesis and carbonic anhydrase inhibitory activity of metal complexes of 4,5-disubstituted-3-mercapto-1,2,4-triazole derivatives.

    Science.gov (United States)

    Scozzafava, A; Cavazza, C; Supuran, C T; Saramet, I; Briganti, F; Banciu, M D

    1998-01-01

    Complexes containing five 4,5-disubstituted-3-mercapto-1,2,4-triazoles and Zn(II), Hg(II) and Cu(I) were synthesized and characterized by standard procedures (elemental analysis; IR, electronic and NMR spectroscopy, conductimetry and TG analysis). Both the thione as well as the thiolate forms of the ligands were evidenced to interact with the metal ions in the prepared complexes. The original mercaptans and their metal complexes behave as inhibitors of three carbonic anhydrase (CA) isozymes, CA I, II and IV, but did not lower intraocular pressure in rabbits in animal models of glaucoma.

  5. High kinetic stability of Zn(II) coordinated by the tris(histidine) unit of carbonic anhydrase towards solvolytic dissociation studied by affinity capillary electrophoresis.

    Science.gov (United States)

    Sato, Yosuke; Hoshino, Hitoshi; Iki, Nobuhiko

    2016-08-01

    Solvolytic dissociation rate constants (kd) of bovine carbonic anhydrase II (CA) and its metallovariants (M-CAs, M=Co(II), Ni(II), Cu(II), Zn(II), and Cd(II)) were estimated by a ligand substitution reaction, which was monitored by affinity capillary electrophoresis to selectively detect the undissociated CAs in the reaction mixture. Using EDTA as the competing ligand for Zn-CA, the dissociation followed the unimolecular nucleophilic substitution (SN1) mechanism with kd=1.0×10(-7)s(-1) (pH7.4, 25°C). The corresponding solvolysis half-life (t1/2) was 80days, showing the exceptionally high kinetic stability of t Zn-CA, in contrast to the highly labile [Zn(II)(H2O)6](2+), where the water exchange rate (kex) is high. This behavior is attributed to the tetrahedral coordination geometry supported by the tris(histidine) unit (His3) of CA. In the case of Co-CA, it showed a somewhat larger kd value (5.7×10(-7)s(-1), pH7.4, 25°C) even though it shares the same tetrahedral coordination environment with Zn-CA, suggesting that the d(7) electronic configuration of Co(II) in the transition state of the dissociation is stabilized by the ligand field. Among M-CAs, only Ni-CA showed a bimolecular nucleophilic substitution (SN2) reaction path in its reaction with EDTA, implying that the large coordination number (6) of Ni(II) in Ni-CA allows EDTA to form an EDTA-Ni-CA intermediate. Overall, kd values roughly correlated with kex values among M-CAs, with the kd value of Zn-CA deviating strongly from the trend and highlighting the exceptionally high kinetic stabilization of Zn-CA by the His3 unit. PMID:27235274

  6. The integrative segment of the quail Coturnix coturnix japonica. Occurrence and distribution of carbonic anhydrase and complex carbohydrates.

    OpenAIRE

    Gabriella, M G; Menghi, G

    1994-01-01

    As part of a more extensive study into the involvement of carbonic anhydrase in avian excretory function, the occurrence and distribution of this enzyme was investigated in the quail integrative segment. The integrative segment represents, in birds, that part of the intestinal tract where ureteral urine undergoes postrenal modification to form definitive urine. To define the structural peculiarities within the intestinal epithelium, the constituent parts, namely cloaca, rectum and caecum, as ...

  7. The impact of Carbonic Anhydrase on the partitioning of leaf and soil CO18O and COS gas exchange across scales

    Science.gov (United States)

    Wingate, L.; Wehr, R. A.; Commane, R.; Ogee, J.; Sauze, J.; Jones, S.; Launois, T.; Wohl, S.; Whelan, M.; Meredith, L. K.; Genty, B.; Gimeno, T.; Kesselmeier, J.; Bosc, A.; Cuntz, M.; Munger, J. W.; Nelson, D. D.; Saleska, S. R.; Wofsy, S. C.; Zahniser, M. S.

    2015-12-01

    Photosynthesis (GPP), the largest CO2 flux to the land surface, is currently estimated with considerable uncertainty at between 100-175 Pg C yr-1. More robust estimates of global GPP could be obtained from the atmospheric budgets of other valuable tracers, such as carbonyl sulfide (COS) or the oxygen isotopic composition (δ18O) of atmospheric CO2. However, quantifying GPP using these tracers hinges on a better understanding of how soil micro-organisms modify the atmospheric concentrations of CO18O and COS at large scales. In particular, understanding better the role and activity of the enzyme Carbonic Anhydrase (CA) in soil micro-organisms is critical. We present novel datasets and model simulations demonstrating the progress in the collection of multi-tracer field datasets and how a new generation of multi-tracer land surface models can provide valuable constraints on photosynthesis and respiration across scales.

  8. 9,10-Dibromo-N-aryl-9,10-dihydro-9,10-[3,4]epipyrroloanthracene-12,14-diones: Synthesis and Investigation of Their Effects on Carbonic Anhydrase Isozymes I, II, IX, and XII.

    Science.gov (United States)

    Göksu, Haydar; Topal, Meryem; Keskin, Ali; Gültekin, Mehmet S; Çelik, Murat; Gülçin, İlhami; Tanc, Muhammet; Supuran, Claudiu T

    2016-06-01

    N-substituted maleimides were synthesized from maleic anhydride and primary amines. 1,4-Dibromo-dibenzo[e,h]bicyclo-[2,2,2]octane-2,3-dicarboximide derivatives (4a-f) were prepared by the [4+2] cycloaddition reaction of dibromoanthracenes with the N-substituted maleimide derivatives. The carbonic anhydrase (CA, EC 4.2.1.1) inhibitory effects of the new derivatives were assayed against the human (h) isozymes hCA I, II, IX, and XII. All tested bicyclo dicarboximide derivatives exhibited excellent inhibitory effects in the nanomolar range, with Ki values in the range of 117.73-232.87 nM against hCA I and of 69.74-111.51 nM against hCA II, whereas they were low micromolar inhibitors against hCA IX and XII. PMID:27174792

  9. Coupling Protein Dynamics with Proton Transport in Human Carbonic Anhydrase II.

    Science.gov (United States)

    Taraphder, Srabani; Maupin, C Mark; Swanson, Jessica M J; Voth, Gregory A

    2016-08-25

    The role of protein dynamics in enzyme catalysis is one of the most highly debated topics in enzymology. The main controversy centers around what may be defined as functionally significant conformational fluctuations and how, if at all, these fluctuations couple to enzyme catalyzed events. To shed light on this debate, the conformational dynamics along the transition path surmounting the highest free energy barrier have been herein investigated for the rate limiting proton transport event in human carbonic anhydrase (HCA) II. Special attention has been placed on whether the motion of an excess proton is correlated with fluctuations in the surrounding protein and solvent matrix, which may be rare on the picosecond and subpicosecond time scales of molecular motions. It is found that several active site residues, which do not directly participate in the proton transport event, have a significant impact on the dynamics of the excess proton. These secondary participants are shown to strongly influence the active site environment, resulting in the creation of water clusters that are conducive to fast, moderately slow, or slow proton transport events. The identification and characterization of these secondary participants illuminates the role of protein dynamics in the catalytic efficiency of HCA II. PMID:27063577

  10. Enzyme renaturation to higher activity driven by the sol-gel transition: Carbonic anhydrase

    Science.gov (United States)

    Vinogradov, Vladimir V.; Avnir, David

    2015-09-01

    We describe a so-far unknown route for renaturing denatured enzymes, namely subjecting the denatured enzyme to an oxide sol-gel transition. The phenomenon was revealed in a detailed study of denatured carbonic anhydrase which was subjected to an alumina sol-gel transition, up to the thermally stabilizing entrapment in the final xerogel. Remarkably, not only that the killed enzyme regained its activity during the sol-gel process, but its activity increased to 180% of the native enzyme. To the best of our knowledge, this is the first report of enhanced activity following by renaturing (a “Phoenix effect”). Kinetic study which revealed a five-orders of magnitude (!) increase in the Arrhenius prefactor upon entrapment compared to solution. Circular dichroism analysis, differential scanning calorimetry, zeta potential analyses as well as synchronous fluorescence measurements, all of which were used to characterize the phenomenon, are consistent with a proposed mechanism which is based on the specific orienting interactions of the active site of the enzyme with respect to the alumina interface and its pores network.

  11. Spectroscopic and MD simulation studies on unfolding processes of mitochondrial carbonic anhydrase VA induced by urea.

    Science.gov (United States)

    Idrees, Danish; Prakash, Amresh; Haque, Md Anzarul; Islam, Asimul; Ahmad, Faizan; Hassan, Md Imtaiyaz

    2016-09-01

    Carbonic anhydrase VA (CAVA) is primarily expressed in the mitochondria and involved in numerous physiological processes including lipogenesis, insulin secretion from pancreatic cells, ureagenesis, gluconeogenesis and neuronal transmission. To understand the biophysical properties of CAVA, we carried out a reversible urea-induced isothermal denaturation at pH 7.0 and 25°C. Spectroscopic probes, [θ]222 (mean residue ellipticity at 222 nm), F344 (Trp-fluorescence emission intensity at 344 nm) and Δε280 (difference absorption at 280 nm) were used to monitor the effect of urea on the structure and stability of CAVA. The urea-induced reversible denaturation curves were used to estimate [Formula: see text], Gibbs free energy in the absence of urea; Cm, the mid-point of the denaturation curve, i.e. molar urea concentration ([urea]) at which ΔGD = 0; and m, the slope (=∂ΔGD/∂[urea]). Coincidence of normalized transition curves of all optical properties suggests that unfolding/refolding of CAVA is a two-state process. We further performed 40 ns molecular dynamics simulation of CAVA to see the dynamics at different urea concentrations. An excellent agreement was observed between in silico and in vitro studies.

  12. Sulfamate inhibitor S4 influences carbonic anhydrase IX ectodomain shedding in colorectal carcinoma cells.

    Science.gov (United States)

    Hektoen, Helga Helseth; Ree, Anne Hansen; Redalen, Kathrine Røe; Flatmark, Kjersti

    2016-10-01

    Carbonic anhydrase IX (CAIX) is a pivotal pH regulator under hypoxia, which by its tumor-specific expression represents an attractive target for cancer therapy. Here, we report on effects of the sulfamate CAIX inhibitor S4 (4-(3'-(3″,5″-dimethylphenyl)ureido)phenyl sulfamate) in colorectal carcinoma cell lines. S4 was administered under experimental hypoxia or normoxia to HT29, KM20L2 and HCT116 cells. Effects on survival, proliferation, pH, lactate extrusion and CAIX protein expression were evaluated. S4 treatment resulted in attenuated hypoxia-induced extracellular acidification and reduced clonogenic survival under hypoxia in HT29 cells. The pH effects were present only in a [Formula: see text]-free buffer system and were accompanied by decreased lactate extrusion. The main finding of this work was that S4 treatment caused alterations in CAIX ectodomain shedding. This merits further investigation to understand how sulfamates influence CAIX activity and how such drugs may be of use in cancer treatment. PMID:26244271

  13. Kinetic and X-ray crystallographic investigations on carbonic anhydrase isoforms I, II, IX and XII of a thioureido analog of SLC-0111.

    Science.gov (United States)

    Lomelino, Carrie L; Mahon, Brian P; McKenna, Robert; Carta, Fabrizio; Supuran, Claudiu T

    2016-03-01

    SLC-0111 (4-(4-fluorophenylureido)-benzenesulfonamide) is the first carbonic anhydrase (CA, EC 4.2.1.1) IX inhibitor to reach phase I clinical trials as an antitumor/antimetastatic agent. Here we report a kinetic and X-ray crystallographic study of a congener of SLC-0111 which incorporates a thioureido instead of ureido linker between the two aromatic rings as inhibitor of four physiologically relevant CA isoforms. Similar to SLC-0111, the thioureido derivative was a weak hCA I and II inhibitor and a potent one against hCA IX and XII. X-ray crystallography of its adduct with hCA II and comparison of the structure with that of other five hCA II-sulfonamide adducts belonging to the SLC-0111 series, afforded us to understand the particular inhibition profile of the new sulfonamide. Similar to SLC-0111, the thioureido sulfonamide primarily interacted with the hydrophobic side of the hCA II active site, with the tail participating in van der Waals interactions with Phe131 and Pro202, in addition to the coordination of the deprotonated sulfonamide to the active site metal ion. On the contrary, the tail of other sulfonamides belonging to the SLC-0111 series (2-isopropyl-phenyl; 3-nitrophenyl) were orientated towards the hydrophilic half of the active site, which was correlated with orders of magnitude better inhibitory activity against hCA II, and a loss of selectivity for the inhibition of the tumor-associated CAs. PMID:26810836

  14. Neutron structure of human carbonic anhydrase II in complex with methazolamide: mapping the solvent and hydrogen-bonding patterns of an effective clinical drug

    Directory of Open Access Journals (Sweden)

    Mayank Aggarwal

    2016-09-01

    Full Text Available Carbonic anhydrases (CAs; EC 4.2.1.1 catalyze the interconversion of CO2 and HCO3−, and their inhibitors have long been used as diuretics and as a therapeutic treatment for many disorders such as glaucoma and epilepsy. Acetazolamide (AZM and methazolamide (MZM, a methyl derivative of AZM are two of the classical CA inhibitory drugs that have been used clinically for decades. The jointly refined X-ray/neutron structure of MZM in complex with human CA isoform II (hCA II has been determined to a resolution of 2.2 Å with an Rcryst of ∼16.0%. Presented in this article, along with only the second neutron structure of a clinical drug-bound hCA, is an in-depth structural comparison and analyses of differences in hydrogen-bonding network, water-molecule orientation and solvent displacement that take place upon the binding of AZM and MZM in the active site of hCA II. Even though MZM is slightly more hydrophobic and displaces more waters than AZM, the overall binding affinity (Ki for both of the drugs against hCA II is similar (∼10 nM. The plausible reasons behind this finding have also been discussed using molecular dynamics and X-ray crystal structures of hCA II–MZM determined at cryotemperature and room temperature. This study not only allows a direct comparison of the hydrogen bonding, protonation states and solvent orientation/displacement of AZM and MZM, but also shows the significant effect that the methyl derivative has on the solvent organization in the hCA II active site.

  15. Bio-sequestration of CO2 Using Carbonic Anhydrase in situ Encapsulated Inside Electrospun Hollow Fibers%静电纺丝制备中空纤维原位固定化碳酸酐酶用于二氧化碳的吸收

    Institute of Scientific and Technical Information of China (English)

    崔建东; 李莹; 姬晓元; 边红杰; 张羽飞; 苏志国; 马光辉; 张松平

    2014-01-01

    Carbonic anhydrase catalyzed bio-sequestration of CO2 to form HCO-3 , followed by trapping as solid CaCO3 is one of the most promising technologies for CO2 capturing. The effects of reaction condition on the CO2 hydration using free carbonic anhydrase were systematically investigated. In order to improve the stability of the enzyme and facility its recycling, the carbonic anhydrase was in situ encapsulated inside hollow fibers via a novel co-axial electrospinning technology. Compared with the free enzyme, the immobilized carbonic an-hydrase showed much improved thermal stability and suffered much reduced inhibitory effects from cation ions, such as Cu2+ and Fe3+. After 11 reuses, the immobilized enzyme retained about 81. 9% of its original activity by comparing the amount of formed CaCO3 precipitation. In the presence of immobilized carbonic anhydrase, both calcite and vaterite CaCO3 solid were formed;while in the absence of enzyme or with free carbonic anhy-drase, only calcite CaCO3 was observed.%考察了游离碳酸酐酶吸收CO2水合体系反应条件,并通过同轴共纺静电纺丝技术制备出中空结构纤维,实现了碳酸酐酶在中空纤维中的原位包埋,提高了酶的稳定性并便于回收和重复利用.实验结果表明,固定化碳酸酐酶的热稳定性显著增强,受Cu2+和Fe3+等金属离子的抑制作用大幅度降低.连续使用11次后所生成的CaCO3沉淀量仍能达到首次使用的81.9%.固定化酶体系生成的CaCO3沉淀包括方解石型和球文石型2种晶形,而无酶和加入游离碳酸酐酶的反应体系则主要生成方解石型CaCO3沉淀.

  16. Roles of Carbonic Anhydrase in Photosynthesis of Skeletonema costatum%碳酸酐酶在中肋骨条藻光合作用中的作用

    Institute of Scientific and Technical Information of China (English)

    陈雄文; 高坤山

    2004-01-01

    探讨了在正常空气条件下生长的中肋骨条藻(Skeletonema costatum)的碳酸酐酶(CA)在其光合固碳中的作用.在中肋骨条藻的胞内和胞外均有CA活性,但胞外CA活性很低.CA抑制剂AZ(乙酰唑磺胺)对中肋骨条藻的光合放氧速率没有明显影响,而CA抑制剂EZ(乙氧苯唑胺)对其光合放氧速率有强烈的抑制作用.EZ的抑制作用使细胞最大光合速率、饱和光强和无机碳亲和力下降,无机碳的补偿点和光呼吸提高,使强光下光抑制作用增强.这些结果表明:中肋骨条藻的胞外CA在其光合作用中所起的作用较小,而其胞内CA通过催化胞内碳库中的HCO-3快速转化成CO2,提高胞内CO2的有效供给,从而提高细胞光合固碳能力和对逆境(高O2、强光和低CO2)的适应能力.%The role of carbonic anhydrase (CA) in photosynthesis of the marine diatom Skeletonema costatum grown at ambient level of CO2 was investigated. Extracellular CA activity was very low. In comparison, intracellular CA activity was great part of total CA activity. The inhibition of external CA by acetazolamide (AZ) caused little change in net photosynthetic rate (Pn), but the inhibition of intracellular CA by ethoxyzolamide (EZ) resulted in the strong reduction of Pn. EZ reduced the light-saturated photosynthesis, the saturation radiance and the affin ity of inorganic carbon for photosynthesis, raised inorganic carbon compensation point and enhanced the inhibition of photosynthesis by high O2 and light. It is concluded that extracellular CA exerted a minor role in the photosynthesis, but intracellular CA enhanced the efficiency of photosynthetic carbon fixation and the capacity of acclimation to stress conditions (high light, O2 and low CO2) by catalytically converting HCO-3 to CO2 and facilitating CO2 supply to the cell.

  17. Carbonic anhydrase II deficiency: Single-base deletion in exon 7 is the predominant mutation in Caribbean Hispanic patients

    Energy Technology Data Exchange (ETDEWEB)

    Hu, P.Y.; Ernst, A.R.; Sly, W.S. (St. Louis Univ. School of Medicine, MO (United States)); Venta, P.J. (Michigan State Univ., East Lansing, MI (United States)); Skaggs, L.A.; Tashian, R.E. (Univ. of Michigan Medical School, Ann Arbor, MI (United States))

    1994-04-01

    To date, three different structural gene mutations have been identified in patients with carbonic anhydrase II deficiency (osteopetrosis with renal tubular acidosis and cerebral calcification). These include a missense mutation (H107Y) in two families, a splice junction mutation in intron 5 in one of these families, and a splice junction mutation in intron 2 for which many Arabic patients are homozygous. The authors report here a novel mutation for which carbonic anhydrase II-deficient patients from seven unrelated Hispanic families were found to be homozygous. The proband was a 2 1/2-year-old Hispanic girl of Puerto Rican ancestry who was unique clinically, in that she had no evidence of renal tubular acidosis, even though she did have osteopetrosis, developmental delay, and cerebral calcification. She proved to be homozygous for a single-base deletion in the coding region of exon 7 that produces a frameshift that changes the next 12 amino acids before leading to chain termination and that also introduces a new MaeIII restriction site. The 27-kD truncated enzyme produced when the mutant cDNA was expressed in COS cells was enzymatically inactive, present mainly in insoluble aggregates, and detectable immunologically at only 5% the level of the 29-kD normal carbonic anhydrase II expressed from the wild-type cDNA. Metabolic labeling revealed that this 27-kD mutant protein has an accelerated rate of degradation. Six subsequent Hispanic patients of Caribbean ancestry, all of whom had osteopetrosis and renal tubular acidosis but who varied widely in clinical severity, were found to be homozygous for the same mutation. These findings identify a novel mutation common to Hispanic patients from the Caribbean islands and provide a ready means for PCR-based diagnosis of the [open quotes]Hispanic mutation.[close quotes] The basis for their phenotypic variability is not yet clear. 15 refs., 5 figs., 1 tab.

  18. Intrinsic Thermodynamics and Structure Correlation of Benzenesulfonamides with a Pyrimidine Moiety Binding to Carbonic Anhydrases I, II, VII, XII, and XIII.

    Directory of Open Access Journals (Sweden)

    Miglė Kišonaitė

    Full Text Available The early stage of drug discovery is often based on selecting the highest affinity lead compound. To this end the structural and energetic characterization of the binding reaction is important. The binding energetics can be resolved into enthalpic and entropic contributions to the binding Gibbs free energy. Most compound binding reactions are coupled to the absorption or release of protons by the protein or the compound. A distinction between the observed and intrinsic parameters of the binding energetics requires the dissection of the protonation/deprotonation processes. Since only the intrinsic parameters can be correlated with molecular structural perturbations associated with complex formation, it is these parameters that are required for rational drug design. Carbonic anhydrase (CA isoforms are important therapeutic targets to treat a range of disorders including glaucoma, obesity, epilepsy, and cancer. For effective treatment isoform-specific inhibitors are needed. In this work we investigated the binding and protonation energetics of sixteen [(2-pyrimidinylthioacetyl]benzenesulfonamide CA inhibitors using isothermal titration calorimetry and fluorescent thermal shift assay. The compounds were built by combining four sulfonamide headgroups with four tailgroups yielding 16 compounds. Their intrinsic binding thermodynamics showed the limitations of the functional group energetic additivity approach used in fragment-based drug design, especially at the level of enthalpies and entropies of binding. Combined with high resolution crystal structural data correlations were drawn between the chemical functional groups on selected inhibitors and intrinsic thermodynamic parameters of CA-inhibitor complex formation.

  19. Recombinant thermoactive phosphoenolpyruvate carboxylase (PEPC) from Thermosynechococcus elongatus and its coupling with mesophilic/thermophilic bacterial carbonic anhydrases (CAs) for the conversion of CO2 to oxaloacetate.

    Science.gov (United States)

    Del Prete, Sonia; De Luca, Viviana; Capasso, Clemente; Supuran, Claudiu T; Carginale, Vincenzo

    2016-01-15

    With the continuous increase of atmospheric CO2 in the last decades, efficient methods for carbon capture, sequestration, and utilization are urgently required. The possibility of converting CO2 into useful chemicals could be a good strategy to both decreasing the CO2 concentration and for achieving an efficient exploitation of this cheap carbon source. Recently, several single- and multi-enzyme systems for the catalytic conversion of CO2 mainly to bicarbonate have been implemented. In order to design and construct a catalytic system for the conversion of CO2 to organic molecules, we implemented an in vitro multienzyme system using mesophilic and thermophilic enzymes. The system, in fact, was constituted by a recombinant phosphoenolpyruvate carboxylase (PEPC) from the thermophilic cyanobacterium Thermosynechococcus elongatus, in combination with mesophilic/thermophilic bacterial carbonic anhydrases (CAs), for converting CO2 into oxaloacetate, a compound of potential utility in industrial processes. The catalytic procedure is in two steps: the conversion of CO2 into bicarbonate by CA, followed by the carboxylation of phosphoenolpyruvate with bicarbonate, catalyzed by PEPC, with formation of oxaloacetate (OAA). All tested CAs, belonging to α-, β-, and γ-CA classes, were able to increase OAA production compared to procedures when only PEPC was used. Interestingly, the efficiency of the CAs tested in OAA production was in good agreement with the kinetic parameters for the CO2 hydration reaction of these enzymes. This PEPC also revealed to be thermoactive and thermostable, and when coupled with the extremely thermostable CA from Sulphurhydrogenibium azorense (SazCA) the production of OAA was achieved even if the two enzymes were exposed to temperatures up to 60 °C, suggesting a possible role of the two coupled enzymes in biotechnological processes.

  20. Recombinant thermoactive phosphoenolpyruvate carboxylase (PEPC) from Thermosynechococcus elongatus and its coupling with mesophilic/thermophilic bacterial carbonic anhydrases (CAs) for the conversion of CO2 to oxaloacetate.

    Science.gov (United States)

    Del Prete, Sonia; De Luca, Viviana; Capasso, Clemente; Supuran, Claudiu T; Carginale, Vincenzo

    2016-01-15

    With the continuous increase of atmospheric CO2 in the last decades, efficient methods for carbon capture, sequestration, and utilization are urgently required. The possibility of converting CO2 into useful chemicals could be a good strategy to both decreasing the CO2 concentration and for achieving an efficient exploitation of this cheap carbon source. Recently, several single- and multi-enzyme systems for the catalytic conversion of CO2 mainly to bicarbonate have been implemented. In order to design and construct a catalytic system for the conversion of CO2 to organic molecules, we implemented an in vitro multienzyme system using mesophilic and thermophilic enzymes. The system, in fact, was constituted by a recombinant phosphoenolpyruvate carboxylase (PEPC) from the thermophilic cyanobacterium Thermosynechococcus elongatus, in combination with mesophilic/thermophilic bacterial carbonic anhydrases (CAs), for converting CO2 into oxaloacetate, a compound of potential utility in industrial processes. The catalytic procedure is in two steps: the conversion of CO2 into bicarbonate by CA, followed by the carboxylation of phosphoenolpyruvate with bicarbonate, catalyzed by PEPC, with formation of oxaloacetate (OAA). All tested CAs, belonging to α-, β-, and γ-CA classes, were able to increase OAA production compared to procedures when only PEPC was used. Interestingly, the efficiency of the CAs tested in OAA production was in good agreement with the kinetic parameters for the CO2 hydration reaction of these enzymes. This PEPC also revealed to be thermoactive and thermostable, and when coupled with the extremely thermostable CA from Sulphurhydrogenibium azorense (SazCA) the production of OAA was achieved even if the two enzymes were exposed to temperatures up to 60 °C, suggesting a possible role of the two coupled enzymes in biotechnological processes. PMID:26712095

  1. Comparison of the sulfonamide inhibition profiles of the α-, β- and γ-carbonic anhydrases from the pathogenic bacterium Vibrio cholerae.

    Science.gov (United States)

    Del Prete, Sonia; Vullo, Daniela; De Luca, Viviana; Carginale, Vincenzo; Osman, Sameh M; AlOthman, Zeid; Supuran, Claudiu T; Capasso, Clemente

    2016-04-15

    Carbonic anhydrases (CA, EC 4.2.1.1) are ubiquitous metalloenzymes, which catalyze the conversion of carbon dioxide (CO2) to bicarbonate (HCO3(-)) and protons (H(+)). In prokaryotes, the existence of genes encoding for α-, β- and γ-classes suggests that these enzymes play an important role in the prokaryotic physiology. It has been demonstrated, in fact, that their inhibition in vivo leads to growth impairment or growth defects of the microorganism. Ultimately, we started to investigate the biochemical properties and the inhibitory profiles of the α- and β-CAs identified in the genome of Vibrio cholerae, which is the causative agent of cholera. The genome of this pathogen encodes for CAs belonging to α, β and γ classes. Here, we report a sulfonamide inhibition study of the γ-CA (named VchCAγ) comparing it with data obtained for the α- and β-CA enzymes. VchCAγ activity (kcat=7.39 × 10(5)s(-1)) was significantly higher than the other γ-CAs. The inhibition study with a panel of sulfonamides and one sulfamate led to the detection of a large number of nanomolar VchCAγ inhibitors, including simple aromatic/heterocyclic sulfonamides (compounds 2-9, 11, 13-15, 24) as well as EZA, DZA, BRZ, BZA, TPM, ZNS, SLP, IND (KIs in the range of 66.2-95.3 nM). As it was proven that bicarbonate is a virulence factor of this bacterium and since ethoxzolamide was shown to inhibit this virulence in vivo, we propose that VchCA, VchCAβ and VchCAγ may be a target for antibiotic development, exploiting a mechanism of action rarely considered up until now, i.e., interference with bicarbonate supply as a virulence factor. PMID:26972117

  2. Evaluation of impacted Brazilian estuaries using the native oyster Crassostrea rhizophorae: Branchial carbonic anhydrase as a biomarker.

    Science.gov (United States)

    Azevedo-Linhares, Maristela; Freire, Carolina A

    2015-12-01

    In this study, we investigated the use of branchial carbonic anhydrase activity in a sessile filter feeding species, the oyster Crassostrea rhizophorae, as a biomarker. The oysters were collected in three human impacted Brazilian estuaries, following a crescent latitudinal gradient: in Pernambuco state (Itamaracá), in Espírito Santo state (Piraquê), and in Paraná state (Paranaguá), in August/2003 (Winter in the southern hemisphere) and February/2004 (Summer). Three sites were chosen in each estuary for oyster sampling: Reference (R), Contaminated 1 (C1, close to industrial/harbor contamination), and Contaminated 2 (C2, near to sewage discharges). Comparing to values in oysters sampled in reference sites, there was apparent inhibition in carbonic anhydrase activity (CAA) in gills of oysters from C1 of Itamaracá and from C2 of Piraquê, both cases in Summer. On the other hand, increased CAA was noted in C2 oysters of Itamaracá in winter, and of Paranaguá, in both seasons. Branchial CAA in C. rhizophorae was thus very responsive to coastal contamination. Data are consistent with its usefulness as a supporting biomarker for inexpensive and rapid analysis in the assessment of estuaries using a sessile osmoconformer species, but preferably allied to other biomarkers and with knowledge on the suite of contaminants present.

  3. Purification and characterization of the carbonic anhydrase enzyme from Black Sea trout (Salmo trutta Labrax Coruhensis) kidney and inhibition effects of some metal ions on enzyme activity.

    Science.gov (United States)

    Kucuk, Murat; Gulcin, İlhami

    2016-06-01

    In this study, the carbonic anhydrase (CA) enzyme was purified from Black Sea trout (Salmo trutta Labrax Coruhensis) kidney with a specific activity of 603.77EU/mg and a yield of 35.5% using Sepharose-4B-l-tyrosine- sulphanilamide affinity column chromatography. For determining the enzyme purity and subunit molecular mass, sodiumdodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) was performed and single band was observed. The molecular mass of subunit was found approximately 29.71kDa. The optimum temperature, activation energy (Ea), activation enthalpy (ΔH) and Q10 values were obtained from Arrhenius plot. Km and Vmax values for p-nitrophenyl acetate of the purified enzyme were calculated from Lineweaver-Burk graphs. In addition, the inhibitory effects of different heavy metal ions (Fe(2+), Pb(2+), Co(2+), Ag(+) and Cu(2+)) on Black Sea trout kidney tissue CA enzyme activities were investigated by using esterase method under in vitro conditions. The heavy metal concentrations inhibiting 50% of enzyme activity (IC50) were obtained. Finally Ki values and inhibition types were calculated from Lineweaver-Burk graphs. PMID:27175889

  4. Influence of Carbonic Anhydrase Activity in Terrestrial Vegetation on the 18O Content of Atmospheric CO2

    Science.gov (United States)

    Gillon, Jim; Yakir, Dan

    2001-03-01

    The oxygen-18 (18O) content of atmospheric carbon dioxide (CO2) is an important indicator of CO2 uptake on land. It has generally been assumed that during photosynthesis, oxygen in CO2 reaches isotopic equilibrium with oxygen in 18O-enriched water in leaves. We show, however, large differences in the activity of carbonic anhydrase (which catalyzes CO2 hydration and 18O exchange in leaves) among major plant groups that cause variations in the extent of 18O equilibrium (θeq). A clear distinction in θeq between C3 trees and shrubs, and C4 grasses makes atmospheric C18OO a potentially sensitive indicator to changes in C3 and C4 productivity. We estimate a global mean θeq value of ~0.8, which reasonably reconciles inconsistencies between 18O budgets of atmospheric O2 (Dole effect) and CO2.

  5. Reconstitution of CO2 Regulation of SLAC1 Anion Channel and Function of CO2-Permeable PIP2;1 Aquaporin as CARBONIC ANHYDRASE4 Interactor.

    Science.gov (United States)

    Wang, Cun; Hu, Honghong; Qin, Xue; Zeise, Brian; Xu, Danyun; Rappel, Wouter-Jan; Boron, Walter F; Schroeder, Julian I

    2016-02-01

    Dark respiration causes an increase in leaf CO2 concentration (Ci), and the continuing increases in atmospheric [CO2] further increases Ci. Elevated leaf CO2 concentration causes stomatal pores to close. Here, we demonstrate that high intracellular CO2/HCO3 (-) enhances currents mediated by the Arabidopsis thaliana guard cell S-type anion channel SLAC1 upon coexpression of any one of the Arabidopsis protein kinases OST1, CPK6, or CPK23 in Xenopus laevis oocytes. Split-ubiquitin screening identified the PIP2;1 aquaporin as an interactor of the βCA4 carbonic anhydrase, which was confirmed in split luciferase, bimolecular fluorescence complementation, and coimmunoprecipitation experiments. PIP2;1 exhibited CO2 permeability. Mutation of PIP2;1 in planta alone was insufficient to impair CO2- and abscisic acid-induced stomatal closing, likely due to redundancy. Interestingly, coexpression of βCA4 and PIP2;1 with OST1-SLAC1 or CPK6/23-SLAC1 in oocytes enabled extracellular CO2 enhancement of SLAC1 anion channel activity. An inactive PIP2;1 point mutation was identified that abrogated water and CO2 permeability and extracellular CO2 regulation of SLAC1 activity. These findings identify the CO2-permeable PIP2;1 as key interactor of βCA4 and demonstrate functional reconstitution of extracellular CO2 signaling to ion channel regulation upon coexpression of PIP2;1, βCA4, SLAC1, and protein kinases. These data further implicate SLAC1 as a bicarbonate-responsive protein contributing to CO2 regulation of S-type anion channels. PMID:26764375

  6. Size and surface chemistry of nanoparticles lead to a variant behavior in the unfolding dynamics of human carbonic anhydrase

    Science.gov (United States)

    Nasir, Irem; Lundqvist, Martin; Cabaleiro-Lago, Celia

    2015-10-01

    The adsorption induced conformational changes of human carbonic anhydrase I (HCAi) and pseudo wild type human carbonic anhydrase II truncated at the 17th residue at the N-terminus (trHCAii) were studied in presence of nanoparticles of different sizes and polarities. Isothermal titration calorimetry (ITC) studies showed that the binding to apolar surfaces is affected by the nanoparticle size in combination with the inherent protein stability. 8-Anilino-1-naphthalenesulfonic acid (ANS) fluorescence revealed that HCAs adsorb to both hydrophilic and hydrophobic surfaces, however the dynamics of the unfolding at the nanoparticle surfaces drastically vary with the polarity. The size of the nanoparticles has opposite effects depending on the polarity of the nanoparticle surface. The apolar nanoparticles induce seconds timescale structural rearrangements whereas polar nanoparticles induce hours timescale structural rearrangements on the same charged HCA variant. Here, a simple model is proposed where the difference in the timescales of adsorption is correlated with the energy barriers for initial docking and structural rearrangements which are firmly regulated by the surface polarity. Near-UV circular dichorism (CD) further supports that both protein variants undergo structural rearrangements at the nanoparticle surfaces regardless of being ``hard'' or ``soft''. However, the conformational changes induced by the apolar surfaces differ for each HCA isoform and diverge from the previously reported effect of silica nanoparticles.The adsorption induced conformational changes of human carbonic anhydrase I (HCAi) and pseudo wild type human carbonic anhydrase II truncated at the 17th residue at the N-terminus (trHCAii) were studied in presence of nanoparticles of different sizes and polarities. Isothermal titration calorimetry (ITC) studies showed that the binding to apolar surfaces is affected by the nanoparticle size in combination with the inherent protein stability. 8-Anilino

  7. Pharmacological inhibition of carbonic anhydrase XII interferes with cell proliferation and induces cell apoptosis in T-cell lymphomas.

    Science.gov (United States)

    Lounnas, Nadia; Rosilio, Célia; Nebout, Marielle; Mary, Didier; Griessinger, Emmanuel; Neffati, Zouhour; Chiche, Johanna; Spits, Hergen; Hagenbeek, Thijs J; Asnafi, Vahid; Poulsen, Sally-Ann; Supuran, Claudiu T; Peyron, Jean-François; Imbert, Véronique

    2013-06-01

    The membrane-bound carbonic anhydrase isoforms CAIX and CAXII, underpin a pH-regulating system that enables hypoxic tumor cell survival. Here, we observed for the first time an upregulation of CAXII in T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/LL) cells. First we showed that CAXII is overexpressed in thymocytes from tPTEN-/- mice suffering of T lymphoma and that its pharmacological inhibition decreased cell proliferation and induced apoptosis. The same results were observed with the SupT1 human T cell lymphoma line. In addition we observed an upregulation of CAXII in human T-ALL samples supporting the case that CAXII may represent a new therapeutic target for T-ALL/LL. PMID:23348702

  8. Modelling the impact of soil Carbonic Anhydrase on the net ecosystem exchange of OCS at Harvard forest using the MuSICA model

    Science.gov (United States)

    Launois, Thomas; Ogée, Jérôme; Commane, Roisin; Wehr, Rchard; Meredith, Laura; Munger, Bill; Nelson, David; Saleska, Scott; Wofsy, Steve; Zahniser, Mark; Wingate, Lisa

    2016-04-01

    The exchange of CO2 between the terrestrial biosphere and the atmosphere is driven by photosynthetic uptake and respiratory loss, two fluxes currently estimated with considerable uncertainty at large scales. Model predictions indicate that these biosphere fluxes will be modified in the future as CO2 concentrations and temperatures increase; however, it still unclear to what extent. To address this challenge there is a need for better constraints on land surface model parameterisations. Additional atmospheric tracers of large-scale CO2 fluxes have been identified as potential candidates for this task. In particular carbonyl sulphide (OCS) has been proposed as a complementary tracer of gross photosynthesis over land, since OCS uptake by plants is dominated by carbonic anhydrase (CA) activity, an enzyme abundant in leaves that catalyses CO2 hydration during photosynthesis. However, although the mass budget at the ecosystem is dominated by the flux of OCS into leaves, some OCS is also exchanged between the atmosphere and the soil and this component of the budget requires constraining. In this study, we adapted the process-based isotope-enabled model MuSICA (Multi-layer Simulator of the Interactions between a vegetation Canopy and the Atmosphere) to include the transport, reaction, diffusion and production of OCS within a forested ecosystem. This model was combined with 3 years (2011-2013) of in situ measurements of OCS atmospheric concentration profiles and fluxes at the Harvard Forest (Massachussets, USA) to test hypotheses on the mechanisms responsible for CA-driven uptake by leaves and soils as well as possible OCS emissions during litter decomposition. Model simulations over the three years captured well the impact of diurnally and seasonally varying environmental conditions on the net ecosystem OCS flux. A sensitivity analysis on soil CA activity and soil OCS emission rates was also performed to quantify their impact on the vertical profiles of OCS inside the

  9. Carbonic anhydrase activators: X-ray crystal structure of the adduct of human isozyme II with L-histidine as a platform for the design of stronger activators.

    Science.gov (United States)

    Temperini, Claudia; Scozzafava, Andrea; Puccetti, Luca; Supuran, Claudiu T

    2005-12-01

    Activation of the carbonic anhydrase (CA, EC 4.2.1.1) isoforms hCA I, II, and IV with l-histidine and some of its derivatives has been investigated by kinetic and X-ray crystallographic methods. l-His was a potent activator of isozymes I and IV (activation constants in the range of 4-33microM), and a moderate hCA II activator (activation constant of 113microM). Both carboxy- as well as amino-substituted l-His derivatives, such as the methyl ester or the dipeptide carnosine (beta-Ala-His), acted as more efficient activators as compared to l-His. The X-ray crystallographic structure of the hCA II-l-His adduct showed the activator to be anchored at the entrance of the active site cavity, participating in an extended network of hydrogen bonds with the amino acid residues His64, Asn67, and Gln92 and, with three water molecules connecting it to the zinc-bound water. Although the binding site of l-His is similar to that of histamine, the first CA activator for which the X-ray crystal structure has been reported in complex with hCA II (Briganti, F.; Mangani, S.; Orioli, P.; Scozzafava, A.; Vernaglione, G.; Supuran, C. T. Biochemistry1997, 36, 10384) there are important differences of binding between the two structurally related activators, since histamine interacts among others with Asn67 and Gln92 (similarly to l-His), but also with Asn62 and not His64, whereas the number of water molecules connecting them to the zinc-bound water is different (two for histamine, three for l-His). Furthermore, the imidazole moieties of the two activators adopt different conformations when bound to the enzyme active site. Since neither the amino- nor carboxy moieties of l-His participate in interactions with amino acid moieties of the active site, they can be derivatized for obtaining more potent activators, with pharmacological applications for the enhancement of synaptic efficacy. This may constitute a novel approach for the treatment of Alzheimer's disease, aging, and other conditions in

  10. The plant carbonic anhydrase at karst area and its ecological effects%植物碳酸酐酶对岩溶作用的影响及其生态效应

    Institute of Scientific and Technical Information of China (English)

    李强; 何媛媛; 曹建华; 梁建宏; 朱敏洁

    2011-01-01

    广泛存在各种类型生物细胞中的碳酸酐酶(CA),通过催化CO2和HCO3之间的相互转化,驱动岩溶过程.文章通过分析我国西南典型岩溶区植物叶片和根系CA活性,探讨其与岩溶作用的相互关系,结果表明:岩溶生态系统中植物的碳酸酐酶活性差异较大,并在植物的生长期发生变动,植株根系CA活性>成熟叶片CA活性,因而在土壤水分充足的条件下,根系分泌的CA催化CO2+H2O(←→)HCO3-+H+过程,促进石灰岩溶解,加快成土速率,并通过固定根呼吸和土壤微生物分解所释放的CO2产生岩溶碳汇效应;非岩溶生态系统由于土壤碳酸钙含量低,造成植物根系CA表达活性较低.%C02 as the important driving force in karstification process, Carbonic anhydrase (CA) can quickly catalyses the reversible interconversion of carbon dioxide and bicarbonate. Typical karst region in Southwest China was selected to investigate the relationship between Carbonic anhydrase of plant and karstification. The results shows that plant CA activity changes with living period and seasons and have the sequence just as root >mature leaves. The high CA activity in root at karst ecosystem indicates that CA in plant can quickly catalyses the reversible interconversion of carbon dioxide and bicarbonate when the soil has sufficient water. It will accelerate the dissolution of limestone and improve the rate of soil rock weathering. In turn, the nutrients released from limestone will improve plant growth and metabolism. It also can produce the CO2 sink from soil. Moreover, at non-karst area, the plants don't need to express high CA activity due to this kind of soil lake of limestone.

  11. Catalysis by cobalt(II)-substituted carbonic anhydrase II of the exchange of oxygen-18 between CO2 and H2O.

    Science.gov (United States)

    Tu, C K; Silverman, D N

    1985-10-01

    We have measured the catalysis by Co(II)-substituted bovine carbonic anhydrase II from red cells of the exchange of 18O between CO2 and H2O using membrane-inlet mass spectrometry. We chose Co(II)-substituted carbonic anhydrase II because the apparent equilibrium dissociation constant of HCO3- and enzyme at pH 7.4, KHCO3-eff approximately equal to 55 mM, was within a practicable range of substrate concentrations for the 18O method. For the native, zinc-containing enzyme KHCO3-eff is close to 500 mM at this pH. The rate constant for the release from the active site of water bearing substrate oxygen kH2O was dependent on the fraction of enzyme that was free, not bound by substrate HCO3- or anions. The pH dependence of kH2O in the pH range 6.0-9.0 can be explained entirely by a rate-limiting, intramolecular proton transfer between cobalt-bound hydroxide and a nearby group, probably His-64. The rate constant for this proton transfer was found to be 7 X 10(5) S-1 for the Co(II)-substituted enzyme and 2 X 10(6) S-1 for the native enzyme. These results are applied to models derived from proton-relaxation enhancement of water exchanging from the inner coordination shell of the cobalt in carbonic anhydrase. The anions iodide, cyanate, and thiocyanate inhibited catalysis of 18O exchange by Co(II)-substituted carbonic anhydrase II in a manner competitive with total substrate (CO2 and HCO3-) at chemical equilibrium and pH 7.4. These results are discussed in terms of observed steady-state inhibition patterns and suggest that there is no significant contribution of a ternary complex between substrate, inhibitor, and enzyme. PMID:3936538

  12. A pilot study on potential plasma hypoxia markers in the radiotherapy of non-small cell lung cancer. Osteopontin, carbonic anhydrase IX and vascular endothelial growth factor

    Energy Technology Data Exchange (ETDEWEB)

    Ostheimer, C.; Bache, M.; Guettler, A.; Vordermark, D. [Martin-Luther-University Halle-Wittenberg, Department of Radiation Oncology, Halle (Saale) (Germany); Kotzsch, M. [Technical University Dresden, Department of Pathology, Dresden (Germany)

    2014-03-15

    Hypoxic radioresistance plays a critical role in the radiotherapy of cancer and adversely impacts prognosis and treatment response. This prospective study investigated the interrelationship and the prognostic significance of several hypoxia-related proteins in non-small cell lung cancer (NSCLC) patients treated by radiotherapy ± chemotherapy. Pretreatment osteopontin (OPN), vascular endothelial growth factor (VEGF) and carbonic anhydrase IX (CA IX) plasma levels were determined by ELISA in 55 NSCLC (M0) patients receiving 66 Gy curative-intent radiotherapy or chemoradiation. Marker correlation, association with clinicopathological parameters and the prognostic value of a biomarker combination was evaluated. All biomarkers were linearly correlated and linked to different clinical parameters including lung function, weight loss (OPN), gross tumor volume (VEGF) and T stage (CA IX). High OPN (p = 0.03), VEGF (p = 0.02) and CA IX (p = 0.04) values were significantly associated with poor survival. Double marker combination additively increased the risk of death by a factor of 2 and high plasma levels of the triple combination OPN/VEGF/CA IX yielded a 5.9-fold risk of death (p = 0.009). The combined assessment of OPN/VEGF/CA IX correlated independently with prognosis (p = 0.03) in a multivariate Cox regression model including N stage, T stage and GTV. This pilot study suggests that a co-detection augments the prognostic value of single markers and that the integration of OPN, VEGF and CA IX into a hypoxic biomarker profile for the identification of patients with largely hypoxic and radioresistant tumors should be further evaluated. (orig.) [German] Hypoxische Radioresistenz spielt eine kritische Rolle in der Radiotherapie maligner Tumoren und beeinflusst Prognose und Therapieansprechen negativ. Diese prospektive Studie untersuchte den Zusammenhang und die prognostische Bedeutung einiger hypoxieassoziierter Proteine bei Patienten mit nicht-kleinzelligem Bronchialkarzinom

  13. Putting the pieces into place: Properties of intact zinc metallothionein 1A determined from interaction of its isolated domains with carbonic anhydrase.

    Science.gov (United States)

    Pinter, Tyler B J; Stillman, Martin J

    2015-11-01

    Mammalian metallothioneins (MTs) bind up to seven Zn(2+) using a large number of cysteine residues relative to their small size and can act as zinc-chaperones. In metal-saturated Zn7-MTs, the seven zinc ions are co-ordinated tetrahedrally into two distinct clusters separated by a linker; the N-terminal β-domain [(Zn3Cys9)(3-)] and C-terminal α-domain [(Zn4Cys11)(3-)]. We report on the competitive zinc metalation of apo-carbonic anhydrase [CA; metal-free CA (apo-CA)] in the presence of apo-metallothionein 1A domain fragments to identify domain specific determinants of zinc binding and zinc donation in the intact two-domain Znn-βαMT1A (human metallothionein 1A isoform; n=0-7). The apo-CA is shown to compete effectively only with Zn2-3-βMT and Zn4-αMT. Detailed modelling of the ESI mass spectral data have revealed the zinc-binding affinities of each of the zinc-binding sites in the two isolated fragments. The three calculated equilibrium zinc affinities [log(KF)] of the isolated β-domain were: 12.2, 11.7 and 11.4 and the four isolated α-domain affinities were: 13.5, 13.2, 12.7 and 12.6. These data provide guidance in identification of the location of the strongest-bound and weakest-bound zinc in the intact two-domain Zn7βαMT. The β-domain has the weakest zinc-binding site and this is where zinc ions are donated from in the Zn7-βαMT. The α-domain with the highest affinity binds the first zinc, which we propose leads to an unscrambling of the cysteine ligands from the apo-peptide bundle. We propose that stabilization of the intact Zn6-MT and Zn7-MT, relative to that of the sum of the separated fragments, is due to the availability of additional cysteine ligand orientations (through interdomain interactions) to support the clustered structures.

  14. Oxygen-18 Exchange as a Measure of Accessibility of CO2 and HCO3− to Carbonic Anhydrase in Chlorella vulgaris (UTEX 263) 1

    Science.gov (United States)

    Tu, C. K.; Acevedo-Duncan, Mildred; Wynns, George C.; Silverman, David N.

    1986-01-01

    We have measured the exchange of 18O between CO2 and H2O in stirred suspensions of Chlorella vulgaris (UTEX 263) using a membrane inlet to a mass spectrometer. The depletion of 18O from CO2 in the fluid outside the cells provides a method to study CO2 and HCO3− kinetics in suspensions of algae that contain carbonic anhydrase since 18O loss to H2O is catalyzed inside the cells but not in the external fluid. Low-CO2 cells of Chlorella vulgaris (grown with air) were added to a solution containing 18O enriched CO2 and HCO3− with 2 to 15 millimolar total inorganic carbon. The observed depletion of 18O from CO2 was biphasic and the resulting 18C content of CO2 was much less than the 18O content of HCO3− in the external solution. Analysis of the slopes showed that the Fick's law rate constant for entry of HCO3− into the cell was experimentally indistinguishable from zero (bicarbonate impermeable) with an upper limit of 3 × 10−4 s−1 due to our experimental errors. The Fick's law rate constant for entry of CO2 to the sites of intracellular carbonic anhydrase was large, 0.013 per second, but not as great as calculated for no membrane barrier to CO2 flux (6 per second). The experimental value may be explained by a nonhomogeneous distribution of carbonic anhydrase in the cell (such as membrane-bound enzyme) or by a membrane barrier to CO2 entry into the cell or both. The CO2 hydration activity inside the cells was 160 times the uncatalyzed CO2 hydration rate. PMID:16664755

  15. Oxygen-18 Exchange as a Measure of Accessibility of CO(2) and HCO(3) to Carbonic Anhydrase in Chlorella vulgaris (UTEX 263).

    Science.gov (United States)

    Tu, C K; Acevedo-Duncan, M; Wynns, G C; Silverman, D N

    1986-04-01

    We have measured the exchange of (18)O between CO(2) and H(2)O in stirred suspensions of Chlorella vulgaris (UTEX 263) using a membrane inlet to a mass spectrometer. The depletion of (18)O from CO(2) in the fluid outside the cells provides a method to study CO(2) and HCO(3) (-) kinetics in suspensions of algae that contain carbonic anhydrase since (18)O loss to H(2)O is catalyzed inside the cells but not in the external fluid. Low-CO(2) cells of Chlorella vulgaris (grown with air) were added to a solution containing (18)O enriched CO(2) and HCO(3) (-) with 2 to 15 millimolar total inorganic carbon. The observed depletion of (18)O from CO(2) was biphasic and the resulting (18)C content of CO(2) was much less than the (18)O content of HCO(3) (-) in the external solution. Analysis of the slopes showed that the Fick's law rate constant for entry of HCO(3) (-) into the cell was experimentally indistinguishable from zero (bicarbonate impermeable) with an upper limit of 3 x 10(-4) s(-1) due to our experimental errors. The Fick's law rate constant for entry of CO(2) to the sites of intracellular carbonic anhydrase was large, 0.013 per second, but not as great as calculated for no membrane barrier to CO(2) flux (6 per second). The experimental value may be explained by a nonhomogeneous distribution of carbonic anhydrase in the cell (such as membrane-bound enzyme) or by a membrane barrier to CO(2) entry into the cell or both. The CO(2) hydration activity inside the cells was 160 times the uncatalyzed CO(2) hydration rate. PMID:16664755

  16. Oxygen-18 exchange as a measure of accessibility of CO2 and HCO3- to carbonic anhydrase in Chlorella vulgaris (UTEX 263)

    International Nuclear Information System (INIS)

    The exchange of 18O between CO2 and H2O in stirred suspensions of Chlorella vulgaris (UTEX 263) was measured using a membrane inlet to a mass spectrometer. The depletion of 18O from CO2 in the fluid outside the cells provides a method to study CO2 and HCO3- kinetics in suspensions of algae that contain carbonic anhydrase since 18O loss to H2O is catalyzed inside the cells but not in the external fluid. Low-CO2 cells of Chlorella vulgaris (grown with air) were added to a solution containing 18O enriched CO2 and HCO3- with 2 to 15 millimolar total inorganic carbon. The observed depletion of 18O from CO2 was biphasic and the resulting 18O content of CO2 was much less than the 18O content of HCO3- in the external solution. Analysis of the slopes showed that the Fick's law rate constant for entry of HCO3- into the cell was experimentally indistinguishable from zero (bicarbonate impermeable) with an upper limit of 3 x 10-4 s-1 due to experimental errors. The Fick's law rate constant for entry of CO2 to the sites of intracellular carbonic anhydrase was large, 0.013 per second, but not as great as calculated for no membrane barrier to CO2 flux (6 per second). The experimental value may be explained by a nonhomogeneous distribution of carbonic anhydrase in the cell (such as membrane-bound enzyme) or by a membrane barrier to CO2 entry into the cell or both. The CO2 hydration activity inside the cells was 160 times the uncatalyzed CO2 hydration rate

  17. Effects of sodium bicarbonate concentration on growth, photosynthesis, and carbonic anhydrase activity of macroalgae Gracilariopsis lemaneiformis, Gracilaria vermiculophylla, and Gracilaria chouae (Gracilariales, Rhodophyta).

    Science.gov (United States)

    Zhou, Wei; Sui, Zhenghong; Wang, Jinguo; Hu, Yiyi; Kang, Kyoung Ho; Hong, Hye Ran; Niaz, Zeeshan; Wei, Huihui; Du, Qingwei; Peng, Chong; Mi, Ping; Que, Zhou

    2016-06-01

    There is potential for bicarbonate to improve crop yields and economic efficiency of marine algae. However, few studies have focused on the effect of bicarbonate on the growth, photosynthesis, and enzyme activity associated with carbon utilization, especially in commercial macroalgae. Here, the addition of bicarbonate (up to 420 mg L(-1)) to macroalgal cultures has been evaluated for Gracilariopsis lemaneiformis, Gracilaria vermiculophylla, and Gracilaria chouae with respect to growth rate, photosynthetic activity, carbonic anhydrase activity, and biochemical composition. The results showed that the effects of NaHCO3 on growth, chlorophyll a, phycoerythrin, photosynthetic oxygen evolution, photochemical parameters of PSI and PSII, carbonic anhydrase activity, and nitrogen content were significant (P 336 mg L(-1) for Gp. lemaneiformis and >420 mg L(-1) for the other two species). Moreover, species-specific differences induced by supplementation with bicarbonate were discovered during culture. Optimal concentrations of NaHCO3 used in this study were 252 mg L(-1) for Gp. lemaneiformis and 336 mg L(-1) for G. vermiculophylla and G. chouae. These results suggest that an adequate supplementation of sodium bicarbonate is a viable strategy for promoting growth and photosynthetic activity in some macroalgae as well as for improving biochemical composition. The study will help to accelerate the growth rate of algae and improve the quality of thalli, and will also be useful for enhancing the understanding of carbon utilization in macroalgae.

  18. Effects of sodium bicarbonate concentration on growth, photosynthesis, and carbonic anhydrase activity of macroalgae Gracilariopsis lemaneiformis, Gracilaria vermiculophylla, and Gracilaria chouae (Gracilariales, Rhodophyta).

    Science.gov (United States)

    Zhou, Wei; Sui, Zhenghong; Wang, Jinguo; Hu, Yiyi; Kang, Kyoung Ho; Hong, Hye Ran; Niaz, Zeeshan; Wei, Huihui; Du, Qingwei; Peng, Chong; Mi, Ping; Que, Zhou

    2016-06-01

    There is potential for bicarbonate to improve crop yields and economic efficiency of marine algae. However, few studies have focused on the effect of bicarbonate on the growth, photosynthesis, and enzyme activity associated with carbon utilization, especially in commercial macroalgae. Here, the addition of bicarbonate (up to 420 mg L(-1)) to macroalgal cultures has been evaluated for Gracilariopsis lemaneiformis, Gracilaria vermiculophylla, and Gracilaria chouae with respect to growth rate, photosynthetic activity, carbonic anhydrase activity, and biochemical composition. The results showed that the effects of NaHCO3 on growth, chlorophyll a, phycoerythrin, photosynthetic oxygen evolution, photochemical parameters of PSI and PSII, carbonic anhydrase activity, and nitrogen content were significant (P 336 mg L(-1) for Gp. lemaneiformis and >420 mg L(-1) for the other two species). Moreover, species-specific differences induced by supplementation with bicarbonate were discovered during culture. Optimal concentrations of NaHCO3 used in this study were 252 mg L(-1) for Gp. lemaneiformis and 336 mg L(-1) for G. vermiculophylla and G. chouae. These results suggest that an adequate supplementation of sodium bicarbonate is a viable strategy for promoting growth and photosynthetic activity in some macroalgae as well as for improving biochemical composition. The study will help to accelerate the growth rate of algae and improve the quality of thalli, and will also be useful for enhancing the understanding of carbon utilization in macroalgae. PMID:26960545

  19. Synthesis of 4-(2-substituted hydrazinyl)benzenesulfonamides and their carbonic anhydrase inhibitory effects.

    Science.gov (United States)

    Gul, Halise Inci; Kucukoglu, Kaan; Yamali, Cem; Bilginer, Sinan; Yuca, Hafize; Ozturk, Iknur; Taslimi, Parham; Gulcin, Ilhami; Supuran, Claudiu T

    2016-08-01

    In this study, 4-(2-substituted hydrazinyl)benzenesulfonamides were synthesized by microwave irradiation and their chemical structures were confirmed by (1)H NMR, (13)CNMR, and HRMS. Ketones used were: Acetophenone (S1), 4-methylacetophenone (S2), 4-chloroacetophenone (S3), 4-fluoroacetophenone (S4), 4-bromoacetophenone (S5), 4-methoxyacetophenone (S6), 4-nitroacetophenone (S7), 2-acetylthiophene (S8), 2-acetylfuran (S9), 1-indanone (S10), 2-indanone (S11). The compounds S9, S10 and S11 were reported for the first time, while S1-S8 was synthesized by different method than literature reported using microwave irradiation method instead of conventional heating in this study. The inhibitory effects of 4-(2-substituted hydrazinyl)benzenesulfonamide derivatives (S1-S11) against hCA I and II were studied. Cytosolic hCA I and II isoenzymes were potently inhibited by new synthesized sulphonamide derivatives with Kis in the range of 1.79 ± 0.22-2.73 ± 0.08 nM against hCA I and in the range of 1.72 ± 0.58-11.64 ± 5.21 nM against hCA II, respectively. PMID:26044365

  20. Synthesis of 4-(2-substituted hydrazinyl)benzenesulfonamides and their carbonic anhydrase inhibitory effects.

    Science.gov (United States)

    Gul, Halise Inci; Kucukoglu, Kaan; Yamali, Cem; Bilginer, Sinan; Yuca, Hafize; Ozturk, Iknur; Taslimi, Parham; Gulcin, Ilhami; Supuran, Claudiu T

    2016-08-01

    In this study, 4-(2-substituted hydrazinyl)benzenesulfonamides were synthesized by microwave irradiation and their chemical structures were confirmed by (1)H NMR, (13)CNMR, and HRMS. Ketones used were: Acetophenone (S1), 4-methylacetophenone (S2), 4-chloroacetophenone (S3), 4-fluoroacetophenone (S4), 4-bromoacetophenone (S5), 4-methoxyacetophenone (S6), 4-nitroacetophenone (S7), 2-acetylthiophene (S8), 2-acetylfuran (S9), 1-indanone (S10), 2-indanone (S11). The compounds S9, S10 and S11 were reported for the first time, while S1-S8 was synthesized by different method than literature reported using microwave irradiation method instead of conventional heating in this study. The inhibitory effects of 4-(2-substituted hydrazinyl)benzenesulfonamide derivatives (S1-S11) against hCA I and II were studied. Cytosolic hCA I and II isoenzymes were potently inhibited by new synthesized sulphonamide derivatives with Kis in the range of 1.79 ± 0.22-2.73 ± 0.08 nM against hCA I and in the range of 1.72 ± 0.58-11.64 ± 5.21 nM against hCA II, respectively.

  1. 呋塞米对碳酸酐酶的抑制效应再研究%Inhibitory effect of furosemide on carbonic anhydrase

    Institute of Scientific and Technical Information of China (English)

    袁美华; 蒋彦; 杨毅

    2013-01-01

    The inhibitory effect of a high efficient diuretic ,furosemide ,on carbonic anhydrase was investigated in this study .Compared with acetazolamide ,furosemide can quickly make BCAⅡ inactive when its concentration is close to the enzyme concentration . The results show that furosemide is a non-competitive inhibitor of carbonic anhydrase ,the vaules of its IC50 and KI are 0 .759 μM ,0 .51 μM . Acetazolamide is a competitive inhibitor of carbonic anhydrase ,the vaules of its IC5 0 and KI are 0.199μM ,0 .099 μM .%呋塞米是一种高效利尿剂,本实验主要探究其对碳酸酐酶的抑制效应.相比较乙酰唑胺而言,呋塞米在其浓度接近碳酸酐酶浓度时能使该酶基本失活.研究发现,呋塞米对碳酸酐酶的抑制效应表现为非竞争性抑制,其 IC50为0.759μM ,KI 为0.61μM ,乙酰唑胺的 IC50为0.199μM , KI 为0.099μM ,表现为竞争性抑制.

  2. Carbonyl sulfide hydrolase from Thiobacillus thioparus strain THI115 is one of the β-carbonic anhydrase family enzymes.

    Science.gov (United States)

    Ogawa, Takahiro; Noguchi, Keiichi; Saito, Masahiko; Nagahata, Yoshiko; Kato, Hiromi; Ohtaki, Akashi; Nakayama, Hiroshi; Dohmae, Naoshi; Matsushita, Yasuhiko; Odaka, Masafumi; Yohda, Masafumi; Nyunoya, Hiroshi; Katayama, Yoko

    2013-03-13

    Carbonyl sulfide (COS) is an atmospheric trace gas leading to sulfate aerosol formation, thereby participating in the global radiation balance and ozone chemistry, but its biological sinks are not well understood. Thiobacillus thioparus strain THI115 can grow on thiocyanate (SCN(-)) as its sole energy source. Previously, we showed that SCN(-) is first converted to COS by thiocyanate hydrolase in T. thioparus strain THI115. In the present work, we purified, characterized, and determined the crystal structure of carbonyl sulfide hydrolase (COSase), which is responsible for the degradation of COS to H2S and CO2, the second step of SCN(-) assimilation. COSase is a homotetramer composed of a 23.4 kDa subunit containing a zinc ion in its catalytic site. The amino acid sequence of COSase is homologous to the β-class carbonic anhydrases (β-CAs). Although the crystal structure including the catalytic site resembles those of the β-CAs, CO2 hydration activity of COSase is negligible compared to those of the β-CAs. The α5 helix and the extra loop (Gly150-Pro158) near the N-terminus of the α6 helix narrow the substrate pathway, which could be responsible for the substrate specificity. The k(cat)/K(m) value, 9.6 × 10(5) s(-1) M(-1), is comparable to those of the β-CAs. COSase hydrolyzes COS over a wide concentration range, including the ambient level, in vitro and in vivo. COSase and its structurally related enzymes are distributed in the clade D in the phylogenetic tree of β-CAs, suggesting that COSase and its related enzymes are one of the catalysts responsible for the global sink of COS. PMID:23406161

  3. Importance of post-translational modifications for functionality of a chloroplast-localized carbonic anhydrase (CAH1 in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Stefan Burén

    Full Text Available BACKGROUND: The Arabidopsis CAH1 alpha-type carbonic anhydrase is one of the few plant proteins known to be targeted to the chloroplast through the secretory pathway. CAH1 is post-translationally modified at several residues by the attachment of N-glycans, resulting in a mature protein harbouring complex-type glycans. The reason of why trafficking through this non-canonical pathway is beneficial for certain chloroplast resident proteins is not yet known. Therefore, to elucidate the significance of glycosylation in trafficking and the effect of glycosylation on the stability and function of the protein, epitope-labelled wild type and mutated versions of CAH1 were expressed in plant cells. METHODOLOGY/PRINCIPAL FINDINGS: Transient expression of mutant CAH1 with disrupted glycosylation sites showed that the protein harbours four, or in certain cases five, N-glycans. While the wild type protein trafficked through the secretory pathway to the chloroplast, the non-glycosylated protein formed aggregates and associated with the ER chaperone BiP, indicating that glycosylation of CAH1 facilitates folding and ER-export. Using cysteine mutants we also assessed the role of disulphide bridge formation in the folding and stability of CAH1. We found that a disulphide bridge between cysteines at positions 27 and 191 in the mature protein was required for correct folding of the protein. Using a mass spectrometric approach we were able to measure the enzymatic activity of CAH1 protein. Under circumstances where protein N-glycosylation is blocked in vivo, the activity of CAH1 is completely inhibited. CONCLUSIONS/SIGNIFICANCE: We show for the first time the importance of post-translational modifications such as N-glycosylation and intramolecular disulphide bridge formation in folding and trafficking of a protein from the secretory pathway to the chloroplast in higher plants. Requirements for these post-translational modifications for a fully functional native

  4. Potentiation of the effect of thiazide derivatives by carbonic anhydrase inhibitors: molecular mechanisms and potential clinical implications.

    Directory of Open Access Journals (Sweden)

    Kamyar Zahedi

    Full Text Available BACKGROUND: Carbonic anhydrase inhibitors (CAI are mild diuretics, hence not widely used in fluid overloaded states. They are however the treatment of choice for certain non-kidney conditions. Thiazides, specific inhibitors of Na-Cl cotransport (NCC, are mild agents and the most widely used diuretics in the world for control of mild hypertension. HYPOTHESIS: In addition to inhibiting the salt reabsorption in the proximal tubule, CAIs down-regulate pendrin, therefore leaving NCC as the major salt absorbing transporter in the distal nephron, and hence allowing for massive diuresis by the inhibitors of NCC in the setting of increased delivery of salt from the proximal tubule. EXPERIMENTAL PROTOCOLS AND RESULTS: Daily treatment of rats with acetazolamide (ACTZ, a known CAI, for 10 days caused mild diuresis whereas daily treatment with hydrochlorothiazide (HCTZ for 4 days caused hardly any diuresis. However, treatment of rats that were pretreated with ACTZ for 6 days with a combination of ACTZ plus HCTZ for 4 additional days increased the urine output by greater than 2 fold (p<0.001, n = 5 compared to ACTZ-treated animals. Sodium excretion increased by 80% in the ACTZ plus HCTZ group and animals developed significant volume depletion, metabolic alkalosis and pre-renal failure. Molecular studies demonstrated ∼75% reduction in pendrin expression by ACTZ. The increased urine output in ACTZ/HCTZ treated rats was associated with a significant reduction in urine osmolality and reduced membrane localization of AQP-2 (aquaporin2. CONCLUSIONS: These results indicate that ACTZ down-regulates pendrin expression and leaves NCC as the major salt absorbing transporter in the distal nephron in the setting of increased delivery of salt from the proximal tubule. Despite being considered mild agents individually, we propose that the combination of ACTZ and HCTZ is a powerful diuretic regimen.

  5. Carbonic Anhydrase Is Essential for Streptococcus pneumoniae Growth in Environmental Ambient Air

    NARCIS (Netherlands)

    Burghout, Peter; Cron, Lorelei E.; Gradstedt, Henrik; Quintero, Beatriz; Simonetti, Elles; Bijlsma, Jetta J. E.; Bootsma, Hester J.; Hermans, Peter W. M.

    2010-01-01

    The respiratory tract pathogen Streptococcus pneumoniae needs to adapt to the different levels of carbon dioxide (CO(2)) it encounters during transmission, colonization, and infection. Since CO(2) is important for various cellular processes, factors that allow optimal CO(2) sequestering are likely t

  6. MODELLING THE INHIBITORY ACTIVITY ON CARBONIC ANHYDRASE IV OF SUBSTITUTED THIADIAZOLE - AND THIADIAZOLINE - DISULFONAMIDES: INTEGRATION OF STRUCTURE INFORMATION

    Directory of Open Access Journals (Sweden)

    Sorana Daniela Bolboaca

    2006-07-01

    Full Text Available ABSTRACT:Purpose: To analyze the relationships between inhibitory activities on carbonic anhydrase IV and structures of substituted 1,3,4-thiadiazole and 1,3,4-thiadiazoline disulfonamide through integration of compounds complex structure information by the use of Molecular Descriptors Family.Method: A number of forty compounds were used to generate and compute the molecular descriptors family and to build structure-activity relationships models. The obtained multi-varied models (the models with two, respectively with four descriptors were validated by computing the cross-validation leave-one-out score (r2cv-loo, and analyzed through assessment of the squared correlation coefficients (r2, and the models stability (r2 - r2cv-loo. The estimation abilities of the multi-varied MDF-SAR model with four descriptors were analyzed in training and test sets.Results: Analysis of the obtained models shows that the best results was obtained by the multi-varied model with four molecular descriptors (r2 = 0.920. The prediction abilities of this model is sustained by the cross validation leave-one-out score (r2cv-loo = 0.903, the model stability (r2 - r2cv-loo = 0.017, and the results on training versus test analysis (no significant differences between correlation coefficients in training and test sets, p > 0.05. The multi-varied model which used four descriptors proved to render higher value of correlation coefficient comparing with previous reported models (p 0.05. El modelo multivariante que utilizó cuatro descriptores mostró un valor más alto del coeficiente de correlación en comparación con los modelos divulgados anteriormente (p < 0.01.Conclusión: El modelo multivariante con cuatro descriptores es sólido y fiable e indica que la actividad de la inhibición en la carboanhidrasa IV producida por las sufonamidas sustituidas del 1,3,4-tiadiazol- y de la 1,3,4-tiadiazolina- dependen de la naturaleza de la geometría y de la topología del compuesto

  7. Oxygen-18 exchange as a measure of accessibility of CO/sub 2/ and HCO/sub 3//sup -/ to carbonic anhydrase in Chlorella vulgaris (UTEX 263)

    Energy Technology Data Exchange (ETDEWEB)

    Tu, C.K.; Acevedo-Duncan, M.; Wynns, G.C.; Silverman, D.N.

    1986-04-01

    The exchange of /sup 18/O between CO/sub 2/ and H/sub 2/O in stirred suspensions of Chlorella vulgaris (UTEX 263) was measured using a membrane inlet to a mass spectrometer. The depletion of /sup 18/O from CO/sub 2/ in the fluid outside the cells provides a method to study CO/sub 2/ and HCO/sub 3//sup -/ kinetics in suspensions of algae that contain carbonic anhydrase since /sup 18/O loss to H/sub 2/O is catalyzed inside the cells but not in the external fluid. Low-CO/sub 2/ cells of Chlorella vulgaris (grown with air) were added to a solution containing /sup 18/O enriched CO/sub 2/ and HCO/sub 3//sup -/ with 2 to 15 millimolar total inorganic carbon. The observed depletion of /sup 18/O from CO/sub 2/ was biphasic and the resulting /sup 18/O content of CO/sub 2/ was much less than the /sup 18/O content of HCO/sub 3//sup -/ in the external solution. Analysis of the slopes showed that the Fick's law rate constant for entry of HCO/sub 3//sup -/ into the cell was experimentally indistinguishable from zero (bicarbonate impermeable) with an upper limit of 3 x 10/sup -4/ s/sup -1/ due to experimental errors. The Fick's law rate constant for entry of CO/sub 2/ to the sites of intracellular carbonic anhydrase was large, 0.013 per second, but not as great as calculated for no membrane barrier to CO/sub 2/ flux (6 per second). The experimental value may be explained by a nonhomogeneous distribution of carbonic anhydrase in the cell (such as membrane-bound enzyme) or by a membrane barrier to CO/sub 2/ entry into the cell or both. The CO/sub 2/ hydration activity inside the cells was 160 times the uncatalyzed CO/sub 2/ hydration rate.

  8. Carborane-Based Carbonic Anhydrase Inhibitors: Insight into CAII/CAIX Specificity from a High-Resolution Crystal Structure, Modeling, and Quantum Chemical Calculations

    Directory of Open Access Journals (Sweden)

    Pavel Mader

    2014-01-01

    Full Text Available Carborane-based compounds are promising lead structures for development of inhibitors of carbonic anhydrases (CAs. Here, we report structural and computational analysis applicable to structure-based design of carborane compounds with selectivity toward the cancer-specific CAIX isoenzyme. We determined the crystal structure of CAII in complex with 1-methylenesulfamide-1,2-dicarba-closo-dodecaborane at 1.0 Å resolution and used this structure to model the 1-methylenesulfamide-1,2-dicarba-closo-dodecaborane interactions with CAIX. A virtual glycine scan revealed the contributions of individual residues to the energy of binding of 1-methylenesulfamide-1,2-dicarba-closo-dodecaborane to CAII and CAIX, respectively.

  9. Carborane-Based Carbonic Anhydrase Inhibitors: Insight into CAII/CAIX Specificity from a High-Resolution Crystal Structure, Modeling, and Quantum Chemical Calculations

    Science.gov (United States)

    Mader, Pavel; Pecina, Adam; Cígler, Petr; Lepšík, Martin; Šícha, Václav; Hobza, Pavel; Grüner, Bohumír; Fanfrlík, Jindřich; Brynda, Jiří; Řezáčová, Pavlína

    2014-01-01

    Carborane-based compounds are promising lead structures for development of inhibitors of carbonic anhydrases (CAs). Here, we report structural and computational analysis applicable to structure-based design of carborane compounds with selectivity toward the cancer-specific CAIX isoenzyme. We determined the crystal structure of CAII in complex with 1-methylenesulfamide-1,2-dicarba-closo-dodecaborane at 1.0 Å resolution and used this structure to model the 1-methylenesulfamide-1,2-dicarba-closo-dodecaborane interactions with CAIX. A virtual glycine scan revealed the contributions of individual residues to the energy of binding of 1-methylenesulfamide-1,2-dicarba-closo-dodecaborane to CAII and CAIX, respectively. PMID:25309911

  10. Metalloprotein-inhibitor binding: human carbonic anhydrase II as a model for probing metal-ligand interactions in a metalloprotein active site.

    Science.gov (United States)

    Martin, David P; Hann, Zachary S; Cohen, Seth M

    2013-11-01

    An ever-increasing number of metalloproteins are being discovered that play essential roles in physiological processes. Inhibitors of these proteins have significant potential for the treatment of human disease, but clinical success of these compounds has been limited. Herein, zinc(II)-dependent metalloprotein inhibitors in clinical use are reviewed, and the potential for using novel metal-binding groups (MBGs) in the design of these inhibitors is discussed. By using human carbonic anhydrase II as a model system, the nuances of MBG-metal interactions in the context of a protein environment can be probed. Understanding how metal coordination influences inhibitor binding may help in the design of new therapeutics targeting metalloproteins.

  11. Intracellular Ca-carbonate biomineralization is widespread in cyanobacteria.

    Science.gov (United States)

    Benzerara, Karim; Skouri-Panet, Feriel; Li, Jinhua; Férard, Céline; Gugger, Muriel; Laurent, Thierry; Couradeau, Estelle; Ragon, Marie; Cosmidis, Julie; Menguy, Nicolas; Margaret-Oliver, Isabel; Tavera, Rosaluz; López-García, Purificación; Moreira, David

    2014-07-29

    Cyanobacteria have played a significant role in the formation of past and modern carbonate deposits at the surface of the Earth using a biomineralization process that has been almost systematically considered induced and extracellular. Recently, a deep-branching cyanobacterial species, Candidatus Gloeomargarita lithophora, was reported to form intracellular amorphous Ca-rich carbonates. However, the significance and diversity of the cyanobacteria in which intracellular biomineralization occurs remain unknown. Here, we searched for intracellular Ca-carbonate inclusions in 68 cyanobacterial strains distributed throughout the phylogenetic tree of cyanobacteria. We discovered that diverse unicellular cyanobacterial taxa form intracellular amorphous Ca-carbonates with at least two different distribution patterns, suggesting the existence of at least two distinct mechanisms of biomineralization: (i) one with Ca-carbonate inclusions scattered within the cell cytoplasm such as in Ca. G. lithophora, and (ii) another one observed in strains belonging to the Thermosynechococcus elongatus BP-1 lineage, in which Ca-carbonate inclusions lie at the cell poles. This pattern seems to be linked with the nucleation of the inclusions at the septum of the cells, showing an intricate and original connection between cell division and biomineralization. These findings indicate that intracellular Ca-carbonate biomineralization by cyanobacteria has been overlooked by past studies and open new perspectives on the mechanisms and the evolutionary history of intra- and extracellular Ca-carbonate biomineralization by cyanobacteria.

  12. Gene cloning, expression and enzyme activity analysis of the carbonic anhydrase from Porphyra haitanensis (Rhodophyta)%坛紫菜碳酸酐酶基因的克隆、表达及酶活性分析

    Institute of Scientific and Technical Information of China (English)

    郇丽; 贾兆君; 张宝玉; 牛建峰; 林阿朋; 何林文; 王广策

    2014-01-01

    以坛紫菜丝状体为材料,采用RACE方法获得坛紫菜碳酸酐酶(CA)基因的全长cDNA。该cDNA全长1081 bp,具有一个825 bp的开放阅读框,可编码274个氨基酸。序列同源性分析显示该cDNA序列推导的氨基酸序列与其他物种的碳酸酐酶具有较高的一致性,其中与条斑紫菜的一致性达到96%。氨基酸序列分析表明该蛋白为β-CA,含有两个CA活性位点,无跨膜结构,可能存在一个信号肽将其定位到叶绿体中,与藻类和细菌聚类。原核诱导表达得到一个72 kDa左右的融合蛋白,酶活测定结果显示此蛋白具有碳酸酐酶活性。该实验对进一步深入研究坛紫菜 CA 的功能及坛紫菜碳代谢、光合作用等生理过程具有重要的参考价值。%Carbonic anhydrase (CA), a zinc-containing enzyme is widespread in living organisms, catalyses the reversible hydration of CO2 and 3HCO-. In this study, a full-length cDNA of CA was isolated from Porphyra haitanensis with rapid amplification of cDNA ends (RACE). This sequence was 1 081 bp in length and encodes a polypeptide of 274 amino acid residues. The deduced polypeptide showed high identities with the CA genes ranging from unicellular algae and bacteria to green plant. Phylogenetic tree analysis showed that the CA gene from P. haitanensis was more closely assembled with algae and bacteria. A ~72 kDa fused protein was obtained by the recombinant prokaryotic expression and the enzyme activity analysis showed that it had the activity of CA.

  13. 苯磺酰胺从碳酸酐酶II中脱离过程的分子动力学模拟%Molecular Dynamics Simulations of the Unbinding of Phenylsulfonamide from Carbonic Anhydrase II

    Institute of Scientific and Technical Information of China (English)

    孙维琦; 张继龙; 郑清川; 孙志伟; 张红星

    2013-01-01

      综合运用分子动力学模拟和自由能计算方法研究了苯磺酰胺分子从碳酸酐酶II (CA II)的活性位点脱离过程中底物与酶之间的动态相互作用。脱离过程的平均力势(PMF)显示,底物脱离时存在一个特殊的结合状态。其中,静电相互作用占据了主导地位。轨迹分析显示,除了金属离子的配位作用之外,底物脱离路径上的关键残基Leu198、Thr199和Thr200通过与底物磺胺基的氢键作用阻碍了底物从酶中的脱离。当前的研究对于深入认识磺胺类药物与CA II的详细结合过程和相关的药物改良与设计具有重要的指导意义。%Molecular dynamics (MD) simulations and free energy calculations were integrated to investigate substrate-enzyme dynamic interactions during the unbinding of phenylsulfonamide from carbonic anhydrase II (CA II). The potential of mean force (PMF) along the unbinding pathway shows that a special ligand-binding state exists, and the electrostatic interaction dominates the ligandʹs binding with CA II. The analysis of trajectories reveals that, apart from the zinc ion, the key residues in the unbinding pathway, Leu198, Thr199, and Thr200, prevent the substrateʹs unbinding from the enzyme by hydrogen bonding with the sulfanilamide group of the substrate. The present results are of direct significance for the in-depth understanding of the sulfonamide-CA II binding process and related drug design.

  14. Over-expression of the β-carboxysomal CcmM protein in Synechococcus PCC7942 reveals a tight co-regulation of carboxysomal carbonic anhydrase (CcaA) and M58 content.

    Science.gov (United States)

    Long, Benedict M; Rae, Benjamin D; Badger, Murray R; Price, G Dean

    2011-09-01

    Carboxysomes, containing the cell's complement of RuBisCO surrounded by a specialized protein shell, are a central component of the cyanobacterial CO(2)-concentrating mechanism. The ratio of two forms of the β-carboxysomal protein CcmM (M58 and M35) may affect the carboxysomal carbonic anhydrase (CcaA) content. We have over-expressed both M35 and M58 in the β-cyanobacterium Synechococcus PCC7942. Over-expression of M58 resulted in a marked increase in the amount of this protein in carboxysomes at the expense of M35, with a concomitant increase in the observed CcaA content of carboxysomes. Conversely, M35 over-expression diminished M58 content of carboxysomes and led to a decrease in CcaA content. Carboxysomes of air-grown wild-type cells contained slightly elevated CcaA and M58 content and slightly lower M35 content compared to their 2% CO(2)-grown counterparts. Over a range of CcmM expression levels, there was a strong correlation between M58 and CcaA content, indicating a constant carboxysomal M58:CcaA stoichiometry. These results also confirm a role for M58 in the recruitment of CcaA into the carboxysome and suggest a tight regulation of M35 and M58 translation is required to produce carboxysomes with an appropriate CA content. Analysis of carboxysomal protein ratios, resulting from the afore-mentioned over-expression studies, revealed that β-carboxysomal protein stoichiometries are relatively flexible. Determination of absolute protein quantities supports the hypothesis that M35 is distributed throughout the β-carboxysome. A modified β-carboxysome packing model is presented.

  15. The Role of Hypoxia-Inducible Factor-1α, Glucose Transporter-1, (GLUT-1 and Carbon Anhydrase IX in Endometrial Cancer Patients

    Directory of Open Access Journals (Sweden)

    Pawel Sadlecki

    2014-01-01

    Full Text Available Hypoxia-inducible factor-1α (HIF-1α, glucose transporter-1 (GLUT-1, and carbon anhydrase IX (CAIX are important molecules that allow adaptation to hypoxic environments. The aim of our study was to investigate the correlation between HIF-1α, GLUT-1, and CAIX protein level with the clinicopathological features of endometrial cancer patients. Materials and Methods. 92 endometrial cancer patients, aged 37–84, were enrolled to our study. In all patients clinical stage, histologic grade, myometrial invasion, lymph node, and distant metastases were determined. Moreover, the survival time was assessed. Immunohistochemical analyses were performed on archive formalin fixed paraffin embedded tissue sections. Results. High significant differences (P=0.0115 were reported between HIF-1α expression and the histologic subtype of cancer. Higher HIF-1α expression was associated with the higher risk of recurrence (P=0.0434. The results of GLUT-1 and CAIX expression did not reveal any significant differences between the proteins expression in the primary tumor and the clinicopathological features. Conclusion. The important role of HIF-1α in the group of patients with the high risk of recurrence and the negative histologic subtype of the tumor suggest that the expression of this factor might be useful in the panel of accessory pathomorphological tests and could be helpful in establishing more accurate prognosis in endometrial cancer patients.

  16. Effect of CO2 concentrations on the activity of photosynthetic CO2 fixation and extracelluar carbonic anhydrase in the marine diatom Skeletonema costatum

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiongwen; GAO Kunshan

    2003-01-01

    The growth and activity of photosynthetic CO2 uptake and extracellular carbonic anhydrase (Caext) of the marine diatom Skeletonema costatum were investigated while cultured at different levels of CO2 in order to see its physiological response to different CO2 concentrations under either a low (30 μmol·m-2·s-1) or high (210 μmol·m-2·s-1) irradiance. The changes in CO2 concentrations (4-31 μmol/L) affected the growth and net photosynthesis to a greater extent under the low than under the high light regime. Caext was detected in the cells grown at 4 μmol/L CO2 but not at 31 and 12 μmol/L CO2, with its activity being about 2.5-fold higher at the high than at the low irradiance. Photo- synthetic CO2 affinity (1/ K1/2(CO2)) of the cells decreased with increased CO2 concentrations in culture. The cells cultured under the high-light show significantly higher photosynthetic CO2 affinity than those grown at the low-light level. It is concluded that the regulations of Caext activity and photosynthetic CO2 affinity are dependent not only on CO2 concentration but also on light availability, and that the development of higher Caext activity and CO2 affinity under higher light level could sufficiently support the photosynthetic demand for CO2 even at low level of CO2.

  17. Targeting carbonic anhydrase IX by nitroimidazole based sulfamides enhances the therapeutic effect of tumor irradiation: A new concept of dual targeting drugs

    International Nuclear Information System (INIS)

    Background and purpose: Carbonic anhydrase IX (CAIX) plays an important role in pH regulation processes critical for tumor cell growth and metastasis. We hypothesize that a dual targeting bioreductive nitroimidazole based anti-CAIX sulfamide drug (DH348) will reduce tumor growth and sensitize tumors to irradiation in a CAIX dependent manner. Material and methods: The effect of the dual targeting anti-CAIX (DH348) and its single targeting control drugs on extracellular acidification and radiosensitivity was examined in HT-29 colorectal carcinoma cells. Tumor growth and time to reach 4× start volume (T4×SV) was monitored for animals receiving DH348 (10 mg/kg) combined with tumor single dose irradiation (10 Gy). Results: In vitro, DH348 reduced hypoxia-induced extracellular acidosis, but did not change hypoxic radiosensitivity. In vivo, DH348 monotherapy decreased tumor growth rate and sensitized tumors to radiation (enhancement ratio 1.50) without systemic toxicity only for CAIX expressing tumors. Conclusions: A newly designed nitroimidazole and sulfamide dual targeting drug reduces hypoxic extracellular acidification, slows down tumor growth at nontoxic doses and sensitizes tumors to irradiation all in a CAIX dependent manner, suggesting no “off-target” effects. Our data therefore indicate the potential utility of a dual drug approach as a new strategy for tumor-specific targeting

  18. Association between dental-oral health in young adults and salivary glutathione, lipid peroxidation and sialic acid levels and carbonic anhydrase activity

    Directory of Open Access Journals (Sweden)

    L.K. Öztürk

    2008-11-01

    Full Text Available The aim of the present study was to evaluate the relationship between salivary oxidative stress and dental-oral health. Healthy young adults, matched for gender and age, with (N = 21, 10 men, mean age: 20.3 ± 1 years and without (N = 16, 8 men, mean age: 21.2 ± 1.8 years caries were included in this study. The World Health Organization (WHO caries diagnostic criteria were used for determining the decayed, missing, filled teeth (DMFT index. The oral hygiene and gingival status were assessed using the simplified oral hygiene index and gingival index, respectively. Unstimulated salivary total protein, glutathione (GSH, lipid peroxidation and total sialic acid levels, carbonic anhydrase activity, and salivary buffering capacity were determined by standard methods. Furthermore, salivary pH was measured with pH paper and salivary flow rate was calculated. Simplified oral hygiene index and gingival index were not significantly different between groups but DMFT scores were significant (P < 0.01. Only, GSH values were significantly different (P < 0.05 between groups (2.2 and 1.6 mg/g protein in young adults without caries and with caries, respectively. There was a significant negative correlation between DMFT and GSH (r = -0.391; P < 0.05; Pearson's correlation coefficient. Our results suggest that there is an association between caries history and salivary GSH levels.

  19. In Vivo Loss of Function Screening Reveals Carbonic Anhydrase IX as a Key Modulator of Tumor Initiating Potential in Primary Pancreatic Tumors

    Directory of Open Access Journals (Sweden)

    Nabendu Pore

    2015-06-01

    Full Text Available Reprogramming of energy metabolism is one of the emerging hallmarks of cancer. Up-regulation of energy metabolism pathways fuels cell growth and division, a key characteristic of neoplastic disease, and can lead to dependency on specific metabolic pathways. Thus, targeting energy metabolism pathways might offer the opportunity for novel therapeutics. Here, we describe the application of a novel in vivo screening approach for the identification of genes involved in cancer metabolism using a patient-derived pancreatic xenograft model. Lentiviruses expressing short hairpin RNAs (shRNAs targeting 12 different cell surface protein transporters were separately transduced into the primary pancreatic tumor cells. Transduced cells were pooled and implanted into mice. Tumors were harvested at different times, and the frequency of each shRNA was determined as a measure of which ones prevented tumor growth. Several targets including carbonic anhydrase IX (CAIX, monocarboxylate transporter 4, and anionic amino acid transporter light chain, xc- system (xCT were identified in these studies and shown to be required for tumor initiation and growth. Interestingly, CAIX was overexpressed in the tumor initiating cell population. CAIX expression alone correlated with a highly tumorigenic subpopulation of cells. Furthermore, CAIX expression was essential for tumor initiation because shRNA knockdown eliminated the ability of cells to grow in vivo. To the best of our knowledge, this is the first parallel in vivo assessment of multiple novel oncology target genes using a patient-derived pancreatic tumor model.

  20. Sulfonamides incorporating heteropolycyclic scaffolds show potent inhibitory action against carbonic anhydrase isoforms I, II, IX and XII.

    Science.gov (United States)

    Barresi, Elisabetta; Salerno, Silvia; Marini, Anna Maria; Taliani, Sabrina; La Motta, Concettina; Simorini, Francesca; Da Settimo, Federico; Vullo, Daniela; Supuran, Claudiu T

    2016-02-15

    Three series of polycyclic compounds possessing either primary sulfonamide or carboxylic acid moieties as zinc-binding groups were investigated as inhibitors of four physiologically relevant CA isoforms, the cytosolic hCA I and II, as well as the transmembrane hCA IX and XII. Most of the new sulfonamides reported here showed excellent inhibitory effects against isoforms hCA II, IX and XII, but no highly isoform-selective inhibition profiles. On the other hand, the carboxylates selectively inhibited hCA IX (KIs ranging between 40.8 and 92.7nM) without inhibiting significantly the other isoforms. Sulfonamides/carboxylates incorporating polycyclic ring systems such as benzothiopyranopyrimidine, pyridothiopyranopyrimidine or dihydrobenzothiopyrano[4,3-c]pyrazole may be considered as interesting candidates for exploring the design of isoform-selective CAIs with various pharmacologic applications. PMID:26796953

  1. Label-free characterization of carbonic anhydrase-novel inhibitor interactions using surface plasmon resonance, isothermal titration calorimetry and fluorescence-based thermal shift assays.

    Science.gov (United States)

    Rogez-Florent, Tiphaine; Duhamel, Laetitia; Goossens, Laurence; Six, Perrine; Drucbert, Anne-Sophie; Depreux, Patrick; Danzé, Pierre-Marie; Landy, David; Goossens, Jean-François; Foulon, Catherine

    2014-01-01

    This work describes the development of biophysical unbiased methods to study the interactions between new designed compounds and carbonic anhydrase II (CAII) enzyme. These methods have to permit both a screening of a series of sulfonamide derivatives and the identification of a lead compound after a thorough study of the most promising molecules. Interactions data were collected using surface plasmon resonance (SPR) and thermal shift assay (TSA). In the first step, experiments were performed with bovine CAII isoform and were extended to human CAII. Isothermal titration calorimetry (ITC) experiments were also conducted to obtain thermodynamics parameters necessary for the processing of the TSA data. Results obtained with this reference methodology demonstrate the effectiveness of SPR and TSA. KD values obtained from SPR data were in perfect accordance with ITC. For TSA, despite the fact that the absolute values of KD were quite different, the same affinity scale was obtained for all compounds. The binding affinities of the analytes studied vary by more than 50 orders of magnitude; for example, the KD value determined by SPR were 6 ± 4 and 299 ± 25 nM for compounds 1 and 3, respectively. This paper discusses some of the theoretical and experimental aspects of the affinity-based methods and evaluates the protein consumption to develop methods for the screening of further new compounds. The double interest of SPR, that is, for screening and for the quick thorough study of the interactions parameters (ka , kd , and KD ), leads us to choose this methodology for the study of new potential inhibitors. PMID:24375583

  2. Label-free characterization of carbonic anhydrase-novel inhibitor interactions using surface plasmon resonance, isothermal titration calorimetry and fluorescence-based thermal shift assays.

    Science.gov (United States)

    Rogez-Florent, Tiphaine; Duhamel, Laetitia; Goossens, Laurence; Six, Perrine; Drucbert, Anne-Sophie; Depreux, Patrick; Danzé, Pierre-Marie; Landy, David; Goossens, Jean-François; Foulon, Catherine

    2014-01-01

    This work describes the development of biophysical unbiased methods to study the interactions between new designed compounds and carbonic anhydrase II (CAII) enzyme. These methods have to permit both a screening of a series of sulfonamide derivatives and the identification of a lead compound after a thorough study of the most promising molecules. Interactions data were collected using surface plasmon resonance (SPR) and thermal shift assay (TSA). In the first step, experiments were performed with bovine CAII isoform and were extended to human CAII. Isothermal titration calorimetry (ITC) experiments were also conducted to obtain thermodynamics parameters necessary for the processing of the TSA data. Results obtained with this reference methodology demonstrate the effectiveness of SPR and TSA. KD values obtained from SPR data were in perfect accordance with ITC. For TSA, despite the fact that the absolute values of KD were quite different, the same affinity scale was obtained for all compounds. The binding affinities of the analytes studied vary by more than 50 orders of magnitude; for example, the KD value determined by SPR were 6 ± 4 and 299 ± 25 nM for compounds 1 and 3, respectively. This paper discusses some of the theoretical and experimental aspects of the affinity-based methods and evaluates the protein consumption to develop methods for the screening of further new compounds. The double interest of SPR, that is, for screening and for the quick thorough study of the interactions parameters (ka , kd , and KD ), leads us to choose this methodology for the study of new potential inhibitors.

  3. Extra and intracelular activities of carbonic anhydrase of the marine microalga Tetraselmis gracilis (Chlorophyta Atividade extra e intracelular da Anidrase Carbônica na microalga marinha Tetraselmis gracilis (Chlorophyta

    Directory of Open Access Journals (Sweden)

    Marilda Rigobello-Masini

    2003-07-01

    Full Text Available The activities of extra and intracellular carbonic anhydrases (CA were studied in the microalgae Tetraselmis gracilis (Kylin Butcher (Chlorophyta, Prasinophyceae growing in laboratory cultivation. During ten days of batch cultivation, daily determinations of pH, cell number, enzymatic activity, and total dissolved inorganic carbon (DIC, as well as its main species, CO2 and HCO3-, were performed. Enzymatic activity increased as the growing cell population depleted inorganic carbon from the medium. Carbon dioxide concentration decreased quickly, especially in the third day of cultivation, when a significant increase of the intracellular enzymatic activity was observed. Bicarbonate concentration had its largest decrease in the cultivation medium in the fourth day, when the activity of the extracellular enzyme had its largest increase, suggesting its use by the alga through CA activity. After the fourth cultivation day, half of the cultures were aerated with CO2-free atmospheric air, which caused an increase in the total and external activity of the enzyme, although, in this condition, the stationary growth phase began earlier than in cultures aerated with atmospheric air. The pH of the media was measured daily, increasing from the first to the fourth day, and remaining almost constant until the end of the cultivation. Algal material transferred to the dark lost all enzymatic activity.As atividades da Anidrase Carbônica (AC extra e intracelular foram estudadas na microalga marinha Tetraselmis gracilis (Kylin Butcher (Chlorophyta, Prasinophyceae crescendo em cultivos laboratoriais. Durante dez dias de cultivo, determinações diárias do pH, número de células, atividades enzimáticas, carbono inorgânico total dissolvido (CID e suas principais espécies CO2 e HCO3- foram feitas. A atividade enzimática aumentou na medida em que a população celular em crescimento retirava carbono inorgânico do meio de cultivo. A concentração de dióxido de

  4. Expression of HIF-1alpha, CA IX, VEGF, and MMP-9 in surgically resected non-small cell lung cancer.

    NARCIS (Netherlands)

    Kim, S.; Rabbani, Z.N.; Dewhirst, M.W.; Vujaskovic, Z.; Vollmer, R.T.; Schreiber, E.G.; Oosterwijk, E.; Kelley, M.J.

    2005-01-01

    Endogenous hypoxia markers have been studied as prognostic indicators because they appear to be associated with tumor aggressiveness. This study was undertaken to compare the expression of two endogenous hypoxia markers, Hypoxia-inducible factor-1alpha (HIF-1alpha) and carbonic anhydrase IX (CA IX),

  5. Formation of local native-like tertiary structures in the slow refolding reaction of human carbonic anhydrase II as monitored by circular dichroism on tryptophan mutants.

    Science.gov (United States)

    Andersson, D; Freskgård, P O; Jonsson, B H; Carlsson, U

    1997-04-15

    In the present study, near-UV CD kinetic measurements on mutants, in which one Trp residue had been replaced, were performed to probe the development of asymmetric environments around specific Trp residues during the refolding of human carbonic anhydrase II (HCAII). In addition, the formation of the active site was probed by the binding of a fluorescent sulfonamide inhibitor. The development of the individual Trp CD spectra during refolding was obtained by subtracting the CD spectrum of the mutant lacking one Trp from that of HCAII at different time points. The same method was used for the particular Trp residues to obtain the kinetic CD traces monitored at a specific wavelength (270 nm). Trp residues 16, 97, and 245 were analyzed. Trp16 probes the N-terminal domain (amino acid residues 1-25), and this part is forming its tertiary structure slower than the major domain (amino acid residues 26-260) of the protein molecule, which contains the active site and a dominating beta-sheet. An essentially native structure of the major domain seems to act as a template for the correct folding of the N terminus. Trp97 is located in a hydrophobic cluster comprising beta-strands 3-5 in the protein core. Previously, we have shown that this region is remarkably stable and compact, and stopped-flow fluorescence data indicate that Trp97 is buried in an apolar compact cluster within a few milliseconds [Svensson, M., Jonasson, P., Freskgård, P.-O., Jonsson, B.-H., Lindgren, M., Martensson, L.-G., Gentile, M., Bóren, K., & Carlsson, U. (1995) Biochemistry 34, 8606-8620; Jonasson, P., Aronsson, G., Carlsson, U., & Jonsson, B.-H. (1997) Biochemistry 36 (in press)]. Here it is shown that the development of the native tertiary structure at Trp97 occurs in the minute time domain. Trp245 is located in a long loop between the N-terminal domain and the core structure. Although this Trp has attained native-like fluorescence properties within the dead time of the CD experiment, it assumes a

  6. Temperature stability of Poly-[hemoglobin-superoxide dismutase-catalase-carbonic anhydrase] in the form of a solution or in the lyophilized form during storage at -80 °C, 4 °C, 25 °C and 37 °C or pasteurization at 70 °C.

    Science.gov (United States)

    Bian, Y Z; Guo, C; Chang, T M S

    2016-01-01

    Polyhemoglobin-superoxide dismutase-catalase-carbonic anhydrase (Poly-[Hb-SOD-CAT-CA]) contains all three major functions of red blood cells (RBCs) at an enhanced level. It transports oxygen, removes oxygen radicals and transports carbon dioxide. Our previous studies in a 90-min 30 mm Hg Mean Arterial Pressure (MAP) sustained hemorrhagic shock rat model shows that it is more effective than blood in the lowering of elevated intracellular pCO2, recovery of ST-elevation and histology of the heart and intestine. This paper is to analyze the storage and temperature stability. Allowable storage time for RBC is about 1 d at room temperature and 42 d at 4 °C. Also, RBC cannot be pasteurized to remove infective agents like HIV and Ebola. PolyHb can be heat sterilized and can be stored for 1 year even at room temperature. However, Poly-[Hb-SOD-CAT-CA] contains both Hb and enzymes and enzymes are particularly sensitive to storage and heat. We thus carried out studies to analyze its storage stability at different temperatures and heat pasteurization stability. Results of storage stability show that lyophilization extends the storage time to 1 year at 4 °C and 40 d at room temperature (compared to respectively, 42 d and 1 d for RBC). After the freeze-dry process, the enzyme activities of Poly-[SFHb-SOD-CAT-CA] was 100 ± 2% for CA, 100 ± 2% for SOD and 93 ± 3.5% for CAT. After heat pasteurization at 70 °C for 2 h, lyophilized Poly-[Hb-SOD-CAT-CA] retained good enzyme activities of CA 97 ± 4%, SOD 100 ± 2.5% and CAT 63.8 ± 4%. More CAT can be added during the crosslinking process to maintain the same enzyme ratio after heat pasteurization. Heat pasteurization is possible only for the lyophilized form of Poly-[Hb-SOD-CAT-CA] and not for the solution. It can be easily reconstituted by dissolving in suitable solutions that continues to have good storage stability though less than that for the lyophilized form. According to the P50 value, Poly-[SFHb-SOD-CAT-CA] retains its

  7. 血清抗碳酸酐酶Ⅲ抗体ELISA检测方法的建立与初步应用%Establishment and preliminary application of the ELISA method for anti-carbonic anhydrase III antibody detection

    Institute of Scientific and Technical Information of China (English)

    刘辰庚; 王培昌

    2011-01-01

    目的 建立人血清抗碳酸酐酶(CA)Ⅲ抗体的ELISA检测方法,并对系统性红斑狼疮、皮肌炎、糖尿病肾病、高血压肾病患者和健康人群的血清抗CAⅢ抗体水平进行初步调查.方法 使用抗CAⅢ抗体标准品、CAⅢ及相应酶标抗体建立血清抗CAⅢ抗体ELISA检测方法,验证试剂稳定性、标本保存稳定性,并进行精密度、灵敏度、回收率、抗干扰性等方法学评价;各项技术指标均合格后对系统性红斑狼疮、皮肌炎、糖尿病肾病和高血压肾病患者的血清进行抗CAⅢ抗体水平检测.结果 成功建立ELISA检测人血清抗CAⅢ抗体的方法,其批内精密度为6.2%,批间精密度为8.2%,灵敏度为0.025,回收率为106%,且具有较好的抗干扰性、试剂稳定性和标本保存稳定性.系统性红斑狼疮和糖尿病肾病患者的血清抗CAⅢ抗体水平高于健康对照相(P<0.05),阳性率分别为43%和18%.皮肌炎和高血压肾病患者的血清抗CAⅢ抗体水平与健康对照组比较无统计学差异(P>0.05),且未出现阳性结果.结论 使用现有市售试剂进行人血清抗CAⅢ抗体的ELISA检测是可行的,抗CAⅢ抗体可能参与了系统性红斑狼疮和糖尿病肾病的发生发展.%Objective To establish an ELISA method for anti-carbonic anhydrase III (CA III ) antibody detection, and to evaluate the serum level of anti-CA III antibody in normal control group and patients with systemic lupus erythemato-sus, dermatomyositis, 2-type diabetic nephropathy and hypertensive nephropathy respectively. Methods To establish the ELISA method using CA III, anti-CA III antibody and enzyme labeled secondary antibody. To evaluate the stability of the regent and sample, and the sensitivity, stability and anti-interference performance of the ELISA method. To investigate the anti-CA III antibody level in serum of normal control group and patients with systemic lupus erythematosus, dermatomyositis, 2-type

  8. Degradation products of the artificial azo dye, Allura red, inhibit esterase activity of carbonic anhydrase II: A basic in vitro study on the food safety of the colorant in terms of enzyme inhibition.

    Science.gov (United States)

    Esmaeili, Sajjad; Ashrafi-Kooshk, Mohammad Reza; Khaledian, Koestan; Adibi, Hadi; Rouhani, Shohre; Khodarahmi, Reza

    2016-12-15

    Allura red is a widely used food colorant, but there is debate on its potential security risk. In the present study, we found that degradation products of the dye were more potent agents with higher carbonic anhydrase inhibitory action than the parent dye. The mechanism by which the compounds inhibit the enzyme activity has been determined as competitive mode. In addition, the enzyme binding properties of the compounds were investigated employing different spectroscopic techniques and molecular docking. The analyses of fluorescence quenching data revealed the existence of the same binding site for the compounds on the enzyme molecule. The thermodynamic parameters of ligand binding were not similar, which indicates that different interactions are responsible in binding of the parent dye and degradation products to the enzyme. It appears that enzyme inhibition should be considered, more seriously, as a new opened dimension in food safety. PMID:27451209

  9. 盐碱胁迫对尼罗罗非鱼鳃Na+/3HCO共转运子、碳酸酐酶基因表达的影响%Effects of salinity and alkalinity on mRNA expression of Na+/3HCO cotransporter and carbonic anhydrase genes fromOreochromis niloticus

    Institute of Scientific and Technical Information of China (English)

    梁从飞; 赵金良; 甘远迪; 王飞; Thammaratsuntorn Jeerawat; 伍勇; 李传阳; 罗明坤

    2016-01-01

    To understand fish osmotic adjustment mechanisms in saline and alkaline water, the partial cDNA se-quence was obtained from gills ofOreochromis niloticus. Physiological changes in serum osmolality, ion concen-tration (Na+, K+, Cl– and Ca2+), and gill carbonic anhydrase (CA) activities were determined, andCAandNBCe1 mRNA gene expressions under saline (10 g/L, 15 g/L NaCl), alkaline (1.5 g/L and 3 g/L NaHCO3), and sa-line-alkaline (salinity 10, 15 g/L NaCl; salinity 1.5, 3 g/L NaHCO3) conditions at different times (0 h, 6 h, 12 h, 24 h, 48 h, 72 h and 96 h) were compared. The results showed that serum osmolality, ion concentration, gill CA activity, CA andNBCe1 mRNA gene expression correlated positively with the strength of saline, alkaline and sa-line-alkaline stress. Over time, serum osmolality and ion concentration trends increased and then decreased. Os-motic pressure insaline and saline-alkaline water was higher than that in alkaline water. Gill CA activity in alkaline and saline-alkaline water was higher than that in saline water. Under low concentrations of stressors, CA activity reached its highest level at a later time. Slightly higherNBCe1 gene mRNA expression was detected in gills under high concentrations of stressors (P>0.05). GillCA mRNA expression in saline, alkaline and saline-alkaline water was increased, but the increase was more evident in alkaline and saline-alkaline water (P0.05)。单碱组和盐碱混合组鳃CA活性较单盐组高,低盐碱胁迫(盐度10,碱度1.5 g/L)下CA活性较晚达最高值;不同胁迫条件下, CA基因mRNA表达均表现上调,单碱、盐碱混合组更为显著(P<0.05),推测CA较NBCe1对体内3HCO-转运作用更为显著。研究结果为尼罗罗非鱼盐碱适应生理调节提供了基础资料。

  10. Seawater nutrient and carbonate ion concentrations recorded as P/Ca, Ba/Ca, and U/Ca in the deep-sea coral D. dianthus

    OpenAIRE

    Anagnostou, Eleni; Sherrell, Robert M; Gagnon, Alex; LaVigne, Michele; Field, M Paul; William F. McDonough

    2011-01-01

    As paleoceanographic archives, deep sea coral skeletons offer the potential for high temporal resolution and precise absolute dating, but have not been fully investigated for geochemical reconstructions of past ocean conditions. Here we assess the utility of skeletal P/Ca, Ba/Ca and U/Ca in the deep sea coral D. dianthus as proxies of dissolved phosphate (remineralized at shallow depths), dissolved barium (trace element with silicate-type distribution) and carbonate ion concentrations, respec...

  11. Fluorescence Lifetime Imaging of Physiological Free Cu(II) Levels in Live Cells with a Cu(II)-Selective Carbonic Anhydrase-Based Biosensor

    Science.gov (United States)

    McCranor, Bryan J.; Szmacinski, Henryk; Zeng, Hui Hui; Stoddard, A.K.; Hurst, Tamiika; Fierke, Carol A.; Lakowicz, J.R.

    2014-01-01

    Copper is a required trace element that plays key roles in a number of human enzymes, such that copper deficiency or genetic defects in copper transport lead to serious or fatal disease. Rae, et al., had famously predicted that free copper ion levels in the cell cytoplasm were extremely low, typically too low to be observable. We recently developed a variant of human apocarbonic anhydrase II for sensing metal ions that exhibits 25-fold better selectivity for Cu(II) over Zn(II) than the wild type protein, enabling us to accurately measure Cu(II) in the presence of ordinary cellular (picomolar) concentrations of free zinc. We inserted a fluorescent labeled Cu(II)-specific variant of human apocarbonic anhydrase into PC-12 cells and found that the levels are indeed extremely low (in the femtomolar range). We imaged the free Cu(II) levels in living cells by means of frequency-domain fluorescence lifetime microscopy. Implications of this finding are discussed. PMID:24671220

  12. The role of extracellular carbonic anhydrase activity in inorganic carbon utilization of Phaeocystis globosa (Prymnesiophyceae) : A comparison with other marine algae using the isotopic disequilibrium technique

    NARCIS (Netherlands)

    Elzenga, JTM; Prins, HBA; Stefels, J

    2000-01-01

    The utilization of inorganic carbon species by the marine microalga Phaeocystis globasa (Prymnesiophyceae) and several other algal species from different taxa, was investigated by determining the time course of C-14 incorporation in isotopic disequilibrium experiments. From these kinetic data, concl

  13. Enhanced biomimetic CO2 sequestration and CaCO3 crystallization using complex encapsulated metal organic framework

    Science.gov (United States)

    Sahoo, Prakash C.; Jang, Young Nam; Lee, Seung Woo

    2013-06-01

    A new biomimetic complex (Co-BBP) that mimics the active site of carbonic anhydrase (CA) was prepared by the coordination of cobalt (II) with 2, 6-bis(2-benzimidazolyl) and was encapsulated into a metal organic framework (Co-BBP@Tb-MOF). Carbon dioxide (CO2) sequestration was carried out via an in vitro mineralization approach using these biomimetic catalysts. The biomimetic catalysts were expected to enhance CO2 hydration and calcium carbonate (CaCO3) crystallization based on the same mechanism as that of CA.

  14. Expression of von Hippel-Lindau tumor suppressor and tumor-associated carbonic anhydrases Ⅸ and Ⅻ in normal and neoplastic colorectal mucosa

    Institute of Scientific and Technical Information of China (English)

    Antti J. Kivela; Abdul Waheed; William S. Sly; Hannu Rajaniemi; Silvia Pastorekova; Jaromir Pastorek; Seppo Parkkila; Juha Saarnio; Tuomo J. Karttunen; Jyrki Kivela; Anna-Kaisa Parkkila; Maria Bartosova; Vojtech Mucha; Michal Novak

    2005-01-01

    AIM: To analyze possible relationships between CA Ⅸ/ CA Ⅻ and pVHL expression in normal and neoplastic colorectal mucosa.METHODS: Immunohistochemical staining of 42 tissue specimens obtained from 17 cancer patients was performed to evaluate the distribution and semi-quantitatively assess the levels of CA Ⅸ, CA Ⅻ and pVHL. VHL mRNAs from 14fresh-frozen tumors was amplified by RT-PCR and subjected to sequencing. CA9 and CA12 mRNA levels were analyzed by semi-quantitative RT-PCR in comparison with VEGF as an indicator of hypoxia that uncouples the pVHL control.RESULTS: Tumor tissues were associated with a borderline increase of CA Ⅸ staining signal and slight but significant decrease of CA Ⅻ immunoreactivity, whereas no association was found for pVHL. Sequence analysis of RT-PCR-amplified VHL mRNAs revealed no deletions/ mutations, suggesting that they were VHL-competent. We did not observe any correlation between pVHL andCA Ⅸ/CA Ⅻ proteins as well as between VEGF and CA9mRNAs, but the tumor-associated changes in mRNA levels of VEGF and CA12showed a significant inverse relationship. CONCLUSION: Our results indicate that CA9 and CA12 are regulated by different intratumoral factors and that lack of apparent relationship between the levels of CA Ⅸ/CA Ⅻ and pVHL cannot be fully assigned to uncoupling of negative regulatory function of pVHL by tumor hypoxia signified by induced VEGF transcription. The interplay between the functional pVHL and CA Ⅸ/CA Ⅻ in colorectal tumors seems rather complex and is not evident merely at the expression levels.

  15. Carbonic anhydrase IX and response to postmastectomy radiotherapy in high-risk breast cancer: a subgroup analysis of the DBCG82 b and c trials

    DEFF Research Database (Denmark)

    Kyndi, Marianne; Sørensen, Flemming Brandt; Knudsen, Helle;

    2008-01-01

    invasive tumour-containing paraffin blocks from 1,000 patients (more than seven nodes surgically removed) were transferred to tissue microarrays. Tissue microarray sections were stained immunohistochemically for CA IX (M75). The median follow up for patients remaining alive was 17 years. Clinical end...... of tumours positive for CA IX was 16% (> or = 10% invasive tumour staining). CA IX was not an independent prognostic marker for survival, distant metastases, or locoregional recurrence in the subgroup of 945 patients or within either of the two randomization arms. In subgroup analyses, however, CA IX...

  16. Carbonic anhydrase IX and response to postmastectomy radiotherapy in high-risk breast cancer: a subgroup analysis of the DBCG82 b and c trials

    DEFF Research Database (Denmark)

    Kyndi, M.; Sorensen, F.B.; Alsner, J.;

    2008-01-01

    invasive tumour-containing paraffin blocks from 1,000 patients (more than seven nodes surgically removed) were transferred to tissue microarrays. Tissue microarray sections were stained immunohistochemically for CA IX (M75). The median follow up for patients remaining alive was 17 years. Clinical end...... of tumours positive for CA IX was 16% (>= 10% invasive tumour staining). CA IX was not an independent prognostic marker for survival, distant metastases, or locoregional recurrence in the subgroup of 945 patients or within either of the two randomization arms. In subgroup analyses, however, CA IX...

  17. The influence of solution stoichiometry on surface-controlled Ca isotope fractionation during Ca carbonate precipitation from Mono Lake, California

    Science.gov (United States)

    Nielsen, L. C.; Depaolo, D. J.

    2010-12-01

    Precipitation of calcite and aragonite from aqueous solution causes kinetic stable Ca isotope fractionation under conditions where Ca2+ is greatly in excess of CO32-. Research on carbonate mineral growth from low Ca2+:CO32- activity ratio solutions is lacking. Mono Lake, California is a highly alkaline lake with a Ca2+:CO32- activity ratio of 9.6 x 10-4, over five orders of magnitude lower than typical terrestrial fresh and ocean water. Aragonitic tufa towers grow along the lakeshore due to the mixing of lake water and Ca-rich spring water, while fine aragonite particles precipitate directly from the lake water, accumulating on the lake bottom. Variations in the Ca2+:CO32- activity ratio affect calcite growth kinetics and could affect the partitioning of Ca isotopes during carbonate precipitation. However, the relationship between solution stoichiometry, microscopic mineral growth mechanisms and calcium isotope fractionation is poorly understood. We analyzed the Sr and Ca isotopic compositions of a suite of lake water, spring, tufa and lake bottom sediment samples from the Mono Basin. Using the Sr isotope signatures of endmember water sources (pure lake water and shoreline spring water), we determined the compositions of carbonate mineral growth solutions, associated isotope separations (Δ44/40Cas-f = δ44/40Casolid - δ44/40Cafluid) and precipitation rates. While lake bottom aragonite precipitates directly from lake water (Ca2+:CO32- ≈ 10-3), tufa grows from mixed solutions with Ca2+:CO32- activity ratios approaching 10, so carbonate precipitation in Mono Lake spans a four order of magnitude range in solution stoichiometry. At Mono Lake, Δ44/40Cas-f and calculated precipitation rates vary between -0.6±0.15‰ at 1.5×10-9 mol m-2 s-1 for aragonite precipitating from lake water and ~ -1.0±0.15‰ at up to 4×10-8 mol m-2 s-1 for tufa growing from mixed spring and lake water. These values are consistent with fractionation observed during CaCO3 precipitation at

  18. Seawater nutrient and carbonate ion concentrations recorded as P/Ca, Ba/Ca, and U/Ca in the deep-sea coral Desmophyllum dianthus

    Science.gov (United States)

    Anagnostou, Eleni; Sherrell, Robert M.; Gagnon, Alex; LaVigne, Michele; Field, M. Paul; McDonough, William F.

    2011-05-01

    As paleoceanographic archives, deep sea coral skeletons offer the potential for high temporal resolution and precise absolute dating, but have not been fully investigated for geochemical reconstructions of past ocean conditions. Here we assess the utility of skeletal P/Ca, Ba/Ca and U/Ca in the deep sea coral D. dianthus as proxies of dissolved phosphate (remineralized at shallow depths), dissolved barium (trace element with silicate-type distribution) and carbonate ion concentrations, respectively. Measurements of these proxies in globally distributed D. dianthus specimens show clear dependence on corresponding seawater properties. Linear regression fits of mean coral Element/Ca ratios against seawater properties yield the equations: P/Ca coral (μmol/mol) = (0.6 ± 0.1) P/Ca sw(μmol/mol) - (23 ± 18), R2 = 0.6, n = 16 and Ba/Ca coral(μmol/mol) = (1.4 ± 0.3) Ba/Ca sw(μmol/mol) + (0 ± 2), R2 = 0.6, n = 17; no significant relationship is observed between the residuals of each regression and seawater temperature, salinity, pressure, pH or carbonate ion concentrations, suggesting that these variables were not significant secondary dependencies of these proxies. Four D. dianthus specimens growing at locations with Ωarag ⩽ 0.6 displayed markedly depleted P/Ca compared to the regression based on the remaining samples, a behavior attributed to an undersaturation effect. These corals were excluded from the calibration. Coral U/Ca correlates with seawater carbonate ion: U/Ca coral(μmol/mol) = (-0.016 ± 0.003) [CO32-] (μmol/kg) + (3.2 ± 0.3), R2 = 0.6, n = 17. The residuals of the U/Ca calibration are not significantly related to temperature, salinity, or pressure. Scatter about the linear calibration lines is attributed to imperfect spatial-temporal matches between the selected globally distributed specimens and available water column chemical data, and potentially to unresolved additional effects. The uncertainties of these initial proxy calibration regressions

  19. B/Ca ratio of foraminifers : a proxy for the carbon cycle in the ocean

    OpenAIRE

    Coadic, Romain

    2012-01-01

    It has been shown recently that the B/Ca ratio of planktonic foraminifers depends on the seasurface water pH, while benthic foraminifer B/Ca depends on the carbonate ion saturation of deep water. This new tracer could allow to better constrain the variations of oceanic carbon cycle, especially during the glacial-interglacial transitions (G/IG) of the Pleistocene. The objectives of this thesis were therefore : (1) to develop the foraminiferal B/Ca analysis by mass spectrometry (ICP-QMS) at LSC...

  20. Simultaneous carbonation and sulfation of CaO in Oxy-Fuel CFB combustion

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C. [School of Energy and Power Engineering, North China Electric Power University, Baoding City, Hebei Province (China); Jia, L.; Tan, Y. [CanmetENERGY, 1 Haanel Drive, Ottawa, Ontario, K1A 1M1 (Canada)

    2011-10-15

    For anthracites and petroleum cokes, the typical combustion temperature in a circulating fluidized bed (CFB) is > 900 C. At CO{sub 2} concentrations of 80-85 % (typical of oxy-fuel CFBC conditions), limestone still calcines. When the ash which includes unreacted CaO cools to the calcination temperature, carbonation of fly ash deposited on cool surfaces may occur. At the same time, indirect and direct sulfation of limestone also will occur, possibly leading to more deposition. In this study, CaO was carbonated and sulfated simultaneously in a thermogravimetric analyzer (TGA) under conditions expected in an oxy-fuel CFBC. It was found that temperature, and concentrations of CO{sub 2}, SO{sub 2}, and especially H{sub 2}O are important factors in determining the carbonation/sulfation reactions of CaO. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. CaCO3, its reaction and carbonate rocks: terahertz spectroscopy investigation

    Science.gov (United States)

    Zhan, Honglei; Wu, Shixiang; Zhao, Kun; Bao, Rima; Xiao, Lizhi

    2016-10-01

    Carbonate-rich rocks cover a primary part of the earth’s petroleum geology reservoir. The study of carbonate has special significance and more effective study methods are now needed. In order to improve the availability of carbonate rock detection, terahertz (THz) spectroscopy was employed to investigate relevant materials in Na2CO3  +  CaCl2  =  CaCO3  +  2NaCl, which is often used to generate CaCO3. By comparing the materials composited with different ions, it can be revealed that Ca2+, \\text{CO}32- , Na+ and Cl- have respective absorption features at different frequencies. Furthermore, by utilizing a conservation equation it can be observed that the average refractive indices of Na2CO3 as well as CaCl2 equal those of CaCO3 and NaCl in the entire range. Combining the absorption and refractive effect of the materials in the reaction can comprehensively characterize the different substances and reveal the inner interaction during the reaction. THz spectra can deduce the process of molecule rearrangement in the chemical reaction of long-term rock evolution. Besides, the absorption features of the real carbonate rock collected from the nearest town of Sinan county, Guizhou province in Yunnan-Guizhou plateau validate the peaks’ central frequencies of ions and the principal components of carbonates, which can be in agreement with the SEM-EDS analysis. This research will supply a spectral tool to identify the particles in the rock and deduce an evolution of petroleum carbonate reservoir.

  2. Carbon Dioxide Captured from Flue Gas by Modified Ca-based Sorbents in Fixed-bed Reactor at High Temperature

    Institute of Scientific and Technical Information of China (English)

    YANG Lei; YU Hongbing; WANG Shengqiang; WANG Haowen; ZHOU Qibin

    2013-01-01

    Four kinds of Ca-based sorbents were prepared by calcination and hydration reactions using different precursors: calcium hydroxide,calcium carbonate,calcium acetate monohydrate and calcium oxide.The CO2 absorption capacity of those sorbents was investigated in a fixed-bed reactor in the temperature range of 350 650 ℃.It was found that all of those sorbents showed higher capacity for CO2 absorption when the operating temperature higher than 450 ℃.The CaAc2-CaO sorbent showed the highest CO2 absorption capacity of 299 mg·g-1.The morphology of those sorbents was examined by scanning electron microscope(SEM),and the changes of composition before and after carbonation were also determined by X-ray diffraction(XRD).Results indicated that those sorbents have the similar chemical compositions and crystalline phases before carbonation reaction [mainly Ca(OH)2],and CaCO3 is the main component after carbonation reaction.The SEM morphology shows clearly that the sorbent pores were filled with reaction products after carbonation reaction,and became much denser than before.The N2 adsorption-desorption isotherms indicated that the CaAc2-CaO and CaCO3-CaO sorbents have higher specific surface area,larger pore volume and appropriate pore size distribution than that of CaO-CaO and Ca(OH)2-CaO.

  3. Porous carbon material containing CaO for acidic gas capture: preparation and properties.

    Science.gov (United States)

    Przepiórski, Jacek; Czyżewski, Adam; Pietrzak, Robert; Toyoda, Masahiro; Morawski, Antoni W

    2013-12-15

    A one-step process for the preparation of CaO-containing porous carbons is described. Mixtures of poly(ethylene terephthalate) with natural limestone were pyrolyzed and thus hybrid sorbents could be easily obtained. The polymeric material and the mineral served as a carbon precursor and CaO delivering agent, respectively. We discuss effects of the preparation conditions and the relative amounts of the raw materials used for the preparations on the porosity of the hybrid products. The micropore areas and volumes of the obtained products tended to decrease with increasing CaO contents. Increase in the preparation temperature entailed a decrease in the micropore volume, whereas the mesopore volume increased. The pore creation mechanism is proposed on the basis of thermogravimetric and temperature-programmed desorption measurements. The prepared CaO-containing porous carbons efficiently captured SO2 and CO2 from air. Washing out of CaO from the hybrid materials was confirmed as a suitable method to obtain highly porous carbon materials.

  4. δ44/40Ca variability in shallow water carbonates and the impact of submarine groundwater discharge on Ca-cycling in marine environments

    Science.gov (United States)

    Holmden, C.; Papanastassiou, D. A.; Blanchon, P.; Evans, S.

    2012-04-01

    Shallow water carbonates from Florida Bay, the Florida Reef Tract, and a Mexican Caribbean fringing reef at Punta Maroma were studied to determine the range of Ca-isotope variation among a cohort of modern carbonate producers and to look for local-scale Ca-cycling effects. The total range of Ca-isotope fractionation is 0.4‰ at Punta Maroma, yielding an allochem-weighted average δ44/40Ca value of -1.12‰ consistent with bulk sediment from the lagoon with a value of -1.09‰. These values are virtually identical to bulk carbonate sediments from the Florida Reef Tract (-1.11‰) and from one location in Florida Bay (-1.09‰) near a tidal inlet in the Florida Keys. No evidence was found for the ∼0.6‰ fractionation between calcite and aragonite which has been observed in laboratory precipitation experiments. Combining these results with carbonate production modes and δ44/40Ca values for pelagic carbonates taken from the literature, we calculate a weighted average value of -1.12 ± 0.11‰ (2σ) for the global-scale Ca-output flux into carbonate sediments. The δ44/40Ca value of the input Ca-flux from rivers and hydrothermal fluids is -1.01 ± 0.04‰ (2σmean), calculated from literature data that have been corrected for inter-laboratory bias. Assuming that the ocean Ca cycle is in steady state, we calculate a δ44/40Ca value of -1.23 ± 0.23‰ (2σ) for submarine groundwater discharge (SGD) on a global scale. The SGD Ca-flux rivals river flows and mid-ocean ridge hydrothermal vent inputs as a source of Ca to the oceans. It has the potential to differ significantly in its isotopic value from these traditional Ca-inputs in the geological past, and to cause small changes in the δ44/40Ca value of oceans through time. In the innermost water circulation restricted region of northeastern Florida Bay, sediments and waters exhibit a 0.7‰ gradient in δ44/40Ca values decreasing towards the Florida Everglades. This lowering of δ44/40Ca is predominantly caused by

  5. Initial reaction between CaO and SO2 under carbonating and non-carbonating conditions

    DEFF Research Database (Denmark)

    Rasmussen, Martin Hagsted; Wedel, Stig; Pedersen, Kim H.;

    2015-01-01

    The initial kinetics of the CaO/SO2 reaction have been investigated for reaction times shorter than 1s and in the temperature interval between 450 and 600°C under both carbonating and non-carbonating conditions (0-20 vol% CO2) to clarify how recirculating CaO influences the emission of SO2 from...... showed that the CaO conversion with respect to SO2 declined when the CO2 concentration was increased. Under all conditions, larger specific surface areas of CaO gave higher reaction rates with SO2. Higher temperatures had a positive effect on the reaction between SO2 and CaO under non...... a modern dry kiln preheater system for cement production. Calcined Faxe Bryozo limestone with a particle size smaller than 400μm was utilized as CaO source. It was shown, both theoretically and experimentally, that the observed reaction rates were influenced by mass transport limitations. The results...

  6. Silicate versus carbonate weathering in Iceland: New insights from Ca isotopes

    Science.gov (United States)

    Jacobson, Andrew D.; Grace Andrews, M.; Lehn, Gregory O.; Holmden, Chris

    2015-04-01

    Several studies have measured riverine fluxes of Ca and carbonate alkalinity in Iceland with the aim of quantifying the role of basalt weathering in the long-term carbon cycle. A major assumption is that all of the Ca and alkalinity originates from the dissolution of Ca-bearing silicate minerals, such as plagioclase and clinopyroxene. However, hydrothermal calcite occurs throughout Iceland, and even trace levels are expected to impact river geochemistry owing to the mineral's high solubility and fast dissolution rate. To test this hypothesis, we used a new, high-precision Ca isotope MC-TIMS method (δ44/40Ca; 2σSD = ± 0.04 ‰) to trace sources of Ca in Icelandic rivers. We report elemental and Ca isotope data for rivers, high- and low-temperature groundwater, basalt, hydrothermal calcite (including Iceland Spar), and stilbite and heulandite, which are two types of zeolites commonly formed during low-grade metamorphism of basalt. In agreement with previous research, we find that rivers have higher δ44/40Ca values than basalt, with a maximum difference of ∼0.40‰. This difference may reflect isotope fractionation in the weathering zone, i.e., preferential uptake of 40Ca during clay mineral formation, adsorption, and other geochemical processes that cycle Ca. However, calcite δ44/40Ca values are also up to ∼0.40‰ higher than bedrock values, and on a diagram of δ44/40Ca versus Sr/Ca, nearly all waters plot within a plausible mixing domain bounded by the measured compositions of basalt and calcite, with glacial rivers plotting closer to calcite than non-glacial rivers. Calcite and heulandite form during hydrothermal alteration of basalt in the deep lava pile and often occur together in metabasalts now exposed at the surface. Because heulandite δ44/40Ca values are ∼1-2‰ lower than basalt, we suggest that 40Ca uptake by heudlandite explains the relatively high δ44/40Ca values of calcite and that calcite weathering in turn elevates riverine δ44/40Ca

  7. A new affinity gel for the purification of α-carbonic anhdrases.

    Science.gov (United States)

    Sahin, Aysegul; Isık, Semra; Arslan, Oktay; Supuran, Claudiu T; Guler, Ozen Ozensoy

    2015-04-01

    The new affinity gel reported in this study was prepared using EUPERGIT C250L as a chromatographic bed material, to which etylenediamine spacer arms were attached to prevent steric hindrance between the matrix and ligand, and to facilitate effective binding of the CA-specific ligand, of the aromatic sulfonamide type for the purification of α-carbonic anhydrases (Cas; EC 4.2.1.1). Indeed, the aminoethyl moieties of the affinity gel were derivatized by reaction with 4-isothiocyanatobenzenesulfonamide, with the formation of a thiourea-based gel, having inhibitory effects against CAs. Both bovine erythrocyte carbonic anhydrase BCA and human (h) erythrocyte CA isoforms I, II (hCA I and II) have been purified from hemolysates, by using this affinity gel. The greatest purification fold and column yields for BCA and for cytosolic (hCA I + II) enzymes were of 181-fold (21.07%) and 184-fold (9.49%), respectively. Maximum binding was achieved at 15 °C and I = 0.3 ionic strength for α-carbonic anhydrases. PMID:24936879

  8. Using CaO- and MgO-rich industrial waste streams for carbon sequestration

    International Nuclear Information System (INIS)

    To prevent rapid climate change, it will be necessary to reduce net anthropogenic CO2 emissions drastically. This likely will require imposition of a tax or tradable permit scheme that creates a subsidy for negative emissions. Here, we examine possible niche markets in the cement and steel industries where it is possible to generate a limited supply of negative emissions (carbon storage or sequestration) cost-effectively. Ca(OH)2 and CaO from steel slag or concrete waste can be dissolved in water and reacted with CO2 in ambient air to capture and store carbon safely and permanently in the form of stable carbonate minerals (CaCO3). The kinetics of Ca dissolution for various particle size fractions of ground steel slag and concrete were measured in batch experiments. The majority of available Ca was found to dissolve on a time scale of hours, which was taken to be sufficiently fast for use in an industrial process. An overview of the management options for steel slag and concrete waste is presented, which indicates how their use for carbon sequestration might be integrated into existing industrial processes. Use of the materials in a carbon sequestration scheme does not preclude subsequent use and is likely to add value by removing the undesirable qualities of water absorption and expansion from the products. Finally, an example scheme is presented which could be built and operated with current technology to sequester CO2 with steel slag or concrete waste. Numerical models and simple calculations are used to establish the feasibility and estimate the operating parameters of the scheme. The operating cost is estimated to be US$8/t-CO2 sequestered. The scheme would be important as an early application of technology for capturing CO2 directly from ambient air

  9. ForCaMF - Decision Support for Landscape-Level Forest Carbon Management

    Science.gov (United States)

    Healey, S. P.; Urbanski, S. P.; Morrison, J. F.; Garrard, C.; Peduzzi, A.; Hernandez, A. J.

    2011-12-01

    Forests have the capacity to store atmospheric carbon, and forest management is seen as a potential way to partially offset high anthropogenic greenhouse gas emissions. However, application of carbon cycle research in this area will depend upon development of new approaches for decision support which address, in a transparent way, the local ecological complexities facing managers without relying upon specialized monitoring campaigns. The Forest Carbon Management Framework (ForCaMF) has been developed to meet these needs. Forest carbon stocks and flows are modeled by applying carbon dynamics from a robust simulation tool (FVS: the Forest Vegetation Simulator) to high-resolution (30m) maps of forest structure and disturbance over the last 25 years. The defining feature of ForCaMF is that the maps used to represent landscape dynamics are modified in two ways: 1) stochastically, to simulate the potential effects of map bias and random error on flux estimates, and 2) purposively, to investigate effects of alternative disturbance scenarios. An empirical measure of the uncertainty of carbon stock and flux estimates associated with each scenario is obtained from the variance of output estimates as inputs are iteratively varied to propagate potential input errors. The immediate and long-term carbon processes of real or hypothetical disturbances can be considered in the context of the larger matrix of undisturbed areas. This approach currently relies only upon inventory and satellite data which are uniformly available across the United States, and could be adapted to data available elsewhere. ForCaMF is being applied in the Northern region of the US National Forest System, which covers approximately 10 million hectares of forest over 5 states. Results are expected to support formal consideration of carbon storage as an environmental service in future regional forest planning efforts.

  10. Isotopic fractionation of Mg 2+(aq), Ca 2+(aq), and Fe 2+(aq) with carbonate minerals

    Science.gov (United States)

    Rustad, James R.; Casey, William H.; Yin, Qing-Zhu; Bylaska, Eric J.; Felmy, Andrew R.; Bogatko, Stuart A.; Jackson, Virgil E.; Dixon, David A.

    2010-11-01

    Density-functional electronic structure calculations are used to compute the equilibrium constants for 26Mg/ 24Mg and 44Ca/ 40Ca isotope exchange between carbonate minerals and uncomplexed divalent aquo ions. The most reliable calculations at the B3LYP/6-311++G(2d,2p) level predict equilibrium constants K, reported as 10 3ln ( K) at 25 °C, of -5.3, -1.1, and +1.2 for 26Mg/ 24Mg exchange between calcite (CaCO 3), magnesite (MgCO 3), and dolomite (Ca 0.5Mg 0.5CO 3), respectively, and Mg 2+(aq), with positive values indicating enrichment of the heavy isotope in the mineral phase. For 44Ca/ 40Ca exchange between calcite and Ca 2+(aq) at 25 °C, the calculations predict values of +1.5 for Ca 2+(aq) in 6-fold coordination and +4.1 for Ca 2+(aq) in 7-fold coordination. We find that the reduced partition function ratios can be reliably computed from systems as small as M(CO)610- and M(HO)62+ embedded in a set of fixed atoms representing the second-shell (and greater) coordination environment. We find that the aqueous cluster representing the aquo ion is much more sensitive to improvements in the basis set than the calculations on the mineral systems, and that fractionation factors should be computed using the best possible basis set for the aquo complex, even if the reduced partition function ratio calculated with the same basis set is not available for the mineral system. The new calculations show that the previous discrepancies between theory and experiment for Fe 3+-hematite and Fe 2+-siderite fractionations arise from an insufficiently accurate reduced partition function ratio for the Fe 3+(aq) and Fe 2+(aq) species.

  11. Effect of Mg/Ca ratios on microbially induced carbonate precipitation

    Science.gov (United States)

    Balci, Nurgul; Demirel, Cansu; Seref Sonmez, M.; Kurt, M. Ali

    2016-04-01

    Influence of Mg/Ca ratios on microbially induced carbonate mineralogy were investigated by series of experiments carried out under various environmental conditions (Mg/Ca ratio, temperature and salinity). Halophilic bacterial cultures used for biomineralization experiments were isolated from hypersaline Lake Acıgöl (Denizli, SW Turkey), displaying extreme water chemistry with an average pH around 8.6 (Balci eta l.,2015). Enriched bacterial culture used in the experiments consisted of Halomonas saccharevitans strain AJ275, Halomonas alimentaria strain L7B; Idiomarina sp. TBZ29, 98% Idiomarina seosensis strain CL-SP19. Biomineralization experiments were set up using above enriched culture with Mg/Ca ratios of 0.05, 1, 4 and 15 and salinity of 8% and 15% experiments at 30oC and 10oC. Additionally, long-term biomineralization experiments were set up to last for a year, for Mg/Ca=4 and Mg/Ca=15 experiments at 30oC. For each experimental condition abiotic experiments were also conducted. Solution chemistry throughout incubation was monitored for Na, K, Mg, Ca, bicarbonate, carbonate, ammonium and phosphate for a month. At the end of the experiments, precipitates were collected and morphology and mineralogy of the biominerals were investigated and results were evaluated using the software DIFFRAC.SUITE EVA. Overall the preliminary results showed chemical precipitation of calcite, halite, hydromagnesite and sylvite. Results obtained from biological experiments indicate that, low Mg/Ca ratios (0.05 and 1) favor chlorapatite precipitation, whereas higher Mg/Ca ratios favor struvite precipitation. Biomineralization of dolomite, huntite and magnesite is favorable at high Mg/Ca ratios (4 and 15), in the presence of halophilic bacteria. Moreover, results indicate that supersaturation with respect to Mg (Mg/Ca=15) combined with NaCl (15%) inhibits biomineralization and forms chemical precipitates. 15% salinity is shown to favor chemical precipitation of mineral phases more than

  12. Structuralization of Ca(2+)-Based Metal-Organic Frameworks Prepared via Coordination Replication of Calcium Carbonate.

    Science.gov (United States)

    Sumida, Kenji; Hu, Ming; Furukawa, Shuhei; Kitagawa, Susumu

    2016-04-01

    The emergence of metal-organic frameworks (MOFs) as potential candidates to supplant existing adsorbent types in real-world applications has led to an explosive growth in the number of compounds available to researchers, as well as in the diversity of the metal salts and organic linkers from which they are derived. In this context, the use of carbonate-based precursors as metal sources is of interest due to their abundance in mineral deposits and their reaction chemistry with acids, resulting in just water and carbon dioxide as side products. Here, we have explored the use of calcium carbonate as a metal source and demonstrate its versatility as a precursor to several known frameworks, as well as a new flexible compound based on the 2,5-dihydroxybenzoquinone (H2dhbq) linker, Ca(dhbq)(H2O)2. Furthermore, inspired by the ubiquity and unique structures of biomineralized forms of calcium carbonate, we also present examples of the preparation of superstructures of Ca-based MOFs via the coordination replication technique. In all, the results confirm the suitability of carbonate-based metal sources for the preparation of MOFs and further expand upon the growing scope of coordination replication as a convenient strategy for the preparation of structuralized materials. PMID:27002690

  13. Calculating carbon mass balance from unsaturated soil columns treated with CaSO₄₋minerals: test of soil carbon sequestration.

    Science.gov (United States)

    Han, Young-Soo; Tokunaga, Tetsu K

    2014-12-01

    Renewed interest in managing C balance in soils is motivated by increasing atmospheric concentrations of CO2 and consequent climate change. Here, experiments were conducted in soil columns to determine C mass balances with and without addition of CaSO4-minerals (anhydrite and gypsum), which were hypothesized to promote soil organic carbon (SOC) retention and soil inorganic carbon (SIC) precipitation as calcite under slightly alkaline conditions. Changes in C contents in three phases (gas, liquid and solid) were measured in unsaturated soil columns tested for one year and comprehensive C mass balances were determined. The tested soil columns had no C inputs, and only C utilization by microbial activity and C transformations were assumed in the C chemistry. The measurements showed that changes in C inventories occurred through two processes, SOC loss and SIC gain. However, the measured SOC losses in the treated columns were lower than their corresponding control columns, indicating that the amendments promoted SOC retention. The SOC losses resulted mostly from microbial respiration and loss of CO2 to the atmosphere rather than from chemical leaching. Microbial oxidation of SOC appears to have been suppressed by increased Ca(2+) and SO4(2)(-) from dissolution of CaSO4 minerals. For the conditions tested, SIC accumulation per m(2) soil area under CaSO4-treatment ranged from 130 to 260 g C m(-1) infiltrated water (20-120 g C m(-1) infiltrated water as net C benefit). These results demonstrate the potential for increasing C sequestration in slightly alkaline soils via CaSO4-treatment.

  14. Interactive Effect of GA3, N and P Ameliorate Growth, Seed and Fibre Yield by Enhancing Photosynthetic Capacity and Carbonic Anhydrase Activity of Linseed:A Dual Purpose Crop

    Institute of Scientific and Technical Information of China (English)

    Mohammad N Khan; Firoz Mohammad

    2013-01-01

    Linseed (Linum usitatissimum L.) is an important dual-purpose, industrial crop. Its seeds are used for the extraction of oil and stem for fibres. However, the production of linseed is not going parallel with the increasing demand of its products. The present work was carried out with an aim to find out whether exogenous application of gibberellic acid (GA3) with or without graded levels of nitrogen (N) and phosphorus (P) could improve the performance of three linseed genotypes Parvati, Shekhar and Shubhra together with minimizing the costly fertilizer input and losses. Four combinations of N and P, viz., 0 mg N+0 mg P kg-1 soil (N0P0), N13.4P4.46, N26.8P8.94 and N40.2P13.4 were constituted. Half dose of each combination was applied basally at the time of sowing and remaining half dose was given at 40 d after sowing (DAS) as foliar spray along with 10-6 mol L-1 GA3. Prior to sowing, the seeds of each linseed genotype were grouped in to two, one group of seeds was soaked in 0 mol L-1 GA3 (control) and the other group was soaked in 10-6 M GA3 solution, each for 8 hours. Treatments were comprised of (i) 0 mol L-1 GA3+N0P0 (T0, control), (ii) 10-6 mol L-1 GA3+N13.4P4.46 (T1), (iii) 10-6 mol L-1 GA3+N26.8P8.94 (T2) and (iv) 10-6 mol L-1 GA3+N40.2P13.4 (T3). The crop performance was assessed in terms of growth, physiological and biochemical parameters at 60 and 75 DAS and yield attributes at harvest (175 DAS). The results showed a parallel increase in most of the parameters with increasing levels of N and P. However, application of 10-6 mol L-1 GA3 in association with N26.8P8.94 proved best, it enhanced seed yield, oil yield and fibre yield by 83.3, 97.3 and 78.7%, respectively accompanied with increase in net photosynthetic rate, carbonic anhydrase activity and dry matter accumulation. Among the genotypes tested, Shubhra performed best, while Parvati the least for most of the parameters studied. Thus, combined application of 10-6 mol L-1 GA3 plus N26.8P8.94 proved best

  15. Effect of carbonation temperature on CO2 adsorption capacity of CaO derived from micro/nanostructured aragonite CaCO3

    Science.gov (United States)

    Hlaing, Nwe Ni; Sreekantan, Srimala; Hinode, Hirofumi; Kurniawan, Winarto; Thant, Aye Aye; Othman, Radzali; Mohamed, Abdul Rahman; Salime, Chris

    2016-07-01

    Recent years, CaO-based synthetic materials have been attracted attention as potential adsorbents for CO2 capture mainly due to their high CO2 adsorption capacity. In this study, micro/nanostructured aragonite CaCO3 was synthesized by a simple hydrothermal method with using polyacrylamide (PAM). The structural, morphological and thermal properties of the synthesized sample were investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and thermogravimetry analysis (TG-DTA). The XRD and FESEM results showed that the obtained sample was aragonite CaCO3 with aggregated nanorods and microspheres composed of nanorods. A TG-DTA apparatus with Thermoplus 2 software was used to investigate the effect of carbonation temperature on the CO2 adsorption capacity of CaO derived from aragonite CaCO3 sample. At 300 °C, the sample reached the CO2 adsorption capacity of 0.098 g-CO2/g-adsorbent, whereas the sample achieved the highest capacity of 0.682 g-CO2/g-adsorbent at 700 °C. The results showed that the carbonation temperature significantly influenced on the CO2 adsorption capacity of the CaO derived from aragonite CaCO3.

  16. Calcification and growth processes in planktonic foraminifera complicate the use of B/Ca and U/Ca as carbonate chemistry proxies

    Science.gov (United States)

    Salmon, Kate H.; Anand, Pallavi; Sexton, Philip F.; Conte, Maureen

    2016-09-01

    Although boron and uranium to calcium ratios (B/Ca, U/Ca) in planktonic foraminifera have recently received much attention as potential proxies for ocean carbonate chemistry, the extent of a carbonate chemistry control on these ratios remains contentious. Here, we use bi-weekly sediment trap samples collected from the subtropical North Atlantic in combination with measured oceanographic data from the same location to evaluate the dominant oceanographic controls on B/Ca and U/Ca in three depth-stratified species of planktonic foraminifera. We also test the control of biological, growth-related, processes on planktonic foraminiferal B and U incorporation by using foraminifer test area density (μ g /μm2) (a monitor of test thickness) and test size from the same samples. B/Ca and U/Ca show little or no significant correlation with carbonate system parameters both within this study and in comparison with other published works. We provide the first evidence for a strong positive relationship between area density (test thickness) and B/Ca, and reveal that this is consistent in all species studied, suggesting a likely role for calcification in controlling boron partitioning into foraminiferal calcite. This finding is consistent with previous observations of less efficient discrimination against trace element 'impurities' (such as B), at higher calcification rates. We observe little or no dependency of B/Ca on test size. In marked contrast, we find that U/Ca displays a strong species-specific dependency on test size in all species, but no relationship with test thickness, implicating some other biological control (possibly related to growth), rather than a calcification control, on U incorporation into foraminiferal calcite. Our results caution against the use of B/Ca and U/Ca in planktonic foraminifera as reliable proxies for the ocean carbonate system and recommend that future work should concentrate on improving the mechanistic understanding of how planktonic

  17. Role of crystal structure on CO2 capture by limestone derived CaO subjected to carbonation/recarbonation/calcination cycles at Ca-looping conditions

    International Nuclear Information System (INIS)

    Highlights: • CO2 capture of limestone subjected to carbonation/recarbonation/calcination cycles is affected by diffusion. • A reduction of crystallinity by ball milling favors diffusion and promotes recarbonation. • Thermal annealing enhances crystallinity and hinders recarbonation. • Milling promotes friability whereas annealing enhances the resistance of particles to fragmentation. • The solid crystal structure determines the efficiency of the novel Ca-looping concept. - Abstract: Large scale pilot plants are currently demonstrating the feasibility of the Calcium-looping (CaL) technology built on the multicyclic calcination/carbonation of natural limestone for post-combustion and pre-combustion CO2 capture. Yet, limestone derived CaO exhibits a drop of conversion when subjected to multiple carbonation/calcination cycles, which lessens the efficiency of the technology. In this paper we analyze a novel CaL concept recently proposed to mitigate this drawback based on the introduction of an intermediate stage wherein carbonation is intensified at high temperature and high CO2 partial pressure. It is shown that carbonation in this stage is mainly driven by solid-state diffusion, which is determined by the solid’s crystal structure. Accordingly, a reduction of crystallinity by ball milling, which favors diffusion, serves to promote recarbonation. Conversely, thermal annealing, which enhances crystallinity, hinders recarbonation. An initial fast phase has been identified in the recarbonation stage along which the rate of carbonation is also a function of the crystal structure indicating a relevant role of surface diffusion. This is consistent with a recently proposed mechanism for nucleation of CaCO3 on the CaO surface in islands with a critical size determined by surface diffusion. A further issue analyzed has been the effects of pretreatment and cycling on the mechanical strength of the material, whose fragility hampers the CaL process efficiency

  18. Reproducing early Martian atmospheric carbon dioxide partial pressure by modeling the formation of Mg-Fe-Ca carbonate identified in the Comanche rock outcrops on Mars

    Science.gov (United States)

    Berk, Wolfgang; Fu, Yunjiao; Ilger, Jan-Michael

    2012-10-01

    The well defined composition of the Comanche rock's carbonate (Magnesite0.62Siderite0.25Calcite0.11Rhodochrosite0.02) and its host rock's composition, dominated by Mg-rich olivine, enable us to reproduce the atmospheric CO2partial pressure that may have triggered the formation of these carbonates. Hydrogeochemical one-dimensional transport modeling reveals that similar aqueous rock alteration conditions (including CO2partial pressure) may have led to the formation of Mg-Fe-Ca carbonate identified in the Comanche rock outcrops (Gusev Crater) and also in the ultramafic rocks exposed in the Nili Fossae region. Hydrogeochemical conditions enabling the formation of Mg-rich solid solution carbonate result from equilibrium species distributions involving (1) ultramafic rocks (ca. 32 wt% olivine; Fo0.72Fa0.28), (2) pure water, and (3) CO2partial pressures of ca. 0.5 to 2.0 bar at water-to-rock ratios of ca. 500 molH2O mol-1rock and ca. 5°C (278 K). Our modeled carbonate composition (Magnesite0.64Siderite0.28Calcite0.08) matches the measured composition of carbonates preserved in the Comanche rocks. Considerably different carbonate compositions are achieved at (1) higher temperature (85°C), (2) water-to-rock ratios considerably higher and lower than 500 mol mol-1 and (3) CO2partial pressures differing from 1.0 bar in the model set up. The Comanche rocks, hosting the carbonate, may have been subjected to long-lasting (>104 to 105 years) aqueous alteration processes triggered by atmospheric CO2partial pressures of ca. 1.0 bar at low temperature. Their outcrop may represent a fragment of the upper layers of an altered olivine-rich rock column, which is characterized by newly formed Mg-Fe-Ca solid solution carbonate, and phyllosilicate-rich alteration assemblages within deeper (unexposed) units.

  19. Dissolved inorganic carbon dynamics in the waters surrounding forested mangroves of the Ca Mau Province (Vietnam)

    OpenAIRE

    Koné, J. M.; Borges, Alberto

    2008-01-01

    Dissolved inorganic carbon (DIC) and ancillary data were obtained during the dry and rainy seasons in the waters surrounding two 10-year-old forested mangrove sites (Tam Giang and Kien Vang) located in the Ca Mau Province (South-West Vietnam). During both seasons, the spatial variations of partial pressure of CO2 (pCO2) were marked, with values ranging from 704 ppm to 11481 ppm during the dry season, and from 1209 ppm to 8136 ppm during the rainy season. During both seasons, DIC, pCO2, total ...

  20. On carbon dioxide storage based on biomineralization strategies.

    Science.gov (United States)

    Lee, Seung-Woo; Park, Seung-Bin; Jeong, Soon-Kwan; Lim, Kyoung-Soo; Lee, Si-Hyun; Trachtenberg, Michael C

    2010-06-01

    This study focuses on the separation and storage of the global warming greenhouse gas CO(2), and the use of natural biocatalysts in the development of technologies to improve CO(2) storage rates and provide new methods for CO(2) capture. Carbonic anhydrase (CA) has recently been used as a biocatalyst to sequester CO(2) through the conversion of CO(2) to HCO(-) in the mineralization of CaCO(3). Biomimetic CaCO(3) mineralization for carbon capture and storage offers potential as a stable CO(2) capture technology. In this report, we review recent developments in this field and assess disadvantages and improvements in the use of CA in industrial applications. We discuss the contribution that understanding of mechanisms of CO(2) conversion to CO(3)(-) in the formation and regeneration of bivalve shells will make to developments in biomimetic CO(2) storage. PMID:20144548

  1. Catalyst Deactivation Simulation Through Carbon Deposition in Carbon Dioxide Reforming over Ni/CaO-Al2O3 Catalyst

    Directory of Open Access Journals (Sweden)

    Istadi Istadi

    2011-11-01

    Full Text Available Major problem in CO2 reforming of methane (CORM process is coke formation which is a carbonaceous residue that can physically cover active sites of a catalyst surface and leads to catalyst deactivation. A key to develop a more coke-resistant catalyst lies in a better understanding of the methane reforming mechanism at a molecular level. Therefore, this paper is aimed to simulate a micro-kinetic approach in order to calculate coking rate in CORM reaction. Rates of encapsulating and filamentous carbon formation are also included. The simulation results show that the studied catalyst has a high activity, and the rate of carbon formation is relatively low. This micro-kinetic modeling approach can be used as a tool to better understand the catalyst deactivation phenomena in reaction via carbon deposition. Copyright © 2011 BCREC UNDIP. All rights reserved.(Received: 10th May 2011; Revised: 16th August 2011; Accepted: 27th August 2011[How to Cite: I. Istadi, D.D. Anggoro, N.A.S. Amin, and D.H.W. Ling. (2011. Catalyst Deactivation Simulation Through Carbon Deposition in Carbon Dioxide Reforming over Ni/CaO-Al2O3 Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 6 (2: 129-136. doi:10.9767/bcrec.6.2.1213.129-136][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.6.2.1213.129-136 || or local:  http://ejournal.undip.ac.id/index.php/bcrec/article/view/1213 ] | View in  |  

  2. The influence of electron discharge and magnetic field on calcium carbonate (CaCO3) precipitation

    Science.gov (United States)

    Putro, Triswantoro; Endarko

    2016-04-01

    The influences of electron discharge and magnetic field on calcium carbonate (CaCO3) precipitation in water have been successfully investigated. The study used three pairs of magnetic field 0.1 T whilst the electron discharge was generated from television flyback transformer type BW00607 and stainless steel SUS 304 as an electrode. The water sample with an initial condition of 230 mg/L placed in the reactor with flow rate 375 mL/minutes, result showed that the electron discharge can be reduced contain of calcium carbonate the water sample around 17.39% within 2 hours. Meanwhile for the same long period of treatment and flow rate, around 56.69% from initial condition of 520 mg/L of calcium carbonate in the water sample can be achieved by three pairs of magnetic field 0.1 T. When the combination of three pairs of magnetic field 0.1 T and the electron discharge used for treatment, the result showed that the combination of electron discharge and magnetic field methods can be used to precipitate calcium carbonate in the water sample 300 mg/L around 76.66% for 2 hours of treatment. The study then investigated the influence of the polar position of the magnetic field on calcium carbonate precipitation. Two positions of magnetic field were tested namely the system with alternated polar magnetics and the system without inversion of the polar magnetics. The influence of the polar position showed that the percentage reduction in levels of calcium carbonate in the water sample (360 mg/L) is significant different. Result showed that the system without inversion of the polar magnetics is generally lower than the system with alternated polar magnetics, with reduction level at 30.55 and 57.69%, respectively.

  3. DUSTER: collection of meteoric CaO and carbon smoke particles in the upper stratosphere .

    Science.gov (United States)

    Della Corte, V.; Rietmeijer, F. J. M.; Rotundi, A.; Ferrari, M.; Palumbo, P.

    Nanometer- to micrometer-size particles present in the upper stratosphere are a mixture of terrestrial and extra-terrestrial origins. They can be extraterrestrial particles condensed after meteor ablation. Meteoric dust in bolides is occasionally deposited into the lower stratosphere around 20 km altitude. Nanometer CaO and pure carbon smoke particles were collected at 38 km altitude in the upper stratosphere in the Arctic during June 2008 using DUSTER (Dust in the Upper Stratosphere Tracking Experiment and Retrieval), a balloon-borne instrument for the non-destructive collection of solid particles between 200 nm to 40 microns. We report the collection of micron sized CaCO_3 (calcite) grains. Their morphologies show evidence of melting and condensation after vaporization suggest at temperatures of approximately 3500 K. The formation environment of the collected grains was probably a dense dust cloud formed by the disintegration of a carbonaceous meteoroid during deceleration in the Earth� atmosphere. For the first time, DUSTER collected meteor ablation products that were presumably associated with the disintegration of a bolide crossing the Earth's atmosphere. The collected mostly CaO and pure carbon nanoparticles from the debris cloud of a fireball, included: 1) intact fragments; 2) quenched melted grains; and 3) vapor phase condensation products. The DUSTER project was funded by the Italian Space Agency (ASI), PRIN2008/MIUR (Ministero dell'Istruzione dell'Universitá e della Ricerca), PNRA 2013(Piano Nazionale Ricerca Antartide). CNES graciously provided this flight opportunity. We thank E. Zona and S. Inarta at the Laboratorio di Fisica Cosmica INAF, Osservatorio Astronomico di Capodimonte-Universitá di Napoli Parthenope. F.J.M.R. was supported by grant NNX07AI39G from the NASA Cosmochemistry Program. We thank three anonymous reviewers who assisted us in introducing our new instrument.

  4. The Effect of Plant Carbonic Anhydrase on the Fractionation of Stable Carbon Isotope%植物碳酸酐酶对稳定碳同位素分馏作用的影响

    Institute of Scientific and Technical Information of China (English)

    吴沿友

    2008-01-01

    碳酸酐酶(CA)能够可逆地催化CO2和HCO-3之间的快速转化.长久以来人们忽视了生物体中CA对稳定碳同位素分馏的影响.本文以微藻碳酸酐酶胞外酶为例,说明细胞的区室化和偶联反应可引起CA可逆催化HCO-3和CO2的转化的不平衡,进而造成稳定碳同位素分馏,并给出体外实验和C4植物实验结果作为依据.此外,本文还讨论了CA对碳同位素分馏的影响的理论和实践意义.

  5. The CaCO3-Fe interaction: Kinetic approach for carbonate subduction to the deep Earth's mantle

    Science.gov (United States)

    Martirosyan, N. S.; Yoshino, T.; Shatskiy, A.; Chanyshev, A. D.; Litasov, K. D.

    2016-10-01

    The CaCO3-Fe0 system, as a model for redox reactions between carbonates and reduced lithologies at the slab-mantle interface during subduction or at core-mantle boundary, was investigated systematically at temperatures from 650 to 1400 °C and pressures from 4 to 16 GPa using multianvil apparatus. CaCO3 reduction via reaction: 3 CaCO3 (aragonite) + 13 Fe0 (metal) = Fe7C3 (carbide) + 3 CaFe2O3 (Ca-wüstite) was observed. The thickness of the reaction-product layer (Δx) increases linearly with the square root of time in the time-series experiments (t), indicating diffusion-controlled process. The reaction rate constant (k = Δx2/2t) is log-linear relative to 1/T. Its temperature dependences was determined to be k [m2/s] = 2.1 × 10-7exp(-162[kJ/mol]/RT) at 4-6 GPa and k [m2/s] = 2.6 × 10-11exp(-65[kJ/mol]/RT) at 16 GPa. The sluggish kinetics of established CaCO3-Fe0 interaction suggests that significant amount of carbonates could survive during subduction from metal saturation boundary near 250 km depth down to the transition zone and presumably to the lower mantle if melting of carbonates is not involved.

  6. Development of a carbonate absorption-based process for post-combustion CO2 capture: The role of biocatalyst to promote CO2 absorption rate

    Science.gov (United States)

    Lu, Y.; Ye, X.; Zhang, Z.; Khodayari, A.; Djukadi, T.

    2011-01-01

    An Integrated Vacuum Carbonate Absorption Process (IVCAP) for post-combustion carbon dioxide (CO2) capture is described. IVCAP employs potassium carbonate (PC) as a solvent, uses waste or low quality steam from the power plant for CO2 stripping, and employs a biocatalyst, carbonic anhydrase (CA) enzyme, for promoting the CO2 absorption into PC solution. A series of experiments were performed to evaluate the activity of CA enzyme mixed in PC solutions in a stirred tank reactor system under various temperatures, CA dosages, CO2 loadings, CO2 partial pressures, and the presence of major flue gas contaminants. It was demonstrated that CA enzyme is an effective biocatalyst for CO2 absorption under IVCAP conditions. ?? 2011 Published by Elsevier Ltd.

  7. Ca-Mg Carbonate Cements in Ophiolite-Hosted Creek Waters of the Del Puerto Ophiolite, CA, and their Potential Significance as a Planetary Biosignature

    Science.gov (United States)

    Blank, J. G.

    2015-12-01

    Serpentinization, the reaction at moderate pressure and temperature of water with olivine and pyroxene that are common in basalts and ultramafic rocks, results in the formation of alkaline fluids and the precipitation of a variety of secondary minerals. Terrestrial localities where active serpentinization is occurring are ideal Mars analogs for examining the characteristics of an environment that possesses two of the key features that we assume necessary to host life: water and an internally generated energy source. This study focuses on a related but different feature present where active serpentinization is occurring - namely, carbonate cements forming under plain air in the vicinity of Adobe Springs, CA. This site is located in the Del Puerto ophiolite about 150 km ESE of San Francisco, in the Coast Range of California. Two alkaline spring water compositions have been described at the site, a Ca-OH water (which is not currently being emitted by the active springs), and a Mg-CO3 water. Abundant dolomitic and calcitic carbonate cements are found in the creek drainages near the springs, associated with a diverse microbial community. We conducted a systematic study of the carbonate cements using SEM, EMP, XRD, TEM, and SIMS, focusing on sub-mm variations in texture, mineral chemistry and stable isotope (COH) composition. We compared our measurements with thermodynamic modeling results constrained by chemical analysis of water chemistry from the site and known partition coefficients and stable isotope fractionation factors. The wide range of carbonate compositions and textures observed at the Adobe Springs site suggests that more than one process is involved in their precipitation, including the possibility of microbially mediated dolomite mineralization. These carbonate cements could be a mineralogic biomarker of serpentinization and microbiological processes on Mars and other rocky planets and, therefore, prime targets for future astrobiological investigations.

  8. Ca-carbonate in the Orgueil (CI) carbonaceous chondrite: Mineralogy, microstructure and implications for parent body history

    Science.gov (United States)

    Lee, Martin R.; Nicholson, Kirsty

    2009-04-01

    The Orgueil CI carbonaceous chondrite is a breccia and some of its constituent clasts contain Ca-carbonate grains whose mineralogy is undetermined, but may yield new information on the history of its asteroidal or cometary parent body. Characterisation of one such clast shows that in addition to Ca-carbonate it contains magnetite, olivine and orthopyroxene grains that are supported within a finely crystalline saponite-serpentine-ferrihydrite groundmass. The Ca-carbonate grains are typically rounded, less than 10 μm in diameter, and backscatter Kikuchi patterns identify all those analysed as calcite. Electron backscatter diffraction orientation contrast maps show that most calcites have sub-μm sized e-twins, some of which are cut by corroded grain margins. These microstructures demonstrate that the clast experienced very mild shock during aqueous alteration and probably accompanying impact 'gardening' of the parent body regolith. The sample studied hosts several other millimeter sized clasts and a fine grained clastic matrix that are free of Ca-carbonate, olivine and orthopyroxene although can contain apatite, dolomite and pyrrhotite. Within one of these clasts is a network of phyllosilicate-magnetite veins that are inferred to have acted as fluid flow conduits during parent body aqueous alteration. Sulphur-rich reaction rims within the same clast are likely to have formed during post-fall remobilization and crystallization of pre-terrestrial sulphates. This study provides good evidence for alteration of the CI carbonaceous chondrites in a dynamic parent body regolith.

  9. Ca-carbonates precipitation and limestone genesis — the microbiogeologist point of view

    Science.gov (United States)

    Castanier, Sabine; Le Métayer-Levrel, Gaële; Perthuisot, Jean-Pierre

    1999-07-01

    and coalesce until forming a rigid coating and/or particles excreted from the cell. All these tiny particles assemble into biomineral aggregates which often display `precrystalline' structures. These aggregates grow and form biocrystalline build-ups which progressively display more crystalline structures with growth. In oligotrophic conditions, the primary solid products are rapidly smoothed in the crystalline structure and leave no trace. In present aqueous environments, apart from deep ocean, the potential efficiency of heterotrophic bacterial carbonatogenesis in Ca-carbonate sedimentation is much higher than autotrophic or abiotic processes. It much more likely accounts for extensive apparently abiotic limestone formation than any of the latter. As far as biodetrital particles are concerned, it may be observed that the shells and tests of organisms are built from the activity of cellular organites which are nowadays considered by a number of biologists as endosymbiotic bacteria. Thus, apart from (probably mythical) purely evaporitic and autotrophic ones, most limestones must be considered as principally of heterotrophic bacterial origin. As the carbon of limestones is issued from organic matter, bacterial heterotrophic carbonatogenesis appears as a fundamental phenomenon in the relationships between atmosphere and lithosphere during the biogeological evolution of the Earth.

  10. Inactivation of ca10a and ca10b Genes Leads to Abnormal Embryonic Development and Alters Movement Pattern in Zebrafish.

    Directory of Open Access Journals (Sweden)

    Ashok Aspatwar

    Full Text Available Carbonic anhydrase related proteins (CARPs X and XI are highly conserved across species and are predominantly expressed in neural tissues. The biological role of these proteins is still an enigma. Ray-finned fish have lost the CA11 gene, but instead possess two co-orthologs of CA10. We analyzed the expression pattern of zebrafish ca10a and ca10b genes during embryonic development and in different adult tissues, and studied 61 CARP X/XI-like sequences to evaluate their phylogenetic relationship. Sequence analysis of zebrafish ca10a and ca10b reveals strongly predicted signal peptides, N-glycosylation sites, and a potential disulfide, all of which are conserved, suggesting that all of CARP X and XI are secretory proteins and potentially dimeric. RT-qPCR showed that zebrafish ca10a and ca10b genes are expressed in the brain and several other tissues throughout the development of zebrafish. Antisense morpholino mediated knockdown of ca10a and ca10b showed developmental delay with a high rate of mortality in larvae. Zebrafish morphants showed curved body, pericardial edema, and abnormalities in the head and eye, and there was increased apoptotic cell death in the brain region. Swim pattern showed abnormal movement in morphant zebrafish larvae compared to the wild type larvae. The developmental phenotypes of the ca10a and ca10b morphants were confirmed by inactivating these genes with the CRISPR/Cas9 system. In conclusion, we introduce a novel zebrafish model to investigate the mechanisms of CARP Xa and CARP Xb functions. Our data indicate that CARP Xa and CARP Xb have important roles in zebrafish development and suppression of ca10a and ca10b expression in zebrafish larvae leads to a movement disorder.

  11. Carbon isotopes in mollusk shell carbonates

    Science.gov (United States)

    McConnaughey, Ted A.; Gillikin, David Paul

    2008-10-01

    Mollusk shells contain many isotopic clues about calcification physiology and environmental conditions at the time of shell formation. In this review, we use both published and unpublished data to discuss carbon isotopes in both bivalve and gastropod shell carbonates. Land snails construct their shells mainly from respired CO2, and shell δ13C reflects the local mix of C3 and C4 plants consumed. Shell δ13C is typically >10‰ heavier than diet, probably because respiratory gas exchange discards CO2, and retains the isotopically heavier HCO3 -. Respired CO2 contributes less to the shells of aquatic mollusks, because CO2/O2 ratios are usually higher in water than in air, leading to more replacement of respired CO2 by environmental CO2. Fluid exchange with the environment also brings additional dissolved inorganic carbon (DIC) into the calcification site. Shell δ13C is typically a few ‰ lower than ambient DIC, and often decreases with age. Shell δ13C retains clues about processes such as ecosystem metabolism and estuarine mixing. Ca2+ ATPase-based models of calcification physiology developed for corals and algae likely apply to mollusks, too, but lower pH and carbonic anhydrase at the calcification site probably suppress kinetic isotope effects. Carbon isotopes in biogenic carbonates are clearly complex, but cautious interpretation can provide a wealth of information, especially after vital effects are better understood.

  12. Simulation Experiments on the Reaction of CH4-CaSO4 and Its Carbon Kinetic Isotope Fractionation

    Institute of Scientific and Technical Information of China (English)

    YueChangtao; LiShuyuan; DingKangle; ZhongNingning

    2005-01-01

    Thermochemical sulfate reduction (TSR) in geological deposits can account for the accumulation of H,S in deep sour gas reservoirs. In this paper, thermal simulation experiments on the reaction of CH4-CaSO4 were carried out using an autoclave at high temperatures and high pressures. The products were characterized with analytical methods including carbon isotope analysis. It is found that the reaction can proceed to produce H2S, H2O and CaCO3 as the main products. Based on the experimental results, the carbon kinetic isotope fractionation was investigated, and the value of Ki(kinetic isotope effect) was calculated. The results obtained in this paper can provide useful information to explain the occurrence of H2S in deep carbonate gas reservoirs.

  13. Nitrate sorption on activated carbon modified with CaCl2: Equilibrium, isotherms and kinetics

    Directory of Open Access Journals (Sweden)

    Zanella Odivan

    2015-01-01

    Full Text Available In this study, nitrate (NO3- removal from aqueous solutions was investigated using granular activated carbon (GAC modified with CaCl2. Batch sorption studies were performed as a function of sorbent dose, initial nitrate concentration and pH. Sorption was maximized between pH 3 and 9. Studies on the effect of pH showed that the ion exchange mechanism might be involved in the sorption process. The percentage of nitrate removed increased with increasing sorbent concentration, and the ideal sorbent dose was found to be 20 g•L-1. Four isotherm models-Langmuir, Freundlich, Redlich-Peterson and Sips-were used to fit the experimental data. The Redlich-Peterson isotherm model explained the sorption process well and showed the best coefficient of determination (0.9979 and Chi-square test statistic (0.0079. Using the Sips isotherm model, the sorption capacity (qe was found to be 1.93 mg nitrate per g of sorbent. Kinetic experiments indicated that sorption was a fast process, reaching equilibrium within 120 min. The nitrate sorption kinetic data were successfully fitted to a pseudo-second-order kinetic model. The overall results demonstrated potential applications of modified GAC for nitrate removal from aqueous solutions.

  14. Ca isotope stratigraphy across the Cenomanian-Turonian OAE 2 : links between volcanism, seawater geochemistry, and the carbonate fractionation factor.

    OpenAIRE

    Du Vivier, Alice D. C.; Jacobson, Andrew D.; Lehn, Gregory O.; Selby, David; Hurtgen, Matthew T.; Sageman, Bradley B.

    2015-01-01

    The Ca isotope composition of marine carbonate rocks offers potential to reconstruct drivers of environmental change in the geologic past. This study reports new, high-precision Ca isotope records (View the MathML source; 2σSD=±0.04‰) for three sections spanning a major perturbation to the Cretaceous ocean-climate system known as Ocean Anoxic Event 2 (OAE 2): central Colorado, USA (Portland #1 core), southeastern France (Pont d'Issole), and Hokkaido, Japan (Oyubari, Yezo Group). In addition, ...

  15. Reduction-melting behaviors of boron-bearing iron concentrate/carbon composite pellets with addition of CaO

    Institute of Scientific and Technical Information of China (English)

    Jing-song Wang

    2015-01-01

    Although the total amount of boron resources in China is high, the grades of these resources are low. The authors have already proposed a new comprehensive utilization process of boron-bearing iron concentrate based on the iron nugget process. The present work de-scribes a further optimization of the conditions used in the previous study. The effects of CaO on the reduction–melting behavior and proper-ties of the boron-rich slag are presented. CaO improved the reduction of boron-bearing iron concentrate/carbon composite pellets when its content was less than 1wt%. Melting separation of the composite pellets became difficult with the CaO content increased. The sulfur content of the iron nugget gradually decreased from 0.16wt%to 0.046wt%as the CaO content of the pellets increased from 1wt%to 5wt%. CaO negatively affected the iron yield and boron extraction efficiency of the boron-rich slag. The mineral phase evolution of the boron-rich slag during the reduction–melting separation of the composite pellets with added CaO was also deduced.

  16. Ca-Rich Carbonate Melts: A Regular-Solution Model, with Applications to Carbonatite Magma + Vapor Equilibria and Carbonate Lavas on Venus

    Science.gov (United States)

    Treiman, Allan H.

    1995-01-01

    A thermochemical model of the activities of species in carbonate-rich melts would be useful in quantifying chemical equilibria between carbonatite magmas and vapors and in extrapolating liquidus equilibria to unexplored PTX. A regular-solution model of Ca-rich carbonate melts is developed here, using the fact that they are ionic liquids, and can be treated (to a first approximation) as interpenetrating regular solutions of cations and of anions. Thermochemical data on systems of alkali metal cations with carbonate and other anions are drawn from the literature; data on systems with alkaline earth (and other) cations and carbonate (and other) anions are derived here from liquidus phase equilibria. The model is validated in that all available data (at 1 kbar) are consistent with single values for the melting temperature and heat of fusion for calcite, and all liquidi are consistent with the liquids acting as regular solutions. At 1 kbar, the metastable congruent melting temperature of calcite (CaCO3) is inferred to be 1596 K, with (Delta)bar-H(sub fus)(calcite) = 31.5 +/- 1 kJ/mol. Regular solution interaction parameters (W) for Ca(2+) and alkali metal cations are in the range -3 to -12 kJ/sq mol; W for Ca(2+)-Ba(2+) is approximately -11 kJ/sq mol; W for Ca(2+)-Mg(2+) is approximately -40 kJ/sq mol, and W for Ca(2+)-La(3+) is approximately +85 kJ/sq mol. Solutions of carbonate and most anions (including OH(-), F(-), and SO4(2-)) are nearly ideal, with W between 0(ideal) and -2.5 kJ/sq mol. The interaction of carbonate and phosphate ions is strongly nonideal, which is consistent with the suggestion of carbonate-phosphate liquid immiscibility. Interaction of carbonate and sulfide ions is also nonideal and suggestive of carbonate-sulfide liquid immiscibility. Solution of H2O, for all but the most H2O-rich compositions, can be modeled as a disproportionation to hydronium (H3O(+)) and hydroxyl (OH(-)) ions with W for Ca(2+)-H3O(+) (approximately) equals 33 kJ/sq mol. The

  17. Impacts of CA9 gene polymorphisms on urothelial cell carcinoma susceptibility and clinicopathologic characteristics in Taiwan.

    Directory of Open Access Journals (Sweden)

    Shian-Shiang Wang

    Full Text Available BACKGROUND: Carbonic anhydrase 9 (CA9 is reportedly overexpressed in several types of carcinomas and is generally considered a marker of malignancy. The current study explored the effect of CA9 gene polymorphisms on the susceptibility of developing urothelial cell carcinoma (UCC and the clinicopathological status. METHODOLOGY AND PRINCIPAL FINDINGS: A total of 442 participants, including 221 healthy people and 221 patients with UCC, were recruited for this study. Four single-nucleotide polymorphisms (SNPs of the CA9 gene were assessed by a real-time PCR with the TaqMan assay. After adjusting for other co-variants, the individuals carrying at least one A allele at CA9 rs1048638 had a 2.303-fold risk of developing UCC than did wild-type (CC carriers. Furthermore, UCC patients who carried at least one A allele at rs1048638 had a higher invasive stage risk (p< 0.05 than did patients carrying the wild-type allele. Moreover, among the UCC patients with smoker, people with at least one A allele of CA9 polymorphisms (rs1048638 had a 4.75-fold (95% CI = 1.204-18.746 increased risk of invasive cancer. CONCLUSION: The rs1048638 polymorphic genotypes of CA9 might contribute to the prediction of susceptibility to and pathological development of UCC. This is the first study to provide insight into risk factors associated with CA9 variants in carcinogenesis of UCC in Taiwan.

  18. Influence of topical carbonic anhydrase inhibitor on the expression of aquaporin-1 in rat cornea with neovascularization%碳酸酐酶抑制剂的局部应用对大鼠角膜新生血管形成过程中水通道蛋白1表达的影响

    Institute of Scientific and Technical Information of China (English)

    张洁; 李立

    2011-01-01

    (t=2.48,P=0.02),2个组AQP1灰度值分别为88.01±11.03和58.10±12.14,差异有统计学意义(t=9.99,P=0.00).结论 布林佐胺滴眼液能抑制大鼠角膜碱烧伤后CNV形成过程中AQP1的高表达,从而间接影响VEGF的表达,抑制或延缓CNV的形成.%Background Researches showed that aquaporin-1 (AQP1) is closely associated with corneal neovescularization(CNV).Carbonic anhydrase inhibitor has the inhibitory effect on the AQP1 and further suppresses the CNV.However,the systemic adverse effect of Carbonic anhydrase inhibitor limit its clinical application.Therefore,the influence of topical carbonic anhydrase inhibitor on CNV is concerned.Objective Present study was to investigate the effects of topical carbonic anhydrase inhibitors on the expression of AQP1 in rat cornea after alkali burn and explore its role in corneal neovascularization (CNV).Methods The alkali-burn animal models were established in 60 eyes of 30 clean Sprague Dawley rats by putting the filter paper soaked 1 mol/L NaOH solution at the central cornea for 40 seconds.1% Brinzolamide was topically administered in the 30 eyes of 15 models (Brinzolamide group),and the normal saline solution was used at the same way in other 30 eyes of 15 rats (model group).The 10 eyes of 5 normal Sprague Dawley received the eye drops of normal saline solution as the normal control group.The corneal burning degree was graded on the Mahoney ' s criteria in the third day,and Ee ' s method was used to score the opacification of cornea and the CNV area was analyzed in 3,5,7,10 days under the slit lamp microscope.The cornea tissue was obtained in the tenth day after burning for the observation of the pathology under the light microscope and the ultrastructure under the transmission electron microscope.The expressions of AQP1 and vascular endothelial growth factor(VEGF) in cornea tissue were detected using immunohistochemistry.The use of animals complied with the Statement of ARVO.Results No significant

  19. 甘油果糖联合碳酸酐酶抑制剂对高眼压大鼠眼睫状体水通道蛋白1表达的影响%The influence of glyc-fructose combined with carbonic anhydrase inhibitor on the expression of AQP1 in rat eyes

    Institute of Scientific and Technical Information of China (English)

    盛毅; 金丽; 王进; 孙哲

    2015-01-01

    Objective To observe the effect of glyc-fructose combined with carbonic anhydrase inhibitor (CAI) on the expression of AQP 1 in rat eyes.Methods The model of intraocular hypertension in rats were established,and intervention on intraocular hypertension model rats were performed using glycerol fructose and carbonic anhydrase inhibitors.The expression of AQP 1 in the chamber angle tissue was detected in the mRNA and protein level.Results The expression of AQP 1 in the intraocular hypertension group (1,6,24,48 and 72 h) was significantly higher than those in the control group (1.55 ± 0.02,2.22±0.03,2.46 ±0.02,1.88 ±0.04,1.44±0.03; 1.21 ±0.02,3.58 ±0.03,3.81 ± 0.02,4.28 ± 0.04,4.44 ± 0.03,all P < 0.05).Carbonic anhydrase inhibitors could inhibit the expression of AQP 1 in the chamber angle tissue of the intraocular hypertension model rats (intraocular hypertension group vs.CAI group:1.41 ±0.02 vs.1.24 ±0.04; 4.41 ±0.02 vs.2.31 ± 0.04,all P < 0.05).The combined use of glyc-fructose with CAI could inhibit the expression more obviously(intraocular hypertension group vs.Glyc-fructose combined with CAI group:1.41 ± 0.02 vs.1.08±0.03; 4.41 ±0.02 vs.1.47 ±0.03,all P <0.05).Conclusion The expression of AQP1 was elevated in the intraocular hypertension group,and co-administrated with glycerol fructose and brinzolamide could inhibit the expression.%目的 观察联合应用甘油果糖和碳酸酐酶抑制剂对急性高眼压大鼠眼组织水通道蛋白1(AQP1)表达的影响.方法 建立高眼压大鼠模型,并使用甘油果糖和碳酸酐酶抑制剂对高眼压大鼠模型鼠进行干预,检测房角组织AQP1的基因及蛋白表达水平.结果 高眼压大鼠房角组织AQP1的基因和蛋白表达水平(造模后1、6、24、48、72 h:1.55±0.02、2.22±0.03、2.46±0.02、1.88±0.04、1.44±0.03;1.21±0.02、3.58±0.03、3.81±0.02、4.28±0.04、4.44±0.03)均显著高于对照组(1.00±0.00、1.00±0.00,P均<0.05).碳酸酐酶抑制剂

  20. In vitro formation of Ca-oxalates and the mineral glushinskite by fungal interaction with carbonate substrates and seawater

    Directory of Open Access Journals (Sweden)

    K. Kolo

    2005-01-01

    Full Text Available This study investigates the in vitro formation of Ca-oxalates and glushinskite through fungal interaction with carbonate substrates and seawater as a process of biologically induced metal recycling and neo-mineral formation. The study also emphasizes the role of the substrates as metal donors. In the first experiment, thin sections prepared from dolomitic rock samples of Terwagne Formation (Carboniferous, Viséan, northern France served as substrates. The thin sections placed in Petri dishes were exposed to fungi grown from naturally existing airborne spores. In the second experiment, fungal growth and mineral formation was monitored using only standard seawater (SSW as a substrate. Fungal growth media consisted of a high protein/carbohydrates and sugar diet with demineralized water for irrigation. Fungal growth process reached completion under uncontrolled laboratory conditions. The newly formed minerals and textural changes caused by fungal attack on the carbonate substrates were investigated using light and scanning electron microscopy (SEM-EDX, x-ray diffraction (XRD and Raman spectroscopy. The fungal interaction and attack on the dolomitic and seawater substrates resulted in the formation of Ca-oxalates (weddellite CaC2O4·2(H2O, whewellite (CaC2O4·(H2O and glushinskite MgC2O4·2(H2O associated with the destruction of the original hard substrates and their replacement by the new minerals. Both of Ca and Mg were mobilized from the experimental substrates by fungi. This metal mobilization involved a recycling of substrate metals into newly formed minerals. The biochemical and diagenetic results of the interaction strongly marked the attacked substrates with a biological fingerprint. Such fingerprints are biomarkers of primitive life. The formation of glushinskite is of specific importance that is related, besides its importance as a biomineral bearing a recycled Mg, to the possibility of its transformation through diagenetic pathway into an

  1. Simultaneous EDS and EELS studies on carbon in CuBa2Ca3Cu4Ox superconductors

    International Nuclear Information System (INIS)

    Carbon contamination in Cu-1234 superconductors was studied using an electron-energy-loss spectroscope which was attached to a field emission electron microscope. The carbon K-edge was detected only when an electron beam of a diameter as small as 1 nm successfully incidented the charge reservoir block in a unit cell. On the other hand, the signal level of the carbon K-edge from the 'infinite layer' block consisting of CuO2 planes and bare Ca planes was very low. This implied that C atoms were present in the charge reservoir blocks which contained Cu. Upon annealing the sample in a reducing atmosphere of 1 atm, it was found that the high-pressure (Cu,C)-1234 phase was stable up to a temperature as high as 500 C and Tc remained constant up until phase decomposition occurred. (orig.)

  2. Extracellular H+ induces Ca2+ signals in respiratory chemoreceptors of zebrafish.

    Science.gov (United States)

    Abdallah, Sara J; Jonz, Michael G; Perry, Steve F

    2015-02-01

    Neuroepithelial cells (NECs) of the fish gill are respiratory chemoreceptors that detect changes in O2 and CO2/H(+) and are homologous to type I cells of the mammalian carotid body. In zebrafish (Danio rerio), stimulation of NECs by hypoxia or hypercapnia initiates inhibition of K(+) channels and subsequent membrane depolarisation. The goal of the present study was to further elucidate, in zebrafish NECs, the signalling pathways that underlie CO2/H(+) sensing and generate intracellular Ca(2+) ([Ca(2+)]i) signals. Breathing frequency was elevated maximally in fish exposed to 5 % CO2 (~37.5 mmHg). Measurement of [Ca(2+)]i in isolated NECs using Fura-2 imaging indicated that [Ca(2+)]i increased in response to acidic hypercapnia (5 % CO2, pH 6.6) and isocapnic acidosis (normocapnia, pH 6.6), but not to isohydric hypercapnia (5 % CO2, pH 7.6). Measurement of intracellular pH (pHi) using BCECF demonstrated a rapid decrease in pHi in response to acidic and isohydric hypercapnia, while isocapnic acidosis produced a smaller change in pHi. Intracellular acidification was reduced by the carbonic anhydrase inhibitor, acetazolamide, without affecting [Ca(2+)]i responses. Moreover, intracellular acidification using acetate (at constant extracellular pH) was without effect on [Ca(2+)]i. The acid-induced increase in [Ca(2+)]i persisted in the absence of extracellular Ca(2+) and was unaffected by Ca(2+) channel blockers (Cd(2+), Ni(2+) or nifedipine). The results of this study demonstrate that, unlike type I cells, extracellular H(+) is critical to the hypercapnia-induced increase in [Ca(2+)]i in NECs. The increase in [Ca(2+)]i occurs independently of pHi and appears to originate primarily from Ca(2+) derived from intracellular stores.

  3. Self-reactivated mesostructured Ca-Al-O composite for enhanced high-temperature CO2 capture and carbonation/calcination cycles performance.

    Science.gov (United States)

    Chang, Po-Hsueh; Huang, Wei-Chen; Lee, Tai-Jung; Chang, Yen-Po; Chen, San-Yuan

    2015-03-25

    In this study, highly efficient high-temperature CO2 sorbents of calcium aluminate (Ca-Al-O) mesostructured composite were synthesized using presynthesized mesoporous alumina (MA) as a porous matrix to react with calcium nitrate through a microwave-assisted process. Upon annealing at 600 °C, a highly stable mesoporous structure composed of poorly crystalline Ca12Al14O33 phase and the CaO matrix was obtained. The Ca-Al-O mesostructured sorbents with a Ca(2+)/Al(3+) ratio of 5:1 exhibit an enhanced increasing CO2 absorption kinetics in the CO2 capture capacity from 37.2 wt % to 48.3 wt % without apparent degradation with increasing carbonation/calcination cycling up to 50 at 700 °C due to the strong self-reactivation effect of the mesoporous Ca-Al-O microstructure. Remarkable improvements in the CaO-CaCO3 conversion attained from the mesostructured Ca-Al-O composite can be explained using the concept combined with available mesoporous structure and Ca12Al14O33 phase content. However, a high Ca(2+)/Al(3+) =8:1 Ca-Al-O composite causes degradation because the pores become blocked and partial sintering induces CaO agglomeration. PMID:25730384

  4. Genomic and physiological analysis of carbon storage in the verrucomicrobial methanotroph "Ca. Methylacidiphilum fumariolicum" SolV

    Directory of Open Access Journals (Sweden)

    Ahmad Fouad eKhadem

    2012-09-01

    Full Text Available Candidatus Methylacidiphilum fumariolicum SolV is a verrucomicrobial methanotroph that can grow in extremely acidic environments at high temperature. Strain SolV fixes carbon dioxide (CO2 via the Calvin-Benson-Bassham cycle with methane as energy source, a trait so far very unusual in methanotrophs. In this study, the ability of Ca. M. fumariolicum to store carbon was explored by genome analysis, physiological studies and electron microscopy. When cell cultures were depleted for nitrogen, glycogen storage was clearly observed in cytoplasmic storage vesicles by electron microscopy. After cessation of growth, the dry weight kept increasing and the bacteria were filled up almost entirely by glycogen. This was confirmed by biochemical analysis, which showed that glycogen accumulated to 36% of the total dry weight of the cells. When methane was removed from the culture, this glycogen was consumed within 47 days. During the period of glycogen consumption, the bacteria kept their viability high when compared to bacteria without glycogen (from cultures growing exponentially. The latter bacteria lost viability already after a few days when starved for methane. Analysis of the draft genome of Ca. M. fumariolicum SolV demonstrated that all known genes for glycogen storage and degradation were present and also transcribed. Phylogenetic analysis of these genes showed that they form a separate cluster with Ca. M. infernorum V4, and the most closely related other sequences only have an identity of 40%. This study presents the first physiological evidence of glycogen storage in the phylum Verrucomicrobia and indicates that carbon storage is important for survival at times of methane starvation.

  5. A Phanerozoic I/Ca compilation: potential links to ocean oxygenation, carbon cycle and bio-diversification

    Science.gov (United States)

    Lu, Z.; Zhou, X.; Algeo, T. J.; Saltzman, M.; Thomas, E.; Jenkyns, H. C.; Rickaby, R. E. M.; Whalen, M. T.; Gutchess, K. M.; Hardisty, D. S.; Lyons, T.

    2015-12-01

    Dissolved iodine in seawater is present as two chemical species: iodide or iodate in anoxic and oxygenated environments, respectively. Because only iodate can be incorporated into the carbonate structure, I/Ca values in marine carbonate and fossils potentially record seawater iodate concentrations. I/Ca has been used as a paleo-proxy for ocean oxygenation across different time scales, ranging from glacial-interglacial cycles to the abrupt warming and/or oceanic anoxic events of the Meso- and Cenozoic to long-term redox evolution during the Precambrian. Here we present a compilation of new and published I/Ca data for the Phanerozoic Eon showing a major increase of I/Ca at about 200 Ma, close to the Triassic-Jurassic boundary. This major change post-dates the rise of other paleo-oxygenation indicators, specifically increasing Mo-isotope compositions during the Devonian (Dahl et al., 2010) and the modeled increase in seawater sulfate concentrations in Carboniferous-Permian (Algeo et al., 2015). I/Ca is more sensitive to the level of dissolved O2 because the redox potential of iodate closely resembles that of O2. By contrast, Mo and S proxies are sensitive to more strongly reducing conditions, specifically the global distribution euxinia in the oceans. The increase of I/Ca in our compilation may indicate that the volume of oxygenated seawater expanded globally to near-modern levels around 200 Ma, which is also the time pelagic calcifiers proliferated (Zeebe and Westbroek, 2003). These planktonic organisms might have shifted the O2 consumption pattern and nutrient cycle, leading to the final oxygenation of ocean interiors. Fundamental changes in global cycling of redox sensitive elements (Mo, S, I) also coincide with diversification of marine invertebrates (Alroy et al., 2008). These observations highlight that stepwise oxygenation of global oceans and the co-evolution of life may have been a protracted process spanning two-thirds of the Phanerozoic. References: Algeo

  6. Synthesis of CaCO3 nanoparticles by carbonation of lime solutions in reverse micellar systems

    NARCIS (Netherlands)

    Heeres, H.J.; Jain, R.; Mehra, A.; Dagaonkar, M.V.

    2004-01-01

    Application of reverse micelles for the synthesis of nano-sized calcium carbonate particles in different solvents (cyclohexane, decane and heptane) has been investigated. The effect of the mole ratio of water-to-surfactant (R) and type of solvent has been studied on the size and nature of the carbon

  7. CaCO3 nanoparticle synthesis by carbonation of lime solution in microemulsion systems

    NARCIS (Netherlands)

    Sugih, A.K.; Shukla, D.; Heeres, H.J.; Mehra, A.

    2007-01-01

    Various aspects of nanoparticle precipitation in gas-reverse micellar systems have been studied. The experimental system chosen for investigation deals with the precipitation of CaCO3 nanoparticles. The effect of operating variables, such as water-to-surfactant molar ratio, different continuous phas

  8. A Fe-C-Ca big cycle in modern carbon-intensive industries: toward emission reduction and resource utilization

    Science.gov (United States)

    Sun, Yongqi; Sridhar, Seetharaman; Seetharaman, Seshadri; Wang, Hao; Liu, Lili; Wang, Xidong; Zhang, Zuotai

    2016-01-01

    Herein a big Fe-C-Ca cycle, clarifying the basic element flows and energy flows in modern carbon-intensive industries including the metallurgical industry and the cement industry, was proposed for the first time in the contexts of emission reduction and iron ore degradation nowadays. This big cycle was focused on three industrial elements of Fe, C and Ca and thus it mainly comprised three interdependent loops, i.e., a C-cycle, a Fe-cycle and a Ca-path. As exemplified, we started from the integrated disposal of hot steel slags, a man-made iron resource via char gasification and the employment of hematite, a natural iron resource greatly extended the application area of this idea. Accordingly, based on this concept, the theoretical potentials for energy saving, emission reduction and Fe resource recovery achieved in modern industry are estimated up to 7.66 Mt of standard coal, 63.9 Mt of CO2 and 25.2 Mt of pig iron, respectively. PMID:26923104

  9. A Fe-C-Ca big cycle in modern carbon-intensive industries: toward emission reduction and resource utilization

    Science.gov (United States)

    Sun, Yongqi; Sridhar, Seetharaman; Seetharaman, Seshadri; Wang, Hao; Liu, Lili; Wang, Xidong; Zhang, Zuotai

    2016-02-01

    Herein a big Fe-C-Ca cycle, clarifying the basic element flows and energy flows in modern carbon-intensive industries including the metallurgical industry and the cement industry, was proposed for the first time in the contexts of emission reduction and iron ore degradation nowadays. This big cycle was focused on three industrial elements of Fe, C and Ca and thus it mainly comprised three interdependent loops, i.e., a C-cycle, a Fe-cycle and a Ca-path. As exemplified, we started from the integrated disposal of hot steel slags, a man-made iron resource via char gasification and the employment of hematite, a natural iron resource greatly extended the application area of this idea. Accordingly, based on this concept, the theoretical potentials for energy saving, emission reduction and Fe resource recovery achieved in modern industry are estimated up to 7.66 Mt of standard coal, 63.9 Mt of CO2 and 25.2 Mt of pig iron, respectively.

  10. Inorganic carbon acquisition in red tide dinoflagellates.

    Science.gov (United States)

    Rost, Björn; Richter, Klaus-Uwe; Riebesell, Ulf; Hansen, Per Juel

    2006-05-01

    Carbon acquisition was investigated in three marine bloom-forming dinollagellates-Prorocentrum minimum, Heterocapsa triquetra and Ceratium lineatum. In vivo activities of extracellular and intracellular carbonic anhydrase (CA), photosynthetic O2 evolution, CO2 and HCO3- uptake rates were measured by membrane inlet mass spectrometry (MIMS) in cells acclimated to low pH (8.0) and high pH (8.5 or 9.1). A second approach used short-term 14C-disequilibrium incubations to estimate the carbon source utilized by the cells. All three species showed negligible extracellular CA (eCA) activity in cells acclimated to low pH and only slightly higher activity when acclimated to high pH. Intracellular CA (iCA) activity was present in all three species, but it increased only in P. minimum with increasing pH. Half-saturation concentrations (K1/2) for photosynthetic O2 evolution were low compared to ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) kinetics. Moreover, apparent affinities for inorganic carbon (Ci) increased with increasing pH in the acclimation, indicating the operation of an efficient CO2 concentration mechanism (CCM) in these dinoflagellates. Rates of CO2 uptake were comparably low and could not support the observed rates of photosynthesis. Consequently, rates of HCO3- uptake were high in the investigated species, contributing more than 80% of the photosynthetic carbon fixation. The affinity for HCO3- and maximum uptake rates increased under higher pH. The strong preference for HCO3- was also confirmed by the 14C-disequilibrium technique. Modes of carbon acquisition were consistent with the 13C-fractionation pattern observed and indicated a strong species-specific difference in leakage. These results suggest that photosynthesis in marine dinoflagellates is not limited by Ci even at high pH, which may occur during red tides in coastal waters. PMID:17087465

  11. Calcium isotope constraints on the marine carbon cycle and CaCO3 deposition during the late Silurian (Ludfordian) positive δ13C excursion

    Science.gov (United States)

    Farkaš, Juraj; Frýda, Jiří; Holmden, Chris

    2016-10-01

    This study investigates calcium isotope variations (δ 44 / 40 Ca) in late Silurian marine carbonates deposited in the Prague Basin (Czech Republic), which records one of the largest positive carbon isotope excursion (CIE) of the entire Phanerozoic, the mid-Ludfordian CIE, which is associated with major climatic changes (abrupt cooling) and global sea-level fluctuations. Our results show that during the onset of the CIE, when δ13 C increases rapidly from ∼0‰ to ∼8.5‰, δ 44 / 40Ca remains constant at about 0.3 ± 0.1 ‰ (relative to NIST 915a), while 87Sr/86Sr in well-preserved carbonates are consistent with a typical Ludfordian seawater composition (ranging from ∼0.70865 to ∼0.70875). Such decoupling between δ13 C and δ 44 / 40Ca trends during the onset of the CIE is consistent with the expected order-of-magnitude difference in the residence times of Ca (∼106yr) and C (∼105yr) in the open ocean, suggesting that the mid-Ludfordian CIE was caused by processes where the biogeochemical pathways of C and Ca in seawater were mechanistically decoupled. These processes may include: (i) near shore methanogenesis and photosynthesis, (ii) changes in oceanic circulation and stratification, and/or (iii) increased production and burial of organic C in the global ocean. The latter, however, is unlikely due to the lack of geological evidence for enhanced organic C burial, and also because of unrealistic parameterization of the ocean C cycle needed to generate the observed CIE over the relatively short time interval. In contrast, higher up in the section where δ13 C shifts back to pre-excursion baseline values, there is a correlated shift to higher δ 44 / 40Ca values. Such coupling of the records of Ca and C isotope changes in this part of the study section is inconsistent with the abovementioned differences in oceanic Ca and C residence times, indicating that the record of δ 44 / 40Ca changes does not faithfully reflect the evolution of the oceanic Ca

  12. Ternary Ca-Fe-Mg carbonates: subsolidus phase relations at 3.5 GPa and a thermodynamic solid solution model including order/disorder

    Science.gov (United States)

    Franzolin, E.; Schmidt, M. W.; Poli, S.

    2011-02-01

    Subduction carries atmospheric and crustal carbon hosted in the altered oceanic crystalline basement and in pelagic sediments back into the mantle. Reactions involving complex carbonate solid solutions(s) lead to the transfer of carbon into the mantle, where it may be stored as graphite/diamond, in fluids or melts, or in carbonates. To constrain the thermodynamics and thus reactions of the ternary Ca-Mg-Fe carbonate solid solution, piston cylinder experiments have been performed in the system CaCO3-MgCO3-FeCO3 at a pressure of 3.5 GPa and temperatures of 900-1,100°C. At 900°C, the system has two miscibility gaps: the solvus dolomite-calcite, which closes at X MgCO3 ~0.7, and the solvus dolomite-magnesite, which ranges from the Mg to the Fe side of the ternary. With increasing temperature, the two miscibility gaps become narrower until complete solid solutions between CaCO3-Ca0.5Mg0.5CO3 is reached at 1,100°C and between CaCO3-FeCO3 at 1,000°C. The solvi are characterized by strong compositional asymmetry and by an order-disorder mechanism. To deal with these features, a solid solution model based on the van Laar macroscopic formalism has been calculated for ternary carbonates. This thermodynamic solid solution model is able to reproduce the experimentally constrained phase relations in the system CaCO3-MgCO3-FeCO3 in a broad P-T range. To test our model, calculated phase equilibria were compared with experiments performed in carbonated mafic protolithes, demonstrating the reliability of our solid solution model at pressures up to 6 GPa in complex systems.

  13. Effects of denervation on expression of carbonic anhydrase Ⅲ and its phosphatase activity in skeletal muscle of rats%去神经对大鼠骨骼肌碳酸酐酶Ⅲ表达和磷酸酶活性的影响

    Institute of Scientific and Technical Information of China (English)

    黄河; 任惠民

    2011-01-01

    目的 观察去神经对骨骼肌碳酸酐酶Ⅲ(carbonic anhydrase Ⅲ,CAⅢ)表达及其磷酸酶(phosphatase)活性的影响,探讨神经冲动受阻是否为重症肌无力(myasthenia gravis,MG)骨骼肌CAⅢ减少的原因.方法 定向切断支配大鼠趾长伸肌(extensor digitorum longus,EDL)和比目鱼肌(soleus,Sol)的神经纤维,术后第7、14、28和56天用Western blot分析EDL和Sol的CAⅢ水平,用固相膜上原位酶活性染色方法评估CAⅢ的磷酸酶活性.结果 (1)正常侧(即去神经对侧)Sol的CAⅢ水平远高于EDL,并且两者都表现出随时间增加(动物年龄增长)而增加的趋势.去神经后,EDL的CAⅢ水平随时间的延长而逐渐增加;Sol的CAⅢ水平则以14 d为分界先增加后降低.(2)正常侧Sol的CAⅢ的磷酸酶活性[随时间增加(动物年龄增长)呈逐渐增加的趋势]均高于EDL(变化不明显).去神经后,Sol的CAⅢ磷酸酶活性(第14、28、56天分别为14.39±1.93、11.48±1.46、9.04±1.46)明显低于正常侧(22.75±1.80、25.26±3.15、25.82±2.97,t=0.002、0.005、0.002,均P<0.05),EDL的CAⅢ磷酸酶活性与正常侧相比亦是降低,但差异无统计学意义.(3)正常侧EDL和Sol的CAⅢ蛋白表达水平和CAⅢ的磷酸酶活性相一致;去神经后CAⅢ蛋白表达水平和CAⅢ的磷酸酶活性发生了背离,即CAⅢ蛋白表达水平增加,但其磷酸酶活性却降低.结论 去神经所致的神经冲动传递障碍与MG自身抗体所致的神经冲动传递障碍对骨骼肌CAⅢ表达水平的影响不同,MG骨骼肌CAⅢ表达水平减少并非是其自身抗体所致的神经冲动传递障碍造成.%Objective To observe the effects of nerve impulses on the expression of carbonic anhydrase Ⅲ ( CAⅢ ) and its phosphatase activity, and to explore whether or not the cause of CAⅢ expressive decreased in skeletal muscles of myasthenia gravis( MG) is resulted from the obstruction of nerve impulse.Methods The motor nerves of extensor digitorum

  14. Malaria parasite carbonic anhydrase:inhibition of aromatic/heterocyclic sulfonamides and its therapeutic potential

    Institute of Scientific and Technical Information of China (English)

    Sudaratana R Krungkrai; Jerapan Krungkrai

    2011-01-01

    Plasmodium falciparum (P. falciparum) is responsible for the majority of life-threatening cases of human malaria, causing 1.5-2.7 million annual deaths. The global emergence of drug-resistant malaria parasites necessitates identification and characterization of novel drug targets and their potential inhibitors. We identified the carbonic anhydrase (CA) genes in P. falciparum. The pfCA gene encodes an α-carbonic anhydrase, a Zn 2+-metalloenzme, possessing catalytic properties distinct from that of the human host CA enzyme. The amino acid sequence of the pfCA enzyme is different from the analogous protozoan and human enzymes. A library of aromatic/heterocyclic sulfonamides possessing a large diversity of scaffolds were found to be very good inhibitors for the malarial enzyme at moderate-low micromolar and submicromolar inhibitions. The structure of the groups substituting the aromatic-ureido- or aromatic-azomethine fragment of the molecule and the length of the parent sulfonamide were critical parameters for the inhibitory properties of the sulfonamides. One derivative, that is, 4- (3, 4-dichlorophenylureido)thioureido-benzenesulfonamide (compound 10) was the most effective in vitro Plasmodium falciparum CA inhibitor, and was also the most effective antimalarial compound on the in vitro P. falciparum growth inhibition. The compound 10 was also effective in vivo antimalarial agent in mice infected with Plasmodium berghei, an animal model of drug testing for human malaria infection. It is therefore concluded that the sulphonamide inhibitors targeting the parasite CA may have potential for the development of novel therapies against human malaria.

  15. Melting Relations of Multicomponent Carbonate System MgCO3 - FeCO3- CaCO3- Na2CO3 at 12-23 GPa

    Science.gov (United States)

    Spivak, Anna; Solopova, Natalia; Litvin, Yuriy; Dubrovinsky, Leonid; Zakharchenko, Egor

    2014-05-01

    Considerable attention is focused on high-pressure high-temperature experimental study of melting phase relations of carbonates which were involved into a 'super-deep' diamond genesis. High-pressure stability of carbonate melts and their role in 'ultra-deep' diamonds genesis are most essential. Experimental study of melting relations of multicomponent carbonate system was carried out using multi-anvil press at the pressures 12 - 23 GPa and temperatures 800 to 1650 oC. Chemical compositions of starting carbonate system used for melting experiment were prepared by mixing: FeCO3 - 26,00; MgCO3- 26,00; CaCO3 - 25,00; Na2CO3 - 23,00 wt %. A region of partial melting for the system is experimentally determined. The partial melting field is arranged between low-temperature boundary of eutectics melting (solidus line) of the multicomponent carbonate and the boundary of complete melting (liquidus line) at higher temperature. From experimental observations, a Mg-Fe carbonate solid solution is the liquidus phase. At temperature lowering, the assemblage (Mg,Fe)CO3 + (Ca,Na2,Fe)CO3 + L (liquid) is formed. Then, the invariant eutectic assemblage (Mg,Fe)CO3 + (Ca,Na2,Fe)CO3 + Na2(Ca,Fe)(CO3)2+ L (liquid) which is determining for subsolidus assemblage (Mg,Fe)CO3 + (Ca,Na2,Fe)CO3 + Na2(Ca,Fe)(CO3)2 is formed. Next to liquidus line is one-phase field of completely miscible multicomponent carbonate melt. On the whole, the results demonstrate phase relations of solid carbonates and multicomponent carbonate liquid in the immediate vicinity to the low-temperature melting boundary. The early melting of the multicomponent carbonate system is compatible with the lower mantle geothermal conditions because the primary melting temperatures are noticeably below than the geothermal values. It is significant that multicomponent carbonate melts are stable and completely miscible under conditions as partial so complete melting. Thus, high-pressure high-temperature experimental data demonstrate

  16. Effects of Inclusions in HSLA Carbon Steel on Pitting Corrosion in CaCl2

    Energy Technology Data Exchange (ETDEWEB)

    M. Ziomek-Moroz; S. Bullard; K. Rozman; J.J. Kruzic

    2011-12-05

    Susceptibility of high strength low alloy steel to localized corrosion was studied in 6.7 M CaCl{sub 2} for oil and natural gas drilling applications. Results of the immersion and electrochemical experiments showed that the steel is susceptible to pitting corrosion. Optical microscopy investigations of the polished samples revealed that 10% of the surface area was occupied by defects in the form of pits. The energy dispersive X-ray (EDX) and wavelength dispersive X-ray (WDX) chemical analyses revealed higher concentrations of Mn and S compared to the metal matrix in defected areas. These areas served as the sites for development of corrosion pits during both immersion and electrochemical experiments. The fatigue results of the corroded samples indicate that if the pit was the most significant defect, the fatigue crack initiated and propagated at this site.

  17. Is my C isotope excursion global, local, or both? Insights from the Mg and Ca isotopic composition of primary, diagenetic, and authigenic carbonates

    Science.gov (United States)

    Higgins, J. A.; Blättler, C. L.; Husson, J. M.

    2014-12-01

    The C isotopic composition of ancient limestones and dolomites is a widely used proxy for the global geochemical cycles of carbon and oxygen in the ocean-atmosphere system and a critical tool for chemostratigraphy in Precambrian rocks. Although relatively robust to diagenesis, the C isotopic composition of bulk carbonates can be reset when conditions favor high water-to-rock ratios or fluids with high C concentrations and distinct isotopic compositions. Authigenic carbonates and different pools of primary carbonate (e.g. calcite vs. aragonite) may also bias the C isotopic composition of bulk carbonates if they are both abundant and isotopically distinct. New approaches to quantifying contributions from diagenesis, authigenesis, and mixing of primary carbonates to the C isotopic composition of bulk sedimentary carbonates are needed. Here we present preliminary Mg and Ca isotope data sets of primary, diagenetic, and authigenic carbonates, both modern and ancient. We show that recrystallization, dolomitization, and authigenesis produce Mg and Ca isotope fingerprints that may be used to identify and characterize these processes in ancient carbonate sediments.

  18. Environmental vs microbial control on ca-carbonate precipitation in fluvial tufa (NW Calabria-Italy)

    Science.gov (United States)

    Manzo, E.; Perri, E.; Tucker, M. E.

    2009-04-01

    Modern freshwater calcium carbonate (tufa) forms in the Parmenta stream, a tributary of the Corvino River, along the west coast of Northern Calabria. The stream flows in a narrow steep-sided wooded valley, receiving three ephemeral tributaries and draining Mesozoic carbonate succession. Tufa deposits vary along the stream length (about 3 Km) occurring scattered up-stream and almost continuously down-stream for at least 1 Km. At the confluence with the Corvino river carbonate deposits end. The tufa deposits belong to the barrage model that includes waterfalls, dams and pools. Pools vary in length and in width from a few decimetres to 5 metres. Carbonate deposits are absent on the larger pool floor, where sand to gravel sediment accumulates. Dams occur as sinuous to irregular barriers usually spanning the channel. An up-stream ramp of the dam is generally steeply inclined, and characterized by an irregular surface covered in partially calcified leaves and wood fragments. The rear wall height for the mature dams ranges between 10-30 cm. In contrast, the down-stream ramp, after a smoothed surface passes to tongue-shaped lobes. Lobes form normally 20-60 cm width deposits, even if there are also meters-size tongues, with a steep slope, occurring in correspondence of the major waterfalls. The downstream surface of dams and the upper surface of the tongue-shaped tufa deposits are colonized by a soft, 1-4 mm thick, biofilm. It consists of an epilithic and partially endolithic community composed mainly of oscillatoriacean cyanobacteria (Phormidium sp.), diatoms, fungi and insect larvae. Carbonate precipitates on the upstream wall of the dams lack a biofilm. Tufas are basically of two main types, essentially distinguish on their internal fabric in laminated-stromatolitic tufas and vacuolar tufas. Both facies are mainly composed of low-Mg calcite with Mg 1-4 mole % and Sr 0,8-1,2 mole %. Stromatolitic tufas form centimetric beds on the external surface of the tongue

  19. Environmental vs microbial control on ca-carbonate precipitation in fluvial tufa (NW Calabria-Italy)

    Science.gov (United States)

    Manzo, E.; Perri, E.; Tucker, M. E.

    2009-04-01

    Modern freshwater calcium carbonate (tufa) forms in the Parmenta stream, a tributary of the Corvino River, along the west coast of Northern Calabria. The stream flows in a narrow steep-sided wooded valley, receiving three ephemeral tributaries and draining Mesozoic carbonate succession. Tufa deposits vary along the stream length (about 3 Km) occurring scattered up-stream and almost continuously down-stream for at least 1 Km. At the confluence with the Corvino river carbonate deposits end. The tufa deposits belong to the barrage model that includes waterfalls, dams and pools. Pools vary in length and in width from a few decimetres to 5 metres. Carbonate deposits are absent on the larger pool floor, where sand to gravel sediment accumulates. Dams occur as sinuous to irregular barriers usually spanning the channel. An up-stream ramp of the dam is generally steeply inclined, and characterized by an irregular surface covered in partially calcified leaves and wood fragments. The rear wall height for the mature dams ranges between 10-30 cm. In contrast, the down-stream ramp, after a smoothed surface passes to tongue-shaped lobes. Lobes form normally 20-60 cm width deposits, even if there are also meters-size tongues, with a steep slope, occurring in correspondence of the major waterfalls. The downstream surface of dams and the upper surface of the tongue-shaped tufa deposits are colonized by a soft, 1-4 mm thick, biofilm. It consists of an epilithic and partially endolithic community composed mainly of oscillatoriacean cyanobacteria (Phormidium sp.), diatoms, fungi and insect larvae. Carbonate precipitates on the upstream wall of the dams lack a biofilm. Tufas are basically of two main types, essentially distinguish on their internal fabric in laminated-stromatolitic tufas and vacuolar tufas. Both facies are mainly composed of low-Mg calcite with Mg 1-4 mole % and Sr 0,8-1,2 mole %. Stromatolitic tufas form centimetric beds on the external surface of the tongue

  20. A sulphonated carbon dot-chitosan hybrid hydrogel nanocomposite as an efficient ion-exchange film for Ca2+ and Mg2+ removal

    Science.gov (United States)

    Baruah, Upama; Konwar, Achyut; Chowdhury, Devasish

    2016-04-01

    We have developed a hybrid hydrogel nanocomposite film via conjugation of oxidised carbon dots synthesized from 11-mercaptoundecanoic acid with chitosan. The potential applicability of the film was then successfully tested for the removal of Ca2+ and Mg2+ ions from solution.We have developed a hybrid hydrogel nanocomposite film via conjugation of oxidised carbon dots synthesized from 11-mercaptoundecanoic acid with chitosan. The potential applicability of the film was then successfully tested for the removal of Ca2+ and Mg2+ ions from solution. Electronic supplementary information (ESI) available: The ESI includes the detailed synthesis and characterization of carbon dots both before and after oxidation and of the carbon dot-chitosan nanocomposite films viz. DLS, SEM, UV-visible, FTIR, PL spectroscopy and TGA. See DOI: 10.1039/c6nr01129b

  1. Self–activation and effect of regeneration conditions in CO2 – carbonate looping with CaO - Ca12Al14O33 sorbent

    OpenAIRE

    STENDARDO Stefano; Andersen, Lars; HERCE C

    2012-01-01

    CO2 capture by solid sorbents through uptake–regeneration cycling is a promising option for high temperature removal of CO2 from combustion gases and synthesis/fuel gases. The present study investigates the influence of regeneration atmosphere and temperature on the CO2 uptake capacity during repeated cycling of CaO–based solid sorbents. The sorbents were synthesised to contain 75 and 85 %w/w of active phase (CaO) and binder (Ca12Al14O33) and were then subjected to cycling tests with repeate...

  2. A new nonlinear optical silicate carbonate K2Ca[Si2O5](CO3) with a hybrid structure of kalsilite and soda-like layered fragments

    Science.gov (United States)

    Belokoneva, Elena L.; Stefanovich, Sergey Yu.; Volkov, Anatoly S.; Dimitrova, Olga V.

    2016-10-01

    Single crystals of a new silicate carbonate, K2Ca[Si2O5](CO3), have been synthesized in a multi-components hydrothermal solution with a pH value close to neutral and a high concentration of a carbonate mineralizer. The new compound has an axial structure (s.g. P6322) with unit cell parameters a = 5.04789 (15), c = 17.8668 (6) Å. Pseudosymmetry of the structure corresponds to s.g. P63/mmc which is broken only by one oxygen position. The structure consists of two layered fragments: one of the type of the mineral kalsilite (KAlSiO4) and the other of the high-temperature soda-like α-Na2CO3, Ca substituting for Na. The electro-neutral layer K2[Si2O5] (denoted K) as well as the layer Ca(CO3) (denoted S) may separately correspond to individual structures. In K2Ca[Si2O5](CO3) the S-K layers are connected together via Ca-O interactions between Ca atoms from the carbonate layer and apical O atoms from the silicate one, and also via K-O interlayer interactions. A hypothetical acentric structure, sp.gr. P-62c, is predicted on the basis of the order-disorder theory. It presents another symmetrical option for the arrangement of K-layers relative to S-layers. The K,Ca-silicate-carbonate powder produces a moderate SHG signal that is two times larger that of the α-quartz powder standard and close to other silicates with acentric structures and low electronic polarizability.

  3. Crystal structure of Brinzolamide: a carbonic anhydrase inhibitor.

    Science.gov (United States)

    Zheng, Huirong; Lou, Benyong

    2016-05-01

    In crystal structure of the title compound, C12H21N3O5S3 [systematic name: (R)-4-ethyl-amino-2-(3-meth-oxy-prop-yl)-3,4-di-hydro-2H-thieno[3,2-e][1,2]thia-zine-6-sulfonamide 1,1-dioxide], there exist three kinds of hydrogen-bonding inter-actions. The sulfonamide group is involved in hydrogen bonding with the secondary amine and the meth-oxy O atom, resulting in the formation of layers parallel to the bc plane. The layers are linked by an N-H⋯O hydrogen bond involving a sulfonamide O atom as acceptor and the secondary amine H atom as donor, which gives rise to the formation of a unique bilayer structure. The absolute structure of the mol-ecule in the crystal was determined by resonant scattering [Flack parameter = 0.01 (4)]. PMID:27308020

  4. Crystal structure of Brinzolamide: a carbonic anhydrase inhibitor

    Directory of Open Access Journals (Sweden)

    Huirong Zheng

    2016-05-01

    Full Text Available In crystal structure of the title compound, C12H21N3O5S3 [systematic name: (R-4-ethylamino-2-(3-methoxypropyl-3,4-dihydro-2H-thieno[3,2-e][1,2]thiazine-6-sulfonamide 1,1-dioxide], there exist three kinds of hydrogen-bonding interactions. The sulfonamide group is involved in hydrogen bonding with the secondary amine and the methoxy O atom, resulting in the formation of layers parallel to the bc plane. The layers are linked by an N—H...O hydrogen bond involving a sulfonamide O atom as acceptor and the secondary amine H atom as donor, which gives rise to the formation of a unique bilayer structure. The absolute structure of the molecule in the crystal was determined by resonant scattering [Flack parameter = 0.01 (4].

  5. Crystal structure of Brinzolamide: a carbonic anhydrase inhibitor

    OpenAIRE

    Zheng, Huirong; Lou, Benyong

    2016-01-01

    In crystal structure of the title compound, C12H21N3O5S3 [systematic name: (R)-4-ethyl­amino-2-(3-meth­oxy­prop­yl)-3,4-di­hydro-2H-thieno[3,2-e][1,2]thia­zine-6-sulfonamide 1,1-dioxide], there exist three kinds of hydrogen-bonding inter­actions. The sulfonamide group is involved in hydrogen bonding with the secondary amine and the meth­oxy O atom, resulting in the formation of layers parallel to the bc plane. The layers are linked by an N—H⋯O hydrogen bond involving a sulfonamide O atom as a...

  6. Synthesis, characterization of core-shell carbon-coated CaSnO3 nanotubes and their performance as anode of lithium ion battery

    Science.gov (United States)

    Hu, Xiaoyan; Xiao, Ting; Huang, Wei; Tao, Wei; Heng, Bojun; Chen, Xinqi; Tang, Yiwen

    2012-06-01

    In this paper, we design a strategy to obtain core-shell carbon-coated CaSnO3 nanotubes (hereafter C-CTO NTs) directly via a facile subsequent solvothermal synthesis using CaSn(OH)6 nanotubes as precursor in a mixed ethanol and water solvent. The mixed solvent not only facilitates the phase transformation of CaSnO3 from CaSn(OH)6 to take place quickly, but also retains the tube-shaped morphology. The uniform decoration of C shell on the surface of CaSnO3 nanotubes (hereafter CTO NTs) was confirmed by EELS (electron energy loss spectroscopy). Moreover we found that the uniform carbon-coating layer on the surface of CTO NTs played roles of a good conductor and a structure buffer to alleviate the strains from the volume variation of CTO NTs cores. So the core-shell structure possesses both the electroactivity of C and the advantages of nanotube structure. When used as an anode for Li ion battery, it shows enhanced cycling performance in term of cycling stability over bare CTO NT electrode and CaSnO3 nanocube (hereafter CTO NC) electrode. To our best knowledge, this is the first attempt to use C-CTO NTs as an anode in Li ion battery.

  7. Effects of solar UV radiation on photosynthesis and enzyme activities (carbonic anhydrase and nitrate reductase in marine macroalgae from southern Spain Efectos de la radiación solar UV sobre la fotosíntesis y actividades enzimáticas (anhidrasa carbónica y nitrato reductasa en macralgas marinas del sur de España

    Directory of Open Access Journals (Sweden)

    FÉLIX L. FIGUEROA

    2001-06-01

    Full Text Available The effects of solar ultraviolet (UV radiation during daily cycles on photosynthesis and two key enzymes involved in carbon incorporation, the carbonic anhydrase, and in inorganic nitrogen reduction, the nitrate reductase, of macroalgae from southern Spain are presented. During daily cycles, photoinhibition in several intertidal macroalgae, expressed as decrease in the effective quantum yield from the morning to noon time, was linearly dependent on the daily integrated irradiance. However, recovery, expressed as the increase in the effective quantum yield from noon to the afternoon, presented a different pattern; full recovery was found below daily integrated irradiance of 1.0 x10(4 kJ m-2. However, recovery reached only 50 % at higher irradiances. The existence of daily photoinhibition and full recovery in intertidal algae suggests that photoinhibition is a photoprotective mechanism against high solar radiation as in higher plants, and that patterns of photoinhibition and recovery are affected by accumulative doses. Activities of carbonic anhidrase and nitrate reductase were determined in three marine macroalgae (Plocamium cartilagineum, Ulva rigida and Fucus spiralis under full (PAR + UV-A + UV-B and excluded UV solar radiation (PAR. Under PAR + UV-A + UV-B, peaks of enzyme activity were found in P. cartilagineum during the evening, and accordingly to data previously published for other red macroalgae. This situation was modified by the absence of UV radiation since the increase in the activities was delayed several hours. In the three macroalgae and under full solar radiation, a significant and negative correlation was found only when data from nitrate reductase activity was shifted in time during at least four hours. This correlation is lost in Ulva rigida when UV radiation is excluded. The existence of these daily variations with a negative correlation of both enzyme activities could reflect a complex regulatory link between carbon and

  8. PERSONAL, INDOOR, AND OUTDOOR CONCENTRATIONS OF PM2.5, PARTICULATE NITRATE, AND ELEMENTAL CARBON FOR INDIVIDUALS WITH COPD IN LOS ANGELES, CA

    Science.gov (United States)

    This study characterizes the personal, indoor, and outdoor concentrations of PM2.5 and the major components of PM2.5, including nitrate (NO3-), elemental carbon (EC), and the elements for individuals with chronic obstructive pulmonary disease (COPD) living in Los Angeles, CA. ...

  9. Steam-Coal Gasification Using CaO and KOH for in Situ Carbon and Sulfur Capture

    Energy Technology Data Exchange (ETDEWEB)

    Siefert, Nicholas S. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Carnegie Mellon Univ., Pittsburgh, PA (United States); Shekhawat, Dushyant [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Litster, Shawn [Carnegie Mellon Univ., Pittsburgh, PA (United States); Berry, David A. [National Energy Technology Lab. (NETL), Morgantown, WV (United States)

    2013-08-15

    We present experimental results of coal gasification with and without the addition of calcium oxide and potassium hydroxide as dual-functioning catalyst-capture agents. Using two different coal types and temperatures between 700 and 900 °C, we studied the effect of these catalyst-capture agents on (1) the syngas composition, (2) CO2 and H2S capture, and (3) the steam-coal gasification kinetic rate. The syngas composition from the gasifier was roughly 20% methane, 70% hydrogen, and 10% other species when a CaO/C molar ratio of 0.5 was added. We demonstrated significantly enhanced steam–coal gasification kinetic rates when adding small amounts of potassium hydroxide to coal when operating a CaO-CaCO3 chemical looping gasification reactor. For example, the steam–coal gasification kinetic rate increased 250% when dry mixing calcium oxide at a Ca/C molar ratio of 0.5 with a sub-bituminous coal, and the kinetic rate increased 1000% when aqueously mixing calcium oxide at a Ca/C molar ratio of 0.5 along with potassium hydroxide at a K/C molar ratio of 0.06. In addition, we conducted multi-cycle studies in which CaCO3 was calcined by heating to 900 °C to regenerate the CaO, which was then reused in repeated CaO-CaCO3 cycles. The increased steam-coal gasification kinetics rates for both CaO and CaO + KOH persisted even when the material was reused in six cycles of gasification and calcination. The ability of CaO to capture carbon dioxide decreased roughly 2-4% per CaO-CaCO3 cycle. We also discuss an important application of this combined gasifier-calciner to electricity generation and selling the purge stream as a precalcined feedstock to a cement kiln. In this scenario, the amount of purge stream required is fixed not by the degradation in the capture ability but rather by the requirements at the cement kiln on the amount of CaSO4 and ash in the precalcined feedstock.

  10. Modeling studies: Adsorption of aniline blue by using Prosopis Juliflora carbon/Ca/alginate polymer composite beads.

    Science.gov (United States)

    Kumar, M; Tamilarasan, R

    2013-02-15

    The research article describes the experimental and modeling study for the adsorptive removal of aniline blue dye (AB dye) from aqueous matrices using a Prosopis Juliflora modified carbon/Ca/alginate polymer bead as a low cost and eco-friendly adsorbent. The rate of adsorption was investigated under various experimental parameters such as contact time, adsorbent dose, dye concentration, pH and temperature. The kinetics, equilibrium and thermodynamic studies were assessed to find out the efficiency of the adsorption process. The equilibrium uptake capacity of the adsorption process was found with Freundlich and Langmuir adsorption isotherm equations and it was evaluated by dimensionless separation factor (R(L)). The dynamics of adsorption was predicted by pseudo-first order, pseudo-second order Lagergren's equation and intra particle diffusion model. Adsorption feasibility was assessed with thermodynamic parameters such as isosteric heat of adsorption (ΔH°), standard entropy (ΔS°) and Gibbs free energy (ΔG°) using VantHoff plot. The alginate bead was characterized with FTIR spectroscopy and Scanning Electron Microscopy (SEM).

  11. Hydrocalcite (CaCO3 * H2O) and Nesquehonite (MgCO3 * 3H2O) in Carbonate Scales.

    Science.gov (United States)

    Marschner, H

    1969-09-12

    Hydrocalcite (CaCO(3) * H(2)O) with exactly one molecule of hydrate water is the main component of carbonate scales deposited from cold water in contact with air. When the magnesium content of the water is high, the hydrocalcite occurs together with MgCO(3) * 3H(2)O (nesquehonite). From the conditions under which hydrocalcite is transformed into calcite and aragonite, it appears that in some cases aragonite in nature may be formed by way of an intermediary of CaCO(3) * H(2)O. PMID:17779803

  12. The B/Ca proxy for past seawater carbonate chemistry reconstructions-laser ablation based calibrations for C. mundulus, C. wuellerstorfi and its morphotype C. cf. wuellerstorfi

    Directory of Open Access Journals (Sweden)

    F. Kersten

    2013-08-01

    Full Text Available B/Ca ratios in Cibicides mundulus and Cibicides wuellerstorfi have been shown to correlate with the degree of calcite saturation in seawater (Δ[CO32−]. In the South Pacific, a region of high importance in the global carbon cycle, these species are not continuously present in down-core records. Small numbers of epibenthic foraminifera in samples present an additional challenge, which can be overcome by using laser ablation-inductively coupled-mass spectrometry (LA-ICP-MS. We present a laser ablation based core-top calibration for Cibicides cf. wuellerstorfi, a C. wuellerstorfi morphotype that is abundant in the South Pacific and extend the existing global core top calibration for C. mundulus and C. wuellerstorfi to this region. B/Ca in C. cf. wuellerstorfi are linearly correlated with Δ[CO32−] and possibly display a higher sensitivity to calcite saturation changes than C. wuellerstorfi. Trace element profiles through C. wuellerstorfi and C. mundulus reveal an intra-shell B/Ca variation of ±36% around the mean shell value. Mg/Ca and B/Ca display opposite trends along the shell. Both phenomena likely result from ontogenetic effects. Intra-shell variability equals intra-sample variability, mean sample B/Ca values can thus be reliably calculated from averaged spot results of single specimen. In the global B/Ca–Δ[CO32−] range, we observe an inverse relationship between water mass age and Δ[CO32−].

  13. Sedimentology and paleoenvironments of the Las Chacritas carbonate paleolake, Cañadón Asfalto Formation (Jurassic), Patagonia, Argentina

    Science.gov (United States)

    Cabaleri, Nora G.; Benavente, Cecilia A.

    2013-02-01

    The Las Chacritas Member is the lower part of the Cañadón Asfalto Formation (Jurassic). The unit is a completely continental limestone succession with volcanic contributions that were deposited during the development of the Cañadón Asfalto Rift Basin (Chubut province, Patagonia, Argentina). A detailed sedimentological analysis was performed in the Fossati depocenter to determine the paleoenvironments that developed in the context of this rift. The Las Chacritas Member represents a carbonate paleolake system with ramp-shaped margins associated with wetlands that were eventually affected by subaerial exposure and pedogenesis. This process is represented by three main subenvironments: a) a lacustrine setting sensu stricto (lacustrine limestone facies association), represented by Mudstones/Wackestones containing porifera spicules (F1), Intraclastic packstones (F6) and Tabular stromatolites (F10) in which deposition and diagenesis were entirely subaqueous; b) a palustrine setting (palustrine limestone facies association) containing Microbial Mudstones (F2), Intraclastic sandy packstone with ostracode remains (F3), Oncolitic packstone (F5), Brecciated limestone (F7) and Nodular-Mottled limestone (F8) representing shallow marginal areas affected by groundwater fluctuations and minor subaerial exposure; and c) a pedogenic paleoenvironment (pedogenic limestone facies association) including Intraclastic limestone (F4) and Packstones containing Microcodium (F9) facies displaying the major features of subaerial exposure, pedogenic diagenesis and the development of paleosols. The fluvial-palustrine-lacustrine succession shows a general shallow upward trend in which contraction-expansion cycles are represented (delimited by exposure and surface erosion). The variations in the successive formations reflect the responses to fluctuations in a combination of two major controls, the tectonic and local climatic variables. The predominance of the palustrine facies associations was

  14. Effects of AlMnCa and AlMnFe Alloys on Deoxidization of Low Carbon and Low Silicon Aluminum Killed Steels

    Institute of Scientific and Technical Information of China (English)

    ZHAN Dong-ping; ZHANG Hui-shu; JIANG Zhou-hua

    2008-01-01

    To confirm the effects of AlMnCa and AIMnFe alloys on the deoxidization and modification of Al2O3 inclu-sions, experiments of 4-heat low carbon and low silicon aluminum killed steels deoxidized by AlMnCa and AlMnFe alloys were done in a MoSi2 furnace at 1 873 K. It is found that the 1# A1MnCa alloy has the best ability of deoxidi-zation and modification of Al2 O3 inclusions than 2# A1MnCa and A1MnFe alloys. Steel A deoxidized by 1# AlMnCa alloy has the lowest total oxygen content in the terminal steel, which is 37 × 10-6. Most of the inclusions in the steel deoxidized by 1# AIMnCa alloy are spherical CaO-containing compound inclusions, and 89. 1% of them are smaller than 10 μm. The diameter of the inclusion bigger than 50 μm is not found in the final steels deoxidized by AlMnCa alloys. Whereas, for the steels deoxidized by AlMnFe alloys, most inclusions in the terminal steel are Al2O3 or Al2O3-MnO inclusions, and a few of them are spherical, and only 76. 8% of them are smaller than 10 μm. Some in-clusions bigger than 50 μm are found in the steel D deoxidized by AlMnFe alloy.

  15. Le rapport B/Ca des foraminifères : un proxy pour le cycle du carbone dans l'océan

    OpenAIRE

    Coadic, Romain

    2012-01-01

    Il a été récemment montré que le rapport B/Ca des foraminifères planctoniques dépend du pH des eaux de surface, tandis que celui des foraminifères benthiques dépend de la saturation en ions carbonates des eaux de fond. Ce nouveau traceur pourrait permettre de mieux contraindre les variations du cycle océanique du carbone, en particulier lors des changements glaciaire-interglaciaires (G/IG) du Pléistocène. Les objectifs de cette thèse étaient donc (1) de développer l'analyse du B/Ca des forami...

  16. High pressure study of low compressibility tetracalcium aluminum carbonate hydrates 3CaO·Al2O3·CaCO3·11H2O

    KAUST Repository

    Moon, Juhyuk

    2012-01-01

    Synchrotron X-ray diffraction data was collected from a sample of monocarboaluminate 3CaO•Al2O3•CaCO 3•11H2O from ambient pressure to 4.3 GPa. The refined crystal structure at ambient pressure is triclinic with parameters a = 5.77(2) Å, b = 8.47(5) Å, c = 9.93(4) Å, α = 64.6(2)°, β = 82.8(3)°, γ = 81.4(4)°, and space group of P1 or P1̄. It showed some degree of perfectly reversible pressure-induced dehydration with a non-hygroscopic pressure-transmitting medium. However the dehydration effect does not critically affect a bulk modulus due to its strong framework. The isothermal bulk modulus of monocarboaluminate was found to be 53(5) GPa and 54(4) GPa with 3rd order and 2nd order Birch-Murnaghan Equation of state, respectively. That value is higher than for any other reported AFm or AFt phase. The pressure-volume behavior of the monocarboaluminate was compared with that of previous studied hemicarboaluminate. © 2011 Elsevier Ltd. All rights reserved.

  17. Mitigative effects of spermidine on photosynthesis and carbon-nitrogen balance of cucumber seedlings under Ca(NO3)2 stress.

    Science.gov (United States)

    Du, Jing; Shu, Sheng; Shao, Qiaosai; An, Yahong; Zhou, Heng; Guo, Shirong; Sun, Jin

    2016-01-01

    Ca(NO3)2 stress is one of the most serious constraints to plants production and limits the plants growth and development. Application of polyamines is a convenient and effective approach for enhancing plant salinity tolerance. The present investigation aimed to discover the photosynthetic carbon-nitrogen (C-N) mechanism underlying Ca(NO3)2 stress tolerance by spermidine (Spd) of cucumber (Cucumis sativus L. cv. Jinyou No. 4). Seedling growth and photosynthetic capacity [including net photosynthetic rate (P N), stomatal conductance (Gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr)] were significantly inhibited by Ca(NO3)2 stress (80 mM). However, a leaf-applied Spd (1 mM) treatment alleviated the reduction in growth and photosynthesis in cucumber caused by Ca(NO3)2 stress. Furthermore, the application of exogenous Spd significantly decreased the accumulation of NO3 (-) and NH4 (+) caused by Ca(NO3)2 stress and remarkably increased the activities of N metabolism enzymes simultaneously. In addition, photosynthesis N-use efficiency (PNUE) and free amino acids were significantly enhanced by exogenous Spd in response to Ca(NO3)2 stress, thus promoting the biosynthesis of N containing compounds and soluble protein. Also, the amounts of several carbohydrates (including sucrose, fructose and glucose), total C content and the C/N radio increased significantly in the presence of Spd. Based on our results, we suggest that exogenous Spd could effectively accelerate nitrate transformation into amino acids and improve cucumber plant photosynthesis and C assimilation, thereby enhancing the ability of the plants to maintain their C/N balance, and eventually promote the growth of cucumber plants under Ca(NO3)2 stress.

  18. Melting relations of multicomponent carbonate MgCO3-FeCO3-CaCO3-Na2CO3 system at 12-26 GPa: application to deeper mantle diamond formation

    Science.gov (United States)

    Spivak, Anna; Solopova, Natalia; Dubrovinsky, Leonid; Litvin, Yuriy

    2015-11-01

    Carbonatic components of parental melts of the deeper mantle diamonds are inferred from their primary inclusions of (Mg, Fe, Ca, Na)-carbonate minerals trapped at PT conditions of the Earth's transition zone and lower mantle. PT phase diagrams of MgCO3-FeCO3-CaCO3-Na2CO3 system and its ternary MgCO3-FeCO3-Na2CO3 boundary join were studied at pressures between 12 and 24 GPa and high temperatures. Experimental data point to eutectic solidus phase relations and indicate liquidus boundaries for completely miscible (Mg, Fe, Ca, Na)- and (Mg, Fe, Ca)-carbonate melts. PT fields for partial carbonate melts associated with (Mg, Fe)-, (Ca, Fe, Na)-, and (Na2Ca, Na2Fe)-carbonate solid solution phases are determined. Effective nucleation and mass crystallization of deeper mantle diamonds are realized in multicomponent (Mg, Fe, Ca, Na)-carbonatite-carbon melts at 18 and 26 GPa. The multicomponent carbonate systems were melted at temperatures that are lower than the geothermal ones. This gives an evidence for generation of diamond-parental carbonatite melts and formation of diamonds at the PT conditions of transition zone and lower mantle.

  19. An alternative model for CaCO3 over-shooting during the PETM : Biological carbonate compensation

    NARCIS (Netherlands)

    Luo, Yiming; Boudreau, Bernard P.; Dickens, Gerald R.; Sluijs, Appy; Middelburg, Jack J.

    2016-01-01

    Decreased CaCO3 content of deep-sea sediments argues for rapid and massive acidification of the oceans during the Paleocene–Eocene Thermal Maximum (PETM, ∼56 Ma BP). In the course of the subsequent recovery from this acidification, sediment CaCO3 content came to exceed pre-PETM levels, known as over

  20. On the effect of aqueous Ca on magnesite growth - Insight into trace element inhibition of carbonate mineral precipitation

    Science.gov (United States)

    Berninger, Ulf-Niklas; Jordan, Guntram; Lindner, Michael; Reul, Alexander; Schott, Jacques; Oelkers, Eric H.

    2016-04-01

    Motivated by the strong effect of aqueous Mg on calcite growth rates, this study used hydrothermal atomic force microscopy (HAFM) and hydrothermal mixed-flow reactor (HMFR) experiments to explore the effect of aqueous Ca on magnesite growth kinetics at 100 °C and pH ∼7.7. Obtuse step velocities on (1 0 4) surfaces during magnesite growth were measured to be 4 ± 3 nm/s at fluid saturation states, equal to the ion activity quotient divided by the equilibrium constant for the magnesite hydrolysis reaction, of 86-117. These rates do not vary systematically with aqueous Ca concentration up to 3 × 10-3 mol/kg. Magnesite growth rates determined by HAFM are found to be negligibly affected by the presence of aqueous Ca at these saturation states and are largely consistent with those previously reported in aqueous Ca-free systems by Saldi et al. (2009) and Gautier et al. (2015). Similarly, magnesite growth rates measured by HMFR exhibit no systematic variation on aqueous Ca concentrations. Rates in this study, however, were extended to higher degrees of fluid supersaturation with respect to magnesite than previous studies. All measured HMFR rates can be accurately described taking account the combined effects of both the spiral growth and two dimensional nucleation/growth mechanisms. Despite the lack of a clear effect of aqueous Ca on magnesite growth rates, Raman spectroscopy confirmed the incorporation of up to 8 mol percent of Ca2+ into the growing magnesite structure.

  1. Accumulation and δ 13C Composition of Soil Carbon Across a Chronosequence of Dune Complexes at Mono Lake, CA

    Science.gov (United States)

    Aanderud, Z. T.; Shuldman, M. I.; Richards, J. H.

    2004-12-01

    The amount of C sequestered and its permanence in some deserts could be higher than normally appreciated. Limited soil water availability and slow decomposition rates in desert soils may induce the long-term accumulation of soil organic C and coarse woody litter. We inventoried C in soils along a chronosequence of Sarcobatus vermiculatus shrub islands and interspaces at the Mono Basin Ecosystem Research Site, CA. Such shrub-island/interspace dune systems are widespread in basin habitats across the Great Basin Desert. We hypothesized that organic C stores would increase across the chronosequence (48, 84, ˜300, and 1800-3000 years since exposure by lake recession) and that δ 13C values of soil organic C (SOC) would become enriched over time due to isotopic fractionation associated with C mineralization of leaf and root litter. C stores quantified in 0-50 cm soils included: SOC, soil inorganic C (SIC; i.e. carbonates removed by 12 M HCl fumigation), and C in partially decomposed woody and fine litter. The youngest dune system contains at least 13.6 Mg C ha-1 and the oldest contains at least 37.9 Mg C ha-1. Our data suggest slow turnover rates of SOC (C:N ratios ˜10) and substantial accumulation of organic C (coarse litter, fine litter, and SOC) in shrub islands across the chronosequence (islands at the youngest site = 8.0 g kg-1 and islands at the oldest site = 24.0 g kg-1. Large pools of SOC and C in woody debris are potentially protected in this shrub-dominated desert, especially in shrub islands of "old-growth" dune systems. Most of the C in the soil is SIC (94% in youngest dunes to 83% at the oldest dunes). The decrease in SIC proportion as the dune systems age is correlated with a decrease in pH across the chronosequence (10.6 at the youngest site and 9.7 at the oldest site). As dunes age, total soil C isotopic composition shifts from positive δ 13C values (2.8 to 3.6 ‰ ), indicative inorganic processes, to slightly negative values (-1.2 to -3.7 ‰ ) as a

  2. A potentially new type of nonchondritic interplanetary dust particle with hematite, organic carbon, amorphous Na,Ca-aluminosilicate, and FeO-spheres

    Science.gov (United States)

    Muñoz Caro, Guillermo M.; Rietmeijer, Frans J. M.; Souza-Egipsy, Virginia; Valles-González, Maria Pilar

    2012-02-01

    We used a combination of different analytical techniques to study particle W7190-D12 using microinfrared spectroscopy, micro-Raman spectroscopy, and field emission scanning electron microscopy (FESEM) energy dispersive X-ray spectroscopy (EDS). The particle consists mainly of hematite (α-Fe2O3) with considerable variations in structural disorder. It further contains amorphous (Na,K)-bearing Ca,Al-silicate and organic carbon. Iron-bearing spherules (cloud. Atmospheric entry flash-heating caused (1) the formation of microenvironments of reduced iron oxide when indigenous carbon materials reacted with hematite covering its surface resulting in the formation of FeO-spheres and (2) Na-loss from Na,Al-plagioclase. The particle of this study, and other similar particles on this collector, may represent a potentially new type of nonchondritic IDPs associated with Jupiter family comets, although an origin in the asteroid belt cannot be ignored.

  3. The Properties and Characteristics of Concretes Containing Calcium Carbonate (CaCO3) and Synthetic Lightweight Aggregate

    Science.gov (United States)

    Ramos, Matthew J.

    The purpose of this study was to investigate the efficacy of precipitated calcium carbonate as a means for enhancing the mechanical and environmental favorability of concretes containing synthetic lightweight aggregates (SLA), which are comprised of recycled mixed plastic and fly ash. Compressive strength tests show that 2% calcium carbonate additions are able to mitigate strength decreases induced by SLA as well as decrease concrete density when compared to NWA concretes. SLA concretes containing 5% calcium carbonate do not show the same trend. Instead, strength decreases and density increases are observed. Furthermore, increases in aluminum trisulphate (AFt) phase mineralization are observed through scanning electron microscopy. Results suggest that calcium carbonate additions increase early hydration and stabilize AFt minerals thaumasite and ettringite throughout hydration. It is proposed that increased AFt phase mineralization causes reductions in concrete density. However, a limit to this relationship was observed as additions of greater than 2% calcium carbonate exceed the potential for increased hydration, causing a threshold effect that resulted in calcium carbonate acting as filler, which increases density. Improved mechanical properties and the ability to stabilize waste plastics, fly ash, and CO2 emissions make the use of 2% calcium carbonate in conjunction with SLA a favorable alternative to ordinary concretes.

  4. CaTMAS : A multi-agent model for simulating the dynamics of carbon resources of West African villages

    OpenAIRE

    Belem, Mahamadou; Manlay, R. J.; Muller, J.P.; Chotte, Jean-Luc

    2011-01-01

    Carbon is an important determinant of the sustainability of West African farming systems and of the atmospheric greenhouse effect. Given the complexity of C dynamics, various simulation models have been developed. Few include socioeconomic factors or handle system heterogeneity. This study proposes a generic, multi-agent model for the analysis of C dynamics at village level. It assumes that a better analysis of carbon dynamics at village level requires account to be taken of social, economic,...

  5. Carbon Dioxide Dry Reforming of Glycerol for Hydrogen Production using Ni/ZrO2 and Ni/CaO as Catalysts

    Directory of Open Access Journals (Sweden)

    Nur Nabillah Mohd Arif

    2016-08-01

    Full Text Available Glycerol, byproduct from the biodiesel production can be effectively utilized as the promising source of synthesis gas (syngas through a dry reforming reaction. Combination of these waste materials with greenhouse gases which is carbon dioxide (CO2 will help to reduce environmental problem such as global warming. This dry reforming reaction has been carried out in a fixed bed batch reactor at 700 °C under the atmospheric pressure for 3 hours. In this experiment, reforming reaction was carried out using Nickel (Ni as based catalyst and supported with zirconium (ZrO2 and calcium (CaO oxides. The catalysts were prepared by wet impregnation method and characterized using Bruanaer-Emmett-Teller (BET surface area, Scanning Electron Microscopy (SEM, X-ray Diffraction (XRD, Thermo Gravimetric (TGA, and Temperature Programmed Reduction (TPR analysis. Reaction studies show that 15% Ni/CaO give the highest hydrogen yield and glycerol conversion that peaked at 24.59% and 30.32%, respectively. This result is verified by XRD analysis where this catalyst shows low crystallinity and fine dispersion of Ni species resulted in high specific surface area which gives 44.93 m2/g that is validated by BET.  Copyright © 2016 BCREC GROUP. All rights reserved Received: 21st January 2016; Revised: 24th February 2016; Accepted: 29th February 2016 How to Cite: Arif, N.M.M., Vo, D.V.N., Azizan,M.T., Abidin S.Z. (2016. Carbon Dioxide Dry Reforming of Glycerol for Hydrogen Production using Ni/ZrO2 and Ni/CaO as Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (2: 200-209 (doi:10.9767/bcrec.11.2.551.200-209 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.2.551.200-209

  6. The system Na2CO3-CaCO3-MgCO3 at 6 GPa and 900-1250°C and its relation to the partial melting of carbonated mantle

    Science.gov (United States)

    Shatskiy, Anton; Litasov, Konstantin D.; Sharygin, Igor S.; Egonin, Ilya A.; Mironov, Aleksandr M.; Palyanov, Yuri N.; Ohtani, Eiji

    2016-01-01

    In order to constrain the Na2CO3-CaCO3-MgCO3 T-X diagram at 6 GPa in addition to the binary and pseudo-binary systems we conducted experiments along the Na2CO3-Ca0.5Mg0.5CO3 join. At 900-1000°C, melting does not occur and isothermal sections are presented by one-, two- and three-phase regions containing Ca-bearing magnesite, aragonite, Na2CO3 (Na2) and Na2(Ca1-0.9Mg0-0.1)3-4(CO3)4-5 (Na2Ca3-4), Na4(Ca1-0.6Mg0-0.4)(CO3)3 (Na4Ca), Na2(Ca0-0.08Mg1-0.92)(CO3)2 (Na2Mg) phases with intermediate compositions. The minimum melting point locates between 1000°C and 1100°C. This point would resemble that of three eutectics: Mgs-Na2Ca3-Na2Mg, Na2Mg-Na2Ca3-Na4Ca or Na2Mg-Na4Ca-Na2, in the compositional interval of [45Na2CO3.55(Ca0.6Mg0.4)CO3]-[60Na2CO3.40Ca0.6Mg0.4CO3]. The liquidus projection has seven primary solidification phase regions for Mgs, Dol, Arg, Na2Ca3, Na4Ca, Na2 and Na2Mg. The results suggest that extraction of Na and Ca from silicate to carbonate components has to decrease minimum melting temperature of carbonated mantle rocks to 1000-1100°C at 6 GPa and yields Na-rich dolomitic melt with a Na# (Na2O/(Na2O + CaO + MgO)) ≥ 28 mol%.

  7. Water management controls net carbon exchange in drained and flooded agricultural peatlands in the Sacramento-San Joaquin Delta, CA

    Science.gov (United States)

    Hatala, J.; Detto, M.; Sonnentag, O.; Verfaillie, J. G.; Baldocchi, D. D.

    2011-12-01

    Draining peatlands for agricultural cultivation creates an ecosystem shift with some of the fastest rates and largest magnitudes of carbon loss attributable to land-use change, yet peatland drainage is practiced around the world due to the high economic benefit of fertile soil. The Sacramento-San Joaquin Delta in California was drained at the end of the 19th century for agriculture and human settlement, and as a result, has lost 5-8m of peat soil due to oxidation. To reverse subsidence and capture carbon, there is increasing interest in converting drained agricultural land-uses back to flooded conditions to inhibit further peat oxidation. However, this method remains relatively untested at the landscape-scale. This study analyzed the short-term effects of drained to flooded land-use conversion on the balance of carbon, water, and energy over two years at two landscapes in the Delta. We used the eddy covariance method to compare CO2, CH4, H2O, and energy fluxes under the same meteorological conditions in two different land-use types: a drained pasture grazed by cattle, and a flooded newly-converted rice paddy. By analyzing differences in the fluxes from these two land-use types we determined that water management and differences in the plant canopy both play a fundamental role in governing the seasonal pattern and the annual budgets of CO2 and CH4 fluxes at these two sites. While the pasture was a source of carbon to the atmosphere in both years, the rice paddy captured carbon through NEE, even after considering losses from CH4. Especially during the fallow winter months, flooding the soil at the rice paddy inhibited loss of CO2 through ecosystem respiration when compared with the carbon exchange from the drained pasture.

  8. Alternative solution model for the ternary carbonate system CaCO3 - MgCO3 - FeCO3 - I. A ternary Bragg-Williams ordering model

    Science.gov (United States)

    McSwiggen, P.L.

    1993-01-01

    The minerals of the ternary carbonate system CaCO3 - MgCO3 - FeCO3 represent a complex series of solid solutions and ordering states. An understanding of those complexities requires a solution model that can both duplicate the subsolidus phase relationships and generate correct values for the activities. Such a solution model must account for the changes in the total energy of the system resulting from a change in the ordering state of the individual constituents. Various ordering models have been applied to binary carbonate systems, but no attempts have previously been made to model the ordering in the ternary system. This study derives a new set of equations that allow for the equilibrium degree of order to be calculated for a system involving three cations mixing on two sites, as in the case of the ternary carbonates. The method is based on the Bragg-Williams approach. From the degree of order, the mole fractions of the three cations in each of the two sites can be determined. Once the site occupancies have been established, a Margules-type mixing model can be used to determine the free energy of mixing in the solid solution and therefore the activities of the various components. ?? 1993 Springer-Verlag.

  9. Carbon-Ion Irradiation Suppresses Migration and Invasiveness of Human Pancreatic Carcinoma Cells MIAPaCa-2 via Rac1 and RhoA Degradation

    International Nuclear Information System (INIS)

    Purpose: To investigate the mechanisms underlying the inhibition of cancer cell migration and invasion by carbon (C)-ion irradiation. Methods and Materials: Human pancreatic cancer cells MIAPaCa-2, AsPC-1, and BxPC-3 were treated by x-ray (4 Gy) or C-ion (0.5, 1, 2, or 4 Gy) irradiation, and their migration and invasion were assessed 2 days later. The levels of guanosine triphosphate (GTP)-bound Rac1 and RhoA were determined by the active GTPase pull-down assay with or without a proteasome inhibitor, and the binding of E3 ubiquitin ligase to GTP-bound Rac1 was examined by immunoprecipitation. Results: Carbon-ion irradiation reduced the levels of GTP-bound Rac1 and RhoA, 2 major regulators of cell motility, in MIAPaCa-2 cells and GTP-bound Rac1 in AsPC-1 and BxPC-3 cells. Proteasome inhibition reversed the effect, indicating that C-ion irradiation induced Rac1 and RhoA degradation via the ubiquitin (Ub)-proteasome pathway. E3 Ub ligase X-linked inhibitor of apoptosis protein (XIAP), which directly targets Rac1, was selectively induced in C-ion–irradiated MIAPaCa-2 cells and coprecipitated with GTP-bound Rac1 in C-ion–irradiated cells, which was associated with Rac1 ubiquitination. Cell migration and invasion reduced by C-ion radiation were restored by short interfering RNA–mediated XIAP knockdown, indicating that XIAP is involved in C-ion–induced inhibition of cell motility. Conclusion: In contrast to x-ray irradiation, C-ion treatment inhibited the activity of Rac1 and RhoA in MIAPaCa-2 cells and Rac1 in AsPC-1 and BxPC-3 cells via Ub-mediated proteasomal degradation, thereby blocking the motility of these pancreatic cancer cells

  10. Carbon-Ion Irradiation Suppresses Migration and Invasiveness of Human Pancreatic Carcinoma Cells MIAPaCa-2 via Rac1 and RhoA Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, Mayumi; Imadome, Kaori; Shoji, Yoshimi [Advanced Radiation Biology Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Isozaki, Tetsurou; Endo, Satoshi; Yamada, Shigeru [Research Center Hospital for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Imai, Takashi, E-mail: imait@nirs.go.jp [Advanced Radiation Biology Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan)

    2015-09-01

    Purpose: To investigate the mechanisms underlying the inhibition of cancer cell migration and invasion by carbon (C)-ion irradiation. Methods and Materials: Human pancreatic cancer cells MIAPaCa-2, AsPC-1, and BxPC-3 were treated by x-ray (4 Gy) or C-ion (0.5, 1, 2, or 4 Gy) irradiation, and their migration and invasion were assessed 2 days later. The levels of guanosine triphosphate (GTP)-bound Rac1 and RhoA were determined by the active GTPase pull-down assay with or without a proteasome inhibitor, and the binding of E3 ubiquitin ligase to GTP-bound Rac1 was examined by immunoprecipitation. Results: Carbon-ion irradiation reduced the levels of GTP-bound Rac1 and RhoA, 2 major regulators of cell motility, in MIAPaCa-2 cells and GTP-bound Rac1 in AsPC-1 and BxPC-3 cells. Proteasome inhibition reversed the effect, indicating that C-ion irradiation induced Rac1 and RhoA degradation via the ubiquitin (Ub)-proteasome pathway. E3 Ub ligase X-linked inhibitor of apoptosis protein (XIAP), which directly targets Rac1, was selectively induced in C-ion–irradiated MIAPaCa-2 cells and coprecipitated with GTP-bound Rac1 in C-ion–irradiated cells, which was associated with Rac1 ubiquitination. Cell migration and invasion reduced by C-ion radiation were restored by short interfering RNA–mediated XIAP knockdown, indicating that XIAP is involved in C-ion–induced inhibition of cell motility. Conclusion: In contrast to x-ray irradiation, C-ion treatment inhibited the activity of Rac1 and RhoA in MIAPaCa-2 cells and Rac1 in AsPC-1 and BxPC-3 cells via Ub-mediated proteasomal degradation, thereby blocking the motility of these pancreatic cancer cells.

  11. Observations of the uptake of carbonyl sulfide (COS by trees under elevated atmospheric carbon dioxide concentrations

    Directory of Open Access Journals (Sweden)

    L. Sandoval-Soto

    2012-02-01

    Full Text Available Global change affects ecosystems to adapt to elevated atmospheric concentrations of carbon dioxide (CO2. We understand that carbonyl sulfide (COS, a trace gas which is involved in building up the stratospheric sulfate aerosol layer, is taken up by vegetation with the same triad of the enzmyes which are metabolizing the CO2, i.e. Ribulose-1,5-bisphosphate Carboxylase-Oxygenase (Rubisco, Phosphoenolpyruvate Carboxylase (PEP-Co and carbonic anhydrase (CA. Therefore, we discuss a physiological/biochemical adaptation of these enzymes to affect the sink strength of vegetation for COS. We investigated the adaption of two European tree species, Fagus sylvatica and Quercus ilex, grown inside chambers under elevated CO2 and determined the exchange characteristics and the content of CA after a 1–2 yr period of adaption from 350 ppm to 800 ppm CO2. We could demonstrate that the COS compensation point, the CA activity and the deposition velocities may change and cause a decrease of the COS uptake by plant ecosystems. As a consequence, the atmospheric COS level may rise leading to higher input of this trace gas into the stratosphere and causing a higher energy reflection by the stratospheric sulfur aerosol into space, thus counteracting the direct radiative forcing by the tropospheric COS.

  12. The site of net absorption of Ca from the intestinal tract of growing pigs and effect of phytic acid, Ca level and Ca source on Ca digestibility.

    Science.gov (United States)

    González-Vega, J Caroline; Walk, Carrie L; Liu, Yanhong; Stein, Hans H

    2014-01-01

    An experiment was conducted to test the hypothesis that the standardised digestibility of Ca in calcium carbonate and Lithothamnium calcareum Ca is not different regardless of the level of dietary Ca, and that phytic acid affects the digestibility of Ca in these two ingredients to the same degree. The objectives were to determine where in the intestinal tract Ca absorption takes place and if there are measurable quantities of basal endogenous Ca fluxes in the stomach, small intestine or large intestine. Diets contained calcium carbonate or L. calcareum Ca as the sole source of Ca, 0% or 1% phytic acid and 0.4% or 0.8% Ca. A Ca-free diet was also formulated and used to measure endogenous fluxes and losses of Ca. Nine growing pigs (initial body weight 23.8 ± 1.3 kg) were cannulated in the duodenum and in the distal ileum, and faecal, ileal and duodenal samples were collected. Duodenal endogenous fluxes of Ca were greater (p interaction, p < 0.05). The standardised duodenal digestibility (SDD), standardised ileal digestibility (SID) and standardised total tract digestibility (STTD) of Ca were not different if calcium carbonate was the source of dietary Ca. However, the STTD of Ca in L. calcareum Ca was greater (p < 0.05) than the SID and SDD of Ca. The SDD, SID and STTD of Ca in calcium carbonate were greater (p < 0.05) than those of L. calcareum Ca. In conclusion, under the conditions of this experiment, standardised digestibility of Ca is not affected by the level of phytic acid, but may be affected by dietary Ca level depending on the Ca source. Calcium from calcium carbonate is mostly absorbed before the duodenum, but Ca from L. calcareum Ca is mostly absorbed in the jejunum and ileum. PMID:24646151

  13. New Data on Food Consumption in Pre-Hispanic Populations from Northwest Argentina (ca. 1000–1550 A.D.): The Contribution of Carbon and Nitrogen Isotopic Composition of Human Bones

    OpenAIRE

    María Soledad Gheggi; Verónica Isabel Williams

    2013-01-01

    We present data on carbon and nitrogen isotopic composition of human bones from Tolombón (Calchaqui Valley, Salta) and Esquina de Huajra (Quebrada de Humahuaca, Jujuy) sites located in Northwest Argentina (NWA). Both are complex archaeological residential settlements ascribed to the Regional Development Period (ca. 900–1430 A.D.), the Inca Period (ca. 1430–1536 A.D.), and the Early Colonial Period (ca. 1536–1600 A.D.). Twelve samples of human bones were collected and analyzed, including remai...

  14. The dynamic ocean biological pump: Insights from a global compilation of particulate organic carbon, CaCO3, and opal concentration profiles from the mesopelagic

    Science.gov (United States)

    Lam, Phoebe J.; Doney, Scott C.; Bishop, James K. B.

    2011-09-01

    We have compiled a global data set of 62 open ocean profiles of particulate organic carbon (POC), CaCO3, and opal concentrations collected by large volume in situ filtration in the upper 1000 m over the last 30 years. We define concentration-based metrics for the strength (POC concentration at depth) and efficiency (attenuation of POC with depth in the mesopelagic) of the biological pump. We show that the strength and efficiency of the biological pump are dynamic and are characterized by a regime of constant and high transfer efficiency at low to moderate surface POC and a bloom regime where the height of the bloom is characterized by a weak deep biological pump and low transfer efficiency. The variability in POC attenuation length scale manifests in a clear decoupling between the strength of the shallow biological pump (e.g., POC at the export depth) and the strength of the deep biological pump (POC at 500 m). We suggest that the paradigm of diatom-driven export production is driven by a too restrictive perspective on upper mesopelagic dynamics. Indeed, our full mesopelagic analysis suggests that large, blooming diatoms have low transfer efficiency and thus may not export substantially to depth; rather, our analysis suggests that ecosystems characterized by smaller cells and moderately high %CaCO3 have a high mesopelagic transfer efficiency and can have higher POC concentrations in the deep mesopelagic even with relatively low surface or near-surface POC. This has negative implications for the carbon sequestration prospects of deliberate iron fertilization.

  15. Evaluation of the potential of additives as corrosion inhibitors of CA-50 carbon steel used as reinforcement in concretes

    International Nuclear Information System (INIS)

    In this work, various compounds were tested to evaluate their potential capability for their use as corrosion inhibitors of carbon steel reinforcement in concretes. The additives tested were sodium benzoate, polyethylene glycol, hexamethylenetetramine, benzotriazole and yttrium carbonate. Initially, exploratory tests were carried out to select the ones to be used as corrosion inhibitors, based on the inhibit ion efficiency determined from electrochemical tests, specifically polarization tests and electrochemical impedance spectroscopy. These tests were carried out in a solution composed of 0.01 N sodium hydroxide (NaOH) and 0.05 N potassium hydroxide (KOH) to simulate the composition of the solution inside the pores in concretes. The additive that presented the most promising potential to be used as corrosion inhibitor was benzotriazole (BTA). After the elimination of some compounds and selection of the additive with higher corrosion inhibit ion efficiency in the test medium, the effect of its concentration on the corrosion inhibition efficiency was evaluated. Sodium nitrite solutions with the same concentrations as those solutions with BTA were tested for comparison reasons. Sodium nitrite is a well established corrosion inhibitor for carbon steel reinforcement in concretes but it has been related to toxic effects. The BTA was associated to higher corrosion inhibition efficiencies than that of sodium nitrite in similar concentrations. A blackish adherent film was formed on the steel surface exposed to BTA solutions during long periods of immersion in the alkaline medium. The results suggest that BTA is a potential candidate for substitution of nitrites as corrosion inhibitor of reinforcements in concrete. (author)

  16. Sulfide capacities of CaO-CaF2-CaCl2 melts

    Science.gov (United States)

    Simeonov, Simeon; Sakai, Toshihiko; Maeda, Masafumi

    1992-06-01

    The sulfide capacityC_{s^{2 - } } = ({text{pct S}}^{{text{2 - }}} )(p_{{text{O}}_{text{2}} } /p_{{text{S}}_{text{2}} } )^{1/2} ) of CaO-CaF2-CaCl2 slag was determined at temperatures from 1000 °C to 1300 °C by equilibrating molten slag, molten silver, and CO-CO2-Ar gas mixture. The sulfide capacity increases with replacing CaCl2 by CaF2 in slags of constant CaO contents. The sulfide capacity also increases with increasing temperature as well as with increasing CaO content at a constant ratio of CaF2/CaCl2 of unity. A linear relationship between the sulfide capacity and carbonate capacity in literature was observed on a logarithmic scale.

  17. Voltammetric Detection of Diquat at the Carbon Paste Electrode Containing a Ca10(PO46(OH2

    Directory of Open Access Journals (Sweden)

    Moulay Abderrahim EL MHAMMEDI

    2007-01-01

    Full Text Available We report a sensitive electrochemical voltammetric method for analyzing diquat (DQ ions using a carbon paste electrochemical (CPE modified by porous material, such as hydroxyapatite (HAP. Diquat strongly adsorbed on a HAP-CPE surface and provides facile electrochemical quantitative methods for electroactive DQ ions. Operational parameters have been optimized, and the stripping voltammetric performance has been studied using square wave voltammetry. The peaks current intensity are highly linear over the 7×10-7–3×10-4 mol L-1 diquat range examined (10-min accumulation time, with a good sensitivity. These findings can lead to a widespread use of electrochemical sensors to detect DQ contaminates.Scanning electron microscopy was used for morphology observation and in particular the X-ray diffraction analysis (XRD and Fourier transformed infrared spectroscopy (FTIR analysis for characterization of synthesis powder.

  18. Characterisation of neurotransmitter-induced electrolyte transport in cockroach salivary glands by intracellular Ca2+, Na+ and pH measurements in duct cells.

    Science.gov (United States)

    Hille, Carsten; Walz, Bernd

    2008-02-01

    Ion-transporting acinar peripheral cells in cockroach salivary glands are innervated by dopaminergic and serotonergic fibres, but saliva-modifying duct cells are innervated only by dopaminergic fibres. We used microfluorometry to record intracellular Na+, Ca2+ and H+ concentrations ([Na+]i, [Ca2+]i and pHi) in duct cells of two types of preparation, viz ;lobes' consisting of acini with their duct system and ;isolated ducts' without acini, in order to obtain information about the transporters involved in saliva secretion and/or modification. Our results indicate that (1) stimulation of lobes by dopamine (DA) causes a strong drop of pHi and increases in [Na+]i and [Ca2+]i in duct cells; (2) in contrast, DA stimulation of isolated ducts produces only a small pHi drop and no changes in [Na+]i and [Ca2+]i; (3) pHi and [Ca2+]i changes are also induced in duct cells by serotonin (5-HT) stimulation of lobes, but not isolated ducts; (4) in the absence of CO2/HCO3(-), the DA-induced pH(i) drop is strongly reduced by removal of extracellular Cl(-) or inhibition of the Na+-K+-2Cl(-) cotransporter (NKCC); (5) in the presence of CO2/HCO3(-), the DA-induced pHi drop is not reduced by NKCC inhibition, but rather by inhibition of the Cl(-)/HCO3(-) exchanger (AE), Na+/H+ exchanger (NHE) or carbonic anhydrase. We suggest that DA and 5-HT act predominantly on acinar peripheral cells. Their activity (secretion of primary saliva) seems to cause changes in ion concentrations in duct cells. NKCC and/or AE/NHE activities are necessary for pHi changes in duct cells; we consider that these transporters are involved in the secretion of the NaCl-rich primary saliva.

  19. Western Indian Ocean circulation and climate variability on different time scales. A study based on stable oxygen and carbon isotopes, benthic foraminiferal assemblages and Mg/Ca paleothermometry

    Energy Technology Data Exchange (ETDEWEB)

    Romahn, Sarah

    2014-08-19

    In order to understand the Earth's climate evolution it is crucial to evaluate the role of low-latitude oceans in the global climate system, as they are connected to both hemispheres via atmospheric and oceanic circulation and thus hold the potential to disentangle the asynchronicity of short-term Pleistocene climate variability. However, the potential of low latitude oceans to respond to and force large-scale changes of the climate system is still debated. The aim of this thesis is to examine and to understand the causal relationship of both atmospheric and oceanic changes in the tropical western Indian Ocean on centennial-, millennial and glacial-interglacial timescales. For this purpose I investigated stable oxygen and carbon isotope compositions of both planktic and benthic foraminiferal tests, Mg/Ca ratios of planktic foraminiferal tests as well as benthic foraminiferal assemblages and sedimentary geochemical parameters on two sediment cores (GeoB12615-4, 446 m and GeoB12616-4, 1449 m) from the continental slope off Tanzania, East Africa.

  20. Ca-rich carbonates associated with ultrabasic-ultramafic melts: Carbonatite or limestone xenoliths? A case study from the late Miocene Morron de Villamayor volcano (Calatrava Volcanic Field, central Spain)

    Science.gov (United States)

    Lustrino, Michele; Prelević, Dejan; Agostini, Samuele; Gaeta, Mario; Di Rocco, Tommaso; Stagno, Vincenzo; Capizzi, Luca Samuele

    2016-07-01

    The volcanic products of the late Miocene Morron de Villamayor volcano (Calatrava Volcanic Field, central Spain) are known for being one of the few outcrops of leucitites in the entire circum-Mediterranean area. These rocks are important because aragonite of mantle origin has been reported as inclusion in olivine macrocrysts. We use petrographic observations, mineral compositions, as well as oxygen and carbon isotope ratios coupled with experimental petrology to understand the origin of carbonate phase in these olivine-phyric rocks. Groundmass and macrocryst olivines range from δ18OVSMOW of +4.8‰, typical of mantle olivine values, to +7.4‰, indicating contamination by sedimentary carbonate. Carbonates are characterized by heavy oxygen isotope compositions (δ18OVSMOW >+24‰), and relatively light carbon isotopes (δ13CPDB <-11‰), resembling skarn values, and distinct from typical mantle carbonatite compositions. Petrography, mineral compositions such as low Mg# of clinopyroxene and biotite, low Ca# and low incompatible element abundance of the carbonate, and isotopic ratios of O and C, do not support a mantle origin for the carbonate. Rather, the carbonate inclusions found in the olivine macrocrysts are interpreted as basement limestone fragments entrapped by the rising crystallizing magma. Comparison with experimental carbonatitic and silicate-carbonatitic melts indicates that low-degree partial melts of a carbonated peridotite must have a dolomitic rather than the aragonitic/calcitic composition as those found trapped in the Morron de Villamayor olivine macrocrysts.

  1. Effect of temperature on the oxygen isotope composition of carbon dioxide (δ18O) prepared from carbonate minerals by reaction with polyphosphoric acid: An example of the rhombohedral CaCO 3-MgCO 3 group minerals

    Science.gov (United States)

    Crowley, Stephen F.

    2010-11-01

    Measurement of the ratio of 18O to 16O in CO 2(δ18O) produced from rhombohedral carbonate minerals in the compositional range CaCO 3-MgCO 3 by reaction with polyphosphoric acid (PPA), at temperatures of between 25 and 110 °C, shows that values of δ18O are linearly correlated ( r o > 0.99) with the reciprocal of absolute reaction temperature (K/ T). This observation is consistent with earlier studies documenting the effect of temperature on the kinetic fractionation of oxygen isotopes between parent carbonate and product CO 2 and H 2O during acid decomposition. However, analysis of the resultant data reveals: (1) a progressive increase in dδ18O/dT-1 with increasing Mg content, and (2) a significant variation in dδ18O/dT-1 between individual samples of carbonate of identical lattice symmetry and similar chemical composition. The overall increase in gradient with increasing Mg content is assumed to reflect cation radius dependent factors that control the bonding environment at the interface between the metal cation exposed at the surface of the reacting carbonate solid and a H 2CO 3 transitional species during disproportionation of H 2CO 3 to CO 2 and H 2O ("cluster model" of Guo et al., 2009). Phase-specific variations in dδ18O/dT-1 might result from differences in lattice structure variables (e.g., degree of lattice distortion, extent of positional disorder, and non-ideal mixing of substituent cations where carbonates depart from end-member compositions). Lattice structure variables may be dependent on geochemical conditions pertaining at the time of carbonate precipitation (e.g., biosynthetic versus inorganic precipitates) and suggests that dδ18O/dT-1 has the potential to vary, within limits, in response to both the chemical composition and structure of each carbonate sample. Because the oxygen isotope composition of carbonate minerals (δ18O) measured on the VPDB scale is defined by the oxygen isotope composition of CO 2 prepared from NBS19 (calcite) by

  2. Revisiting carbonate chemistry controls on planktic foraminifera Mg / Ca: implications for sea surface temperature and hydrology shifts over the Paleocene-Eocene Thermal Maximum and Eocene-Oligocene transition

    Science.gov (United States)

    Evans, David; Wade, Bridget S.; Henehan, Michael; Erez, Jonathan; Müller, Wolfgang

    2016-04-01

    Much of our knowledge of past ocean temperatures comes from the foraminifera Mg / Ca palaeothermometer. Several nonthermal controls on foraminifera Mg incorporation have been identified, of which vital effects, salinity, and secular variation in seawater Mg / Ca are the most commonly considered. Ocean carbonate chemistry is also known to influence Mg / Ca, yet this is rarely examined as a source of uncertainty, either because (1) precise pH and [CO32-] reconstructions are sparse or (2) it is not clear from existing culture studies how a correction should be applied. We present new culture data of the relationship between carbonate chemistry and Mg / Ca for the surface-dwelling planktic species Globigerinoides ruber and compare our results to data compiled from existing studies. We find a coherent relationship between Mg / Ca and the carbonate system and argue that pH rather than [CO32-] is likely to be the dominant control. Applying these new calibrations to data sets for the Paleocene-Eocene Thermal Maximum (PETM) and Eocene-Oligocene transition (EOT) enables us to produce a more accurate picture of surface hydrology change for the former and a reassessment of the amount of subtropical precursor cooling for the latter. We show that pH-adjusted Mg / Ca and δ18O data sets for the PETM are within error of no salinity change and that the amount of precursor cooling over the EOT has been previously underestimated by ˜ 2 °C based on Mg / Ca. Finally, we present new laser-ablation data of EOT-age Turborotalia ampliapertura from St. Stephens Quarry (Alabama), for which a solution inductively coupled plasma mass spectrometry (ICPMS) Mg / Ca record is available (Wade et al., 2012). We show that the two data sets are in excellent agreement, demonstrating that fossil solution and laser-ablation data may be directly comparable. Together with an advancing understanding of the effect of Mg / Casw, the coherent picture of the relationship between Mg / Ca and pH that we outline

  3. PP/CaCO3复合材料的制备及性能研究%Preparation and performance of polypropylene and calcium carbonate composite material

    Institute of Scientific and Technical Information of China (English)

    刘建波

    2016-01-01

    在聚丙烯(PP)中添加CaCO3进行填充改性,研究了不同含量、不同颗粒级配的CaCO3,对复合材料(PP/Ca-CO3)力学性能和缺口冲击断面形貌以及流变性能的影响,并采用偏光显微镜(PLM)、广角X射线衍射仪(WAXD)、扫描电镜(SEM),对PP/WCaCO3的结晶形态进行表征.结果表明,在微米CaCO3(m-CaC03)和纳米CaCO3(n-CaC03)的复配比例m(m-CaC03):m(n-CaCO3)=3:1,且复配CaCO3(C-CaC03)总添加量为25%时,PP/C-CaC03的冲击强度达到12.7kJ/m2,比纯PP提高111.67%.PLM以及WAXD分析表明,在一定程度上,n-CaCO3有β成核剂的作用,加快了PP结晶速率,并使球晶细化,有利于PP/CaCO3的增韧.

  4. Revisiting carbonate chemistry controls on planktic foraminifera Mg / Ca: implications for sea surface temperature and hydrology shifts over the Paleocene–Eocene Thermal Maximum and Eocene–Oligocene Transition

    Directory of Open Access Journals (Sweden)

    D. Evans

    2015-07-01

    Full Text Available Much of our knowledge of past ocean temperatures comes from the foraminifera Mg / Ca palaeothermometer. Several non-thermal controls on foraminifera Mg incorporation have been identified, of which vital-effects, salinity and secular variation in seawater Mg / Ca are the most commonly considered. Ocean carbonate chemistry is also known to influence Mg / Ca, yet this is rarely considered as a source of uncertainty either because (1 precise pH and [CO32−] reconstructions are sparse, or (2 it is not clear from existing culture studies how a correction should be applied. We present new culture data of the relationship between carbonate chemistry for the surface-dwelling planktic species Globigerinoides ruber, and compare our results to data compiled from existing studies. We find a coherent relationship between Mg / Ca and the carbonate system and argue that pH rather than [CO32−] is likely to be the dominant control. Applying these new calibrations to datasets for the Paleocene–Eocene Thermal Maximum (PETM and Eocene–Oligocene Transition (EOT enable us to produce a more accurate picture of surface hydrology change for the former, and a reassessment of the amount of subtropical precursor cooling for the latter. We show that properly corrected Mg / Ca and δ18O datasets for the PETM imply no salinity change, and that the amount of precursor cooling over the EOT has been previously underestimated by ∼ 2 °C based on Mg / Ca. Finally, we present new laser-ablation data of EOT-age Turborotalia ampliapertura from St Stephens Quarry (Alabama, for which a solution ICPMS Mg / Ca record is available (Wade et al., 2012. We show that the two datasets are in excellent agreement, demonstrating that fossil solution and laser-ablation data may be directly comparable. Together with an advancing understanding of the effect of Mg / Casw, the coherent picture of the relationship between Mg / Ca and pH that we outline here represents a step towards producing

  5. Biotic Control of Surface pH and Evidence of Light-Induced H+ Pumping and Ca2+-H+ Exchange in a Tropical Crustose Coralline Alga.

    Directory of Open Access Journals (Sweden)

    Laurie C Hofmann

    Full Text Available Presently, an incomplete mechanistic understanding of tropical reef macroalgae photosynthesis and calcification restricts predictions of how these important autotrophs will respond to global change. Therefore, we investigated the mechanistic link between inorganic carbon uptake pathways, photosynthesis and calcification in a tropical crustose coralline alga (CCA using microsensors. We measured pH, oxygen (O2, and calcium (Ca2+ dynamics and fluxes at the thallus surface under ambient (8.1 and low (7.8 seawater pH (pHSW and across a range of irradiances. Acetazolamide (AZ was used to inhibit extracellular carbonic anhydrase (CAext, which mediates hydrolysis of HCO3-, and 4,4' diisothiocyanatostilbene-2,2'-disulphonate (DIDS that blocks direct HCO3- uptake by anion exchange transport. Both inhibited photosynthesis, suggesting both diffusive uptake of CO2 via HCO3- hydrolysis to CO2 and direct HCO3- ion transport are important in this CCA. Surface pH was raised approximately 0.3 units at saturating irradiance, but less when CAext was inhibited. Surface pH was lower at pHSW 7.8 than pHSW 8.1 in the dark, but not in the light. The Ca2+ fluxes were large, complex and temporally variable, but revealed net Ca2+ uptake under all conditions. The temporal variability in Ca2+ dynamics was potentially related to localized dissolution during epithallial cell sloughing, a strategy of CCA to remove epiphytes. Simultaneous Ca2+ and pH dynamics suggest the presence of Ca2+/H+ exchange. Rapid light-induced H+ surface dynamics that continued after inhibition of photosynthesis revealed the presence of a light-mediated, but photosynthesis-independent, proton pump. Thus, the study indicates metabolic control of surface pH can occur in CCA through photosynthesis and light-inducible H+ pumps. Our results suggest that complex light-induced ion pumps play an important role in biological processes related to inorganic carbon uptake and calcification in CCA.

  6. Biotic Control of Surface pH and Evidence of Light-Induced H+ Pumping and Ca2+-H+ Exchange in a Tropical Crustose Coralline Alga.

    Science.gov (United States)

    Hofmann, Laurie C; Koch, Marguerite; de Beer, Dirk

    2016-01-01

    Presently, an incomplete mechanistic understanding of tropical reef macroalgae photosynthesis and calcification restricts predictions of how these important autotrophs will respond to global change. Therefore, we investigated the mechanistic link between inorganic carbon uptake pathways, photosynthesis and calcification in a tropical crustose coralline alga (CCA) using microsensors. We measured pH, oxygen (O2), and calcium (Ca2+) dynamics and fluxes at the thallus surface under ambient (8.1) and low (7.8) seawater pH (pHSW) and across a range of irradiances. Acetazolamide (AZ) was used to inhibit extracellular carbonic anhydrase (CAext), which mediates hydrolysis of HCO3-, and 4,4' diisothiocyanatostilbene-2,2'-disulphonate (DIDS) that blocks direct HCO3- uptake by anion exchange transport. Both inhibited photosynthesis, suggesting both diffusive uptake of CO2 via HCO3- hydrolysis to CO2 and direct HCO3- ion transport are important in this CCA. Surface pH was raised approximately 0.3 units at saturating irradiance, but less when CAext was inhibited. Surface pH was lower at pHSW 7.8 than pHSW 8.1 in the dark, but not in the light. The Ca2+ fluxes were large, complex and temporally variable, but revealed net Ca2+ uptake under all conditions. The temporal variability in Ca2+ dynamics was potentially related to localized dissolution during epithallial cell sloughing, a strategy of CCA to remove epiphytes. Simultaneous Ca2+ and pH dynamics suggest the presence of Ca2+/H+ exchange. Rapid light-induced H+ surface dynamics that continued after inhibition of photosynthesis revealed the presence of a light-mediated, but photosynthesis-independent, proton pump. Thus, the study indicates metabolic control of surface pH can occur in CCA through photosynthesis and light-inducible H+ pumps. Our results suggest that complex light-induced ion pumps play an important role in biological processes related to inorganic carbon uptake and calcification in CCA. PMID:27459463

  7. Influence of organic carbon loading, sediment associated metal oxide content and sediment grain size distributions upon Cryptosporidium parvum removal during riverbank filtration operations, Sonoma County, CA

    Science.gov (United States)

    Metge, D.W.; Harvey, R.W.; Aiken, G.R.; Anders, R.; Lincoln, G.; Jasperse, J.

    2010-01-01

    This study assessed the efficacy for removing Cryptosporidium parvum oocysts of poorly sorted, Fe- and Al-rich, subsurface sediments collected from 0.9 to 4.9 and 1.7-13.9??m below land surface at an operating riverbank filtration (RBF) site (Russian River, Sonoma County, CA). Both formaldehyde-killed oocysts and oocyst-sized (3????m) microspheres were employed in sediment-packed flow-through and static columns. The degree of surface coverage of metal oxides on sediment grain surfaces correlated strongly with the degrees of oocyst and microsphere removals. In contrast, average grain size (D50) was not a good indicator of either microsphere or oocyst removal, suggesting that the primary mechanism of immobilization within these sediments is sorptive filtration rather than physical straining. A low specific UV absorbance (SUVA) for organic matter isolated from the Russian River, suggested that the modest concentration of the SUVA component (0.8??mg??L-1) of the 2.2??mg??L-1 dissolved organic carbon (DOC) is relatively unreactive. Nevertheless, an amendment of 2.2??mg??L-1 of isolated river DOC to column sediments resulted in up to a 35.7% decrease in sorption of oocysts and (or) oocyst-sized microspheres. Amendments (3.2????M) of the anionic surfactant, sodium dodecyl benzene sulfonate (SDBS) also caused substantive decreases (up to 31.9 times) in colloid filtration. Although the grain-surface metal oxides were found to have a high colloid-removal capacity, our study suggested that any major changes within the watershed that would result in long-term alterations in either the quantity and (or) the character of the river's DOC could alter the effectiveness of pathogen removal during RBF operations.

  8. Influence of mass recovery on the performance of a heat pipe type ammonia sorption refrigeration system using CaCl2/activated carbon as compound adsorbent

    International Nuclear Information System (INIS)

    The performance analyses of a sorption refrigeration system with different mass recovery processes are presented, in which compound adsorbent of CaCl2 and activated carbon is used to improve the mass and heat transfer performances of sorption bed. The heating, cooling and heat recovery processes between two sorption beds were performed by multifunction heat pipes without additional power consumption. The experimental Clapeyron diagrams showed that the cycles with mass recovery (MR), with heat and mass recoveries (HMR), and with mass and heat recoveries (MHR), have better thermodynamic performances when compared with the sorption cycle without mass recovery (MR0). The implementary order of mass recovery and heat recovery has strong influence on the efficacy of mass recovery while it has little influence on the efficacy of heat recovery. In sorption cycles with HMR and with MHR, the hot beds can be pre-cooled and cold beds can be pre-heated effectively during the switching process, and heat consumption from external heat source during desorption phase is thereby reduced. Mass recovery can enlarge cycled refrigerant mass due to the transfer of refrigerant gas between two sorption beds during mass recovery process. In comparison with sorption cycle with MR0, sorption cycles with MR, with HMR, and with MHR can generally improve the coefficient of performance (COP) and specific cooling power (SCP) by more than 20% and 16%, respectively. Especially, sorption cycle with MHR has the highest performance among different mass recovery processes due to the fact that MHR has the advantages of MR and HMR, and it can improve the COP by 46.7% when compared with the cycle with MR0

  9. Comparative Mechanisms of Photosynthetic Carbon Acquisitionin Hizikiafusiforme Under Submersed and Emersed Conditions

    Institute of Scientific and Technical Information of China (English)

    ZOUDing-Hui; GAOKun-Shan

    2004-01-01

    The economic seaweed Hizikia fusiforme (Harv.) Okamura (Sargassaceae, Phaeophyta) usually experiences periodical exposures to air at low tide. Photosynthetic carbon acquisition mechanisms were comparatively studied under submersed and emersed conditions in order to establish a general understanding of its photosynthetic characteristics associated with tidal cycles. When submersed in seawater, H.fusiforme was capable of acquiring HCO3- as a source of inorganic carbon (Ci) to drive photosynthesis, while emersed and exposed to air, it used atmospheric 002 for photosynthesis. The pH changes surroundingthe H.fusiforme fronds had less influence on the photosynthetic rates under emersed condition than under submersed condition. When the pH was as high as 10.0, emersed H.fusiforme could photosynthesize efficiently, but the submersed alga exhibited very poor photosynthesis. Extracellular carbonic anhydrase (CA) played an important role in the photosynthetic acquisitions of exogenous Ci in water as well as in air. Both the concentrations of dissolved inorganic carbon in general seawater and CO2 in air were demonstrated to limit the photosynthesis of H.fusiforme, which was sensitive to O2. It appeared that the exogenous carbon acquisition system, being dependent of external CA activity, operates in a way not enough to raise intracellular CO2 level to prevent photorespiration. The inability of H.fusiforme to achieve its maximum photosynthetic rate at the current ambient Ci levels under both submersed and emersed conditions suggested that the yield of aquaculture for this economic species would respond profitably to future increases in CO2 concentration in the sea and air.

  10. 纳米CaCO3表面改性方法综述%Review on the methods of surface modification of nanometer calcium carbonate

    Institute of Scientific and Technical Information of China (English)

    王训遒; 蒋登高

    2007-01-01

    简述了纳米CaCO3表面改性的原因,综述了国内外纳米CaCO3表面改性的方法,着重介绍了表面活性剂、偶联剂、无机改性剂和复合改性剂等在纳米CaCO3表面改性方面的应用,并对我国纳米CaCO3产业的发展提出了建议.

  11. The effect of biological activity, CaCO3 mineral dynamics, and CO2 degassing in the inorganic carbon cycle in sea ice in late winter-early spring in the Weddell Sea, Antarctica

    Science.gov (United States)

    Papadimitriou, S.; Kennedy, H.; Norman, L.; Kennedy, D. P.; Dieckmann, G. S.; Thomas, D. N.

    A large-scale geographical study of the ice pack in the seasonal ice zone of the Weddell Sea, Antarctica, took place from September to October 2006. Sea ice brines with a salinity greater than 58 and temperature lower than -3.6°C were sampled from 22 ice stations. The brines had large deficits in total alkalinity and in the concentrations of the major dissolved macronutrients (total dissolved inorganic carbon, nitrate, and soluble reactive phosphorus) relative to their concentrations in the surface oceanic water and conservative behavior during seawater freezing. The concentration deficits were related to the dissolved inorganic carbon-consuming processes of photosynthesis, CaCO3 precipitation, and CO2 degassing. The largest concentration deficits in total dissolved inorganic carbon were found to be associated with CaCO3 precipitation and CO2 degassing, because the magnitude of the photosynthesis-induced concentration deficit in total dissolved inorganic carbon is controlled by the size of the inorganic nutrient pool, which can be limited in sea ice by its openness to exchange with the surrounding oceanic water.

  12. 硫酸化反应对天然CO2载体CaO高温循环碳捕集的影响%Effect of sulfation on carbon capture using natural CO_2 carrier CaO looping cycle at high temperature

    Institute of Scientific and Technical Information of China (English)

    李英杰; 孙荣岳; 刘红玲; 路春美

    2011-01-01

    The effects of sulfation of CaO on average carbonation conversion,CO2 capture efficiency and energy requirement in a calcinier for the regeneration of CaO at existence of SO2 in flue gas which entered a carbonator were investigated.The results show that the sulfation of CaO induces a decrease in average carbonation conversion and CO2 capture efficiency at the same natural CO2 carrier flow ratios.The energy requirement in the calciner with the sulfation of CaO is higher than that without the sulfation of CaO at the same carrier flow ratios.Also,increasing the carrier supplement flow ratio minimizes the effect of the sulfation of CaO on energy requirement in the calciner,while improving the carrier recycled flow ratio aggravates the effect.The energy requirement in the calciner with sulfation of CaO is greater than that without sulfation at the same CO2 capture efficiency.When the volume ratio of SO2 to CO2 is 1% and CO2 capture efficiency is 90%,the energy requirement in the calciner with the sulfation of CaO is 290 kJ/mol CO2,which shows a 14% rise compared with that without the sulfation.%研究了碳酸化炉烟气中存在SO2时,CaO硫酸化反应对系统平均碳酸化转化率、CO2捕集效率和煅烧炉再生CaO所需能量的影响。结果表明:在相同CO2载体流量比率时,硫酸化引起了平均碳酸化转化率和CO2捕集效率下降;当载体流量比率相同时,硫酸化时煅烧炉所需能量均低于无硫酸化时,增加载体补充流量比率能减缓硫酸化对煅烧炉所需能量的影响,增大载体循环流量比率能加剧硫酸化对能量的影响作用;在相同CO2捕集效率时,硫酸化时煅烧炉所需能量均高于无硫酸化时;当烟气中SO2为CO2体积的1%和CO2捕集效率达到90%时,硫酸化

  13. New Data on Food Consumption in Pre-Hispanic Populations from Northwest Argentina (ca. 1000–1550 A.D.: The Contribution of Carbon and Nitrogen Isotopic Composition of Human Bones

    Directory of Open Access Journals (Sweden)

    María Soledad Gheggi

    2013-01-01

    Full Text Available We present data on carbon and nitrogen isotopic composition of human bones from Tolombón (Calchaqui Valley, Salta and Esquina de Huajra (Quebrada de Humahuaca, Jujuy sites located in Northwest Argentina (NWA. Both are complex archaeological residential settlements ascribed to the Regional Development Period (ca. 900–1430 A.D., the Inca Period (ca. 1430–1536 A.D., and the Early Colonial Period (ca. 1536–1600 A.D.. Twelve samples of human bones were collected and analyzed, including remains from individuals of both sexes and different ages at death. We also present the carbon and nitrogen isotopic composition of modern plants from nearby areas in order to start building an isotopic ecology of the area and compile available information on food consumption from different lines of evidence. The isotopic results obtained reveal the consumption of C4 plants, which for the area are maize and amaranth, combined with animal proteins. The integration of these results with the broader database was useful to discuss the political and economical implications of the findings, especially in the context of this area under the Inca domination.

  14. 钙基吸收剂循环煅烧/碳酸化反应特性%Characteristics of Cyclic Calcination/Carbonation Reaction of Ca-based Absorbent

    Institute of Scientific and Technical Information of China (English)

    赵士林; 刘浩; 夏雯; 吴昊; 杨宏旻

    2013-01-01

    Aiming at the effects of cycle number,absorbent particle size,CO2 concentration in calcinations,carbonation atmosphere and water vapour concentration on characteristics of cyclic calcination/carbonation reaction of Ca-based absorbent,they are investigated experimentally on a lab-scale setup. The results show that the carbonation conversion of Ca-based absorbent decreases from 72% to 30% after 10 cycles in the calcination/carbonation reaction. The small particle size can improve the carbonation conversion of absorbent. The increase of CO2 concentration in carbonation atmosphere can restrain the decrease of conversion rate in carbonation process. The increase of CO2 concentration in calcination atmosphere can accelerate the decrease of the conversion rate in carbonation conversion process,which results in the decrease of cycle performance for CO2 capture. Water vapour reduces the energy barrier of the diffusion across the solid production,which prolongs carbonation reaction time and increases conversion rate.%针对循环次数、吸收剂粒径的大小、碳酸化气氛中CO2的浓度、煅烧气氛中CO2的浓度和水蒸气的浓度对于钙基吸收剂循环煅烧/碳酸化反应特性的影响,在钙基吸收剂循环煅烧/碳酸化反应实验装置上进行实验研究。结果表明:钙基吸收剂碳酸化阶段的转化率在循环煅烧/碳酸化反应中存在衰减现象,10次循环反应之后,转化率会从72%降至30%以下;吸收剂碳酸化阶段的转化率随其粒径的增大而减小;碳酸化气氛中CO2浓度的提高,会抑制钙基吸收剂碳酸化阶段转化率的衰减;煅烧气氛中CO2浓度的增加会加速钙基吸收剂碳酸化阶段转化率的衰减,导致循环捕集CO2性能锐减;水蒸气能降低固体产物扩散的能量壁垒,延长碳酸化反应时间,提高转化率。

  15. ``Stacked reservoirs`` in the Zechstein 2 carbonate (Ca2): inversion tectonics in the pre-Zechstein subdivision-saline base of the Lower Saxony basin (Germany); ``Stacked Reservoirs`` im Zechstein 2 Karbonat (Ca2): Inversionstektonik im prae-Zechstein-salinaren Sockel des Niedersaechsischen Beckens (NW-Deutschland)

    Energy Technology Data Exchange (ETDEWEB)

    Rockenbauch, K.; Brauckmann, F.; Schaefer, H.G.; Utermoehlen, S. [BEB Erdgas und Erdoel GmbH, Hannover (Germany)

    1998-12-31

    This article looks at areas in the Lower Saxony basis of North-West Germany where the carbonate of the 2nd Zechstein subdivision cycle (Ca2) was tectonically removed from its stratigraphic compound and is found in several stacks elsewhere. Modern 3D seismology and deep drillings were evaluated and tectonic models were developed which could be compared with examples from other saline provinces. This revealed new aspects of exploration for sour natural gas in the Zechstein subdivision (orig.). [Deutsch] Der Artikel behandelt Bereiche innerhalb des Niedersaechsischen Beckens von Nordwestdeutschland, wo das Karbonat des 2. Zechstein-Zyklus (Ca2) tektonisch aus seinem stratigraphischen Verband geloest wurde und an anderer Stelle mehrfach uebereinander gestapelt anzutreffen ist. Hierzu wurden moderne 3D Seismik sowie Tiefbohrungen ausgewertet und tektonische Modelle entwickelt, die mit Beispielen aus anderen Salinarprovinzen verglichen wurden. Hinsichtlich der Exploration auf Sauergas im Zechstein ergeben sich daraus neue Aspekte und Moeglichkeiten. (orig.)

  16. Self-Assembled Enzyme Nanoparticles for Carbon Dioxide Capture.

    Science.gov (United States)

    Shanbhag, Bhuvana Kamath; Liu, Boyin; Fu, Jing; Haritos, Victoria S; He, Lizhong

    2016-05-11

    Enzyme-based processes have shown promise as a sustainable alternative to amine-based processes for carbon dioxide capture. In this work, we have engineered carbonic anhydrase nanoparticles that retain 98% of hydratase activity in comparison to their free counterparts. Carbonic anhydrase was fused with a self-assembling peptide that facilitates the noncovalent assembly of the particle and together were recombinantly expressed from a single gene construct in Escherichia coli. The purified enzymes, when subjected to a reduced pH, form 50-200 nm nanoparticles. The CO2 capture capability of enzyme nanoparticles was demonstrated at ambient (22 ± 2 °C) and higher (50 °C) temperatures, under which the nanoparticles maintain their assembled state. The carrier-free enzymatic nanoparticles demonstrated here offer a new approach to stabilize and reuse enzymes in a simple and cost-effective manner.

  17. Carbon allocation and element composition in four Chlamydomonas mutants defective in genes related to the CO2 concentrating mechanism.

    Science.gov (United States)

    Memmola, Francesco; Mukherjee, Bratati; Moroney, James V; Giordano, Mario

    2014-09-01

    Four mutants of Chlamydomonas reinhardtii with defects in different components of the CO2 concentrating mechanism (CCM) or in Rubisco activase were grown autotrophically at high pCO2 and then transferred to low pCO2, in order to study the role of different components of the CCM on carbon allocation and elemental composition. To study carbon allocation, we measured the relative size of the main organic pools by Fourier Transform Infrared spectroscopy. Total reflection X-ray fluorescence was used to analyze the elemental composition of algal cells. Our data show that although the organic pools increased their size at high CO2 in all strains, their stoichiometry was highly homeostatic, i.e., the ratios between carbohydrates and proteins, lipid and proteins, and carbohydrates and lipids, did not change significantly. The only exception was the wild-type 137c, in which proteins decreased relative to carbohydrates and lipids, when the cells were transferred to low CO2. It is noticeable that the two wild types used in this study responded differently to the transition from high to low CO2. Malfunctions of the CCM influenced the concentration of several elements, somewhat altering cell elemental stoichiometry: especially the C/P and N/P ratios changed appreciably in almost all strains as a function of the growth CO2 concentration, except in 137c and the Rubisco activase mutant rca1. In strain cia3, defective in the lumenal carbonic anhydrase (CA), the cell quotas of P, S, Ca, Mn, Fe, and Zn were about 5-fold higher at low CO2 than at high CO2. A Principle Components Analysis showed that, mostly because of its elemental composition, cia3 behaved in a substantially different way from all other strains, at low CO2. The lumenal CA thus plays a crucial role, not only for the correct functioning of the CCM, but also for element utilization. Not surprisingly, growth at high CO2 attenuated differences among strains.

  18. Observations of the uptake of carbonyl sulfide (COS by trees under elevated atmospheric carbon dioxide concentrations

    Directory of Open Access Journals (Sweden)

    L. Sandoval-Soto

    2012-08-01

    Full Text Available Global change forces ecosystems to adapt to elevated atmospheric concentrations of carbon dioxide (CO2. We understand that carbonyl sulfide (COS, a trace gas which is involved in building up the stratospheric sulfate aerosol layer, is taken up by vegetation with the same triad of the enzymes which are metabolizing CO2, i.e. ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, phosphoenolpyruvate carboxylase (PEP-Co and carbonic anhydrase (CA. Therefore, we discuss a physiological/biochemical acclimation of these enzymes affecting the sink strength of vegetation for COS. We investigated the acclimation of two European tree species, Fagus sylvatica and Quercus ilex, grown inside chambers under elevated CO2, and determined the exchange characteristics and the content of CA after a 1–2 yr period of acclimation from 350 ppm to 800 ppm CO2. We demonstrate that a compensation point, by definition, does not exist. Instead, we propose to discuss a point of uptake affinity (PUA. The results indicate that such a PUA, the CA activity and the deposition velocities may change and may cause a decrease of the COS uptake by plant ecosystems, at least as long as the enzyme acclimation to CO2 is not surpassed by an increase of atmospheric COS. As a consequence, the atmospheric COS level may rise causing an increase of the radiative forcing in the troposphere. However, this increase is counterbalanced by the stronger input of this trace gas into the stratosphere causing a stronger energy reflection by the stratospheric sulfur aerosol into space (Brühl et al., 2012. These data are very preliminary but may trigger a discussion on COS uptake acclimation to foster measurements with modern analytical instruments.

  19. EFFECT OF MAGNETIC FIELD ON CRYSTALLIZATION PROCESS OF CALCIUM CARBONATE%磁场对CaCO3结晶过程的影响

    Institute of Scientific and Technical Information of China (English)

    张东升; 刘振法

    2006-01-01

    本文利用电导率的变化,研究了磁场对CaCO3结晶过程的影响,发现当Ca2+浓度高于2mmol/L、磁化水的水温低于70℃时,磁场有加快碳酸钙结晶的作用;磁化水经过磁水器次数多,则促进碳酸钙结晶的作用强.

  20. Carbonic Anhydrase IX Expression Correlates with FDG Uptake by Primary Non-Small Cell Lung Cancer

    NARCIS (Netherlands)

    Mees, Gilles; Vangestel, Christel; Dierckx, Rudi; Pauwels, Patrick; Van Meerbeeck, Jan; Van de Wiele, Christophe

    2010-01-01

    Tumor cells are characterized by an increased rate of glucose consumption and glycolysis. This increased glucose consumption leads to tumor acidification, which represents a major obstacle for several therapeutic strategies. Tumor cells have adapted to this acidification by upregulation of several H

  1. Effect of electrostatic interactions on the formation of proton transfer pathways in human carbonic anhydrase II

    Indian Academy of Sciences (India)

    Arijit Roy; Srabani Taraphder

    2007-09-01

    We report here a theoretical study on the effect of electrostatic interactions on the formation of dynamical, proton-conducting hydrogen-bonded networks in the protein HCA II. The conformational fluctuations of His-64 is found to contribute crucially to the mechanism of such path formation irrespective of the way electrostatic interactions are modelled.

  2. Cadmium tolerance of carbon assimilation enzymes and chloroplast in Zn/Cd hyperaccumulator Picris divaricata.

    Science.gov (United States)

    Ying, Rong-Rong; Qiu, Rong-Liang; Tang, Ye-Tao; Hu, Peng-Jie; Qiu, Hao; Chen, Hong-Ru; Shi, Tai-Hong; Morel, Jean-Louis

    2010-01-15

    To better understand the photosynthesis under stress, the effect of cadmium on carbon assimilation and chloroplast ultrastructure of a newly found Zn/Cd hyperaccumulator Picris divaricata in China was investigated in solution culture. The shoot and root Cd concentrations increased with increase in Cd supply, reaching maxima of 1109 and 5604mgkg(-1) dry weight at 75microM Cd, respectively. As Cd supply to P. divaricata increased, the shoot and root dry weight, leaf water content (except 75microM Cd), concentrations of chlorophyll a and b, chlorophyll a/b ratio and the concentration of carotenoids were not depressed at high Cd. However, the stomatal conductance, transpiration rate, net photosynthetic rate and intercellular CO(2) concentration were significantly affected when the Cd concentration reached 10, 10, 25 and 75microM, respectively. Meanwhile, carbonic anhydrase (CA; EC 4.2.1.1) activity and Rubisco (EC 4.1.1.39) content reached maxima in the presence of 50 and 5microM Cd, respectively. In addition, CA activity correlated positively with shoot Cd in plants treated with Cd at a range of 0-50microM. Moreover, the activities of NADP(+)-glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.13), Rubisco and fructose-1, 6-bisphosphatase (EC 3.1.3.11) were not significantly suppressed by increased Cd supply. Although the mesophyll cell size was reduced, chloroplast ultrastructure remained intact at the highest Cd treatment. Our finding revealed that P. divaricata chloroplast and the enzymes of carbon assimilation tolerate high levels of Cd, demonstrating its potential in possible application in phytoremediation. PMID:19683362

  3. Evaluation of the potential of additives as corrosion inhibitors of CA-50 carbon steel used as reinforcement in concretes; Avaliacao da potencialidade de aditivos como inibidores de corrosao do aco carbono CA-50 usado como armadura de estruturas de concreto

    Energy Technology Data Exchange (ETDEWEB)

    Mennucci, Marina Martins

    2006-07-01

    In this work, various compounds were tested to evaluate their potential capability for their use as corrosion inhibitors of carbon steel reinforcement in concretes. The additives tested were sodium benzoate, polyethylene glycol, hexamethylenetetramine, benzotriazole and yttrium carbonate. Initially, exploratory tests were carried out to select the ones to be used as corrosion inhibitors, based on the inhibit ion efficiency determined from electrochemical tests, specifically polarization tests and electrochemical impedance spectroscopy. These tests were carried out in a solution composed of 0.01 N sodium hydroxide (NaOH) and 0.05 N potassium hydroxide (KOH) to simulate the composition of the solution inside the pores in concretes. The additive that presented the most promising potential to be used as corrosion inhibitor was benzotriazole (BTA). After the elimination of some compounds and selection of the additive with higher corrosion inhibit ion efficiency in the test medium, the effect of its concentration on the corrosion inhibition efficiency was evaluated. Sodium nitrite solutions with the same concentrations as those solutions with BTA were tested for comparison reasons. Sodium nitrite is a well established corrosion inhibitor for carbon steel reinforcement in concretes but it has been related to toxic effects. The BTA was associated to higher corrosion inhibition efficiencies than that of sodium nitrite in similar concentrations. A blackish adherent film was formed on the steel surface exposed to BTA solutions during long periods of immersion in the alkaline medium. The results suggest that BTA is a potential candidate for substitution of nitrites as corrosion inhibitor of reinforcements in concrete. (author)

  4. LDEO Carbonate Data - CaCO3 Percentages for 328 Sediments Cores, Principally from The Atlantic Ocean Spanning 100,000 to 200,000 Years bp

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — LDEO Carbonate data were compiled under the direction of A. Esmay and W.F. Ruddiman at the Lamont-Doherty Earth Observatory of Columbia University. Data include...

  5. Biomimetic sequestration of CO2 in carbonate form: Role of produced waters and other brines

    International Nuclear Information System (INIS)

    The objective of our research is the development of a system resembling a CO2 scrubber, in which carbonic anhydrase catalyzes the rate of CO2 hydration for subsequent fixation into stable mineral carbonates. The present focus is on the use of produced waters as one of various possible sources of the counterions for precipitation. Carbonate precipitation has been studied from synthetic brines corresponding to a range of compositions of produced waters from the Permian and San Juan Basins, and promising results have been obtained with carbonic anhydrase. CO2 sequestration capacities are estimated to be 0.49-1.85x103 tonnes CO2/year and 1.28-2.80x105 tonnes CO2/year for the San Juan and Permian Basins, respectively, per cycle, up to ∼3mt CO2 per year total, based on the volumes of produced waters in 2002. (author)

  6. Covalent enzyme immobilization onto carbon nanotubes using a membrane reactor

    Science.gov (United States)

    Voicu, Stefan Ioan; Nechifor, Aurelia Cristina; Gales, Ovidiu; Nechifor, Gheorghe

    2011-05-01

    Composite porous polysulfone-carbon nanotubes membranes were prepared by dispersing carbon nanotubes into a polysulfone solution followed by the membrane formation by phase inversion-immersion precipitation technique. The carbon nanotubes with amino groups on surface were functionalized with different enzymes (carbonic anhydrase, invertase, diastase) using cyanuric chloride as linker between enzyme and carbon nanotube. The composite membrane was used as a membrane reactor for a better dispersion of carbon nanotubes and access to reaction centers. The membrane also facilitates the transport of enzymes to active carbon nanotubes centers for functionalization (amino groups). The functionalized carbon nanotubes are isolated by dissolving the membranes after the end of reaction. Carbon nanotubes with covalent immobilized enzymes are used for biosensors fabrications. The obtained membranes were characterized by Scanning Electron Microscopy, Thermal analysis, FT-IR Spectroscopy, Nuclear Magnetic Resonance, and functionalized carbon nanotubes were characterized by FT-IR spectroscopy.

  7. Low energy 40Ca + 40Ca collisions

    International Nuclear Information System (INIS)

    This paper deals with the classical microscopic study of 40Ca + 40Ca collisions. Fusion cross-sections (σsub(CF)) for various incident energies, energy variations with time, shape deformation and the life time of resonance scattering (T) have been studied. Comparison of 40Ca + 40Ca results with those of 16O + 16O have also been made. (author)

  8. Synthesis, characterization and solubility of alkaline earth uranyl carbonates M2[UO2(CO3)3].xH20; M: Mg, Ca, Sr, Ba

    International Nuclear Information System (INIS)

    The release and dispersion of uranium from closed uranium mining sites and the resulting uranium contamination of the natural environment of such sites is a major problem examined in this dissertation. Knowledge of the pollution pathways and processes is indispensable for an assessment of the radiological implications for the human population, to be taken into account in the planning of site rehabilitation work. The formation of secondary uranium minerals may contribute to an immobilization of the uranium, but it is possible as well that such secondary uranium minerals will release uranium. A major task of this dissertation therefore was to examine the conditions of formation of alkaline earth uranyl carbonates in the context of their natural occurrence as observed at some sites, and to answer the question of whether hitherto unknown alkaline earth uranyl carbonates may form in the natural environment, and ought to be taken into account as new source terms. (orig./CB)

  9. Contrasting modes of inorganic carbon acquisition amongst Symbiodinium (Dinophyceae) phylotypes.

    Science.gov (United States)

    Brading, Patrick; Warner, Mark E; Smith, David J; Suggett, David J

    2013-10-01

    Growing concerns over ocean acidification have highlighted the need to critically understand inorganic carbon acquisition and utilization in marine microalgae. Here, we contrast these characteristics for the first time between two genetically distinct dinoflagellate species of the genus Symbiodinium (phylotypes A13 and A20) that live in symbiosis with reef-forming corals. Both phylotypes were grown in continuous cultures under identical environmental conditions. Rubisco was measured using quantitative Western blots, and radioisotopic (14) C uptake was used to characterize light- and total carbon dioxide (TCO2 )-dependent carbon fixation, as well as inorganic carbon species preference and external carbonic anhydrase activity. A13 and A20 exhibited similar rates of carbon fixation despite cellular concentrations of Rubisco being approximately four-fold greater in A13. The uptake of CO2 over HCO3 - was found to support the majority of carbon fixation in both phylotypes. However, A20 was also able to indirectly utilize HCO3 - by first converting it to CO2 via external carbonic anhydrase. These results show that adaptive differences in inorganic carbon acquisition have evolved within the Symbiodinium genus, which thus carries fundamental implications as to how this functionally key genus will respond to ocean acidification, but could also represent a key trait factor that influences their productivity when in hospite of their coral hosts.

  10. Proteomic analysis of carbon concentrating chemolithotrophic bacteria Serratia sp. for sequestration of carbon dioxide.

    Directory of Open Access Journals (Sweden)

    Randhir K Bharti

    Full Text Available A chemolithotrophic bacterium enriched in the chemostat in presence of sodium bicarbonate as sole carbon source was identified as Serratia sp. by 16S rRNA sequencing. Carbon dioxide sequestering capacity of bacterium was detected by carbonic anhydrase enzyme and ribulose-1, 5- bisphosphate carboxylase/oxygenase (RuBisCO. The purified carbonic anhydrase showed molecular weight of 29 kDa. Molecular weight of RuBisCO was 550 kDa as determined by fast protein liquid chromatography (FPLC, however, sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE showed presence of two subunits whose molecular weights were 56 and 14 kDa. The Western blot analysis of the crude protein and purified sample cross reacted with RuBisCO large-subunit polypeptides antibodies showed strong band pattern at molecular weight around 56 kDa regions. Whole cell soluble proteins of Serratia sp. grown under autotrophic and heterotrophic conditions were resolved by two-dimensional gel electrophoresis and MALDI-TOF/MS for differential expression of proteins. In proteomic analysis of 63 protein spots, 48 spots were significantly up-regulated in the autotrophically grown cells; seven enzymes showed its utilization in autotrophic carbon fixation pathways and other metabolic activities of bacterium including lipid metabolisms indicated sequestration potency of carbon dioxide and production of biomaterials.

  11. 水蒸气改善钙基CO2吸收剂循环活性的研究%Study on the improvement of the carbonation characteristics of Ca-based CO2 absorbent by steam repetitive calcination-carbonation

    Institute of Scientific and Technical Information of China (English)

    乔春珍; 陈伟娇

    2012-01-01

    Repetitive calcination-carbonation of Ca-based CO2 absorbent with adding steam was performed experimentally to investigate the effect of steam on the cyclic characteristics of Ca-based CO2 absorbent. The maximum conversion rate, pore radius and specific surface area microstructure of hydrated Ca-based CO2 absorbent was analyzed. Results showed that the cyclic characteristics of the hydrated Ca-based CO2 absorbent was improved, the maximum conversion of Ca-based CO; absorbent was increased by 50 % than dry ones. The reason was that the steam treatment could greatly increase the specific surface area of the absorbent and improve the distributions of pore radius. From the experiment we can conclude that direct hydrogen production by carbon energy could be realized without any additives or auxiliary conditions, which would meatain the cyclic activity of Ca-based CO2 absorbent.%对钙基CO2吸收剂的循环活性改善进行了研究,分析了水蒸气处理对吸收剂的最大转化率、比表面积及孔分布等微观结构变化的影响.结果表明,经水蒸气处理后,钙基CO2吸收剂的循环活性得到了改善,最大转化率比未经水蒸气处理可提高约50百分点;水蒸气处理可大大提高钙基CO2吸收剂的比表面积,并有效改善其孔径分布状态,可使其稳定保持较高的转化率;含碳能源直接制氢过程可在不需要任何添加剂或辅助手段的条件下,有效保持钙基CO2吸收剂的循环活性.

  12. Carbonyl sulfide (COS) as a tracer to constrain surface carbon fluxes

    Science.gov (United States)

    Yakir, Dan; Berkelhammer, Max; Miller, John; Montzka, Steve; Chen, Huilin

    2014-05-01

    The potential use of COS as tracer of CO2 flux into leaves associated gross primary productivity (GPP), and separately from CO2 flux associated with ecosystem respiration (Re), stimulate research on COS-CO2 interactions during biosphere-atmosphere gas exchange. This is based on the observation that COS co-diffuse with CO2 into vegetation, but without an emission outflux. Recent advances in laser spectroscopy and the availability of high precision field deployable quantum cascade laser systems resulted in accumulation of new results from laboratory-scale control experiments, field studies, atmospheric measurements and, in turn, large scale modeling. These studies demonstrate the potential in the COS application to carbon cycle research, but also highlight key uncertainties, such as associated with soil uptake of COS. Soil uptake is based on dissolution and hydrolysis in soil moisture, which can be enhanced by carbonic anhydrase (CA) that can exist in soil and litter and microorganisms. Our recent in-situ measurements over the diurnal cycle and across a range of ecosystems and tree species supported the idea of a robust COS to CO2 uptake ratio of near 1.6, and indicated that soils act mostly as a relatively small COS sink, equivalent to 2-6% of canopy uptake during peak activity period. The results also indicated that small soil net COS emission can be observed under certain conditions. The importance of CA activities has been demonstrated in soils in CO2 studies using stable isotopes (18O), and for COS in leaves using anti-sense lines, but quantifying its importance for soil COS uptake is still lacking. Measurements in canopy air showed that the daily co-variation between COS and CO2 reflects the interplay among the effects of soil, leaf and atmospheric boundary layer dynamics. Further extending observations to background tropospheric measurements of the seasonal drawdown in CO2 and in COS demonstrates that comparing the drawdowns of COS, CO2 and its 13C, could

  13. Corrosion Inhibition by Sorbitol/Diethylenetriamine Condensation Product for Carbon Steel in 3.5% NaCl Saturated Ca(OH)2 Solution%3.5%NaCl饱和Ca(OH)2溶液中醇胺缩聚物对碳钢腐蚀的抑制

    Institute of Scientific and Technical Information of China (English)

    周欣; 杨怀玉; 王福会

    2011-01-01

    The inhibitive action of a sorbitol/diethylenetriamine condensation (SDC) product toward carbon steel corrosion in saturated Ca(OH)2 solution containing 3.5% NaCl was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), surface morphological observations, and quantum chemical calculations. The results indicate that the addition of SDC can effectively decrease the corrosion current densities of the carbon steel and increase the pitting corrosion potential suggesting that the local corrosion induced by CI- is strongly restricted by the inhibitor, which acts as a mixed type inhibitor. In the studied concentration range, the inhibition efficiency increased with an increase in inhibitor concentration. The overall inhibition behavior of SDC is attributed to the stabile adsorption film formd by the dominantly physical adsorption on the carbon steel surface according to the Langmuir adsorption isotherm.%利用动电位极化,电化学阻抗谱(EIS)和表面形貌观察方法,并结合量子化学计算,在3.5%NaCl饱和Ca(OH)2溶液中研究探讨了山梨醇与二乙烯三胺缩聚物(SDC)对碳钢腐蚀的抑制行为.结果表明:SDC的加入可有效降低碳钢的腐蚀电流密度,提高碳钢的点蚀电位,表明阻绣剂对Cl-诱导的局部腐蚀具有良好的抑制作用,为混合型阻锈剂;且在所研究浓度范围内,随添加浓度增加,缓蚀效率提高.化合物对碳钢腐蚀的抑制主要源自阻锈剂分子在碳钢表面的静电吸附,且吸附遵循Langmuir等温吸附规律.

  14. Effect of synthetic carbon amino saccharides on the transfer of labeled mineral 45Ca2+ and 32PO 4 3- ions from drinking water to blood serum in mice

    Science.gov (United States)

    Navarrete, J. M.; Muller, G.; Martinez, T.; Cabrera, L.; Gracia, I.; Fabila, L.; Urbina, V. M.

    2006-01-01

    The favorable effects of fulvic acids as fertilizers are very well known and they have been used long time ago in their natural state in dead leaves. Their extraction from natural sources is rather expensive, but the production of very similar carbon amino saccharides by sugar oxidation has been industrially applied in Mexico. Good properties of this commercial product as fertilizer have been proved empirically in different crops as well as at laboratory level, by the efficient absorption of radioactive labeled mineral ions in vegetables when they are carried by this synthetic organic matter in aqueous solution. Now, its effect has been tested by filtration of radioactively labeled 45Ca2+ and 32PO 4 3- ions from drinking water to blood serum through mice liver and kidneys. The results indicate that the filtration and diffusion of these mineral ions also improved, the same that in vegetables, in the presence of the synthetic carbon amino saccharides highly soluble in water. These results suggest the appropriateness of further research to evaluate their possible use either as a dietary complement or as auxiliaries in the treatment of liver and kidney diseases.

  15. Brain carbonic acid acidosis after acetazolamide

    DEFF Research Database (Denmark)

    Heuser, D; Astrup, J; Lassen, N A;

    1975-01-01

    of the carbonic anhydrase inhibition on the brain tissue. As a further support for this conclusion was considered the finding of a prolonged response time of brain pH to HCO3-minus i.v. to CO2-minus inhalation, and to hyperventilation after the acetazolamide inhibtion. No changes in brain extracelllular potassium......In cats in barbiturate anesthesia extracellular pH and potassium were continously recorded from brian cortex by implanted microelectrodes. Implantation of the electrodes preserved the low permeability of the blood-brain-barrier to HCO3-minus and H+ions as indicated by the development of brain...

  16. Simulation Experiments on the Reaction of CH4-CaSO4 and Its Carbon Kinetic Isotope Fractionation%甲烷和硫酸钙反应体系热模拟实验及碳同位素分馏研究

    Institute of Scientific and Technical Information of China (English)

    岳长涛; 李术元; 丁康乐; 钟宁宁

    2005-01-01

    Thermochemical sulfate reduction (TSR) in geological deposits can account for the accumulation of H2S in deep sour gas reservoirs. In this paper, thermal simulation experiments on the reaction of CH4-CaSO4 were carried out using an autoclave at high temperatures and high pressures. The products were characterized with analytical methods including carbon isotope analysis. It is found that the reaction can proceed to produce H2S, H2O and CaCO3 as the main products. Based on the experimental results, the carbon kinetic isotope fractionation was investigated, and the value of Ki (kinetic isotope effect) was calculated. The results obtained in this paper can provide useful information to explain the occurrence of H2S in deep carbonate gas reservoirs.

  17. Effects of Sodium Sulfate and Sodium Chloride on Ca2+ , Mg2+ Removal from Glauber Type Brine by Sodium Hydroxide and Sodium Carbonate%芒硝型卤水中盐硝组分对碱法脱除钙镁的影响

    Institute of Scientific and Technical Information of China (English)

    董泽亮; 张琦; 王俐聪; 蔡荣华; 马来波; 黄西平

    2013-01-01

    Ca2+ 、Mg2+ removal from Glauber type brine by sodium hydroxide and sodium carbonate has been studied.The effects of sodium sulfate and sodium chloride on removal efficiency of Ca2+,Mg2+ at room temperature were investigated in detail when addition amount of sodium hydroxide and sodium carbonate was theoretical value,reaction time was 30 min,aging time was 60 min.The experimental results show that the presence of sodium sulfate has large effect on removal efficiency of Ca2+.The removal rate of Ca2+ is more than 90% when the concentration of sodium sulfate is below 30 g/L.The presence of sodium sulfate has good but little effect on removal efficiency of Mg2+.The presence of sodium chloride has small effect on removal efficiency of Ca2+ and Mg2+.When the concentration of sodium chloride increases,the removal rate of Ca2+ increases significantly,but the removal rate of Mg2+ declines slightly.%采用“烧碱-纯碱”法,对芒硝型卤水中Ca2+和Mg2+的脱除进行了研究,在常温、两碱用量为理论用量、反应时间为30 min和陈化时间为60 min的条件下详细考察了卤水中氯化钠和硫酸钠含量的变化对Ca2+和Mg2脱除效果的影响.结果表明,硫酸钠组分对Ca2+的脱除效果影响较大,当硫酸钠含量在30 g/L以下时,Ca2+脱除率在90%以上,硫酸钠浓度增加有利于Mg2+的脱除,但影响不大.氯化钠组分对Ca2、Mg2+脱除效果的影响相对较小,氯化钠含量增加,Ca2+脱除率明显增加,而Mg2+脱除率略有下降.

  18. Sulfide capacity of CaO-CaF2-SiO2 slags

    Science.gov (United States)

    Susaki, Katsujiro; Maeda, Masafumi; Sano, Nobuo

    1990-02-01

    The sulfide capacity C S 2- = (pct S2-) · ( P O 2/ P S 2)1/2) of CaO-CaF2-SiO2 slags saturated with CaO, 3CaO · SiO2 or 2CaOSiO2 was determined at 1200 °C, 1250 °C, 1300 °C, and 1350 °C by equilibrating molten slag, molten silver, and CO-CO2 gas mixtures. Higher sulfide capacities were obtained for CaO-saturated slags. A drastic decrease was observed in those values when the ratio pct CaO/pct SiO2 is less than 2. The sulfur partition between carbon-saturated iron melts and presently investigated slags was calculated by using the sulfide capacities obtained and the activity coefficient of sulfur in carbon-saturated iron, which was also experimentally determined. For slags saturated with CaO, partitions of sulfur as high as 10,000 were obtained at 1300 °C and 1350 °C. Correlations between the sulfide capacity and other basicity indexes such as carbonate capacity and theoretical optical basicity were also discussed.

  19. Preparation of Ultrafine Calcium Carbonate with Different Shapes and Their Applications in the HTPB Propellant%多种形状超细CaCO3的制备及在HTPB推进剂中的应用

    Institute of Scientific and Technical Information of China (English)

    李晓东; 杨荣杰; 杨燕

    2009-01-01

    用微乳液法制备了棒状、纺锤形、椭球形、竹节状、球形、树枝状、珊瑚状、黏连状、立方形和片状的超细CaCO3,用X射线衍射(XRD)和扫描电子显微镜(SEM)对超细CaCO3进行了表征.研究了普通CaCO3、立方形超细CaCO3、球形超细CaCO3和用乳化剂处理后的球形超细CaCO3对HTPB推进剂燃速的影响.结果表明,超细CaCO3以方解石和文石晶型存在,其粒径小于1 μm.不同实验条件对超细CaCO3的形貌影响很大.3%的普通CaCO3、立方形超细CaCO3、球形超细CaCO3和用乳化剂处理后的球形超细CaCO3使HTPB推进剂在7 MPa下的燃速分别降低了29.6%、39.3%、46.2%和48.6%.超细CaCO3降低HTPB推进剂燃速的幅度大于普通CaCO3.CaCO3处理方法对其降低HTPB推进剂燃速影响不大.

  20. Pressure-induced structural transformation of CaC2

    Science.gov (United States)

    Wang, Lu; Huang, Xiaoli; Li, Da; Huang, Yanping; Bao, Kuo; Li, Fangfei; Wu, Gang; Liu, Bingbing; Cui, Tian

    2016-05-01

    The high pressure structural changes of calcium carbide CaC2 have been investigated with Raman spectroscopy and synchrotron X-ray diffraction (XRD) techniques in a diamond anvil cell at room temperature. At ambient conditions, two forms of CaC2 co-exist. Above 4.9 GPa, monoclinic CaC2-ii diminished indicating the structural phase transition from CaC2-ii to CaC2-i. At about 7.0 GPa, both XRD patterns and Raman spectra confirmed that CaC2-i transforms into a metallic Cmcm structure which contains polymeric carbon chains. Along with the phase transition, the isolated C2 dumbbells are polymerized into zigzag chains resulting in a large volume collapse with 22.4%. Above 30.0 GPa, the XRD patterns of CaC2 become featureless and remain featureless upon decompression, suggesting an irreversible amorphization of CaC2.

  1. Development and Evaluation of a Novel Integrated Vacuum Carbonate Absorption Process

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yongqi; Rostam-Abadi, Massoud; Ye, Xinhuai; Zhang, Shihan; Ruhter, David; Khodayari, Arezoo; Rood, Mark

    2012-04-30

    This project was aimed at obtaining process engineering and scale-up data at a laboratory scale to investigate the technical and economic feasibility of a patented post-combustion carbon dioxide (CO{sub 2}) capture process?the Integrated Vacuum Carbonate Absorption Process (IVCAP). Unique features of the IVCAP include its ability to be fully-integrated with the power plant?s steam cycle and potential for combined sulfur dioxide (SO{sub 2}) removal and CO{sub 2} capture. Theoretical and experimental studies of this project were aimed at answering three major technical questions: 1) What additives can effectively reduce the water vapor saturation pressure and energy requirement for water vaporization in the vacuum stripper of the IVCAP? 2) What catalysts can promote CO{sub 2} absorption into the potassium carbonate (PC) solution to achieve an overall absorption rate comparable to monoethanolamine (MEA) and are the catalysts stable at the IVCAP conditions and in the flue gas environment? 3) Are any process modifications needed to combine SO{sub 2} and CO{sub 2} removal in the IVCAP? Lab-scale experiments and thermodynamic and process simulation studies performed to obtain detailed information pertinent to the above three technical questions produced the following results: 1) Two additives were identified that lower the saturation pressure of water vapor over the PC solution by about 20%. 2) The carbonic anhydrase (CA) enzyme was identified as the most effective catalyst for promoting CO{sub 2} absorption. The absorption rate into the CO{sub 2}-lean PC solution promoted with 300 mg/L CA was several times slower than the corresponding 5 M MEA solution, but absorption into the CO{sub 2}-rich PC solution was comparable to the CO{sub 2}-rich MEA solution. The tested CA enzymes demonstrated excellent resistance to major flue gas impurities. A technical-grade CA enzyme was stable at 40{degrees}C (104{degrees}F) over a six-month test period, while its half-life was about two

  2. Inorganic Carbon Utilization in Some Marine Phytoplankton Species%海洋浮游藻类无机碳利用机理的研究

    Institute of Scientific and Technical Information of China (English)

    缪晓玲; 吴庆余

    2002-01-01

    In order to learn the ways and possible utilization mechanisms of dissolved inorganic carbon (DIC) in marine phytoplankton species under carbon-replete or -limited conditions, the activity of extracellular carbonic anhydrase (CA) was assayed in different pH, CO2 and DIC concentrations. Extracellular CA in Amphidinium carterae and Prorocentrum minimum was detected under carbon-replete conditions, while in Melosira sp., Phaeodactylum tricornutum, Skeletonema costatum, Thalassiosira rotula, Emiliania huxleyi and Pleurochrysis carterae, CA activity was assayed under conditions of carbon limitation. No CA activity was found even under carbon-limited conditions in Chaetoceros compressus, Glenodinium foliaceum, Coccolithus pelagicus, Gephrocapsa oceanica and Heterosigma akashiwo. In species without extracellular CA activity, the direct HCO-3 uptake was investigated using a pH drift technique and the anion exchange inhibitor 4′4′-diisothiocyanatostilbene-2,2-disulfonic acid (DIDS) in a closed system. The result showed that direct HCO-3 transport might occur by an anion exchange mechanism in species Coc. pelagicus and G. oceanica. Of the 13 species investigated, only H. akashiwo did not have the potential for direct uptake or extracellular CA-catalyzed HCO-3 utilization.%为了认识海洋浮游藻类在碳充足和碳受限条件下对水体中溶解无机碳(DIC)的利用方式与可能机理,对13种海洋浮游藻类在不同pH和CO2浓度及不同DIC条件下细胞外碳酸酐酶(CA)的活性进行了分析测定.结果显示:13种藻中,只有Amphidinium carterae和Prorocentrum minimum在碳充足条件下具细胞外CA活性.Melosira sp.、Phaeodactylum tricornutum、Skeletonema costatum、Thalassiosira rotula、Emiliania huxleyi和Pleurochrysis carterae则在碳受限条件下才具细胞外CA活性.Chaetoceros compressus、Glenodinium foliaceum、Coccolithus pelagicus、 Gephrocapsa oceanica和Heterosigma akashiwo即使在碳受限条件下也未检测到细

  3. Carbonate precipitates and bicarbonate secretion in the intestine of sea bass, Dicentrarchus labrax.

    Science.gov (United States)

    Faggio, Caterina; Torre, Agata; Lando, Gabriele; Sabatino, Giuseppe; Trischitta, Francesca

    2011-05-01

    The aim of this paper was to study the chemical composition of the precipitates found in the intestine of Dicentrarchus labrax and the source of HCO(3)(-) secreted into the intestinal lumen. The chemical analysis was performed by employing the potentiometric double titration method and by means of an electron microscope coupled with a spectrometer and X-ray powder diffraction. The results obtained suggest the presence of very insoluble intestinal precipitates, presumably formed by a mixture of CaCO(3) and MgCO(3), with a higher quantity of the former with respect to the latter. HCO(3)(-) secretion rate was investigated with the aid of the pH stat method in isolated tissues mounted in Ussing chamber, where the transepithelial electrical parameters were also measured. When the serosal surface of the intestinal mucosa was bathed in HCO(3)(-)-Ringer bubbled with 1% CO(2) in O(2) while the serosal surface was bathed in HCO(3)(-) free Ringer solution bubbled with pure O(2), bicarbonate secretion proceeded at an almost stable rate of 0.9 ± 0.05 μeq cm(-2) h(-1) for about 3 h while I(sc) maintained a constant value of 38 ± 1.5 μA cm(-2). The carbonic anhydrase inhibitor ethoxyzolamide elicited a progressive reduction of HCO(3)(-) secretion that was about 75% of the initial value after 80 min. When serosal HCO(3)(-)-CO(2) saline was substituted with Hepes-O(2) saline base secretion progressively declined reaching a value of about 20% of the initial value. It was also strongly inhibited when Na(+) was substituted with the impermeant cation choline and when either DIDS or ouabain were added to the basolateral side. These results suggest that most of the bicarbonate secreted is of extracellular source and is probably transported across the basolateral membrane by both Na(+) independent mechanism and Na(+) dependent transporter, presumably a NaHCO(3) cotransport. PMID:21152925

  4. Cryptococcus neoformans Senses CO2 through the Carbonic Anhydrase Can2 and the Adenylyl Cyclase Cac1

    OpenAIRE

    Mogensen, Estelle Gewiss; Janbon, Guilhem; Chaloupka, James; Steegborn, Clemens; Fu, Man Shun; Moyrand, Frédérique; Klengel, Torsten; Pearson, David S.; Geeves, Michael A.; Buck, Jochen; Levin, Lonny R.; Mühlschlegel, Fritz A.

    2006-01-01

    Cryptococcus neoformans, a fungal pathogen of humans, causes fatal meningitis in immunocompromised patients. Its virulence is mainly determined by the elaboration of a polysaccharide capsule surrounding its cell wall. During its life, C. neoformans is confronted with and responds to dramatic variations in CO2 concentrations; one important morphological change triggered by the shift from its natural habitat (0.033% CO2) to infected hosts (5% CO2) is the induction of capsule biosynthesis. In ce...

  5. Combination of carbonic anhydrase inhibitor, acetazolamide, and sulforaphane, reduces the viability and growth of bronchial carcinoid cell lines

    International Nuclear Information System (INIS)

    Bronchial carcinoids are pulmonary neuroendocrine cell-derived tumors comprising typical (TC) and atypical (AC) malignant phenotypes. The 5-year survival rate in metastatic carcinoid, despite multiple current therapies, is 14-25%. Hence, we are testing novel therapies that can affect the proliferation and survival of bronchial carcinoids. In vitro studies were used for the dose–response (AlamarBlue) effects of acetazolamide (AZ) and sulforaphane (SFN) on clonogenicity, serotonin-induced growth effect and serotonin content (LC-MS) on H-727 (TC) and H-720 (AC) bronchial carcinoid cell lines and their derived NOD/SCID mice subcutaneous xenografts. Tumor ultra structure was studied by electron microscopy. Invasive fraction of the tumors was determined by matrigel invasion assay. Immunohistochemistry was conducted to study the effect of treatment(s) on proliferation (Ki67, phospho histone-H3) and neuroendocrine phenotype (chromogranin-A, tryptophan hydroxylase). Both compounds significantly reduced cell viability and colony formation in a dose-dependent manner (0–80 μM, 48 hours and 7 days) in H-727 and H-720 cell lines. Treatment of H-727 and H-720 subcutaneous xenografts in NOD/SCID mice with the combination of AZ + SFN for two weeks demonstrated highly significant growth inhibition and reduction of 5-HT content and reduced the invasive capacity of H-727 tumor cells. In terms of the tumor ultra structure, a marked reduction in secretory vesicles correlated with the decrease in 5-HT content. The combination of AZ and SFN was more effective than either single agent. Since the effective doses are well within clinical range and bioavailability, our results suggest a potential new therapeutic strategy for the treatment of bronchial carcinoids

  6. Carbon anhydrase IX specific immune responses in patients with metastatic renal cell carcinoma potentially cured by interleukin-2 based immunotherapy

    DEFF Research Database (Denmark)

    Rasmussen, Susanne; Donskov, Frede; Pedersen, Johannes W;

    2013-01-01

    carcinoma (mRCC). However, the involvement of CAIX specific CD8+ T cells and/or NK cells in the tumor eradication is unknown. We investigated T cell and antibody reactivity against overlapping 15-mer CAIX-peptides as well as HLA haplotype frequency and NK cell cytotoxicity in 11 patients with no evidence of...... during treatment and samples from healthy controls. We observed more focused but only weak and not consistent CAIX specific T-cells in the late observation and early observation response groups compared with the healthy control group. An increased frequency of the class II alleles HLA-DRB4 01:01, HLA......-DPB 01:01 and HLA-DPB 03:01 was noted in the NED patients. In contrast, NK cytotoxicity was low even in the late observation response group as compared with controls. In particular, a HLA-B*40:01 restricted CD8+ T cell response recognizing the CAIX- derived peptide SEEEGSLKL was identified. This may have...

  7. Precipitation kinetics of calcite in the system CaCO 3H2OC02: The conversion to CO 2 by the slow process H ++HCO 3- → CO 2+H 2O as a rate limiting step

    Science.gov (United States)

    Dreybrodt, W.; Eisenlohr, L.; Madry, B.; Ringer, S.

    1997-09-01

    Precipitation rates of CaCO 3 from supersaturated solutions in the H 2OCO 2CaCO 3 system are controlled by three rate-determining processes: the kinetics of precipitation at the mineral surface, mass transport of the reaction species involved to and from the mineral surface, and the slow kinetics of the overall reaction HCO 3-+H + → CO 2+H 2O. A theoretical model by Buhmann and Dreybrodt (1985a,b) taking these processes into account predicts that, due to the slow kinetics of this reaction, precipitation rates to the surface of CaC0 3 minerals depend critically on the ratio V/A of the volume V of the solution to the surface area A of the mineral in contact with it, for both laminar and turbulent flow. We have performed measurements of precipitation rates in a porous medium of sized particles of marble, limestone, and synthetic calcite, with V/A ratios ranging from 3·10 -4 to 1.2·10 -2 cm at 10°C. Calcite was precipitated from supersaturated solutions with [Ca 2+] ≈ 4 mmol/L and an initial PCO2 of 5·10 -3 or 1·10 -3 atm, respectively, using experimental conditions which prevented exchange of CO 2 with the atmosphere, i.e., closed system. The results are in qualitative agreement with the theoretical predictions. Agreement with the observed data, however, is obtained by modifying the rate law of Plummer et al. (1978) to take into account surface-controlled inhibition effects. Experiments with supersaturated solutions containing carbonic anhydrase, an enzyme which enhances the conversion of HCO 3- into CO 2, yield rates increased by a factor of up to 15. This provides for the first time unambiguous experimental evidence that this reaction is rate limiting. We have also measured precipitation rates in batch experiments, stirring sized mineral particles in a solution with V/A ranging from 0.03 to 0.75 cm. These experiments also give clear evidence on the importance of the conversion of HCO 3- into CO 2 as rate limiting step. Taken together our experiments

  8. (Meta)stable CaC{sub 2}; (Meta)stabiles CaC{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Glaser, J.; Dill, S.; Marzini, M.; Mayer, H.A.; Meyer, H.J. [Tuebingen Univ. (Germany). Inst. fuer Anorganische Chemie

    2001-05-01

    One out of four modifications of CaC{sub 2} is the so-called metastable calcium carbide, CaC{sub 2}-III, which was synthesized as pure material. It forms by heating monoclinic CaC{sub 2}-II (C2/c) above 150 C and remains stable after cooling down to room temperature. The structure was refined from X-ray powder patterns (C2/m, Z = 4, a = 722.6(1) pm, b = 385.26(7) pm, c = 737.6(1) pm, {beta} = 107.345(2) ). After grinding CaC{sub 2}-III transforms back into CaC{sub 2}-II. Heating CaC{sub 2}-III induces a reversible phase transition into the cubic modification (CaC{sub 2}-IV) at 460 C. Differences between the three different structures of CaC{sub 2} I-III, being stable at ambient conditions are also shown by {sup 13}C-MAS-NMR measurements, especially the presence of two distinct types of carbon atoms in the structure of the title compound. (orig.)

  9. The effect of CaF2 on thermodynamics of CaO-CaF2-SiO2(-MgO) slags

    Science.gov (United States)

    Choi, Chul-Hwan; Jo, Sung-Koo; Kim, Seon-Hyo; Lee, Kwang-Ro; Kim, Jeong-Tae

    2004-02-01

    To address the role of CaF2 in the CaO-CaF2-SiO2(-MgO) slag system employed for the production of low-pressure rotor steels, the thermodynamic aspects of the slag were investigated by equilibrating it with liquid iron at 1873 K in CaO or MgO crucibles. Presaturation of slag with an oxide block piece of CaO or MgO in a Pt crucible and application of a carbon paste to the outside of an oxide crucible were designed to prevent crucible failure during the slag-metal experiments. The liquidus isotherm and phase boundary of the preceding slag system were investigated using the slag-metal equilibria. Also, the effect of CaF2 on the sulfide capacity and the activity coefficient of Fe t O were of particular interest in controlling the sulfur level and cleanliness of low-pressure rotor steels.

  10. The Ca(2+)/Calmodulin/CaMKK2 Axis: Nature's Metabolic CaMshaft.

    Science.gov (United States)

    Marcelo, Kathrina L; Means, Anthony R; York, Brian

    2016-10-01

    Calcium (Ca(2+)) is an essential ligand that binds its primary intracellular receptor calmodulin (CaM) to trigger a variety of downstream processes and pathways. Central to the actions of Ca(2+)/CaM is the activation of a highly conserved Ca(2+)/CaM kinase (CaMK) cascade that amplifies Ca(2+) signals through a series of subsequent phosphorylation events. Proper regulation of Ca(2+) flux is necessary for whole-body metabolism and disruption of Ca(2+) homeostasis has been linked to various metabolic diseases. Here we provide a synthesis of recent advances that highlight the roles of the Ca(2+)/CaMK axis in key metabolic tissues. An appreciation of this information is critical to understanding the mechanisms by which Ca(2+)/CaM-dependent signaling contributes to metabolic homeostasis and disease.

  11. The Modern Marine Ca-isotope Budget and its Application to the Phanerozoic Ca-isotope Record

    Science.gov (United States)

    Blattler, C. L.; Jenkyns, H. C.; Henderson, G. M.

    2011-12-01

    Variations in the calcium-isotope ratio (δ44/40Ca) of ancient seawater have been recorded in several studies using marine carbonate, barite, or apatite, but the causes of these variations have not been explored quantitatively. Seawater Ca-isotope ratios are affected by the average fractionation factor between seawater and the carbonate that precipitates from it, which is defined by the composition of the marine carbonate sink. To investigate possible changes in the fractionation factor of marine carbonate over the Phanerozoic, a Ca-isotope budget has been constructed for the modern oceans. Over 250 Ca-isotope measurements have been compiled from a wide variety of carbonate sources to describe the modern marine Ca-isotope budget. This dataset includes over 50 new measurements to characterize several components of the carbonate system, such as coral reefs, which are quantitatively important but have been undersampled, for example, relative to planktic foraminifera. δ44/40Ca values have been temperature-normalized using the relationship of +0.02% per °C, which permits observations and comparisons based on mineralogy, taxonomy, and locus of carbonate precipitation. A general offset of ~0.25%, increasing up to ~0.8% for certain taxa, is observed between subsets of aragonite and calcite samples; no statistical difference is observed between high-Mg calcite and low-Mg calcite. Additionally, within the data for calcite skeletons, two broad groups appear based on taxonomic patterns. Taxa with generally weak control over their biomineralization, such as sclerosponges, brachiopods, and calcareous red algae, are 0.4-0.5% heavier than organisms with more controlled calcification mechanisms, such as coccolithophores and planktic foraminifera. The patterns that emerge from this dataset for different clades demonstrate the usefulness of fossil carbonate for reconstructing the Ca-isotope ratio of ancient seawater. The composition of the modern Ca-isotope budget provides a basis

  12. The prognostic value of the hypoxia markers CA IX and GLUT 1 and the cytokines VEGF and IL 6 in head and neck squamous cell carcinoma treated by radiotherapy ± chemotherapy

    Directory of Open Access Journals (Sweden)

    Goethals Laurence

    2005-04-01

    Full Text Available Abstract Background Several parameters of the tumor microenvironment, such as hypoxia, inflammation and angiogenesis, play a critical role in tumor aggressiveness and treatment response. A major question remains if these markers can be used to stratify patients to certain treatment protocols. The purpose of this study was to investigate the inter-relationship and the prognostic significance of several biological and clinicopathological parameters in patients with head and neck squamous cell carcinoma (HNSCC treated by radiotherapy ± chemotherapy. Methods We used two subgroups of a retrospective series for which CT-determined tumoral perfusion correlated with local control. In the first subgroup (n = 67, immunohistochemistry for carbonic anhydrase IX (CA IX and glucose transporter-1 (GLUT-1 was performed on the pretreatment tumor biopsy. In the second subgroup (n = 34, enzyme linked immunosorbent assay (ELISA was used to determine pretreatment levels of the cytokines vascular endothelial growth factor (VEGF and interleukin-6 (IL-6 in serum. Correlation was investigated between tumoral perfusion and each of these biological markers, as well as between the markers mutually. The prognostic value of these microenvironmental parameters was also evaluated. Results For CA IX and GLUT-1, the combined assessment of patients with both markers expressed above the median showed an independent correlation with local control (p = 0.02 and disease-free survival (p = 0.04 with a trend for regional control (p = 0.06. In the second subgroup, IL-6 pretreatment serum level above the median was the only independent predictor of local control (p = 0.009, disease-free survival (p = 0.02 and overall survival (p = 0.005. Conclusion To our knowledge, we are the first to report a link in HNSCC between IL-6 pretreatment serum levels and radioresistance in vivo. This link is supported by the strong prognostic association of pretreatment IL-6 with local control, known to be

  13. Teale CA. Counties

    Data.gov (United States)

    California Department of Resources — California Spatial Information System (CaSIL) is a project designed to improve access to geo-spatial and geo-spatial related data information throughout the state...

  14. Expression of genes involved in the uptake of inorganic carbon in the gill of a deep-sea vesicomyid clam harboring intracellular thioautotrophic bacteria.

    Science.gov (United States)

    Hongo, Yuki; Ikuta, Tetsuro; Takaki, Yoshihiro; Shimamura, Shigeru; Shigenobu, Shuji; Maruyama, Tadashi; Yoshida, Takao

    2016-07-10

    Deep-sea vesicomyid clams, including the genus Phreagena (formerly Calyptogena), harbor thioautotrophic bacterial symbionts in the host symbiosome, which consists of cytoplasmic vacuoles in gill epithelial cells called bacteriocytes. The symbiont requires inorganic carbon (Ci), such as CO2, HCO3(-), and CO3(2-), to synthesize organic compounds, which are utilized by the host clam. The dominant Ci in seawater is HCO3(-), which is impermeable to cell membranes. Within the bacteriocyte, cytoplasmic carbonic anhydrase (CA) from the host, which catalyzes the inter-conversion between CO2 and HCO3(-), has been shown to be abundant and is thought to supply intracellular CO2 to symbionts in the symbiosome. However, the mechanism of Ci uptake by the host gill from seawater is poorly understood. To elucidate the influx pathway of Ci into the bacteriocyte, we isolated the genes related to Ci uptake via the pyrosequencing of cDNA from the gill of Phreagena okutanii, and investigated their expression patterns. Using phylogenetic and amino acid sequence analyses, three solute carrier family 4 (SLC4) bicarbonate transporters (slc4co1, slc4co2, and slc4co4) and two membrane-associated CAs (mcaco1 and mcaco2) were identified as candidate genes for Ci uptake. In an in situ hybridization analysis of gill sections, the expression of mcaco1 and mcaco2 was detected in the bacteriocytes and asymbiotic non-ciliated cells, respectively, and the expression of slc4co1 and slc4co2 was detected in the asymbiotic cells, including the intermediate cells of the inner area and the non-ciliated cells of the external area. Although subcellular localizations of the products of these genes have not been fully elucidated, they may play an important role in the uptake of Ci into the bacteriocytes. These findings will improve our understanding of the Ci transport system in the symbiotic relationships of chemosynthetic bivalves. PMID:27016297

  15. Development and evaluation of materials for thermochemical heat storage based on the CaO/CaCO3 reaction couple

    Science.gov (United States)

    Sakellariou, Kyriaki G.; Tsongidis, Nikolaos I.; Karagiannakis, George; Konstandopoulos, Athanasios G.; Baciu, Diana; Charalambopoulou, Georgia; Steriotis, Theodore; Stubos, Athanasios; Arlt, Wolfgang

    2016-05-01

    The current work relates to the development of synthetic calcium oxide (CaO) based compositions as candidate materials for energy storage under a cyclic carbonation/decarbonation reaction scheme. Although under such a cyclic scheme the energy density of natural lime based CaO is high (˜ 3MJ/kg), the particular materials suffer from notable cycle-to-cycle deactivation. To this direction, pure CaO and CaO/Al2O3 composites have been prepared and preliminarily evaluated under the suggested cyclic carbonation/decarbonation scheme in the temperature range of 600-800°C. For the composite materials, Ca/Al molar ratios were in the range between 95/5 and 52/48 and upon calcination the formation of mixed Ca/Al phases was verified. The preliminary evaluation of materials studied was conducted under 3 carbonation/decarbonation cycles and the loss of activity for the case of natural CaO was obvious. Synthetic materials with superior stability/capture c.f. natural CaO were further subjected to multi-cyclic carbonation/decarbonation, via which the positive effect of alumina addition was made evident. Selected compositions exhibited adequately high CO2 capture capacity and stable performance during multi-cyclic operation. Moreover, this study contains preliminary experiments referring to proof-of-principle validation of a concept based on the utilization of a CaO-based honeycomb reactor/heat exchanger preliminary design. In particular, cordierite monolithic structures were coated with natural CaO and in total 11 cycles were conducted. Upon operation, clear signs of heat