Acyl-CoA metabolism and partitioning

DEFF Research Database (Denmark)

Grevengoed, Trisha J; Klett, Eric L; Coleman, Rosalind A

2014-01-01

Long-chain fatty acyl-coenzyme As (CoAs) are critical regulatory molecules and metabolic intermediates. The initial step in their synthesis is the activation of fatty acids by one of 13 long-chain acyl-CoA synthetase isoforms. These isoforms are regulated independently and have different tissue...

Biochemical characterization and substrate specificity of jojoba fatty acyl-CoA reductase and jojoba wax synthase.

Science.gov (United States)

Miklaszewska, Magdalena; Banaś, Antoni

2016-08-01

Wax esters are used in industry for production of lubricants, pharmaceuticals and cosmetics. The only natural source of wax esters is jojoba oil. A much wider variety of industrial wax esters-containing oils can be generated through genetic engineering. Biotechnological production of tailor-made wax esters requires, however, a detailed substrate specificity of fatty acyl-CoA reductases (FAR) and wax synthases (WS), the two enzymes involved in wax esters synthesis. In this study we have successfully characterized the substrate specificity of jojoba FAR and jojoba WS. The genes encoding both enzymes were expressed heterologously in Saccharomyces cerevisiae and the activity of tested enzymes was confirmed by in vivo studies and in vitro assays using microsomal preparations from transgenic yeast. Jojoba FAR exhibited the highest in vitro activity toward 18:0-CoA followed by 20:1-CoA and 22:1-CoA. The activity toward other 11 tested acyl-CoAs was low or undetectable as with 18:2-CoA and 18:3-CoA. In assays characterizing jojoba WS combinations of 17 fatty alcohols with 14 acyl-CoAs were tested. The enzyme displayed the highest activity toward 14:0-CoA and 16:0-CoA in combination with C16-C20 alcohols as well as toward C18 acyl-CoAs in combination with C12-C16 alcohols. 20:1-CoA was efficiently utilized in combination with most of the tested alcohols. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Structural and Functional Studies of Fatty Acyl Adenylate Ligases from E. coli and L. pneumophila

Energy Technology Data Exchange (ETDEWEB)

Zhang, Z.; Swaminathan, S.; Zhou, R.; Sauder, J. M.; Tonge, P. J.; Burley, S. K.

2011-02-18

Fatty acyl-AMP ligase (FAAL) is a new member of a family of adenylate-forming enzymes that were recently discovered in Mycobacterium tuberculosis. They are similar in sequence to fatty acyl-coenzyme A (CoA) ligases (FACLs). However, while FACLs perform a two-step catalytic reaction, AMP ligation followed by CoA ligation using ATP and CoA as cofactors, FAALs produce only the acyl adenylate and are unable to perform the second step. We report X-ray crystal structures of full-length FAAL from Escherichia coli (EcFAAL) and FAAL from Legionella pneumophila (LpFAAL) bound to acyl adenylate, determined at resolution limits of 3.0 and 1.85 {angstrom}, respectively. The structures share a larger N-terminal domain and a smaller C-terminal domain, which together resemble the previously determined structures of FAAL and FACL proteins. Our two structures occur in quite different conformations. EcFAAL adopts the adenylate-forming conformation typical of FACLs, whereas LpFAAL exhibits a unique intermediate conformation. Both EcFAAL and LpFAAL have insertion motifs that distinguish them from the FACLs. Structures of EcFAAL and LpFAAL reveal detailed interactions between this insertion motif and the interdomain hinge region and with the C-terminal domain. We suggest that the insertion motifs support sufficient interdomain motions to allow substrate binding and product release during acyl adenylate formation, but they preclude CoA binding, thereby preventing CoA ligation.

Natural separation of the acyl-CoA ligase reaction results in a non-adenylating enzyme.

Science.gov (United States)

Wang, Nan; Rudolf, Jeffrey D; Dong, Liao-Bin; Osipiuk, Jerzy; Hatzos-Skintges, Catherine; Endres, Michael; Chang, Chin-Yuan; Babnigg, Gyorgy; Joachimiak, Andrzej; Phillips, George N; Shen, Ben

2018-06-04

Acyl-coenzyme A (CoA) ligases catalyze the activation of carboxylic acids via a two-step reaction of adenylation followed by thioesterification. Here, we report the discovery of a non-adenylating acyl-CoA ligase PtmA2 and the functional separation of an acyl-CoA ligase reaction. Both PtmA1 and PtmA2, two acyl-CoA ligases from the biosynthetic pathway of platensimycin and platencin, are necessary for the two steps of CoA activation. Gene inactivation of ptmA1 and ptmA2 resulted in the accumulation of free acid and adenylate intermediates, respectively. Enzymatic and structural characterization of PtmA2 confirmed its ability to only catalyze thioesterification. Structural characterization of PtmA2 revealed it binds both free acid and adenylate substrates and undergoes the established mechanism of domain alternation. Finally, site-directed mutagenesis restored both the adenylation and complete CoA activation reactions. This study challenges the currently accepted paradigm of adenylating enzymes and inspires future investigations on functionally separated acyl-CoA ligases and their ramifications in biology.

Characterization of the "Escherichia Coli" Acyl Carrier Protein Phosphodiesterase

Science.gov (United States)

Thomas, Jacob

2009-01-01

Acyl carrier protein (ACP) is a small essential protein that functions as a carrier of the acyl intermediates of fatty acid synthesis. ACP requires the posttranslational attachment of a 4'phosphopantetheine functional group, derived from CoA, in order to perform its metabolic function. A Mn[superscript 2+] dependent enzymatic activity that removes…

Clinical aspects of short-chain acyl-CoA dehydrogenase deficiency

NARCIS (Netherlands)

Maldegem, B.T.; Wanders, R.J.A.; Wijburg, F.A.

2010-01-01

Short-chain acyl-CoA dehydrogenase deficiency (SCADD) is an autosomal recessive inborn error of mitochondrial fatty acid oxidation. SCADD is biochemically characterized by increased C4-carnitine in plasma and ethylmalonic acid in urine. The diagnosis of SCADD is confirmed by DNA analysis showing

Tissue carnitine homeostasis in very-long-chain acyl-CoA dehydrogenase-deficient mice

NARCIS (Netherlands)

Spiekerkoetter, Ute; Tokunaga, Chonan; Wendel, Udo; Mayatepek, Ertan; Ijlst, Lodewijk; Vaz, Frederic M.; van Vlies, Naomi; Overmars, Henk; Duran, Marinus; Wijburg, Frits A.; Wanders, Ronald J.; Strauss, Arnold W.

2005-01-01

Deficiency of very-long-chain acyl-CoA dehydrogenase (VLCAD) is the most common long-chain fatty acid oxidation defect and presents with heterogeneous clinical manifestations. Accumulation of long-chain acylcarnitines and deficiency of free carnitine have often been proposed to play an important

Mutations in COA3 cause isolated complex IV deficiency associated with neuropathy, exercise intolerance, obesity, and short stature.

Science.gov (United States)

Ostergaard, Elsebet; Weraarpachai, Woranontee; Ravn, Kirstine; Born, Alfred Peter; Jønson, Lars; Duno, Morten; Wibrand, Flemming; Shoubridge, Eric A; Vissing, John

2015-03-01

We investigated a subject with an isolated cytochrome c oxidase (COX) deficiency presenting with an unusual phenotype characterised by neuropathy, exercise intolerance, obesity, and short stature. Blue-native polyacrylamide gel electrophoresis (BN-PAGE) analysis showed an almost complete lack of COX assembly in subject fibroblasts, consistent with the very low enzymatic activity, and pulse-labelling mitochondrial translation experiments showed a specific decrease in synthesis of the COX1 subunit, the core catalytic subunit that nucleates assembly of the holoenzyme. Whole exome sequencing identified compound heterozygous mutations (c.199dupC, c.215A>G) in COA3, a small inner membrane COX assembly factor, resulting in a pronounced decrease in the steady-state levels of COA3 protein. Retroviral expression of a wild-type COA3 cDNA completely rescued the COX assembly and mitochondrial translation defects, confirming the pathogenicity of the mutations, and resulted in increased steady-state levels of COX1 in control cells, demonstrating a role for COA3 in the stabilisation of this subunit. COA3 exists in an early COX assembly complex that contains COX1 and other COX assembly factors including COX14 (C12orf62), another single pass transmembrane protein that also plays a role in coupling COX1 synthesis with holoenzyme assembly. Immunoblot analysis showed that COX14 was undetectable in COA3 subject fibroblasts, and that COA3 was undetectable in fibroblasts from a COX14 subject, demonstrating the interdependence of these two COX assembly factors. The mild clinical course in this patient contrasts with nearly all other cases of severe COX assembly defects that are usually fatal early in life, and underscores the marked tissue-specific involvement in mitochondrial diseases. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Insight into Coenzyme A cofactor binding and the mechanism of acyl-transfer in an acylating aldehyde dehydrogenase from Clostridium phytofermentans.

Science.gov (United States)

Tuck, Laura R; Altenbach, Kirsten; Ang, Thiau Fu; Crawshaw, Adam D; Campopiano, Dominic J; Clarke, David J; Marles-Wright, Jon

2016-02-22

The breakdown of fucose and rhamnose released from plant cell walls by the cellulolytic soil bacterium Clostridium phytofermentans produces toxic aldehyde intermediates. To enable growth on these carbon sources, the pathway for the breakdown of fucose and rhamnose is encapsulated within a bacterial microcompartment (BMC). These proteinaceous organelles sequester the toxic aldehyde intermediates and allow the efficient action of acylating aldehyde dehydrogenase enzymes to produce an acyl-CoA that is ultimately used in substrate-level phosphorylation to produce ATP. Here we analyse the kinetics of the aldehyde dehydrogenase enzyme from the fucose/rhamnose utilisation BMC with different short-chain fatty aldehydes and show that it has activity against substrates with up to six carbon atoms, with optimal activity against propionaldehyde. We have also determined the X-ray crystal structure of this enzyme in complex with CoA and show that the adenine nucleotide of this cofactor is bound in a distinct pocket to the same group in NAD(+). This work is the first report of the structure of CoA bound to an aldehyde dehydrogenase enzyme and our crystallographic model provides important insight into the differences within the active site that distinguish the acylating from non-acylating aldehyde dehydrogenase enzymes.

A Turkish Patient With Succinyl-CoA:3-Oxoacid CoA Transferase Deficiency Mimicking Diabetic Ketoacidosis

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Sahin Erdol MD

2016-05-01

Full Text Available Succinyl-CoA:3-oxoacid CoA transferase (SCOT deficiency is an autosomal recessive disorder of ketone body utilization that is clinically characterized with intermittent ketoacidosis crises. We report here the second Turkish case with SCOT deficiency. She experienced 3 ketoacidotic episodes: The first ketoacidotic crisis mimicked diabetic ketoacidosis because of the associated hyperglycemia. Among patients with SCOT deficiency, the blood glucose levels at the first crises were variable, and this case had the highest ever reported blood glucose level. She is a compound heterozygote with 2 novel mutations, c.517A>G (K173E and c.1543A>G (M515V, in exons 5 and 17 of the OXCT1 gene, respectively. In patient’s fibroblasts, SCOT activity was deficient and, by immunoblot analysis, SCOT protein was much reduced. The patient attained normal development and had no permanent ketosis. The accurate diagnosis of SCOT deficiency in this case had a vital impact on the management strategy and outcome.

Clear correlation of genotype with disease phenotype in very-long-chain acyl-CoA dehydrogenase deficiency

DEFF Research Database (Denmark)

Andresen, B S; Olpin, S; Poorthuis, B J

1999-01-01

Very-long-chain acyl-CoA dehydrogenase (VLCAD) catalyzes the initial rate-limiting step in mitochondrial fatty acid beta-oxidation. VLCAD deficiency is clinically heterogenous, with three major phenotypes: a severe childhood form, with early onset, high mortality, and high incidence of cardiomyop......Very-long-chain acyl-CoA dehydrogenase (VLCAD) catalyzes the initial rate-limiting step in mitochondrial fatty acid beta-oxidation. VLCAD deficiency is clinically heterogenous, with three major phenotypes: a severe childhood form, with early onset, high mortality, and high incidence...... of cardiomyopathy; a milder childhood form, with later onset, usually with hypoketotic hypoglycemia as the main presenting feature, low mortality, and rare cardiomyopathy; and an adult form, with isolated skeletal muscle involvement, rhabdomyolysis, and myoglobinuria, usually triggered by exercise or fasting......-phenotype relationship is in sharp contrast to what has been observed in medium-chain acyl-CoA dehydrogenase deficiency, in which no correlation between genotype and phenotype can be established....

Acquired multiple Acyl-CoA dehydrogenase deficiency in 10 horses with atypical myopathy.

Science.gov (United States)

Westermann, C M; Dorland, L; Votion, D M; de Sain-van der Velden, M G M; Wijnberg, I D; Wanders, R J A; Spliet, W G M; Testerink, N; Berger, R; Ruiter, J P N; van der Kolk, J H

2008-05-01

The aim of the current study was to assess lipid metabolism in horses with atypical myopathy. Urine samples from 10 cases were subjected to analysis of organic acids, glycine conjugates, and acylcarnitines revealing increased mean excretion of lactic acid, ethylmalonic acid, 2-methylsuccinic acid, butyrylglycine, (iso)valerylglycine, hexanoylglycine, free carnitine, C2-, C3-, C4-, C5-, C6-, C8-, C8:1-, C10:1-, and C10:2-carnitine as compared with 15 control horses (12 healthy and three with acute myopathy due to other causes). Analysis of plasma revealed similar results for these predominantly short-chain acylcarnitines. Furthermore, measurement of dehydrogenase activities in lateral vastus muscle from one horse with atypical myopathy indeed showed deficiencies of short-chain acyl-CoA dehydrogenase (0.66 as compared with 2.27 and 2.48 in two controls), medium-chain acyl-CoA dehydrogenase (0.36 as compared with 4.31 and 4.82 in two controls) and isovaleryl-CoA dehydrogenase (0.74 as compared with 1.43 and 1.61 nmol min(-1) mg(-1) in two controls). A deficiency of several mitochondrial dehydrogenases that utilize flavin adenine dinucleotide as cofactor including the acyl-CoA dehydrogenases of fatty acid beta-oxidation, and enzymes that degrade the CoA-esters of glutaric acid, isovaleric acid, 2-methylbutyric acid, isobutyric acid, and sarcosine was suspected in 10 out of 10 cases as the possible etiology for a highly fatal and prevalent toxic equine muscle disease similar to the combined metabolic derangements seen in human multiple acyl-CoA dehydrogenase deficiency also known as glutaric acidemia type II.

2-ethylhydracrylic aciduria in short/branched-chain acyl-CoA dehydrogenase deficiency

DEFF Research Database (Denmark)

Korman, Stanley H; Andresen, Brage S; Zeharia, Avraham

2005-01-01

BACKGROUND: Isolated excretion of 2-methylbutyrylglycine (2-MBG) is the hallmark of short/branched-chain acyl-CoA dehydrogenase deficiency (SBCADD), a recently identified defect in the proximal pathway of L-isoleucine oxidation. SBCADD might be underdiagnosed because detection and recognition...

Identification of a novel CoA synthase isoform, which is primarily expressed in Brain

International Nuclear Information System (INIS)

Nemazanyy, Ivan; Panasyuk, Ganna; Breus, Oksana; Zhyvoloup, Alexander; Filonenko, Valeriy; Gout, Ivan T.

2006-01-01

CoA and its derivatives Acetyl-CoA and Acyl-CoA are important players in cellular metabolism and signal transduction. CoA synthase is a bifunctional enzyme which mediates the final stages of CoA biosynthesis. In previous studies, we have reported molecular cloning, biochemical characterization, and subcellular localization of CoA synthase (CoASy). Here, we describe the existence of a novel CoA synthase isoform, which is the product of alternative splicing and possesses a 29aa extension at the N-terminus. We termed it CoASy β and originally identified CoA synthase, CoASy α. The transcript specific for CoASy β was identified by electronic screening and by RT-PCR analysis of various rat tissues. The existence of this novel isoform was further confirmed by immunoblot analysis with antibodies directed to the N-terminal peptide of CoASy β. In contrast to CoASy α, which shows ubiquitous expression, CoASy β is primarily expressed in Brain. Using confocal microscopy, we demonstrated that both isoforms are localized on mitochondria. The N-terminal extension does not affect the activity of CoA synthase, but possesses a proline-rich sequence which can bring the enzyme into complexes with signalling proteins containing SH3 or WW domains. The role of this novel isoform in CoA biosynthesis, especially in Brain, requires further elucidation

Myopathy in very-long-chain acyl-CoA dehydrogenase deficiency

DEFF Research Database (Denmark)

Scholte, H R; Van Coster, R N; de Jonge, P C

1999-01-01

was deficient in muscle and fibroblasts, consistent with deficiency of very-long-chain acyl-CoA dehydrogenase (VLCAD). The gene of this enzyme had a homozygous deletion of three base pairs in exon 9, skipping lysine residue 238. Fibroblasts oxidised myristate, palmitate and oleate at a rate of 129, 62 and 38......A 30-year-old man suffered since the age of 13 years from exercise induced episodes of intense generalised muscle pain, weakness and myoglobinuria. Fasting ketogenesis was low, while blood glucose remained normal. Muscle mitochondria failed to oxidise palmitoylcarnitine. Palmitoyl-CoA dehydrogenase......% of controls. In contrast to patients with cardiac VLCAD deficiency, our patient had no lipid storage, a normal heart function, a higher rate of oleate oxidation in fibroblasts and normal free carnitine in plasma and fibroblasts. 31P-nuclear magnetic resonance spectroscopy of muscle showed a normal oxidative...

Cobalt-vitamin B12 deficiency and the activity of methylmalonyl CoA mutase and methionine synthase in cattle.

Science.gov (United States)

Kennedy, D G; Young, P B; Kennedy, S; Scott, J M; Molloy, A M; Weir, D G; Price, J

1995-01-01

Cobalt deficiency was induced in cattle by feeding two groups of animals either a basal diet that was very low in Co (12.9-17.6 micrograms Co per kg), or the same diet supplemented with cobalt, for a total of 64 weeks. Vitamin B12 deficiency was induced, as judged by hepatic concentrations of vitamin B12 and plasma concentrations of MMA. However, the activity of holo-methylmalonyl CoA mutase was significantly reduced only in brain. This was reflected in very minor alterations in the tissue concentrations of branched chain- and odd numbered-fatty acids. The activity of holo-methionine synthase was significantly reduced in liver and brain, but there were no consequent alterations in the concentrations of phosphatidyl choline and phosphatidyl ethanolamine. This study confirms that cattle are less susceptible to the effects of cobalt deficiency than sheep, and concludes that prolonged cobalt deficiency had little significant effect on tissue metabolism.

Short-chain Acyl-CoA dehydrogenase deficiency: studies in a large family adding to the complexity of the disorder

NARCIS (Netherlands)

Bok, Levinus A.; Vreken, Peter; Wijburg, Frits A.; Wanders, Ronald J. A.; Gregersen, Niels; Corydon, Morten J.; Waterham, Hans R.; Duran, Marinus

2003-01-01

OBJECTIVE: To understand the expanding clinical and biochemical spectrum of short-chain acyl-CoA dehydrogenase (SCAD) deficiency, the impact of which is not fully understood. STUDY DESIGN: We studied a family with SCAD deficiency and determined urinary ethylmalonic acid excretion, plasma

Transient multiple acyl-CoA dehydrogenation deficiency in a newborn female caused by maternal riboflavin deficiency

DEFF Research Database (Denmark)

Chiong, M A; Sim, K G; Carpenter, K

2007-01-01

in intact fibroblasts both in normal and riboflavin depleted media showed normal oxidation of fatty acids excluding defects in electron transfer flavoprotein (ETF), or ETF ubiquinone oxidoreductase (ETF:QO), or a genetic abnormality in flavin metabolism. In addition, sequencing of the genes encoding ETF...... and ETF:QO in the proband did not reveal any pathogenic mutations. Determination of the maternal riboflavin status after delivery showed that the mother was riboflavin deficient. Repeat testing done two years after the infant's birth and while on a normal diet showed that the mother was persistently...

Disruption of the acyl-coa binding protein gene delays hepatic adaptation to metabolic changes at weaning

DEFF Research Database (Denmark)

Neess, Ditte; Bloksgaard, Maria; Sørensen, Signe Bek

2011-01-01

The acyl-CoA binding protein/diazepam binding inhibitor (ACBP/DBI) is an intracellular protein that binds C14-C22 acyl-CoA esters and is thought to act as an acyl-CoA transporter. In vitro analyses have indicated that ACBP can transport acyl-CoA esters between different enzymatic systems; however....... The delayed induction of SREBP target genes around weaning is caused by a compromised processing and decreased expression of SREBP precursors leading to reduced binding of SREBP to target sites in chromatin. In conclusion, lack of ACBP interferes with the normal metabolic adaptation to weaning and leads...

Deficiency of acyl-CoA: Dihydroxyacetone phosphate acyltransferase in patients with Zellweger (cerebro-hepato-renal) syndrome

NARCIS (Netherlands)

Bosch, H. van den; Schutgens, R.B.H.; Romeyn, G.J.; Wanders, R.J.A.; Schrakamp, G.; Heymans, H.S.A.

1984-01-01

We have recently reported on plasmalogen deficiency in tissues and fibroblasts from patients with Zellweger syndrome. In this paper we have analyzed the activity of the first enzyme in the pathway leading to plasmalogen biosynthesis, i.e. acyl-CoA: dihydroxyacetone phosphate acyltransferase in

The frequency of a disease-causing point mutation in the gene coding for medium-chain acyl-CoA dehydrogenase in sudden infant death syndrome

DEFF Research Database (Denmark)

Banner, Jytte; Gregersen, N; Kølvraa, S

1993-01-01

A number of rare inherited metabolic disorders are known to lead to death in infancy. Deficiency of medium-chain acyl CoA dehydrogenase has, on clinical grounds, been related particularly to sudden infant death syndrome. The contribution of this disorder to the etiology of sudden infant death...... syndrome is still a matter of controversy. The present study investigated 120 well-defined cases of sudden infant death syndrome in order to detect the frequency of the most common disease-causing point mutation in the gene coding for medium-chain acyl-CoA dehydrogenase (G985) compared with the frequency...... in the general population. A highly specific polymerase chain reaction assay was applied on dried blood spots. No over-representation of homo- or heterozygosity for G985 appears to exist in such a strictly defined population, for which reason it may be more relevant to look at a broader spectrum of clinical...

Cholesterol esterification by mouse liver homogenate. Contribution to the study of ACYL-CoA: Cholesterol ACYL transferase in mammalian liver

International Nuclear Information System (INIS)

Soares, M.G.C.B.

1976-01-01

A cholesterol- esterifying enzyme from mouse liver has been partially characterized. The enzyme which showed optimum activity at pH 7,1 and required ATP and CoA, was identified as an acyl CoA: cholesterol acyl transferase (E.C.2.3.1.26). As a fuction of time the percentage of esterified cholesterol increased linearly during the first hour of incubation and continued to increase but not linearly with 4 hours, after which time no further net esterefication was observed. The relative concentration of esterified cholesterol remained constant between the fourth and twelveth hours of incubation but afterwards decreased when the incubation continued until 24 hours. The cholesterol- esterifying activity was 24,0+- 2,9 nmoles cholesterol esterified per gram tissue wet weight per minute. The mean percentages of free cholesterol esterified in and 24 hours respectively were 14,8+- 1,6 e 21,9+- 4,5. The subfractionation of labelled cholesteryl esters after one hour incubation of liver homogenate with 4-C 14 -Cholesterol showed the order of preference for the formation of the different ester classes to be monounsatured > diunsatured ≥ saturated >> polyunsaturated. The properties of the enzyme frommouse liver do not markedly differ from those of the previously recorded ACAT activity of rat liver. (Author) [pt

Effects of hematopoietic stem cell transplantation on acyl-CoA oxidase deficiency: a sibling comparison study

NARCIS (Netherlands)

Wang, Raymond Y.; Monuki, Edwin S.; Powers, James; Schwartz, Phillip H.; Watkins, Paul A.; Shi, Yang; Moser, Ann; Shrier, David A.; Waterham, Hans R.; Nugent, Diane J.; Abdenur, Jose E.

2014-01-01

Acyl-CoA oxidase (ACOX1) deficiency is a rare disorder of peroxisomal very-long chain fatty acid oxidation. No reports detailing attempted treatment, longitudinal imaging, or neuropathology exist. We describe the natural history of clinical symptoms and brain imaging in two siblings with ACOX1

Altered Energetics of Exercise Explain Risk of Rhabdomyolysis in Very Long-Chain Acyl-CoA Dehydrogenase Deficiency

NARCIS (Netherlands)

Diekman, E. F.; Visser, G.; Schmitz, J. P. J.; Nievelstein, R. A. J.; de Sain-van der Velden, M.; Wardrop, M.; van der Pol, W. L.; Houten, S. M.; van Riel, N. A. W.; Takken, T.; Jeneson, J. A. L.

2016-01-01

Rhabdomyolysis is common in very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) and other metabolic myopathies, but its pathogenic basis is poorly understood. Here, we show that prolonged bicycling exercise against a standardized moderate workload in VLCADD patients is associated with

Patients with medium-chain acyl-coenzyme a dehydrogenase deficiency have impaired oxidation of fat during exercise but no effect of L-carnitine supplementation

DEFF Research Database (Denmark)

Madsen, K L; Preisler, N; Orngreen, M C

2013-01-01

It is not clear to what extent skeletal muscle is affected in patients with medium-chain acyl-coenzyme A dehydrogenase deficiency (MCADD). l-Carnitine is commonly used as a supplement in patients with MCADD, although its beneficial effect has not been verified.......It is not clear to what extent skeletal muscle is affected in patients with medium-chain acyl-coenzyme A dehydrogenase deficiency (MCADD). l-Carnitine is commonly used as a supplement in patients with MCADD, although its beneficial effect has not been verified....

Acyl-CoA binding proteins; structural and functional conservation over 2000 MYA

DEFF Research Database (Denmark)

Faergeman, Nils J; Wadum, Majken; Feddersen, Søren

2007-01-01

-CoA binding protein, ACBP, has been proposed to play a pivotal role in the intracellular trafficking and utilization of long-chain fatty acyl-CoA esters. Depletion of acyl-CoA binding protein in yeast results in aberrant organelle morphology incl. fragmented vacuoles, multi-layered plasma membranes...... and accumulation of vesicles of variable sizes. In contrast to synthesis and turn-over of glycerolipids, the levels of very-long-chain fatty acids, long-chain bases and ceramide are severely affected by Acb1p depletion, suggesting that Acb1p, rather than playing a general role, serves specific roles in cellular...

Fluorescently labelled bovine acyl-CoA-binding protein acting as an acyl-CoA sensor: interaction with CoA and acyl-CoA esters and its use in measuring free acyl-CoA esters and non-esterified fatty acids

DEFF Research Database (Denmark)

Wadum, M.C.; Villadsen, J.K.; Feddersen, S.

2002-01-01

methods for the determination of free acyl-CoA concentrations. No such method is presently available. In the present study, we describe the synthesis of two acyl-CoA sensors for measuring free acyl-CoA concentrations using acyl-CoA-binding protein as a scaffold. Met24 and Ala53 of bovine acyl...... of ligand (excitation 387nm). Titration of FACI-24 and FACI-53 with hexadecanoyl-CoA and dodecanoyl-CoA increased the fluorescence yield 5.5-and 4.7-fold at 460 and 495nm respectively. FACI-24 exhibited a high, and similar increase in, fluorescence yield at 460nm upon binding of C14-C20 saturated...

Very long-chain acyl-coenzyme A dehydrogenase deficiency

Directory of Open Access Journals (Sweden)

A. V. Degtyareva

2014-01-01

Full Text Available The paper describes a case of a baby with a severe infant form of very long-chain acyl-coenzyme A dehydrogenase deficiency, a very rare genetic disorder. The basis for the disease is a disorder of mitochondrial β-oxidation of long-chain fatty acids. Accumulation of acyl-CoA-derived fatty acids causes a toxic effect on the myocardium and cardiac conduction system, liver, skeletal muscles, and other organs. The development of hypoglycemia is typical. Treatment in the acute period involves the immediately ceased delivery of long-chain triglycerides, the provision of the body with medium-chain triglycerides, and the correction of glycemia. In our observation the baby was born at term with a satisfactory condition in a family with a poor history (the first baby had suddenly died at the age of 3,5 months. The disease manifested itself as bradyarrhythmia and cardiac arrest on day 2 of life. The clinical symptom complex also included hepatomegalia, hypoglycemic episodes, lactate acidosis, and elevated blood levels of cytolytic enzymes and creatine phosphokinase. The diagnosis was suspected on the basis of the high blood values of acylcarnitines (primarily C14:1 and verified by a molecular genetic examination. Syndrome therapy and dietotherapy resulted in the abolishment of the abnormality. At the age of 2 years of life, the infant’s physical, motor, mental, and speech development corresponded to his age although he had mild right-sided hemiparesis. Thus, timely therapy determines the favorable prognosis of the disease even in its severe infant forms. 

Malonyl CoA decarboxylase deficiency: C to T transition in intron 2 of the MCD gene.

Science.gov (United States)

Surendran, S; Sacksteder, K A; Gould, S J; Coldwell, J G; Rady, P L; Tyring, S K; Matalon, R

2001-09-15

Malonyl CoA decarboxylase (MCD) is an enzyme involved in the metabolism of fatty acids synthesis. Based on reports of MCD deficiency, this enzyme is particular important in muscle and brain metabolism. Mutations in the MCD gene result in a deficiency of MCD activity, that lead to psychomotor retardation, cardiomyopathy and neonatal death. To date however, only a few patients have been reported with defects in MCD. We report here studies of a patient with MCD deficiency, who presented with hypotonia, cardiomyopathy and psychomotor retardation. DNA sequencing of MCD revealed a homozygous intronic mutation, specifically a -5 C to T transition near the acceptor site for exon 3. RT-PCR amplification of exons 2 and 3 revealed that although mRNA from a normal control sample yielded one major DNA band, the mutant mRNA sample resulted in two distinct DNA fragments. Sequencing of the patient's two RT-PCR products revealed that the larger molecular weight fragments contained exons 2 and 3 as well as the intervening intronic sequence. The smaller size band from the patient contained the properly spliced exons, similar to the normal control. Western blotting analysis of the expressed protein showed only a faint band in the patient sample in contrast to a robust band in the control. In addition, the enzyme activity of the mutant protein was lower than that of the control protein. The data indicate that homozygous mutation in intron 2 disrupt normal splicing of the gene, leading to lower expression of the MCD protein and MCD deficiency. Copyright 2001 Wiley-Liss, Inc.

Activities of acyl-CoA:diacylglycerol acyltransferase (DGAT) and phospholipid:diacylglycerol acyltransferase (PDAT) in microsomal preparations of developing sunflower and safflower seeds.

Science.gov (United States)

Banaś, Walentyna; Sanchez Garcia, Alicia; Banaś, Antoni; Stymne, Sten

2013-06-01

The last step in triacylglycerols (TAG) biosynthesis in oil seeds, the acylation of diacylglycerols (DAG), is catalysed by two types of enzymes: the acyl-CoA:diacylglycerol acyltransferase (DGAT) and phospholipid:diacylglycerol acyltransferase (PDAT). The relative contribution of these enzymes in the synthesis of TAG has not yet been defined in any plant tissue. In the presented work, microsomal preparations were obtained from sunflower and safflower seeds at different stages of development and used in DGAT and PDAT enzyme assays. The ratio between PDAT and DGAT activity differed dramatically between the two different species. DGAT activities were measured with two different acyl acceptors and assay methods using two different acyl-CoAs, and in all cases the ratio of PDAT to DGAT activity was significantly higher in safflower than sunflower. The sunflower DGAT, measured by both methods, showed significant higher activity with 18:2-CoA than with 18:1-CoA, whereas the opposite specificity was seen with the safflower enzyme. The specificities of PDAT on the other hand, were similar in both species with 18:2-phosphatidylcholine being a better acyl donor than 18:1-PC and with acyl groups at the sn-2 position utilised about fourfold the rate of the sn-1 position. No DAG:DAG transacylase activity could be detected in the microsomal preparations.

Identification of the human mitochondrial FAD transporter and its potential role in multiple acyl-CoA dehydrogenase deficiency

NARCIS (Netherlands)

Spaan, András N.; Ijlst, Lodewijk; van Roermund, Carlo W. T.; Wijburg, Frits A.; Wanders, Ronald J. A.; Waterham, Hans R.

2005-01-01

Multiple acyl-CoA dehydrogenase deficiency (MADD) or glutaric aciduria type II (GAII) is most often caused by mutations in the genes encoding the alpha- or beta-subunit of electron transfer flavoprotein (ETF) or electron transfer flavoprotein dehydrogenase (ETF-DH). Since not all patients have

Molecular diagnosis and characterization of medium-chain acyl-CoA dehydrogenase deficiency

DEFF Research Database (Denmark)

Andresen, B S; Bross, P; Jensen, T G

1995-01-01

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is the most common defect in mitochondrial beta-oxidation in humans. It is an autosomal recessive disorder which usually presents in infancy. The disease manifests itself in periods of metabolic stress to the beta-oxidation system and may...... of correct enzyme structure, and does not directly affect the catalytically active regions of the enzyme. We find that our diagnostic set up, consisting of an initial testing by the G985 assay, followed by semi-automated sequencing of DNA from those patients who were indicated to be compound heterozygous...

Asymmetric Chemoenzymatic Reductive Acylation of Ketones by a Combined Iron-Catalyzed Hydrogenation-Racemization and Enzymatic Resolution Cascade

KAUST Repository

El-Sepelgy, Osama

2017-02-28

A general and practical process for the conversion of prochiral ketones into the corresponding chiral acetates has been realized. An iron carbonyl complex is reported to catalyze the hydrogenation-dehydrogenation-hydrogenation of prochiral ketones. By merging the iron-catalyzed redox reactions with enantioselective enzymatic acylations a wide range of benzylic, aliphatic and (hetero)aromatic ketones, as well as diketones, were reductively acylated. The corresponding products were isolated with high yields and enantioselectivities. The use of an iron catalyst together with molecular hydrogen as the hydrogen donor and readily available ethyl acetate as acyl donor make this cascade process highly interesting in terms of both economic value and environmental credentials.

Fulminant lipid storage myopathy due to multiple acyl-coenzyme a dehydrogenase deficiency.

Science.gov (United States)

Whitaker, Charles H; Felice, Kevin J; Silvers, David; Wu, Qian

2015-08-01

The lipid storage myopathies, primary carnitine deficiency, neutral lipid storage disease, and multiple acyl coenzyme A dehydrogenase deficiency (MADD), are progressive disorders that cause permanent weakness. These disorders of fatty acid metabolism and intracellular triglyceride degradation cause marked fat deposition and damage to muscle cells. We describe a rapidly progressive myopathy in a previously healthy 33-year-old woman. Over 4 months, she developed a proximal and axial myopathy associated with diffuse myalgia and dysphagia, ultimately leading to respiratory failure and death. Muscle biopsy showed massive accumulation of lipid. Plasma acylcarnitine and urine organic acid analysis was consistent with MADD. This was confirmed by molecular genetic testing, which revealed 2 pathogenic mutations in the ETFDH gene. This report illustrates a late-onset case of MADD and reviews the differential diagnosis and evaluation of patients with proximal myopathy and excessive accumulation of lipid on muscle biopsy. © 2014 Wiley Periodicals, Inc.

Evidence for involvement of medium chain acyl-CoA dehydrogenase in the metabolism of phenylbutyrate.

Science.gov (United States)

Kormanik, Kaitlyn; Kang, Heejung; Cuebas, Dean; Vockley, Jerry; Mohsen, Al-Walid

2012-12-01

Sodium phenylbutyrate is used for treating urea cycle disorders, providing an alternative for ammonia excretion. Following conversion to its CoA ester, phenylbutyryl-CoA is postulated to undergo one round of β-oxidation to phenylacetyl-CoA, the active metabolite. Molecular modeling suggests that medium chain acyl-CoA dehydrogenase (MCAD; EC 1.3.99.3), a key enzyme in straight chain fatty acid β-oxidation, could utilize phenylbutyryl-CoA as substrate. Moreover, phenylpropionyl-CoA has been shown to be a substrate for MCAD and its intermediates accumulate in patients with MCAD deficiency. We have examined the involvement of MCAD and other acyl-CoA dehydrogenases (ACADs) in the metabolism of phenylbutyryl-CoA. Anaerobic titration of purified recombinant human MCAD with phenylbutyryl-CoA caused changes in the MCAD spectrum that are similar to those induced by octanoyl-CoA, its bona fide substrate, and unique to the development of the charge transfer ternary complex. The calculated apparent dissociation constant (K(D app)) for these substrates was 2.16 μM and 0.12 μM, respectively. The MCAD reductive and oxidative half reactions were monitored using the electron transfer flavoprotein (ETF) fluorescence reduction assay. The catalytic efficiency and the K(m) for phenylbutyryl-CoA were 0.2 mM 34(-1)·sec(-1) and 5.3 μM compared to 4.0 mM(-1)·sec(-1) and 2.8 μM for octanoyl-CoA. Extracts of wild type and MCAD-deficient lymphoblast cells were tested for the ability to reduce ETF using phenylbutyryl-CoA as substrate. While ETF reduction activity was detected in extracts of wild type cells, it was undetectable in extracts of cells deficient in MCAD. The results are consistent with MCAD playing a key role in phenylbutyrate metabolism. Copyright © 2012 Elsevier Inc. All rights reserved.

Overexpression of human fatty acid transport protein 2/very long chain acyl-CoA synthetase 1 (FATP2/Acsvl1) reveals distinct patterns of trafficking of exogenous fatty acids

Energy Technology Data Exchange (ETDEWEB)

Melton, Elaina M. [Department of Biochemistry, University of Nebraska, Lincoln, NE (United States); Center for Cardiovascular Sciences, Albany Medical College, Albany, NY (United States); Cerny, Ronald L. [Department of Chemistry, University of Nebraska, Lincoln, NE (United States); DiRusso, Concetta C. [Department of Biochemistry, University of Nebraska, Lincoln, NE (United States); Black, Paul N., E-mail: pblack2@unl.edu [Department of Biochemistry, University of Nebraska, Lincoln, NE (United States)

2013-11-01

Highlights: •Roles of FATP2 in fatty acid transport/activation contribute to lipid homeostasis. •Use of 13C- and D-labeled fatty acids provide novel insights into FATP2 function. •FATP2-dependent trafficking of FA into phospholipids results in distinctive profiles. •FATP2 functions in the transport and activation pathways for exogenous fatty acids. -- Abstract: In mammals, the fatty acid transport proteins (FATP1 through FATP6) are members of a highly conserved family of proteins, which function in fatty acid transport proceeding through vectorial acylation and in the activation of very long chain fatty acids, branched chain fatty acids and secondary bile acids. FATP1, 2 and 4, for example directly function in fatty acid transport and very long chain fatty acids activation while FATP5 does not function in fatty acid transport but activates secondary bile acids. In the present work, we have used stable isotopically labeled fatty acids differing in carbon length and saturation in cells expressing FATP2 to gain further insights into how this protein functions in fatty acid transport and intracellular fatty acid trafficking. Our previous studies showed the expression of FATP2 modestly increased C16:0-CoA and C20:4-CoA and significantly increased C18:3-CoA and C22:6-CoA after 4 h. The increases in C16:0-CoA and C18:3-CoA suggest FATP2 must necessarily partner with a long chain acyl CoA synthetase (Acsl) to generate C16:0-CoA and C18:3-CoA through vectorial acylation. The very long chain acyl CoA synthetase activity of FATP2 is consistent in the generation of C20:4-CoA and C22:6-CoA coincident with transport from their respective exogenous fatty acids. The trafficking of exogenous fatty acids into phosphatidic acid (PA) and into the major classes of phospholipids (phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), and phosphatidyserine (PS)) resulted in distinctive profiles, which changed with the expression of FATP2. The

Overexpression of human fatty acid transport protein 2/very long chain acyl-CoA synthetase 1 (FATP2/Acsvl1) reveals distinct patterns of trafficking of exogenous fatty acids

International Nuclear Information System (INIS)

Melton, Elaina M.; Cerny, Ronald L.; DiRusso, Concetta C.; Black, Paul N.

2013-01-01

Highlights: •Roles of FATP2 in fatty acid transport/activation contribute to lipid homeostasis. •Use of 13C- and D-labeled fatty acids provide novel insights into FATP2 function. •FATP2-dependent trafficking of FA into phospholipids results in distinctive profiles. •FATP2 functions in the transport and activation pathways for exogenous fatty acids. -- Abstract: In mammals, the fatty acid transport proteins (FATP1 through FATP6) are members of a highly conserved family of proteins, which function in fatty acid transport proceeding through vectorial acylation and in the activation of very long chain fatty acids, branched chain fatty acids and secondary bile acids. FATP1, 2 and 4, for example directly function in fatty acid transport and very long chain fatty acids activation while FATP5 does not function in fatty acid transport but activates secondary bile acids. In the present work, we have used stable isotopically labeled fatty acids differing in carbon length and saturation in cells expressing FATP2 to gain further insights into how this protein functions in fatty acid transport and intracellular fatty acid trafficking. Our previous studies showed the expression of FATP2 modestly increased C16:0-CoA and C20:4-CoA and significantly increased C18:3-CoA and C22:6-CoA after 4 h. The increases in C16:0-CoA and C18:3-CoA suggest FATP2 must necessarily partner with a long chain acyl CoA synthetase (Acsl) to generate C16:0-CoA and C18:3-CoA through vectorial acylation. The very long chain acyl CoA synthetase activity of FATP2 is consistent in the generation of C20:4-CoA and C22:6-CoA coincident with transport from their respective exogenous fatty acids. The trafficking of exogenous fatty acids into phosphatidic acid (PA) and into the major classes of phospholipids (phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), and phosphatidyserine (PS)) resulted in distinctive profiles, which changed with the expression of FATP2. The

Successful adaptation to ketosis by mice with tissue-specific deficiency of ketone body oxidation.

Science.gov (United States)

Cotter, David G; Schugar, Rebecca C; Wentz, Anna E; d'Avignon, D André; Crawford, Peter A

2013-02-15

During states of low carbohydrate intake, mammalian ketone body metabolism transfers energy substrates originally derived from fatty acyl chains within the liver to extrahepatic organs. We previously demonstrated that the mitochondrial enzyme coenzyme A (CoA) transferase [succinyl-CoA:3-oxoacid CoA transferase (SCOT), encoded by nuclear Oxct1] is required for oxidation of ketone bodies and that germline SCOT-knockout (KO) mice die within 48 h of birth because of hyperketonemic hypoglycemia. Here, we use novel transgenic and tissue-specific SCOT-KO mice to demonstrate that ketone bodies do not serve an obligate energetic role within highly ketolytic tissues during the ketogenic neonatal period or during starvation in the adult. Although transgene-mediated restoration of myocardial CoA transferase in germline SCOT-KO mice is insufficient to prevent lethal hyperketonemic hypoglycemia in the neonatal period, mice lacking CoA transferase selectively within neurons, cardiomyocytes, or skeletal myocytes are all viable as neonates. Like germline SCOT-KO neonatal mice, neonatal mice with neuronal CoA transferase deficiency exhibit increased cerebral glycolysis and glucose oxidation, and, while these neonatal mice exhibit modest hyperketonemia, they do not develop hypoglycemia. As adults, tissue-specific SCOT-KO mice tolerate starvation, exhibiting only modestly increased hyperketonemia. Finally, metabolic analysis of adult germline Oxct1(+/-) mice demonstrates that global diminution of ketone body oxidation yields hyperketonemia, but hypoglycemia emerges only during a protracted state of low carbohydrate intake. Together, these data suggest that, at the tissue level, ketone bodies are not a required energy substrate in the newborn period or during starvation, but rather that integrated ketone body metabolism mediates adaptation to ketogenic nutrient states.

Equine acquired multiple acyl-CoA dehydrogenase deficiency (MADD) in 14 horses associated with ingestion of Maple leaves (Acer pseudoplatanus) covered with European tar spot (Rhytisma acerinum).

Science.gov (United States)

van der Kolk, J H; Wijnberg, I D; Westermann, C M; Dorland, L; de Sain-van der Velden, M G M; Kranenburg, L C; Duran, M; Dijkstra, J A; van der Lugt, J J; Wanders, R J A; Gruys, E

2010-01-01

This case-series describes fourteen horses suspected of equine acquired multiple acyl-CoA dehydrogenase deficiency (MADD) also known as atypical myopathy of which seven cases were confirmed biochemically with all horses having had access to leaves of the Maple tree (Acer pseudoplatanus) covered with European tar spot (Rhytisma acerinum). Assessment of organic acids, glycine conjugates, and acylcarnitines in urine was regarded as gold standard in the biochemical diagnosis of equine acquired multiple acyl-CoA dehydrogenase deficiency. Copyright © 2010 Elsevier Inc. All rights reserved.

Highly enantioselective catalytic cross-dehydrogenative coupling of N-carbamoyl tetrahydroisoquinolines and terminal alkynes.

Science.gov (United States)

Sun, Shutao; Li, Chengkun; Floreancig, Paul E; Lou, Hongxiang; Liu, Lei

2015-04-03

The first catalytic asymmetric cross-dehydrogenative coupling of cyclic carbamates and terminal alkynes has been established. The reaction features high enantiocontrol and excellent functional group tolerance and displays a wide range of structurally and electronically diverse carbamates as well as terminal alkynes. N-Acyl hemiaminals were identified as the reactive intermediates through preliminary control experiments. Employing readily removable carbamates as substrates rather than traditionally adopted N-aryl amines allows applications in complex molecule synthesis and therefore advances the C-H functionalization strategy to a synthetically useful level.

Structural characterization and comparison of three acyl-carrier-protein synthases from pathogenic bacteria

Energy Technology Data Exchange (ETDEWEB)

Halavaty, Andrei S. [Center for Structural Genomics of Infectious Diseases, (United States); Northwestern University, Chicago, IL 60611 (United States); Kim, Youngchang [Center for Structural Genomics of Infectious Diseases, (United States); Argonne National Laboratory, Argonne, IL 60439 (United States); University of Chicago, Chicago, IL 60637 (United States); Minasov, George; Shuvalova, Ludmilla; Dubrovska, Ievgeniia; Winsor, James [Center for Structural Genomics of Infectious Diseases, (United States); Northwestern University, Chicago, IL 60611 (United States); Zhou, Min [Center for Structural Genomics of Infectious Diseases, (United States); Argonne National Laboratory, Argonne, IL 60439 (United States); University of Chicago, Chicago, IL 60637 (United States); Onopriyenko, Olena; Skarina, Tatiana [Center for Structural Genomics of Infectious Diseases, (United States); University of Toronto, Toronto, Ontario M5G 1L6 (Canada); Papazisi, Leka; Kwon, Keehwan; Peterson, Scott N. [Center for Structural Genomics of Infectious Diseases, (United States); J. Craig Venter Institute, Rockville, MD 20850 (United States); Joachimiak, Andrzej [Center for Structural Genomics of Infectious Diseases, (United States); Argonne National Laboratory, Argonne, IL 60439 (United States); University of Chicago, Chicago, IL 60637 (United States); Savchenko, Alexei [Center for Structural Genomics of Infectious Diseases, (United States); University of Toronto, Toronto, Ontario M5G 1L6 (Canada); Anderson, Wayne F., E-mail: wf-anderson@northwestern.edu [Center for Structural Genomics of Infectious Diseases, (United States); Northwestern University, Chicago, IL 60611 (United States)

2012-10-01

The structural characterization of acyl-carrier-protein synthase (AcpS) from three different pathogenic microorganisms is reported. One interesting finding of the present work is a crystal artifact related to the activity of the enzyme, which fortuitously represents an opportunity for a strategy to design a potential inhibitor of a pathogenic AcpS. Some bacterial type II fatty-acid synthesis (FAS II) enzymes have been shown to be important candidates for drug discovery. The scientific and medical quest for new FAS II protein targets continues to stimulate research in this field. One of the possible additional candidates is the acyl-carrier-protein synthase (AcpS) enzyme. Its holo form post-translationally modifies the apo form of an acyl carrier protein (ACP), which assures the constant delivery of thioester intermediates to the discrete enzymes of FAS II. At the Center for Structural Genomics of Infectious Diseases (CSGID), AcpSs from Staphylococcus aureus (AcpS{sub SA}), Vibrio cholerae (AcpS{sub VC}) and Bacillus anthracis (AcpS{sub BA}) have been structurally characterized in their apo, holo and product-bound forms, respectively. The structure of AcpS{sub BA} is emphasized because of the two 3′, 5′-adenosine diphosphate (3′, 5′-ADP) product molecules that are found in each of the three coenzyme A (CoA) binding sites of the trimeric protein. One 3′, 5′-ADP is bound as the 3′, 5′-ADP part of CoA in the known structures of the CoA–AcpS and 3′, 5′-ADP–AcpS binary complexes. The position of the second 3′, 5′-ADP has never been described before. It is in close proximity to the first 3′, 5′-ADP and the ACP-binding site. The coordination of two ADPs in AcpS{sub BA} may possibly be exploited for the design of AcpS inhibitors that can block binding of both CoA and ACP.

Structural characterization and comparison of three acyl-carrier-protein synthases from pathogenic bacteria

International Nuclear Information System (INIS)

Halavaty, Andrei S.; Kim, Youngchang; Minasov, George; Shuvalova, Ludmilla; Dubrovska, Ievgeniia; Winsor, James; Zhou, Min; Onopriyenko, Olena; Skarina, Tatiana; Papazisi, Leka; Kwon, Keehwan; Peterson, Scott N.; Joachimiak, Andrzej; Savchenko, Alexei; Anderson, Wayne F.

2012-01-01

The structural characterization of acyl-carrier-protein synthase (AcpS) from three different pathogenic microorganisms is reported. One interesting finding of the present work is a crystal artifact related to the activity of the enzyme, which fortuitously represents an opportunity for a strategy to design a potential inhibitor of a pathogenic AcpS. Some bacterial type II fatty-acid synthesis (FAS II) enzymes have been shown to be important candidates for drug discovery. The scientific and medical quest for new FAS II protein targets continues to stimulate research in this field. One of the possible additional candidates is the acyl-carrier-protein synthase (AcpS) enzyme. Its holo form post-translationally modifies the apo form of an acyl carrier protein (ACP), which assures the constant delivery of thioester intermediates to the discrete enzymes of FAS II. At the Center for Structural Genomics of Infectious Diseases (CSGID), AcpSs from Staphylococcus aureus (AcpS SA ), Vibrio cholerae (AcpS VC ) and Bacillus anthracis (AcpS BA ) have been structurally characterized in their apo, holo and product-bound forms, respectively. The structure of AcpS BA is emphasized because of the two 3′, 5′-adenosine diphosphate (3′, 5′-ADP) product molecules that are found in each of the three coenzyme A (CoA) binding sites of the trimeric protein. One 3′, 5′-ADP is bound as the 3′, 5′-ADP part of CoA in the known structures of the CoA–AcpS and 3′, 5′-ADP–AcpS binary complexes. The position of the second 3′, 5′-ADP has never been described before. It is in close proximity to the first 3′, 5′-ADP and the ACP-binding site. The coordination of two ADPs in AcpS BA may possibly be exploited for the design of AcpS inhibitors that can block binding of both CoA and ACP

Flavin Adenine Dinucleotide Status and the Effects of High-Dose Riboflavin Treatment in Short-Chain Acyl-CoA Dehydrogenase Deficiency

NARCIS (Netherlands)

van Maldegem, Bianca T.; Duran, Marinus; Wanders, Ronald J. A.; Waterham, Hans R.; Wijburg, Frits A.

2010-01-01

Short-chain acyl-CoA dehydrogenase deficiency (SCADD) is an inborn error, biochemically characterized by increased plasma butyrylcarnitine (C4-C) concentration and increased ethylmalonic acid (EMA) excretion and caused by rare mutations and/or common gene variants in the SCAD encoding gene. Although

A severe genotype with favourable outcome in very long chain acyl-CoA dehydrogenase deficiency

DEFF Research Database (Denmark)

Touma, E H; Rashed, M S; Vianey-Saban, C

2001-01-01

A patient with very long chain acyl-CoA dehydrogenase (VLCAD) deficiency is reported. He had a severe neonatal presentation and cardiomyopathy. He was found to be homozygous for a severe mutation with no residual enzyme activity. Tandem mass spectrometry on dried blood spots revealed increased lo...... chain acylcarnitines. VLCAD enzyme activity was severely decreased to 2% of control levels. Dietary management consisted of skimmed milk supplemented with medium chain triglycerides and L-carnitine. Outcome was good and there was no acute recurrence....

Differences among Adult COAs and Adult Non-COAs on Levels of Self-Esteem, Depression, and Anxiety.

Science.gov (United States)

Dodd, David T.; Roberts, Richard L.

1994-01-01

Examined self-esteem, depression, and anxiety among 60 adult children of alcoholics (COAs) and 143 adult non-COAs. Subjects completed Children of Alcoholics Screening Test, demographic questionnaire, Beck Depression Inventory, State-Trait Anxiety Inventory, and Coopersmith Self-Esteem Inventory. Found no significant differences between COAs and…

Evolution of the acyl-CoA binding protein (ACBP)

DEFF Research Database (Denmark)

Burton, Mark; Rose, Timothy M; Faergeman, Nils J

2005-01-01

-CoA pool size, donation of acyl-CoA esters for beta-oxidation, vesicular trafficking, complex lipid synthesis and gene regulation. In the present study, we delineate the evolutionary history of ACBP to get a complete picture of its evolution and distribution among species. ACBP homologues were identified...... duplication and/or retrotransposition events. The ACBP protein is highly conserved across phylums, and the majority of ACBP genes are subjected to strong purifying selection. Experimental evidence indicates that the function of ACBP has been conserved from yeast to humans and that the multiple lineage...

Cost-effectiveness analysis of universal newborn screening for medium chain acyl-CoA dehydrogenase deficiency in France

OpenAIRE

Hamers, Françoise F; Rumeau-Pichon, Catherine

2012-01-01

Abstract Background Five diseases are currently screened on dried blood spots in France through the national newborn screening programme. Tandem mass spectrometry (MS/MS) is a technology that is increasingly used to screen newborns for an increasing number of hereditary metabolic diseases. Medium chain acyl-CoA dehydrogenase deficiency (MCADD) is among these diseases. We sought to evaluate the cost-effectiveness of introducing MCADD screening in France. Methods We developed a decision model t...

Insulin signaling regulates fatty acid catabolism at the level of CoA activation.

Directory of Open Access Journals (Sweden)

Xiaojun Xu

2012-01-01

Full Text Available The insulin/IGF signaling pathway is a highly conserved regulator of metabolism in flies and mammals, regulating multiple physiological functions including lipid metabolism. Although insulin signaling is known to regulate the activity of a number of enzymes in metabolic pathways, a comprehensive understanding of how the insulin signaling pathway regulates metabolic pathways is still lacking. Accepted knowledge suggests the key regulated step in triglyceride (TAG catabolism is the release of fatty acids from TAG via the action of lipases. We show here that an additional, important regulated step is the activation of fatty acids for beta-oxidation via Acyl Co-A synthetases (ACS. We identify pudgy as an ACS that is transcriptionally regulated by direct FOXO action in Drosophila. Increasing or reducing pudgy expression in vivo causes a decrease or increase in organismal TAG levels respectively, indicating that pudgy expression levels are important for proper lipid homeostasis. We show that multiple ACSs are also transcriptionally regulated by insulin signaling in mammalian cells. In sum, we identify fatty acid activation onto CoA as an important, regulated step in triglyceride catabolism, and we identify a mechanistic link through which insulin regulates lipid homeostasis.

Comparative genomics and proteomics of vertebrate diacylglycerol acyltransferase (DGAT), acyl CoA wax alcohol acyltransferase (AWAT) and monoacylglycerol acyltransferase (MGAT).

Science.gov (United States)

Holmes, Roger S

2010-03-01

BLAT (BLAST-Like Alignment Tool) analyses of the opossum (Monodelphis domestica) and zebrafish (Danio rerio) genomes were undertaken using amino acid sequences of the acylglycerol acyltransferase (AGAT) superfamily. Evidence is reported for 8 opossum monoacylglycerol acyltransferase-like (MGAT) (E.C. 2.3.1.22) and diacylglycerol acyltransferase-like (DGAT) (E.C. 2.3.1.20) genes and proteins, including DGAT1, DGAT2, DGAT2L6 (DGAT2-like protein 6), AWAT1 (acyl CoA wax alcohol acyltransferase 1), AWAT2, MGAT1, MGAT2 and MGAT3. Three of these genes (AWAT1, AWAT2 and DGAT2L6) are closely localized on the opossum X chromosome. Evidence is also reported for six zebrafish MGAT- and DGAT-like genes, including two DGAT1-like genes, as well as DGAT2-, MGAT1-, MGAT2- and MGAT3-like genes and proteins. Predicted primary, secondary and transmembrane structures for the opossum and zebrafish MGAT-, AWAT- and DGAT-like subunits and the intron-exon boundaries for genes encoding these enzymes showed a high degree of similarity with other members of the AGAT superfamily, which play major roles in triacylglyceride (DGAT), diacylglyceride (MGAT) and wax ester (AWAT) biosynthesis. Alignments of predicted opossum, zebrafish and other vertebrate DGAT1, DGAT2, other DGAT2-like and MGAT-like amino acid sequences with known human and mouse enzymes demonstrated conservation of residues which are likely to play key roles in catalysis, lipid binding or in maintaining structure. Phylogeny studies of the human, mouse, opossum, zebrafish and pufferfish MGAT- and DGAT-like enzymes indicated that the common ancestors for these genes predated the appearance of bony fish during vertebrate evolution whereas the AWAT- and DGAT2L6-like genes may have appeared more recently prior to the appearance of marsupial and eutherian mammals. Copyright 2009 Elsevier Inc. All rights reserved.

Genetic Basis for Correction of Very‐Long‐Chain Acyl-Coenzyme A Dehydrogenase Deficiency by Bezafibrate in Patient Fibroblasts: Toward a Genotype‐Based Therapy

DEFF Research Database (Denmark)

Gobin‐Limballe, S.; Djouadi, F.; Aubey, F.

2007-01-01

Very‐long‐chain acyl-coenzyme A dehydrogenase (VLCAD) deficiency is an inborn mitochondrial fatty‐acid β‐oxidation (FAO) defect associated with a broad mutational spectrum, with phenotypes ranging from fatal cardiopathy in infancy to adolescent‐onset myopathy, and for which there is no established...

Development of Non-Noble Metal Ni-Based Catalysts for Dehydrogenation of Methylcyclohexane

KAUST Repository

Al-ShaikhAli, Anaam H.

2016-11-30

of strongly chemisorbed intermediate originating from TOL. DFT calculation indicated that Zn metal prefers to occupy the step sites of Ni where unselective C–C bond breaking was considered to preferentially occur, explaining suppression of hydrogenolysis activity. Additionally, it confirmed that the H-deficient species at methyl position group (C6H5CH2) was stable on the surface, making its hydrogenation being rate determining step, consistent with positive order in H2 pressure on TOL formation rate. This may explain the conclusive role by H2 in facilitating desorption of the H-deficient surface species that was produced through further dehydrogenation of TOL.

Short/branched-chain acyl-CoA dehydrogenase deficiency due to an IVS3+3A>G mutation that causes exon skipping

DEFF Research Database (Denmark)

Madsen, Pia Pinholt

2006-01-01

Short/branched-chain acyl-CoA dehydrogenase deficiency (SBCADD) is an autosomal recessive disorder of L: -isoleucine catabolism. Little is known about the clinical presentation associated with this enzyme defect, as it has been reported in only a limited number of patients. Because the presence...... is relevant to the interpretation of the functional consequences of this type of mutation in other disease genes....

Effects of two mutations detected in medium chain acyl-CoA dehydrogenase (MCAD)-deficient patients on folding, oligomer assembly, and stability of MCAD enzyme

DEFF Research Database (Denmark)

Bross, P; Jespersen, C; Jensen, T G

1995-01-01

We have used expression of human medium chain acyl-CoA dehydrogenase (MCAD) in Escherichia coli as a model system for dissecting the molecular effects of two mutations detected in patients with MCAD deficiency. We demonstrate that the R28C mutation predominantly affects polypeptide folding...

Remote control of regioselectivity in acyl-acyl carrier protein-desaturases.

Science.gov (United States)

Guy, Jodie E; Whittle, Edward; Moche, Martin; Lengqvist, Johan; Lindqvist, Ylva; Shanklin, John

2011-10-04

Regiospecific desaturation of long-chain saturated fatty acids has been described as approaching the limits of the discriminatory power of enzymes because the substrate entirely lacks distinguishing features close to the site of dehydrogenation. To identify the elusive mechanism underlying regioselectivity, we have determined two crystal structures of the archetypal Δ9 desaturase from castor in complex with acyl carrier protein (ACP), which show the bound ACP ideally situated to position C9 and C10 of the acyl chain adjacent to the diiron active site for Δ9 desaturation. Analysis of the structures and modeling of the complex between the highly homologous ivy Δ4 desaturase and ACP, identified a residue located at the entrance to the binding cavity, Asp280 in the castor desaturase (Lys275 in the ivy desaturase), which is strictly conserved within Δ9 and Δ4 enzymes but differs between them. We hypothesized that interaction between Lys275 and the phosphate of the pantetheine, seen in the ivy model, is key to positioning C4 and C5 adjacent to the diiron center for Δ4 desaturation. Mutating castor Asp280 to Lys resulted in a major shift from Δ9 to Δ4 desaturation. Thus, interaction between desaturase side-chain 280 and phospho-serine 38 of ACP, approximately 27 Å from the site of double-bond formation, predisposes ACP binding that favors either Δ9 or Δ4 desaturation via repulsion (acidic side chain) or attraction (positively charged side chain), respectively. Understanding the mechanism underlying remote control of regioselectivity provides the foundation for reengineering desaturase enzymes to create designer chemical feedstocks that would provide alternatives to those currently obtained from petrochemicals.

Studies of Human 2,4-Dienoyl CoA Reductase Shed New Light on Peroxisomal β-Oxidation of Unsaturated Fatty Acids

Energy Technology Data Exchange (ETDEWEB)

Hua, Tian; Wu, Dong; Ding, Wei; Wang, Jiangyun; Shaw, Neil; Liu, Zhi-Jie [Nankai; (Chinese Aca. Sci.)

2012-10-15

Peroxisomes play an essential role in maintaining fatty acid homeostasis. Although mitochondria are also known to participate in the catabolism of fatty acids via β-oxidation, differences exist between the peroxisomal and mitochondrial β-oxidation. Only peroxisomes, but not mitochondrion, can shorten very long chain fatty acids. Here, we describe the crystal structure of a ternary complex of peroxisomal 2,4-dienoyl CoA reductases (pDCR) with hexadienoyl CoA and NADP, as a prototype for comparison with the mitochondrial 2,4-dienoyl CoA reductase (mDCR) to shed light on the differences between the enzymes from the two organelles at the molecular level. Unexpectedly, the structure of pDCR refined to 1.84 Å resolution reveals the absence of the tyrosine-serine pair seen in the active site of mDCR, which together with a lysine and an asparagine have been deemed a hallmark of the SDR family of enzymes. Instead, aspartate hydrogen-bonded to the Cα hydroxyl via a water molecule seems to perturb the water molecule for protonation of the substrate. Our studies provide the first structural evidence for participation of water in the DCR-catalyzed reactions. Biochemical studies and structural analysis suggest that pDCRs can catalyze the shortening of six-carbon-long substrates in vitro. However, the Km values of pDCR for short chain acyl CoAs are at least 6-fold higher than those for substrates with 10 or more aliphatic carbons. Unlike mDCR, hinge movements permit pDCR to process very long chain polyunsaturated fatty acids.

Tandem mass spectrometry screening for very long-chain acyl-CoA dehydrogenase deficiency: the value of second-tier enzyme testing.

Science.gov (United States)

Spiekerkoetter, Ute; Haussmann, Ulrike; Mueller, Martina; ter Veld, Frank; Stehn, Maren; Santer, Rene; Lukacs, Zoltan

2010-10-01

To evaluate newborn screening (NBS) for very long-chain acyl-CoA dehydrogenase deficiency (VLCADD), we further characterized newborns with elevation of one or all C14-carnitine derivatives on NBS from a total of 90 338 newborns. Palmitoyl-CoA oxidation was performed in lymphocytes to define very long-chain acyl-CoA dehydrogenase function. Molecular analysis followed in children with residual activitiesvalues and acylcarnitine ratios did not allow correct identification of the newborn as a patient with VLCADD. Reliable diagnosis is not feasible with acylcarnitine analysis alone. Enzyme analysis in lymphocytes is a reliable and rapid method for correctly assessing all newborns with VLCADD and should be carried out in all newborns identified during the first screening, regardless of the results of a later acylcarnitine profile. Copyright (c) 2010 Mosby, Inc. All rights reserved.

Shale gas opportunities. Dehydrogenation of light alkanes

Energy Technology Data Exchange (ETDEWEB)

Patcas, F.C.; Dieterle, M.; Rezai, A.; Asprion, N. [BASF SE, Ludwigshafen (Germany)

2013-11-01

The discovery and use of shale gas in North America has become a game changer for the chemical industry by access to a cheaper feedstock compared to conventional oil. Increased number of ethane crackers spurred increasing interest in light alkanes dehydrogenation. Several companies have announced their interest in new propane dehydrogenation units in North America. BASF is developing light alkanes dehydrogenation technologies for two decades now. BASF developed jointly with Linde the isothermal C3 dehydrogenation process. The latest dehydrogenation catalyst development at BASF focused on a supported and steam resistant Pt-Sn catalyst which yielded excellent selectivity and activity. Intense research work both internally as well as in cooperation with universities contributed to the understanding of the relationship between the surface structure and catalyst performances like activity, selectivity and coking resistance. Using such type of catalysts BASF developed an autothermal propane dehydrogenation as well as a butane dehydrogenation process. The most recent catalyst development was a dehydrogenation catalyst coated on a honeycomb monolith to improve catalyst usage and pressure drop. This will probably be the first industrial usage of catalytic monoliths in a chemical synthesis process. (orig.) (Published in summary form only)

A pharmacologic increase in activity of plasma transaminase derived from small intestine in animals receiving an acyl CoA: diacylglycerol transferase (DGAT) 1 inhibitor.

Science.gov (United States)

Yokoyama, Hideaki; Kobayashi, Akio; Kondo, Kazuma; Oshida, Shin-Ichi; Takahashi, Tadakazu; Masuyama, Taku; Shoda, Toshiyuki; Sugai, Shoichiro

2018-01-01

Acyl CoA: diacylglycerol acyltransferase (DGAT) 1 is an enzyme that catalyzes the re-synthesis of triglycerides (TG) from free fatty acids and diacylglycerol. JTT-553 is a DGAT1 inhibitor and exhibits its pharmacological action (inhibition of re-synthesis of TG) in the enterocytes of the small intestine leading to suppression of a postprandial elevation of plasma lipids. After repeated oral dosing JTT-553 in rats and monkeys, plasma transaminase levels were increased but there were neither changes in other hepatic function parameters nor histopathological findings suggestive of hepatotoxicity. Based on the results of exploratory studies for investigation of the mechanism of the increase in transaminase levels, plasma transaminase levels were increased after dosing JTT-553 only when animals were fed after dosing and a main factor in the diet contributing to the increase in plasma transaminase levels was lipids. After dosing JTT-553, transaminase levels were increased in the small intestine but not in the liver, indicating that the origin of transaminase increased in the plasma was not the liver but the small intestine where JTT-553 exhibits its pharmacological action. The increase in small intestinal transaminase levels was due to increased enzyme protein synthesis and was suppressed by inhibiting fatty acid-transport to the enterocytes. In conclusion, the JTT-553-related increase in plasma transaminase levels is considered not to be due to release of the enzymes from injured cells into the circulation but to be phenomena resulting from enhancement of enzyme protein synthesis in the small intestine due to the pharmacological action of JTT-553 in this organ.

Catalytic dehydrogenation of alcohol over solid-state molybdenum sulfide clusters with an octahedral metal framework

Energy Technology Data Exchange (ETDEWEB)

Kamiguchi, Satoshi, E-mail: kamigu@riken.jp [Advanced Catalysis Research Group, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako City, Saitama 351-0198 (Japan); Organometallic Chemistry Laboratory, RIKEN, 2-1 Hirosawa, Wako City, Saitama 351-0198 (Japan); Okumura, Kazu [School of Advanced Engineering, Kogakuin University, Nakano-machi, Hachioji City, Tokyo 192-0015 (Japan); Nagashima, Sayoko; Chihara, Teiji [Graduate School of Science and Engineering, Saitama University, Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570 (Japan)

2015-12-15

Graphical abstract: - Highlights: • Solid-state molybdenum sulfide clusters catalyzed the dehydrogenation of alcohol. • The dehydrogenation proceeded without the addition of any oxidants. • The catalytic activity developed when the cluster was activated at 300–500 °C in H{sub 2}. • The Lewis-acidic molybdenum atom and basic sulfur ligand were catalytically active. • The clusters function as bifunctional acid–base catalysts. - Abstract: Solid-state molybdenum sulfide clusters with an octahedral metal framework, the superconducting Chevrel phases, are applied to catalysis. A copper salt of a nonstoichiometric sulfur-deficient cluster, Cu{sub x}Mo{sub 6}S{sub 8–δ} (x = 2.94 and δ ≈ 0.3), is stored in air for more than 90 days. When the oxygenated cluster is thermally activated in a hydrogen stream above 300 °C, catalytic activity for the dehydrogenation of primary alcohols to aldehydes and secondary alcohols to ketones develops. The addition of pyridine or benzoic acid decreases the dehydrogenation activity, indicating that both a Lewis-acidic coordinatively unsaturated molybdenum atom and a basic sulfur ligand synergistically act as the catalytic active sites.

The utilization of the acyl-CoA and the involvement PDAT and DGAT in the biosynthesis of erucic acid-rich triacylglycerols in Crambe seed oil.

Science.gov (United States)

Furmanek, Tomasz; Demski, Kamil; Banaś, Walentyna; Haslam, Richard; Napier, Jonathan; Stymne, Sten; Banaś, Antoni

2014-04-01

The triacylglycerol of Crambe abyssinica seeds consist of 95% very long chain (>18 carbon) fatty acids (86% erucic acid; 22:1∆13) in the sn-1 and sn-3 positions. This would suggest that C. abyssinica triacylglycerols are not formed by the action of the phospholipid:diacylglycerol acyltransferase (PDAT), but are rather the results of acyl-CoA:diacylglycerol acyltransferase (DGAT) activity. However, measurements of PDAT and DGAT activities in microsomal membranes showed that C. abyssinica has significant PDAT activity, corresponding to about 10% of the DGAT activity during periods of rapid seed oil accumulation. The specific activity of DGAT for erucoyl-CoA had doubled at 19 days after flowering compared to earlier developmental stages, and was, at that stage, the preferred acyl donor, whereas the activities for 16:0-CoA and 18:1-CoA remained constant. This indicates that an expression of an isoform of DGAT with high specificity for erucoyl-CoA is induced at the onset of rapid erucic acid and oil accumulation in the C. abyssinica seeds. Analysis of the composition of the acyl-CoA pool during different stages of seed development showed that the percentage of erucoyl groups in acyl-CoA was much higher than in complex lipids at all stages of seed development except in the desiccation phase. These results are in accordance with published results showing that the rate limiting step in erucic acid accumulation in C. abyssinica oil is the utilization of erucoyl-CoA by the acyltransferases in the glycerol-3-phosphate pathway.

Succinyl-CoA:3-ketoacid CoA transferase (SCOT) deficiency: two pathogenic mutations, V133E and C456F, in Japanese siblings.

Science.gov (United States)

Song, X Q; Fukao, T; Watanabe, H; Shintaku, H; Hirayama, K; Kassovska-Bratinova, S; Kondo, N; Mitchell, G A

1998-01-01

Succinyl-CoA:3-ketoacid CoA transferase (SCOT; EC 2.8.3.5; locus symbol OXCT) is the key enzyme of ketone body utilization. Hereditary SCOT deficiency (MIM 245050) causes episodes of severe ketoacidosis. We developed a transient expression system for mutant SCOT cDNAs, using immortalized SCOT-deficient fibroblasts. This paper describes and characterizes three missense mutations in two SCOT-deficient siblings from Japan. They are genetic compounds who inherited the mutation C456F (c1367 G-->T) from their mother. Their paternal allele contains two mutations in cis, T58M (c173 C-->T) and V133E (c398T-->A). Expression of SCOT cDNAs containing either V133E or C456F produces no detectable SCOT activity, whereas T58M is functionally neutral. T58M is a rare sequence variant not detected in 100 control Japanese alleles. In fibroblasts from the proband (GS02), in whom immunoblot demonstrated no detectable SCOT peptide, we measured an apparent residual SCOT activity of 20-35%. We hypothesize that the high residual SCOT activity in homogenates may be an artifact caused by use of the substrate, acetoacetyl-CoA by other enzymes. Expression of mutant SCOT cDNAs more accurately reflects the residual activity of SCOT than do currently available assays in cell or tissue homogenates.

Interstellar dehydrogenated PAH anions: vibrational spectra

Science.gov (United States)

Buragohain, Mridusmita; Pathak, Amit; Sarre, Peter; Gour, Nand Kishor

2018-03-01

Interstellar polycyclic aromatic hydrocarbon (PAH) molecules exist in diverse forms depending on the local physical environment. Formation of ionized PAHs (anions and cations) is favourable in the extreme conditions of the interstellar medium (ISM). Besides in their pure form, PAHs are also likely to exist in substituted forms; for example, PAHs with functional groups, dehydrogenated PAHs etc. A dehydrogenated PAH molecule might subsequently form fullerenes in the ISM as a result of ongoing chemical processes. This work presents a density functional theory (DFT) calculation on dehydrogenated PAH anions to explore the infrared emission spectra of these molecules and discuss any possible contribution towards observed IR features in the ISM. The results suggest that dehydrogenated PAH anions might be significantly contributing to the 3.3 μm region. Spectroscopic features unique to dehydrogenated PAH anions are highlighted that may be used for their possible identification in the ISM. A comparison has also been made to see the size effect on spectra of these PAHs.

Equine acquired multiple acyl-CoA dehydrogenase deficiency (MADD) in 14 horses associated with ingestion of Maple leaves (Acer pseudoplatanus) covered with European tar spot (Rhytisma acerinum)

NARCIS (Netherlands)

van der Kolk, J. H.; Wijnberg, I. D.; Westermann, C. M.; Dorland, L.; de Sain-van der Velden, M. G. M.; Kranenburg, L. C.; Duran, M.; Dijkstra, J. A.; van der Lugt, J. J.; Wanders, R. J. A.; Gruys, E.

2010-01-01

This case-series describes fourteen horses suspected of equine acquired multiple acyl-CoA dehydrogenase deficiency (MADD) also known as atypical myopathy of which seven cases were confirmed biochemically with all horses having had access to leaves of the Maple tree (Acer pseudoplatanus) covered with

Dehydrogenation of benzene on Pt(111) surface

Science.gov (United States)

Gao, W.; Zheng, W. T.; Jiang, Q.

2008-10-01

The dehydrogenation of benzene on Pt(111) surface is studied by ab initio density functional theory. The minimum energy pathways for benzene dehydrogenation are found with the nudge elastic band method including several factors of the associated barriers, reactive energies, intermediates, and transient states. The results show that there are two possible parallel minimum energy pathways on the Pt(111) surface. Moreover, the tilting angle of the H atom in benzene can be taken as an index for the actual barrier of dehydrogenation. In addition, the properties of dehydrogenation radicals on the Pt(111) surface are explored through their adsorption energy, adsorption geometry, and electronic structure on the surface. The vibrational frequencies of the dehydrogenation radicals derived from the calculations are in agreement with literature data.

Dehydrogenative Diels-Alder reaction.

Science.gov (United States)

Ozawa, Takuya; Kurahashi, Takuya; Matsubara, Seijiro

2011-10-07

The dehydrogenative cycloaddition of dieneynes, which possess a diene in the form of a styrene moiety and a dienophile in the form of an alkyne moiety, produces naphthalene derivatives when heated. It was found that a key requirement of this process is the presence of a silyl group attached to the alkyne moiety, which forces a dehydrogenation reaction to occur. © 2011 American Chemical Society

Deficiency of cardiac Acyl-CoA synthetase-1 induces diastolic dysfunction, but pathologic hypertrophy is reversed by rapamycin

DEFF Research Database (Denmark)

Paul, David S; Grevengoed, Trisha J; Pascual, Florencia

2014-01-01

In mice with temporally-induced cardiac-specific deficiency of acyl-CoA synthetase-1 (Acsl1(H-/-)), the heart is unable to oxidize long-chain fatty acids and relies primarily on glucose for energy. These metabolic changes result in the development of both a spontaneous cardiac hypertrophy...... and B-type natriuretic peptide. mTOR activation of the related Acsl3 gene, usually associated with pathologic hypertrophy, was also attenuated in the Acsl1(H-/-) hearts, indicating that alternative pathways of fatty acid activation did not compensate for the loss of Acsl1. Compared to controls, Acsl1(H......-/-) hearts exhibited an 8-fold higher uptake of 2-deoxy[1-(14)C]glucose and a 35% lower uptake of the fatty acid analog 2-bromo[1-(14)C]palmitate. These data indicate that Acsl1-deficiency causes diastolic dysfunction and that mTOR activation is linked to the development of cardiac hypertrophy in Acsl1(H...

Effects of hematopoietic stem cell transplantation on acyl-CoA oxidase deficiency: a sibling comparison study

Science.gov (United States)

Monuki, Edwin S.; Powers, James; Schwartz, Phillip H.; Watkins, Paul A.; Shi, Yang; Moser, Ann; Shrier, David A.; Waterham, Hans R.; Nugent, Diane J.; Abdenur, Jose E.

2015-01-01

Objective Acyl-CoA oxidase (ACOX1) deficiency is a rare disorder of peroxisomal very-long chain fatty acid oxidation. No reports detailing attempted treatment, longitudinal imaging, or neuropathology exist. We describe the natural history of clinical symptoms and brain imaging in two siblings with ACOX1 deficiency, including the younger sibling's response to allogeneic unrelated donor hematopoietic stem cell transplantation (HSCT). Methods We conducted retrospective chart review to obtain clinical history, neuro-imaging, and neuropathology data. ACOX1 genotyping were performed to confirm the disease. In vitro fibroblast and neural stem cell fatty acid oxidation assays were also performed. Results Both patients experienced a fatal neurodegenerative course, with late-stage cerebellar and cerebral gray matter atrophy. Serial brain magnetic resonance imaging in the younger sibling indicated demyelination began in the medulla and progressed rostrally to include the white matter of the cerebellum, pons, midbrain, and eventually subcortical white matter. The successfully engrafted younger sibling had less brain inflammation, cortical atrophy, and neuronal loss on neuroimaging and neuropathology compared to the untreated older sister. Fibroblasts and stem cells demonstrated deficient very long chain fatty acid oxidation. Interpretation Although HSCT did not halt the course of ACOX1 deficiency, it reduced the extent of white matter inflammation in the brain. Demyelination continued because of ongoing neuronal loss, which may be due to inability of transplant to prevent progression of gray matter disease, adverse effects of chronic corticosteroid use to control graft-versus-host disease, or intervention occurring beyond a critical point for therapeutic efficacy. PMID:24619150

Determination of hydrophobic coenzyme a esters and other lipids using a biosensor comprising a modified coenzyme a- and acyl-coa binding protein (acbp)

DEFF Research Database (Denmark)

2002-01-01

, food and feed preparations, tissue extracts, acyl-CoA synthetase reaction media and various laboratory conditions using a modified Coenzyme A- and acyl-CoA binding protein (ACBP) is provided. Furthermore the invention relates to a construct comprising a peptide and a signal moiety for performing...

Misfolding, degradation, and aggregation of variant proteins. The molecular pathogenesis of short chain acyl-CoA dehydrogenase (SCAD) deficiency

DEFF Research Database (Denmark)

Pedersen, Christina Bak; Bross, P.; Winter, V.S.

2003-01-01

and aggregation of variant SCAD proteins. In this study we investigated the processing of a set of disease-causing variant SCAD proteins (R22W, G68C, W153R, R359C, and Q341H) and two common variant proteins (R147W and G185S) that lead to reduced SCAD activity. All SCAD proteins, including the wild type, associate...... proteolytic degradation by mitochondrial proteases or, especially at elevated temperature, aggregation of non-native conformers. The latter finding may indicate that accumulation of aggregated SCAD proteins may play a role in the pathogenesis of SCAD deficiency.......Short chain acyl-CoA dehydrogenase (SCAD) deficiency is an inborn error of the mitochondrial fatty acid metabolism caused by rare variations as well as common susceptibility variations in the SCAD gene. Earlier studies have shown that a common variant SCAD protein (R147W) was impaired in folding...

Parental Experiences of Raising a Child With Medium Chain Acyl-CoA Dehydrogenase Deficiency

Directory of Open Access Journals (Sweden)

Hilary Piercy

2017-05-01

Full Text Available Newborn screening enabling early diagnosis of medium chain acyl-CoA dehydrogenase deficiency (MCADD has dramatically improved health outcomes in children with MCADD. Achieving those outcomes depends on effective management by parents. Understanding parental management strategies and associated anxieties and concerns is needed to inform provision of appropriate care and support. Semistructured interviews were conducted with a purposive sample of parents of children aged 2 to 12 years. Thematic analysis identified two main themes. Managing dietary intake examined how parents managed day-to-day dietary intake to ensure adequate intake and protection of safe fasting intervals. Managing and preventing illness events explored parental experiences of managing illness events and their approach to preventing these events. Management strategies were characterized by caution and vigilance and influenced by a lack of confidence in others to manage the condition. The study identifies the need for increased awareness of the condition, particularly in relation to emergency treatment.

CoaSim Guile Manual — Using the Guile-based CoaSim Simulator

DEFF Research Database (Denmark)

Mailund, T

2006-01-01

CoaSim is a tool for simulating the coalescent process with recombination and geneconversion, under either constant population size or exponential population growth. It effectively constructs the ancestral recombination graph for a given number of chromosomes and uses this to simulate samples...

Medium-Chain Acyl-CoA Deficiency: Outlines from Newborn Screening, In Silico Predictions, and Molecular Studies

Directory of Open Access Journals (Sweden)

Serena Catarzi

2013-01-01

Full Text Available Medium-chain acyl-CoA dehydrogenase deficiency (MCADD is a disorder of fatty acid oxidation characterized by hypoglycemic crisis under fasting or during stress conditions, leading to lethargy, seizures, brain damage, or even death. Biochemical acylcarnitines data obtained through newborn screening by liquid chromatography-tandem mass spectrometry (LC-MS/MS were confirmed by molecular analysis of the medium-chain acyl-CoA dehydrogenase (ACADM gene. Out of 324.000 newborns screened, we identified 14 MCADD patients, in whom, by molecular analysis, we found a new nonsense c.823G>T (p.Gly275* and two new missense mutations: c.253G>C (p.Gly85Arg and c.356T>A (p.Val119Asp. Bioinformatics predictions based on both phylogenetic conservation and functional/structural software were used to characterize the new identified variants. Our findings confirm the rising incidence of MCADD whose existence is increasingly recognized due to the efficacy of an expanded newborn screening panel by LC-MS/MS making possible early specific therapies that can prevent possible crises in at-risk infants. We noticed that the “common” p.Lys329Glu mutation only accounted for 32% of the defective alleles, while, in clinically diagnosed patients, this mutation accounted for 90% of defective alleles. Unclassified variants (UVs or VUSs are especially critical when considering screening programs. The functional and pathogenic characterization of genetic variants presented here is required to predict their medical consequences in newborns.

Medium-Chain Acyl-CoA Deficiency: Outlines from Newborn Screening, In Silico Predictions, and Molecular Studies

Science.gov (United States)

Catarzi, Serena; Caciotti, Anna; Thusberg, Janita; Tonin, Rodolfo; Malvagia, Sabrina; la Marca, Giancarlo; Pasquini, Elisabetta; Cavicchi, Catia; Ferri, Lorenzo; Donati, Maria A.; Baronio, Federico; Guerrini, Renzo; Mooney, Sean D.; Morrone, Amelia

2013-01-01

Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is a disorder of fatty acid oxidation characterized by hypoglycemic crisis under fasting or during stress conditions, leading to lethargy, seizures, brain damage, or even death. Biochemical acylcarnitines data obtained through newborn screening by liquid chromatography-tandem mass spectrometry (LC-MS/MS) were confirmed by molecular analysis of the medium-chain acyl-CoA dehydrogenase (ACADM) gene. Out of 324.000 newborns screened, we identified 14 MCADD patients, in whom, by molecular analysis, we found a new nonsense c.823G>T (p.Gly275∗) and two new missense mutations: c.253G>C (p.Gly85Arg) and c.356T>A (p.Val119Asp). Bioinformatics predictions based on both phylogenetic conservation and functional/structural software were used to characterize the new identified variants. Our findings confirm the rising incidence of MCADD whose existence is increasingly recognized due to the efficacy of an expanded newborn screening panel by LC-MS/MS making possible early specific therapies that can prevent possible crises in at-risk infants. We noticed that the “common” p.Lys329Glu mutation only accounted for 32% of the defective alleles, while, in clinically diagnosed patients, this mutation accounted for 90% of defective alleles. Unclassified variants (UVs or VUSs) are especially critical when considering screening programs. The functional and pathogenic characterization of genetic variants presented here is required to predict their medical consequences in newborns. PMID:24294134

In HepG2 cells, coexisting carnitine deficiency masks important indicators of marginal biotin deficiency.

Science.gov (United States)

Bogusiewicz, Anna; Boysen, Gunnar; Mock, Donald M

2015-01-01

A large number of birth defects are related to nutrient deficiencies; concern that biotin deficiency is teratogenic in humans is reasonable. Surprisingly, studies indicate that increased urinary 3-hydroxyisovalerylcarnitine (3HIAc), a previously validated marker of biotin deficiency, is not a valid biomarker in pregnancy. In this study we hypothesized that coexisting carnitine deficiency can prevent the increase in 3HIAc due to biotin deficiency. We used a 2-factor nutrient depletion design to induce isolated and combined biotin and carnitine deficiency in HepG2 cells and then repleted cells with carnitine. To elucidate the metabolic pathogenesis, we quantitated intracellular and extracellular free carnitine, acylcarnitines, and acylcarnitine ratios using liquid chromatography-tandem mass spectrometry. Relative to biotin-sufficient, carnitine-sufficient cells, intracellular acetylcarnitine increased by 90%, propionylcarnitine more than doubled, and 3HIAc increased by >10-fold in biotin-deficient, carnitine-sufficient (BDCS) cells, consistent with a defensive mechanism in which biotin-deficient cells transesterify the acyl-coenzyme A (acyl-CoA) substrates of the biotin-dependent carboxylases to the related acylcarnitines. Likewise, in BDCS cells, the ratio of acetylcarnitine to malonylcarnitine and the ratio of propionylcarnitine to methylmalonylcarnitine both more than tripled, and the ratio of 3HIAc to 3-methylglutarylcarnitine (MGc) increased by >10-fold. In biotin-deficient, carnitine-deficient (BDCD) cells, the 3 substrate-derived acylcarnitines changed little, but the substrate:product ratios were masked to a lesser extent. Moreover, carnitine repletion unmasked biotin deficiency in BDCD cells as shown by increases in acetylcarnitine, propionylcarnitine, and 3HIAc (each increased by >50-fold). Likewise, ratios of acetylcarnitine:malonylcarnitine, propionylcarnitine:methylmalonylcarnitine, and 3HIAc:MGc all increased by >8-fold. Our findings provide strong

CoAs: The line of 3 d demarcation

Science.gov (United States)

Campbell, Daniel J.; Wang, Limin; Eckberg, Chris; Graf, Dave; Hodovanets, Halyna; Paglione, Johnpierre

2018-05-01

Transition metal-pnictide compounds have received attention for their tendency to combine magnetism and unconventional superconductivity. Binary CoAs lies on the border of paramagnetism and the more complex behavior seen in isostructural CrAs, MnP, FeAs, and FeP. Here we report the properties of CoAs single crystals grown with two distinct techniques along with density functional theory calculations of its electronic structure and magnetic ground state. While all indications are that CoAs is paramagnetic, both experiment and theory suggest proximity to a ferromagnetic instability. Quantum oscillations are seen in torque measurements up to 31.5 T and support the calculated paramagnetic Fermiology.

In HepG2 Cells, Coexisting Carnitine Deficiency Masks Important Indicators of Marginal Biotin Deficiency123

Science.gov (United States)

Bogusiewicz, Anna; Boysen, Gunnar; Mock, Donald M

2015-01-01

Background: A large number of birth defects are related to nutrient deficiencies; concern that biotin deficiency is teratogenic in humans is reasonable. Surprisingly, studies indicate that increased urinary 3-hydroxyisovalerylcarnitine (3HIAc), a previously validated marker of biotin deficiency, is not a valid biomarker in pregnancy. Objective: In this study we hypothesized that coexisting carnitine deficiency can prevent the increase in 3HIAc due to biotin deficiency. Methods: We used a 2-factor nutrient depletion design to induce isolated and combined biotin and carnitine deficiency in HepG2 cells and then repleted cells with carnitine. To elucidate the metabolic pathogenesis, we quantitated intracellular and extracellular free carnitine, acylcarnitines, and acylcarnitine ratios using liquid chromatography–tandem mass spectrometry. Results: Relative to biotin-sufficient, carnitine-sufficient cells, intracellular acetylcarnitine increased by 90%, propionylcarnitine more than doubled, and 3HIAc increased by >10-fold in biotin-deficient, carnitine-sufficient (BDCS) cells, consistent with a defensive mechanism in which biotin-deficient cells transesterify the acyl-coenzyme A (acyl-CoA) substrates of the biotin-dependent carboxylases to the related acylcarnitines. Likewise, in BDCS cells, the ratio of acetylcarnitine to malonylcarnitine and the ratio of propionylcarnitine to methylmalonylcarnitine both more than tripled, and the ratio of 3HIAc to 3-methylglutarylcarnitine (MGc) increased by >10-fold. In biotin-deficient, carnitine-deficient (BDCD) cells, the 3 substrate-derived acylcarnitines changed little, but the substrate:product ratios were masked to a lesser extent. Moreover, carnitine repletion unmasked biotin deficiency in BDCD cells as shown by increases in acetylcarnitine, propionylcarnitine, and 3HIAc (each increased by >50-fold). Likewise, ratios of acetylcarnitine:malonylcarnitine, propionylcarnitine:methylmalonylcarnitine, and 3HIAc:MGc all increased

Dehydrogenation in large ingot casting process

International Nuclear Information System (INIS)

Ubukata, Takashi; Suzuki, Tadashi; Ueda, Sou; Shibata, Takashi

2009-01-01

Forging components (for nuclear power plants) have become larger and larger because of decreased weld lines from a safety point of view. Consequently they have been manufactured from ingots requirement for 200 tons or more. Dehydrogenation is one of the key issues for large ingot manufacturing process. In the case of ingots of 200 tons or heavier, mold stream degassing (MSD) has been applied for dehydrogenation. Although JSW had developed mold stream degassing by argon (MSD-Ar) as a more effective dehydrogenating practice, MSD-Ar was not applied for these ingots, because conventional refractory materials of a stopper rod for the Ar blowing hole had low durability. In this study, we have developed a new type of stopper rod through modification of both refractory materials and the stopper rod construction and have successfully expanded the application range of MSD-Ar up to ingots weighting 330 tons. Compared with the conventional MSD, the hydrogen content in ingots after MSD-Ar has decreased by 24 percent due to the dehydrogenation rate of MSD-Ar increased by 34 percent. (author)

Getting Started with CoaSim — An Introduction to the Simulator CoaSim

DEFF Research Database (Denmark)

Mailund, T

2005-01-01

CoaSim is a tool for simulating the coalescent process with recombination and geneconversion, under either constant population size or exponential population growth. It effectively constructs the ancestral recombination graph for a given number of chromosomes and uses this to simulate samples...

Severe sensory neuropathy in patients with adult-onset multiple acyl-CoA dehydrogenase deficiency.

Science.gov (United States)

Wang, Zhaoxia; Hong, Daojun; Zhang, Wei; Li, Wurong; Shi, Xin; Zhao, Danhua; Yang, Xu; Lv, He; Yuan, Yun

2016-02-01

Multiple Acyl-CoA dehydrogenase deficiency (MADD) is an autosomal recessive disorder of fatty acid oxidation. Most patients with late-onset MADD are clinically characterized by lipid storage myopathy with dramatic responsiveness to riboflavin treatment. Abnormalities of peripheral neuropathy have rarely been reported in patients with late-onset MADD. We describe six patients who presented with proximal limb weakness and loss of sensation in the distal limbs. Muscle biopsy revealed typical myopathological patterns of lipid storage myopathy and blood acylcarnitine profiles showed a combined elevation of multiple acylcarnitines supporting the diagnosis of MADD. However, nerve conduction investigations and sural nerve biopsies in these patients indicated severe axonal sensory neuropathy. Causative ETFDH gene mutations were found in all six cases. No other causative gene mutations were identified in mitochondrial DNA and genes associated with hereditary neuropathies through next-generation-sequencing panel. Late-onset patients with ETFDH mutations can present with proximal muscle weakness and distal sensory neuropathy, which might be a new phenotypic variation, but the precise underlying pathogenesis remains to be elucidated. Copyright © 2015. Published by Elsevier B.V.

Fatty acid oxidation disorders as primary cause of sudden and unexpected death in infants and young children

DEFF Research Database (Denmark)

Banner, Jytte; Kølvraa, S; Gregersen, N

1997-01-01

Disorders of fatty acid metabolism are known to be responsible for cases of sudden and unexpected death in infancy. At least 14 disorders are known at present. 120 cases of sudden infant death syndrome (SIDS) had been examined for a prevalent mutation (G985) causing medium chain acyl Co......A dehydrogenase deficiency, which is inherited in an autosomal recessive mode. No over-representation of either homozygous or heterozygous cases was found....

Biosynthesis of triacylglycerols containing very long chain monounsaturated acyl moieties in developing seeds

International Nuclear Information System (INIS)

Fehling, E.; Murphy, D.J.; Mukherjee, K.D.

1990-01-01

Particulate (15,000g) fractions from developing seeds of honesty (Lunaria annua L.) and mustard (Sinapis alba L.) synthesize radioactive very long chain monounsaturated fatty acids (gadoleic, erucic, and nervonic) from [1- 14 C]oleoyl-CoA and malonyl-CoA or from oleoyl-CoA and [2- 14 C]malonyl-CoA. The very long chain monounsaturated fatty acids are rapidly channeled to triacylglycerols and other acyl lipids without intermediate accumulation of their CoA thioesters. When [1- 14 C]oleoyl-CoA is used as the radioactive substrate, phosphatidylcholines and other phospholipids are most extensively radiolabeled by oleoyl moieties rather than by very long chain monounsaturated acyl moieties. When [2- 14 C]malonyl-CoA is used as the radioactive substrate, no radioactive oleic acid is formed and the newly synthesized very long chain monounsaturated fatty acids are extensively incorporated into phosphatidylcholines and other phospholipids as well as triacylglycerols. The pattern of labeling of the key intermediates of the Kennedy pathway, e.g. lysophosphatidic acids, phosphatidic acids, and diacylglycerols by the newly synthesized very long chain monounsaturated fatty acids is consistent with the operation of this pathway in the biosynthesis of triacylglycerols

Acyl CoA Binding Domain Containing 3 (ACBD3) Protein in Huntington’s Disease 
Human Skin Fibroblasts

Czech Academy of Sciences Publication Activity Database

Kratochvílová, H.; Rodinová, M.; Sládková, J.; Klempíř, J.; Lišková, Irena; Motlík, Jan; Zeman, J.; Hansíková, H.; Tesařová, M.

2015-01-01

Roč. 78, Suppl. 2 (2015), s. 34-38 ISSN 1210-7859. [Conference on Animal Models for neurodegenerative Diseases /3./. Liblice, 08.11.2015-10.11.2015] R&D Projects: GA MŠk ED2.1.00/03.0124 Institutional support: RVO:67985904 Keywords : Huntington’s disease * Acyl-CoA binding domain containing 3 protein * human skin fibroblasts Subject RIV: FH - Neurology Impact factor: 0.209, year: 2015

Role of Feedback Regulation of Pantothenate Kinase (CoaA) in Control of Coenzyme A Levels in Escherichia coli

Science.gov (United States)

Rock, Charles O.; Park, Hee-Won; Jackowski, Suzanne

2003-01-01

Pantothenate kinase (CoaA) is a key regulator of coenzyme A (CoA) biosynthesis in Escherichia coli, and its activity is controlled by feedback inhibition by CoA and its thioesters. The importance of feedback inhibition in the control of the intracellular CoA levels was tested by constructing three site-directed mutants of CoaA that were predicted to be feedback resistant based on the crystal structure of the CoaA-CoA binary complex. CoaA[R106A], CoaA[H177Q], and CoaA[F247V] were purified and shown to retain significant catalytic activity and be refractory to inhibition by CoA. CoaA[R106A] retained 50% of the catalytic activity of CoaA, whereas the CoaA[H177Q] and CoaA[F247V] mutants were less active. The importance of feedback control of CoaA to the intracellular CoA levels was assessed by expressing either CoaA or CoaA[R106A] in strain ANS3 [coaA15(Ts) panD2]. Cells expressing CoaA[R106A] had significantly higher levels of phosphorylated pantothenate-derived metabolites and CoA in vivo and excreted significantly more 4′-phosphopantetheine into the medium compared to cells expressing the wild-type protein. These data illustrate the key role of feedback regulation of pantothenate kinase in the control of intracellular CoA levels. PMID:12754240

Stearoyl-acyl carrier protein and unusual acyl-acyl carrier protein desaturase activities are differentially influenced by ferredoxin.

Science.gov (United States)

Schultz, D J; Suh, M C; Ohlrogge, J B

2000-10-01

Acyl-acyl carrier protein (ACP) desaturases function to position a single double bond into an acyl-ACP substrate and are best represented by the ubiquitous Delta9 18:0-ACP desaturase. Several variant acyl-ACP desaturases have also been identified from species that produce unusual monoenoic fatty acids. All known acyl-ACP desaturase enzymes use ferredoxin as the electron-donating cofactor, and in almost all previous studies the photosynthetic form of ferredoxin rather than the non-photosynthetic form has been used to assess activity. We have examined the influence of different forms of ferredoxin on acyl-ACP desaturases. Using combinations of in vitro acyl-ACP desaturase assays and [(14)C]malonyl-coenzyme A labeling studies, we have determined that heterotrophic ferredoxin isoforms support up to 20-fold higher unusual acyl-ACP desaturase activity in coriander (Coriandrum sativum), Thunbergia alata, and garden geranium (Pelargonium x hortorum) when compared with photosynthetic ferredoxin isoforms. Heterotrophic ferredoxin also increases activity of the ubiquitous Delta9 18:0-ACP desaturase 1.5- to 3.0-fold in both seed and leaf extracts. These results suggest that ferredoxin isoforms may specifically interact with acyl-ACP desaturases to achieve optimal enzyme activity and that heterotrophic isoforms of ferredoxin may be the in vivo electron donor for this reaction.

Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

DEFF Research Database (Denmark)

Christensen, Rasmus Bjerregaard; Lu, Jing Tao; Hedegard, Per

2016-01-01

We employ a semi-classical Langevin approach to study current-induced atomic dynamics in a partially dehydrogenated armchair graphene nanoribbon. All parameters are obtained from density functional theory. The dehydrogenated carbon dimers behave as effective impurities, whose motion decouples from...

Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

DEFF Research Database (Denmark)

Christensen, Rasmus Bjerregaard; Lu, Jing Tao; Hedegard, Per

2016-01-01

We employ a semi-classical Langevin approach to study current-induced atomic dynamics in a partially dehydrogenated armchair graphene nanoribbon. All parameters are obtained from density functional theory. The dehydrogenated carbon dimers behave as effective impurities, whose motion decouples fro...

Characterization of CG6178 gene product with high sequence similarity to firefly luciferase in Drosophila melanogaster.

Science.gov (United States)

Oba, Yuichi; Ojika, Makoto; Inouye, Satoshi

2004-03-31

This is the first identification of a long-chain fatty acyl-CoA synthetase in Drosophila by enzymatic characterization. The gene product of CG6178 (CG6178) in Drosophila melanogaster genome, which has a high sequence similarity to firefly luciferase, has been expressed and characterized. CG6178 showed long-chain fatty acyl-CoA synthetic activity in the presence of ATP, CoA and Mg(2+), suggesting a fatty acyl adenylate is an intermediate. Recently, it was revealed that firefly luciferase has two catalytic functions, monooxygenase (luciferase) and AMP-mediated CoA ligase (fatty acyl-CoA synthetase). However, unlike firefly luciferase, CG6178 did not show luminescence activity in the presence of firefly luciferin, ATP, CoA and Mg(2+). The enzymatic properties of CG6178 including substrate specificity, pH dependency and optimal temperature were close to those of firefly luciferase and rat fatty acyl-CoA synthetase. Further, phylogenic analyses strongly suggest that the firefly luciferase gene may have evolved from a fatty acyl-CoA synthetase gene as a common ancestral gene.

Stearoyl-Acyl Carrier Protein and Unusual Acyl-Acyl Carrier Protein Desaturase Activities Are Differentially Influenced by Ferredoxin1

Science.gov (United States)

Schultz, David J.; Suh, Mi Chung; Ohlrogge, John B.

2000-01-01

Acyl-acyl carrier protein (ACP) desaturases function to position a single double bond into an acyl-ACP substrate and are best represented by the ubiquitous Δ9 18:0-ACP desaturase. Several variant acyl-ACP desaturases have also been identified from species that produce unusual monoenoic fatty acids. All known acyl-ACP desaturase enzymes use ferredoxin as the electron-donating cofactor, and in almost all previous studies the photosynthetic form of ferredoxin rather than the non-photosynthetic form has been used to assess activity. We have examined the influence of different forms of ferredoxin on acyl-ACP desaturases. Using combinations of in vitro acyl-ACP desaturase assays and [14C]malonyl-coenzyme A labeling studies, we have determined that heterotrophic ferredoxin isoforms support up to 20-fold higher unusual acyl-ACP desaturase activity in coriander (Coriandrum sativum), Thunbergia alata, and garden geranium (Pelargonium × hortorum) when compared with photosynthetic ferredoxin isoforms. Heterotrophic ferredoxin also increases activity of the ubiquitous Δ9 18:0-ACP desaturase 1.5- to 3.0-fold in both seed and leaf extracts. These results suggest that ferredoxin isoforms may specifically interact with acyl-ACP desaturases to achieve optimal enzyme activity and that heterotrophic isoforms of ferredoxin may be the in vivo electron donor for this reaction. PMID:11027717

Base metal dehydrogenation of amine-boranes

Science.gov (United States)

Blacquiere, Johanna Marie [Ottawa, CA; Keaton, Richard Jeffrey [Pearland, TX; Baker, Ralph Thomas [Los Alamos, NM

2009-06-09

A method of dehydrogenating an amine-borane having the formula R.sup.1H.sub.2N--BH.sub.2R.sup.2 using base metal catalyst. The method generates hydrogen and produces at least one of a [R.sup.1HN--BHR.sup.2].sub.m oligomer and a [R.sup.1N--BR.sup.2].sub.n oligomer. The method of dehydrogenating amine-boranes may be used to generate H.sub.2 for portable power sources, such as, but not limited to, fuel cells.

Mitochondrial storage form of acetyl CoA carboxylase in fasted and alloxan diabetic rats

International Nuclear Information System (INIS)

Roman-Lopez, C.R.; Allred, J.B.

1986-01-01

Sodium dodecyl sulfate-denatured biotinyl proteins will bind [ 14 C]methyl avidin which remains bound through polyacrylamide gel electrophoresis. The method has been used to demonstrate the presence of two high molecular weight subunit forms of acetyl CoA carboxylase in rat liver cytoplasm, both of which are precipitated by antibody to purifed rat liver acetyl CoA carboxylase prepared from sheep serum. Rat liver mitochondria contained five distinct biotinyl protein subunits, the two largest of which have been identified as acetyl CoA carboxylase subunits on the basis of precipitation by anti-acetyl CoA carboxylase antibody. The small quantity of acetyl CoA carboxylase associated with rat liver microsomes could be attributed to cytoplasmic contamination. The binding of radioactive avidin is sufficiently tight to use as a measure of the quantity of acetyl CoA carboxylase. The quantity and activity of the cytoplasmic enzyme was reduced in fasted and in alloxan diabetic rats compared to that in fed controls but the quantity of the enzyme associated with isolated mitochondria was not reduced. The results indicate that there is a mitochondrial storage form of acetyl CoA carboxylase

Dehydrogenation mechanism of LiBH{sub 4} by Poly(methyl methacrylate)

Energy Technology Data Exchange (ETDEWEB)

Huang, Jianmei [School of Materials Science and Engineering, and Key Laboratory of Advanced Energy Storage Materials of Guangdong Province, South China University of Technology, Guangzhou 510641 (China); China-Australia Joint Laboratory for Energy & Environmental Materials, South China University of Technology, Guangzhou 510641 (China); Yan, Yurong [School of Materials Science and Engineering, and Key Laboratory of Advanced Energy Storage Materials of Guangdong Province, South China University of Technology, Guangzhou 510641 (China); Ouyang, Liuzhang, E-mail: meouyang@scut.edu.cn [School of Materials Science and Engineering, and Key Laboratory of Advanced Energy Storage Materials of Guangdong Province, South China University of Technology, Guangzhou 510641 (China); China-Australia Joint Laboratory for Energy & Environmental Materials, South China University of Technology, Guangzhou 510641 (China); Key Laboratory for Fuel Cell Technology in Guangdong Province, South China University of Technology, Guangzhou 510641 (China); Wang, Hui [School of Materials Science and Engineering, and Key Laboratory of Advanced Energy Storage Materials of Guangdong Province, South China University of Technology, Guangzhou 510641 (China); China-Australia Joint Laboratory for Energy & Environmental Materials, South China University of Technology, Guangzhou 510641 (China); Zhu, Min, E-mail: memzhu@scut.edu.cn [School of Materials Science and Engineering, and Key Laboratory of Advanced Energy Storage Materials of Guangdong Province, South China University of Technology, Guangzhou 510641 (China); China-Australia Joint Laboratory for Energy & Environmental Materials, South China University of Technology, Guangzhou 510641 (China)

2015-10-05

Highlights: • LiBH{sub 4} is amorphous after modified with PMMA. • Dehydrogenation temperature of LiBH{sub 4} decreases by 120 °C after modifying with PMMA. • The LiBH{sub 4}@PMMA composite releases 10 wt.% hydrogen at 360 °C within 1 h. • C=O group of PMMA weakens the B−H bonds to lower dehydrogenation temperature. - Abstract: We investigated the dehydrogenation properties and mechanism of Poly(methyl methacrylate) (PMMA) confined LiBH{sub 4}. Thermal stability of LiBH{sub 4} was reduced by PMMA, with a decrease in dehydrogenation temperature by 120 °C. At 360 °C, the composite showed fast dehydrogenation kinetics with 10 wt.% of hydrogen released within 1 h. The improved dehydrogenation performance was mainly attributed to the reaction between LiBH{sub 4} and PMMA forming Li{sub 3}BO{sub 3} as a final product. Furthermore, the presence of electrostatic interaction between B atom of LiBH{sub 4} and O atom in the carbonyl group of PMMA may weaken the B−H bonding of [BH{sub 4}]{sup −} and lower the hydrogen desorption temperature.

Safe and unsafe duration of fasting for children with MCAD deficiency

NARCIS (Netherlands)

Derks, Terry G J; van Spronsen, Francjan J; Rake, Jan Peter; van der Hilst, Christian S; Span, Mark M; Smit, G Peter A

OBJECTIVE: To study the safe and unsafe duration of fasting in children with medium chain acyl-Coenzyme A dehydrogenase (MCAD) deficiency, the literature and the database on Dutch MCAD-deficient patients were searched for data on fasting studies in patients with MCAD deficiency. MATERIALS AND

MCAD deficiency in Denmark

DEFF Research Database (Denmark)

Andresen, Brage Storstein; Lund, Allan Meldgaard; Hougaard, David Michael

2012-01-01

Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is the most common defect of fatty acid oxidation. Many countries have introduced newborn screening for MCADD, because characteristic acylcarnitines can easily be identified in filter paper blood spot samples by tandem mass spectrometry (MS/M...

Biocatalysis of a Paclitaxel Analogue: Conversion of Baccatin III to N-Debenzoyl-N-(2-furoyl)paclitaxel and Characterization of an Amino Phenylpropanoyl CoA Transferase.

Science.gov (United States)

Thornburg, Chelsea K; Walter, Tyler; Walker, Kevin D

2017-11-07

In this study, we demonstrate an enzyme cascade reaction using a benzoate CoA ligase (BadA), a modified nonribosomal peptide synthase (PheAT), a phenylpropanoyltransferase (BAPT), and a benzoyltransferase (NDTNBT) to produce an anticancer paclitaxel analogue and its precursor from the commercially available biosynthetic intermediate baccatin III. BAPT and NDTNBT are acyltransferases on the biosynthetic pathway to the antineoplastic drug paclitaxel in Taxus plants. For this study, we addressed the recalcitrant expression of BAPT by expressing it as a soluble maltose binding protein fusion (MBP-BAPT). Further, the preparative-scale in vitro biocatalysis of phenylisoserinyl CoA using PheAT enabled thorough kinetic analysis of MBP-BAPT, for the first time, with the cosubstrate baccatin III. The turnover rate of MBP-BAPT was calculated for the product N-debenzoylpaclitaxel, a key intermediate to various bioactive paclitaxel analogues. MBP-BAPT also converted, albeit more slowly, 10-deacetylbaccatin III to N-deacyldocetaxel, a precursor of the pharmaceutical docetaxel. With PheAT available to make phenylisoserinyl CoA and kinetic characterization of MBP-BAPT, we used Michaelis-Menten parameters of the four enzymes to adjust catalyst and substrate loads in a 200-μL one-pot reaction. This multienzyme network produced a paclitaxel analogue N-debenzoyl-N-(2-furoyl)paclitaxel (230 ng) that is more cytotoxic than paclitaxel against certain macrophage cell types. Also in this pilot reaction, the versatile N-debenzoylpaclitaxel intermediate was made at an amount 20-fold greater than the N-(2-furoyl) product. This reaction network has great potential for optimization to scale-up production and is attractive in its regioselective O- and N-acylation steps that remove protecting group manipulations used in paclitaxel analogue synthesis.

Shaking table test study on seismic performance of dehydrogenation fan for nuclear power plants

International Nuclear Information System (INIS)

Liu Kaiyan; Shi Weixing; Cao Jialiang; Wang Yang

2011-01-01

Seismic performance of the dehydrogenation fan for nuclear power plants was evaluated based on the shaking table test of earthquake simulation. Dynamic characteristics including the orthogonal tri-axial fundamental frequencies and equivalent damping ratios were measured by the white noise scanning method. Artificial seismic waves were generated corresponding to the floor acceleration response spectra for nuclear power plants. Furthermore, five OBE and one SSE shaking table tests for dehydrogenation fan were performed by using the artificial seismic waves as the seismic inputs along the orthogonal axis simultaneity. Operating function of dehydrogenation fan was monitored and observed during all seismic tests, and performance indexes of dehydrogenation fan were compared before and after seismic tests. The results show that the structural integrity and operating function of the dehydrogenation fan are perfect during all seismic tests; and the performance indexes of the dehydrogenation fan can remain consistent before and after seismic tests; the seismic performance of the dehydrogenation fan can satisfy relevant technical requirements. (authors)

Adsorption and dehydrogenation of tetrahydroxybenzene on Cu(111)

DEFF Research Database (Denmark)

Bebensee, Fabian; Svane, K.; Bombis, Christian

2013-01-01

Adsorption of tetrahydroxybenzene (THB) on Cu(111) and Au(111) surfaces is studied using a combination of STM, XPS, and DFT. THB is deposited intact, but on Cu(111) it undergoes gradual dehydrogenation of the hydroxyl groups as a function of substrate temperature, yielding a pure dihydroxy......-benzoquinone phase at 370 K. Subtle changes to the adsorption structure upon dehydrogenation are explained from differences in molecule–surface bonding....

Succinyl-CoA:3-ketoacid CoA transferase (SCOT): cloning of the human SCOT gene, tertiary structural modeling of the human SCOT monomer, and characterization of three pathogenic mutations

NARCIS (Netherlands)

Fukao, T.; Mitchell, G. A.; Song, X. Q.; Nakamura, H.; Kassovska-Bratinova, S.; Orii, K. E.; Wraith, J. E.; Besley, G.; Wanders, R. J.; Niezen-Koning, K. E.; Berry, G. T.; Palmieri, M.; Kondo, N.

2000-01-01

The activity of succinyl-CoA:3-ketoacid CoA transferase (SCOT; locus symbol OXCT; EC 2.8.3.5) is the main determinant of the ketolytic capacity of tissues. Hereditary SCOT deficiency causes episodic ketoacidosis. Here we describe the human SCOT gene, which spans more than 100 kb and contains 17

Abnormal myelin formation in rhizomelic chondrodysplasia punctata type 2 (DHAPAT-deficiency)

NARCIS (Netherlands)

Sztriha, L.; Al-Gazali, L. I.; Wanders, R. J.; Ofman, R.; Nork, M.; Lestringant, G. G.

2000-01-01

The case of a Yemeni girl with isolated peroxisomal acyl-CoA:dihydroxyacetonephosphate acyltransferase (DHAPAT) deficiency is reported. She had rhizomelic chondrodysplasia punctata, microcephaly, failure to thrive, delayed motor and mental development, and spastic quadriplegia. Deficient de novo

COA based robust output feedback UPFC controller design

Energy Technology Data Exchange (ETDEWEB)

Shayeghi, H., E-mail: hshayeghi@gmail.co [Technical Engineering Department, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of); Shayanfar, H.A. [Center of Excellence for Power System Automation and Operation, Electrical Engineering Department, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Jalilzadeh, S.; Safari, A. [Technical Engineering Department, Zanjan University, Zanjan (Iran, Islamic Republic of)

2010-12-15

In this paper, a novel method for the design of output feedback controller for unified power flow controller (UPFC) using chaotic optimization algorithm (COA) is developed. Chaotic optimization algorithms, which have the features of easy implementation, short execution time and robust mechanisms of escaping from the local optimum, is a promising tool for the engineering applications. The selection of the output feedback gains for the UPFC controllers is converted to an optimization problem with the time domain-based objective function which is solved by a COA based on Lozi map. Since chaotic mapping enjoys certainty, ergodicity and the stochastic property, the proposed chaotic optimization problem introduces chaos mapping using Lozi map chaotic sequences which increases its convergence rate and resulting precision. To ensure the robustness of the proposed stabilizers, the design process takes into account a wide range of operating conditions and system configurations. The effectiveness of the proposed controller for damping low frequency oscillations is tested and demonstrated through non-linear time-domain simulation and some performance indices studies. The results analysis reveals that the designed COA based output feedback UPFC damping controller has an excellent capability in damping power system low frequency oscillations and enhance greatly the dynamic stability of the power systems.

Acylation of Therapeutic Peptides

DEFF Research Database (Denmark)

Trier, Sofie; Henriksen, Jonas Rosager; Jensen, Simon Bjerregaard

) , which promotes intestinal growth and is used to treat bowel disorders such as inflammatory bowel diseases and short bowel syndrome, and the 32 amino acid salmon calcitonin (sCT), which lowers blood calcium and is employed in the treatment of post-menopausal osteoporosis and hypercalcemia. The two...... peptides are similar in size and structure, but oppositely charged at physiological pH. Both peptides were acylated with linear acyl chains of systematically increasing length, where sCT was furthermore acylated at two different positions on the peptide backbone. For GLP-2, we found that increasing acyl...... remained optimal overall. The results indicate that rational acylation of GLP-2 can increase its in vitro intestinal absorption, alone or in combination with permeation enhancers, and are consistent with the initial project hypothesis. For sCT, an unpredicted effect of acylation largely superseded...

The most common mutation causing medium-chain acyl-CoA dehydrogenase deficiency is strongly associated with a particular haplotype in the region of the gene

DEFF Research Database (Denmark)

Kølvraa, S; Gregersen, N; Blakemore, A I

1991-01-01

RFLP haplotypes in the region containing the medium-chain acyl-CoA dehydrogenase (MCAD) gene on chromosome 1 have been determined in patients with MCAD deficiency. The RFLPs were detected after digestion of patient DNA with the enzymes BanII. PstI and TaqI and with an MCAD cDNA-clone as a probe....... Of 32 disease-causing alleles studied, 31 possessed the previously published A----G point-mutation at position 985 of the cDNA. This mutation has been shown to result in inactivity of the MCAD enzyme. In at least 30 of the 31 alleles carrying this G985 mutation a specific RFLP haplotype was present...

Stepwise dehydrogenation of ammonia on Fcc-Co surfaces: A DFT study

Energy Technology Data Exchange (ETDEWEB)

Ma, F.F.; Ma, S.H., E-mail: mash.phy@htu.edu.cn; Jiao, Z.Y.; Dai, X.Q.

2017-05-31

Highlights: • On Co surfaces, oxygen atom not only strengthens ammonia-substrate interaction but also facilitates ammonia dissociation on the Co surfaces. • Pre-adsorbed O atom significantly promotes the stepwise dehydrogenation of ammonia on Co(110), giving rise to N atom strongly binding with the surface. • The dissociation of NH appears to be the rate-determining step on O-covered Co(111) and Co(100) surfaces. • The species N and NH produced in ammonia dehydrogenation are likely responsible for cobalt catalyst deactivation in the excess of oxygen atom. - Abstract: The stepwise dehydrogenation of ammonia on clean and O-covered Co surfaces have been studied by performing density functional theory (DFT) calculations. It is found that the interaction of species NH{sub x} (x = 0–3) with the Co surfaces become stronger with its further dehydrogenation, and oxygen atom not only strengthens ammonia-substrate interaction but also facilitates ammonia dissociation. Specifically, pre-adsorbed O atom significantly promotes the stepwise dehydrogenation of ammonia on Co(110), giving rise to N atom strongly binding with the surface. In contrast, the dissociation of NH appears to be the rate-determining step on O-covered Co(111) and Co(100) surfaces, due to the high energy barriers. And present results demonstrate that the species N and NH produced in ammonia dehydrogenation are likely responsible for cobalt catalyst deactivation in the excess of oxygen atom.

Stepwise dehydrogenation of ammonia on Fcc-Co surfaces: A DFT study

International Nuclear Information System (INIS)

Ma, F.F.; Ma, S.H.; Jiao, Z.Y.; Dai, X.Q.

2017-01-01

Highlights: • On Co surfaces, oxygen atom not only strengthens ammonia-substrate interaction but also facilitates ammonia dissociation on the Co surfaces. • Pre-adsorbed O atom significantly promotes the stepwise dehydrogenation of ammonia on Co(110), giving rise to N atom strongly binding with the surface. • The dissociation of NH appears to be the rate-determining step on O-covered Co(111) and Co(100) surfaces. • The species N and NH produced in ammonia dehydrogenation are likely responsible for cobalt catalyst deactivation in the excess of oxygen atom. - Abstract: The stepwise dehydrogenation of ammonia on clean and O-covered Co surfaces have been studied by performing density functional theory (DFT) calculations. It is found that the interaction of species NH x (x = 0–3) with the Co surfaces become stronger with its further dehydrogenation, and oxygen atom not only strengthens ammonia-substrate interaction but also facilitates ammonia dissociation. Specifically, pre-adsorbed O atom significantly promotes the stepwise dehydrogenation of ammonia on Co(110), giving rise to N atom strongly binding with the surface. In contrast, the dissociation of NH appears to be the rate-determining step on O-covered Co(111) and Co(100) surfaces, due to the high energy barriers. And present results demonstrate that the species N and NH produced in ammonia dehydrogenation are likely responsible for cobalt catalyst deactivation in the excess of oxygen atom.

Ruthenium-Catalyzed Dehydrogenative Decarbonylation of Primary Alcohols

DEFF Research Database (Denmark)

Mazziotta, Andrea; Madsen, Robert

2017-01-01

Dehydrogenative decarbonylation of a primary alcohol involves the release of both dihydrogen and carbon monoxide to afford the one-carbon shorter product. The transformation has now been achieved with a ruthenium-catalyzed protocol by using the complex Ru(COD)Cl2 and the hindered monodentate ligand...... P(o-tolyl)3 in refluxing p-cymene. The reaction can be applied to both benzylic and long chain linear aliphatic alcohols. The intermediate aldehyde can be observed during the transformation, which is therefore believed to proceed through two separate catalytic cycles involving first dehydrogenation...... of the alcohol and then decarbonylation of the resulting aldehyde....

A protocol for amide bond formation with electron deficient amines and sterically hindered substrates

DEFF Research Database (Denmark)

Due-Hansen, Maria E; Pandey, Sunil K; Christiansen, Elisabeth

2016-01-01

A protocol for amide coupling by in situ formation of acyl fluorides and reaction with amines at elevated temperature has been developed and found to be efficient for coupling of sterically hindered substrates and electron deficient amines where standard methods failed.......A protocol for amide coupling by in situ formation of acyl fluorides and reaction with amines at elevated temperature has been developed and found to be efficient for coupling of sterically hindered substrates and electron deficient amines where standard methods failed....

Molecular rational for riboflavin and CoQ10

DEFF Research Database (Denmark)

Cornelius, Nanna

2013-01-01

A new PhD project from Health, Aarhus University, shows that there is a molecular rationale for riboflavin and CoQ10 treatment in patients with Riboflavin Responsive Multiple acyl-CoA dehydrogenation deficiency. The project was carried out by Nanna Cornelius, a molecular biologist who defended her......-QO) protein. High dosis Riboflavin treatment nearly normalizes the clinical and biochemical symptoms of these patients. Until now, no studies have investigated the molecular effect of riboflavin in the patients. However, in her recently completed PhD project, Nanna Cornelius shows that riboflavin has...

Anesthetic agents in patients with very long-chain acyl-coenzyme A dehydrogenase deficiency: a literature review.

Science.gov (United States)

Redshaw, Charlotte; Stewart, Catherine

2014-11-01

Very long-chain acyl-coenzyme A dehydrongenase deficiency (VLCADD) is a rare disorder of fatty acid metabolism that renders sufferers susceptible to hypoglycemia, liver failure, cardiomyopathy, and rhabdomyolysis. The literature about the management of these patients is hugely conflicting, suggesting that both propofol and volatile anesthesia should be avoided. We have reviewed the literature and have concluded that the source papers do not support the statements that volatile anesthetic agents are unsafe. The reports on rhabdomyolysis secondary to anesthesia appear to be due to inadequate supply of carbohydrate not volatile agents. Catabolism must be avoided with minimal fasting, glucose infusions based on age and weight, and attenuation of emotional and physical stress. General anesthesia appears to be protective of stress-induced catabolism and may offer benefits in children and anxious patients over regional anesthesia. Propofol has not been demonstrated to be harmful in VLCADD but is presented in an emulsion containing very long-chain fatty acids which can cause organ lipidosis and itself can inhibit mitochondrial fatty acid metabolism. It is therefore not recommended. Suxamethonium-induced myalgia may mimic symptoms of rhabdomyolysis and cause raised CK therefore should be avoided. Opioids, NSAIDS, regional anesthesia, and local anesthetic techniques have all been used without complication. © 2014 John Wiley & Sons Ltd.

α-Lipoic acid prevents lipotoxic cardiomyopathy in acyl CoA-synthase transgenic mice

International Nuclear Information System (INIS)

Lee, Young; Naseem, R. Haris; Park, Byung-Hyun; Garry, Daniel J.; Richardson, James A.; Schaffer, Jean E.; Unger, Roger H.

2006-01-01

α-Lipoic acid (α-LA) mimics the hypothalamic actions of leptin on food intake, energy expenditure, and activation of AMP-activated protein kinase (AMPK). To determine if, like leptin, α-LA protects against cardiac lipotoxicity, α-LA was fed to transgenic mice with cardiomyocyte-specific overexpression of the acyl CoA synthase (ACS) gene. Untreated ACS-transgenic mice died prematurely with increased triacylglycerol content and dilated cardiomyopathy, impaired systolic function and myofiber disorganization, apoptosis, and interstitial fibrosis on microscopy. In α-LA-treated ACS-transgenic mice heart size, echocardiogram and TG content were normal. Plasma TG fell 50%, hepatic-activated phospho-AMPK rose 6-fold, sterol regulatory element-binding protein-1c declined 50%, and peroxisome proliferator-activated receptor-γ cofactor-1α mRNA rose 4-fold. Since food restriction did not prevent lipotoxicity, we conclude that α-LA treatment, like hyperleptinemia, protects the heart of ACS-transgenic mice from lipotoxicity

Oxidative dehydrogenation of isobutane over a titanium pyrophosphate catalyst

Directory of Open Access Journals (Sweden)

IOAN-CEZAR MARCU

2005-06-01

Full Text Available The catalytic properties of titanium pyrophosphate in the oxidative dehydrogenation of isobutane to isobutylene were investigated in the 400 – 550 ºC temperature range. Asignificant change of the product distribution and of the apparent activation energy of the reactionwas observed at about 490 ºC. This phenomenon, already observed in the oxidative dehydrogenation of n-butane, has been interpreted by the existence of two reaction mechanisms depending upon the reaction temperature. Comparison with the n-butane reaction allowed different activation pathways for the activation of alkanes to be proposed. The catalytic properties of TiP2O7 in the oxidative dehydrogenation of isobutane was also compared to those obtained previously with several other pyrophosphates and TiP2O7 was found to be less active and selective for this reaction.

Synthesis and magnetic properties of superparamagnetic CoAs nanostructures

Science.gov (United States)

Desai, P.; Ashokaan, N.; Masud, J.; Pariti, A.; Nath, M.

2015-03-01

This article provides a comprehensive guide on the synthesis and characterization of superparamagnetic CoAs nanoparticles and elongated nanostructures with high blocking temperature, (TB), via hot-injection precipitation and solvothermal methods. Cobalt arsenides constitute an important family of magnetically active solids that find a variety of applications ranging from magnetic semiconductors to biomedical imaging. While the higher temperature hot-injection precipitation technique (300 °C) yields pure CoAs nanostructures, the lower temperature solvothermal method (200 °C) yields a mixture of CoAs nanoparticles along with other Co-based impurity phases. The synthesis in all these cases involved usage of triphenylarsine ((C6H5)3As) as the As precursor which reacts with solid Co2(CO)8 by ligand displacement to yield a single source precursor. The surfactant, hexadecylamine (HDA) further assists in controlling the morphology of the nanostructures. HDA also provides a basic medium and molten flux-like conditions for the redox chemistry to occur between Co and As at elevated temperatures. The influence of the length of reaction time was investigated by studying the evolution of product morphology over time. It was observed that while spontaneous nucleation at higher temperature followed by controlled growth led to the predominant formation of short nanorods, with longer reaction time, the nanorods were further converted to nanoparticles. The size of the nanoparticles obtained, was mostly in the range of 10-15 nm. The key finding of this work is exceptionally high coercivity in CoAs nanostructures for the first time. Coercivity observed was as high as 0.1 T (1000 Oe) at 2 K. These kinds of magnetic nanostructures find multiple applications in spintronics, whereas the superparamagnetic nanoparticles are viable for use in magnetic storage, ferrofluids and as contrast enhancing agents in MRI.

Diminished exercise capacity and mitochondrial bc1 complex deficiency in tafazzin-knockdown mice.

Directory of Open Access Journals (Sweden)

Corey ePowers

2013-04-01

Full Text Available The phospholipid, cardiolipin, is essential for maintaining mitochondrial structure and optimal function. Cardiolipin-deficiency in humans, Barth syndrome, is characterized by exercise intolerance, dilated cardiomyopathy, neutropenia and 3-methyl-glutaconic aciduria. The causative gene is the mitochondrial acyl-transferase, tafazzin that is essential for remodeling acyl chains of cardiolipin. We sought to determine metabolic rates in tafazzin-deficient mice during resting and exercise, and investigate the impact of cardiolipin deficiency on mitochondrial respiratory chain activities. Tafazzin knockdown in mice markedly impaired oxygen consumption rates during an exercise, without any significant effect on resting metabolic rates. CL-deficiency resulted in significant reduction of mitochondrial respiratory reserve capacity in neonatal cardiomyocytes that is likely to be caused by diminished activity of complex-III, which requires CL for its assembly and optimal activity. Our results may provide mechanistic insights of Barth syndrome pathogenesis.

Nationwide survey of extended newborn screening by tandem mass spectrometry in Taiwan.

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Niu, Dau-Ming; Chien, Yin-Hsiu; Chiang, Chuan-Chi; Ho, Hui-Chen; Hwu, Wuh-Liang; Kao, Shu-Min; Chiang, Szu-Hui; Kao, Chuan-Hong; Liu, Tze-Tze; Chiang, Hung; Hsiao, Kwang-Jen

2010-10-01

In Taiwan, during the period March 2000 to June 2009, 1,495,132 neonates were screened for phenylketonuria (PKU) and homocystinuria (HCU), and 1,321,123 neonates were screened for maple syrup urine disease (MSUD), methylmalonic academia (MMA), medium-chain acyl-coenzyme A (CoA) dehydrogenase (MCAD) deficiency, isovaleric academia (IVA), and glutaric aciduria type 1 (GA-1) using tandem mass spectrometry (MS/MS). In a pilot study, 592,717 neonates were screened for citrullinemia, 3-methylcrotonyl-CoA carboxylase deficiency (3-MCC) and other fatty acid oxidation defects in the MS/MS newborn screening. A total of 170 newborns and four mothers were confirmed to have inborn errors of metabolism. The overall incidence was approximately 1/5,882 (1/6,219 without mothers). The most common inborn errors were defects of phenylalanine metabolism [five classic PKU, 20 mild PKU, 40 mild hyperphenylalaninemia (HPA), and 13 6-pyruvoyl-tetrahydropterin synthase (PTPS) deficiency]. MSUD was the second most common amino acidopathy and, significantly, most MSUD patients (10/13) belonged to the Austronesian aboriginal tribes of southern Taiwan. The most frequently detected among organic acid disorders was 3-MCC deficiency (14 newborns and four mothers). GA-1 and MMA were the second most common organic acid disorders (13 and 13 newborns, respectively). In fatty acid disorders, five carnitine transport defect (CTD), five short-chain acyl-CoA dehydrogenase deficiency (SCAD), and two medium-chain acyl-CoA dehydrogenase (MCAD) deficiency were confirmed. This is the largest case of MS/MS newborn screening in an East-Asian population to date. We hereby report the incidences and outcomes of metabolic inborn error diseases found in our nationwide MS/MS newborn screening program.

A Canonical Biotin Synthesis Enzyme, 8-Amino-7-Oxononanoate Synthase (BioF), Utilizes Different Acyl Chain Donors in Bacillus subtilis and Escherichia coli.

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Manandhar, Miglena; Cronan, John E

2018-01-01

BioF (8-amino-7-oxononanoate synthase) is a strictly conserved enzyme that catalyzes the first step in assembly of the fused heterocyclic rings of biotin. The BioF acyl chain donor has long been thought to be pimeloyl-CoA. Indeed, in vitro the Escherichia coli and Bacillus sphaericus enzymes have been shown to condense pimeloyl-CoA with l-alanine in a pyridoxal 5'-phosphate-dependent reaction with concomitant CoA release and decarboxylation of l-alanine. However, recent in vivo studies of E. coli and Bacillus subtilis suggested that the BioF proteins of the two bacteria could have different specificities for pimelate thioesters in that E. coli BioF may utilize either pimeloyl coenzyme A (CoA) or the pimelate thioester of the acyl carrier protein (ACP) of fatty acid synthesis. In contrast, B. subtilis BioF seemed likely to be specific for pimeloyl-CoA and unable to utilize pimeloyl-ACP. We now report genetic and in vitro data demonstrating that B. subtilis BioF specifically utilizes pimeloyl-CoA. IMPORTANCE Biotin is an essential vitamin required by mammals and birds because, unlike bacteria, plants, and some fungi, these organisms cannot make biotin. Currently, the biotin included in vitamin tablets and animal feeds is made by chemical synthesis. This is partly because the biosynthetic pathways in bacteria are incompletely understood. This paper defines an enzyme of the Bacillus subtilis pathway and shows that it differs from that of Escherichia coli in the ability to utilize specific precursors. These bacteria have been used in biotin production and these data may aid in making biotin produced by biotechnology commercially competitive with that produced by chemical synthesis. Copyright © 2017 American Society for Microbiology.

Central nervous system and muscle involvement in an adolescent patient with riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency.

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Ishii, Kiyoko; Komaki, Hirofumi; Ohkuma, Aya; Nishino, Ichizo; Nonaka, Ikuya; Sasaki, Masayuki

2010-09-01

We report an adolescent case of late-onset riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency (MADD) characterized by intermittent nausea and depressive state as early symptoms. At the age of 12 years and 11 months, the patient experienced intermittent nausea and vomiting, and depressive state. She was on medication for depression for 5 months but it was ineffective. Brain magnetic resonance imaging showed disseminated high-intensity areas in the periventricular white matter and in the splenium of the corpus callosum on T2-weighted images and fluid-attenuated inversion-recovery images. Progressive muscle weakness occurred and blood creatine kinase level was found to be elevated. The muscle biopsy revealed lipid storage myopathy. Urine organic acid analysis and mutation analysis of the ETFDH gene confirmed the diagnosis of MADD. With oral supplements of riboflavin and l-carnitine, in addition to a high-calorie and reduced-fat diet, her clinical symptoms improved dramatically. Early diagnosis is important because riboflavin treatment has been effective in a significant number of patients with MADD. Copyright 2009 Elsevier B.V. All rights reserved.

Riboflavin-Responsive Multiple Acyl-CoA Dehydrogenase Deficiency Associated with Hepatoencephalomyopathy and White Matter Signal Abnormalities on Brain MRI.

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Vieira, Päivi; Myllynen, Päivi; Perhomaa, Marja; Tuominen, Hannu; Keski-Filppula, Riikka; Rytky, Seppo; Risteli, Leila; Uusimaa, Johanna

2017-06-01

Multiple acyl-CoA dehydrogenase deficiency (MADD) is a rare inborn error of metabolism affecting both fatty acid and amino acid oxidation. It can manifest at any age, but riboflavin-responsiveness has mainly been described in less severely affected patients. We describe an infant with severe MADD presenting with profound hypotonia and hepatomegaly. Treatment with riboflavin improved his muscle strength, liver size, and biochemical markers. A homozygous mutation of electron transfer flavoprotein dehydrogenase ( ETFDH ) was found. His motor skills continued to progress until a fatal infection-triggered deterioration at the age of 34 months. We show changes in brain magnetic resonance imaging over the course of the disease, with profound white matter abnormalities during the deterioration phase. Aggregates of mitochondria with abnormal cristae in muscle electron microscopy were noticed already in infancy. An unusual lactate dehydrogenase (LDH) isoenzyme pattern with LDH-1 predominance was additionally observed. This case demonstrates riboflavin-responsiveness in a severely affected infant with both muscular and extramuscular involvement and further underlines the variable nature of this disease. Georg Thieme Verlag KG Stuttgart · New York.

Dehydrogenation of aromatic molecules under a scanning tunneling microscope: pathways and inelastic spectroscopy simulations.

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Lesnard, Hervé; Bocquet, Marie-Laure; Lorente, Nicolas

2007-04-11

We have performed a theoretical study on the dehydrogenation of benzene and pyridine molecules on Cu(100) induced by a scanning tunneling microscope (STM). Density functional theory calculations have been used to characterize benzene, pyridine, and different dehydrogenation products. The adiabatic pathways for single and double dehydrogenation have been evaluated with the nudge elastic band method. After identification of the transition states, the analysis of the electronic structure along the reaction pathway yields interesting information on the electronic process that leads to H-scission. The adiabatic barriers show that the formation of double dehydrogenated fragments is difficult and probably beyond reach under the actual experimental conditions. However, nonadiabatic processes cannot be ruled out. Hence, in order to identify the final dehydrogenation products, the inelastic spectra are simulated and compared with the experimental ones. We can then assign phenyl (C6H5) and alpha-pyridil (alpha-C5H4N) as the STM-induced dehydrogenation products of benzene and pyridine, respectively. Our simulations permit us to understand why phenyl, pyridine, and alpha-pyridil present tunneling-active C-H stretch modes in opposition to benzene.

Acetyl CoA Carboxylase 2 Is Dispensable for CD8+ T Cell Responses.

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Jang Eun Lee

Full Text Available Differentiation of T cells is closely associated with dynamic changes in nutrient and energy metabolism. However, the extent to which specific metabolic pathways and molecular components are determinative of CD8+ T cell fate remains unclear. It has been previously established in various tissues that acetyl CoA carboxylase 2 (ACC2 regulates fatty acid oxidation (FAO by inhibiting carnitine palmitoyltransferase 1 (CPT1, a rate-limiting enzyme of FAO in mitochondria. Here, we explore the cell-intrinsic role of ACC2 in T cell immunity in response to infections. We report here that ACC2 deficiency results in a marginal increase of cellular FAO in CD8+ T cells, but does not appear to influence antigen-specific effector and memory CD8+ T cell responses during infection with listeria or lymphocytic choriomeningitis virus. These results suggest that ACC2 is dispensable for CD8+ T cell responses.

Regulation of schistosome egg production by HMG CoA reductase

International Nuclear Information System (INIS)

VandeWaa, E.A.; Bennett, J.L.

1986-01-01

Hydroxymethylglutaryl coenzyme A reductase (HMG CoA reductase) catalyzes the conversion of HMG CoA to mevalonate in the synthesis of steroids, isoprenoids and terpenes. Mevinolin, an inhibitor of this enzyme, decreased egg production in Schistosoma mansoni during in vitro incubations. This was associated with a reduction in the incorporation of 14 C-acetate into polyisoprenoids and a reduction in the formation of a lipid-linked oligosaccharide. In vivo, mevinolin in daily doses of 50 mg/kg (p.o., from days 30-48 post-infection) caused no change in gross liver pathology in S. mansoni infected mice. However, when parasites exposed to mevinolin or its vehicle in vivo were cultured in vitro, worms from mevinolin-treated mice produced six times more eggs than control parasites. When infected mice were dosed with 250 mg/kg mevinolin daily (p.o., from days 35-45 post-infection), liver pathology was reduced in comparison to control mice. Thus, during in vivo exposure to a high dose of the drug egg production is decreased, while at a lower dose it appears unaffected until the parasites are cultured in a drug-free in vitro system wherein egg production is stimulated to extraordinarily high levels. It may be that at low doses mevinolin, by inhibiting the enzyme, is blocking the formation of a product (such as an isoprenoid) which normally acts to down-regulate enzyme synthesis, resulting in enzyme induction. Induction of HMG CoA reductase is then expressed as increased egg production when the worms are removed from the drug. These data suggest that HMG CoA reductase plays a role in schistosome egg production

iPLA2β deficiency attenuates obesity and hepatic steatosis in ob/ob mice through hepatic fatty-acyl phospholipid remodeling.

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Deng, Xiuling; Wang, Jiliang; Jiao, Li; Utaipan, Tanyarath; Tuma-Kellner, Sabine; Schmitz, Gerd; Liebisch, Gerhard; Stremmel, Wolfgang; Chamulitrat, Walee

2016-05-01

PLA2G6 or GVIA calcium-independent PLA2 (iPLA2β) is identified as one of the NAFLD modifier genes in humans, and thought to be a target for NAFLD therapy. iPLA2β is known to play a house-keeping role in phospholipid metabolism and remodeling. However, its role in NAFLD pathogenesis has not been supported by results obtained from high-fat feeding of iPLA2β-null (PKO) mice. Unlike livers of human NAFLD and genetically obese rodents, fatty liver induced by high-fat diet is not associated with depletion of hepatic phospholipids. We therefore tested whether iPLA2β could regulate obesity and hepatic steatosis in leptin-deficient mice by cross-breeding PKO with ob/ob mice to generate ob/ob-PKO mice. Here we observed an improvement in ob/ob-PKO mice with significant reduction in serum enzymes, lipids, glucose, insulin as well as improved glucose tolerance, and reduction in islet hyperplasia. The improvement in hepatic steatosis measured by liver triglycerides, fatty acids and cholesterol esters was associated with decreased expression of PPARγ and de novo lipogenesis genes, and the reversal of β-oxidation gene expression. Notably, ob/ob livers contained depleted levels of lysophospholipids and phospholipids, and iPLA2β deficiency in ob/ob-PKO livers lowers the former, but replenished the latter particularly phosphatidylethanolamine (PE) and phosphatidylcholine (PC) that contained arachidonic (AA) and docosahexaenoic (DHA) acids. Compared with WT livers, PKO livers also contained increased PE and PC containing AA and DHA. Thus, iPLA2β deficiency protected against obesity and ob/ob fatty liver which was associated with hepatic fatty-acyl phospholipid remodeling. Our results support the deleterious role of iPLA2β in severe obesity associated NAFLD. Copyright © 2016 Elsevier B.V. All rights reserved.

Localization of acyl ghrelin- and des-acyl ghrelin-immunoreactive cells in the rat stomach and their responses to intragastric pH.

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Mizutani, Makoto; Atsuchi, Kaori; Asakawa, Akihiro; Matsuda, Norifumi; Fujimura, Masaki; Inui, Akio; Kato, Ikuo; Fujimiya, Mineko

2009-11-01

Acyl ghrelin has a 28-amino acid sequence with O-n-octanoyl acid modification at the serine 3 position, whereas des-acyl ghrelin has no octanoyl acid modification. Although these peptides exert different physiological functions, no previous studies have shown the different localization of acyl ghrelin and des-acyl ghrelin in the stomach. Here we have developed an antibody specific for des-acyl ghrelin that does not crossreact with acyl ghrelin. Both acyl ghrelin- and des-acyl ghrelin-immunoreactive cells were distributed in the oxyntic and antral mucosa of the rat stomach, with higher density in the antral mucosa than oxyntic mucosa. Immunofluorescence double staining showed that acyl ghrelin- and des-acyl ghrelin-positive reactions overlapped in closed-type round cells, whereas des-acyl ghrelin-positive reaction was found in open-type cells in which acyl ghrelin was negative. Acyl ghrelin-/des-acyl ghrelin-positive closed-type cells contain obestatin; on the other hand, des-acyl ghrelin-positive open-type cells contain somatostatin. We measured the release of acyl ghrelin and des-acyl ghrelin in vascularly perfused rat stomach by ELISA, and the effects of different intragastric pH levels on the release of each peptide were examined. The release of des-acyl ghrelin from the perfused stomach was greater at pH 2 than at pH 4; however, the release of acyl ghrelin was not affected by intragastric pH. The present study demonstrated the differential localization of acyl ghrelin and des-acyl ghrelin in the rat stomach and their different responses to the intragastric pH.

Abnormal mitochondrial bioenergetics and heart rate dysfunction in mice lacking very-long-chain acyl-CoA dehydrogenase

NARCIS (Netherlands)

Exil, VJ; Gardner, CD; Rottman, JN; Sims, H; Bartelds, B; Khuchua, Z; Sindhal, R; Ni, GM; Strauss, AW

Mitochondrial very-long-chain acyl-CoA dehydrogenase ( VLCAD) deficiency is associated with severe hypoglycemia, cardiac dysfunction, and sudden death in neonates and children. Sudden death is common, but the underlying mechanisms are not fully understood. We report on a mouse model of VLCAD

The domain-specific and temperature-dependent protein misfolding phenotype of variant medium-chain acyl-CoA dehydrogenase

NARCIS (Netherlands)

Jank, Johanna M.; Maier, Esther M.; Reiβ, Dunja D.; Haslbeck, Martin; Kemter, Kristina F.; Truger, Marietta S.; Sommerhoff, Christian P.; Ferdinandusse, Sacha; Wanders, Ronald J.; Gersting, Søren W.; Muntau, Ania C.

2014-01-01

The implementation of expanded newborn screening programs reduced mortality and morbidity in medium-chain acyl-CoA dehydrogenase deficiency (MCADD) caused by mutations in the ACADM gene. However, the disease is still potentially fatal. Missense induced MCADD is a protein misfolding disease with a

Xanthomonas campestris RpfB is a Fatty Acyl-CoA Ligase Required to Counteract the Thioesterase Activity of the RpfF Diffusible Signal Factor (DSF) Synthase

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Bi, Hongkai; Yu, Yonghong; Dong, Huijuan; Wang, Haihong; Cronan, John E.

2014-01-01

SUMMARY In Xanthomonas campestris pv. campestris (Xcc), the proteins encoded by the rpf (regulator of pathogenicity factor) gene cluster produce and sense a fatty acid signal molecule called diffusible signaling factor (DSF, 2(Z)-11-methyldodecenoic acid). RpfB was reported to be involved in DSF processing and was predicted to encode an acyl-CoA ligase. We report that RpfB activates a wide range of fatty acids to their CoA esters in vitro. Moreover, RpfB can functionally replace the paradigm bacterial acyl-CoA ligase, Escherichia coli FadD, in the E. coli β-oxidation pathway and deletion of RpfB from the Xcc genome results in a strain unable to utilize fatty acids as carbon sources. An essential RpfB function in the pathogenicity factor pathway was demonstrated by the properties of a strain deleted for both the rpfB and rpfC genes. The ΔrpfB ΔrpfC strain grew poorly and lysed upon entering stationary phase. Deletion of rpfF, the gene encoding the DSF synthetic enzyme, restored normal growth to this strain. RpfF is a dual function enzyme that synthesizes DSF by dehydration of a 3-hydroxyacyl-acyl carrier protein (ACP) fatty acid synthetic intermediate and also cleaves the thioester bond linking DSF to ACP. However, the RpfF thioesterase activity is of broad specificity and upon elimination of its RpfC inhibitor RpfF attains maximal activity and its thioesterase activity proceeds to block membrane lipid synthesis by cleavage of acyl-ACP intermediates. This resulted in release of the nascent acyl chains to the medium as free fatty acids. This lack of acyl chains for phospholipid synthesis results in cell lysis unless RpfB is present to counteract the RpfF thioesterase activity by catalyzing uptake and activation of the free fatty acids to give acyl-CoAs that can be utilized to restore membrane lipid synthesis. Heterologous expression of a different fatty acid activating enzyme, the Vibrio harveyi acyl-ACP synthetase, replaced RpfB in counteracting the effects of

Selective and Stable Ethylbenzene Dehydrogenation to Styrene over Nanodiamonds under Oxygen-lean Conditions.

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Diao, Jiangyong; Feng, Zhenbao; Huang, Rui; Liu, Hongyang; Hamid, Sharifah Bee Abd; Su, Dang Sheng

2016-04-07

For the first time, significant improvement of the catalytic performance of nanodiamonds was achieved for the dehydrogenation of ethylbenzene to styrene under oxygen-lean conditions. We demonstrated that the combination of direct dehydrogenation and oxidative dehydrogenation indeed occurred on the nanodiamond surface throughout the reaction system. It was found that the active sp(2)-sp(3) hybridized nanostructure was well maintained after the long-term test and the active ketonic carbonyl groups could be generated in situ. A high reactivity with 40% ethylbenzene conversion and 92% styrene selectivity was obtained over the nanodiamond catalyst under oxygen-lean conditions even after a 240 h test, demonstrating the potential of this procedure for application as a promising industrial process for the ethylbenzene dehydrogenation to styrene without steam protection. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Genetic manipulation of the ghrelin signaling system in male mice reveals bone compartment specificity of acylated and unacylated ghrelin in the regulation of bone remodeling

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Ghrelin receptor-deficient (Ghsr-/-) mice that lack acylated ghrelin (AG) signaling retain a metabolic response to unacylated ghrelin (UAG). Recently, we showed that Ghsr-deficiency affects bone metabolism. The aim of this study was to further establish the impact of AG and UAG on bone metabolism. W...

Theoretical investigation of the mechanism of tritiated methane dehydrogenation reaction using nickel-based catalysts

Energy Technology Data Exchange (ETDEWEB)

Dong, Liang; Li, Jiamao; Deng, Bing; Yang, Yong; Wang, Heyi [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Li, Weiyi [School of Physics and Chemistry, Xihua University, Chengdu 610065 (China); Li, Shuo, E-mail: lishuo@cqut.edu.cn [School of Chemical Engineering, Chongqing University of Technology, Chongqing 400054 (China); Tan, Zhaoyi, E-mail: tanzhaoyi@caep.cn [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)

2015-06-15

Graphical abstract: - Highlights: • Four-step dehydrogenation of CT{sub 4} catalyzed by Ni to form Ni–C by releasing T{sub 2}. • The process of Ni + CT{sub 4} → NiCT{sub 2} + T{sub 2} is more achievable than that of NiCT{sub 2} → NiC + T{sub 2}. • TNiCT → T{sub 2}NiC step is the RDS with the rate constant of k = 2.8 × 10{sup 13} exp(−313,136/RT). • The hydrogen isotope effect value of k{sub H}/k{sub T} is 2.94, and k{sub D}/k{sub T} is 1.39. • CH{sub 4} and CD{sub 4} dehydrogenations are likely to occur, accompanied by the CT{sub 4} cracking. - Abstract: The mechanism of tritiated methane dehydrogenation reaction catalyzed by nickel-based catalyst was investigated in detail by density functional theory (DFT) at the B3LYP/[6-311++G(d, p), SDD] level. The computational results indicated that the dehydrogenation of tritiated methane is endothermic. The decomposition of tritiated methane catalyzed by Ni to form Ni-based carbon (Ni–C) after a four-step dehydrogenation companied with releasing tritium. After the first and second dehydrogenation steps, Ni + CT{sub 4} formed NiCT{sub 2}. After the third and fourth dehydrogenation steps, NiCT{sub 2} formed NiC. The first and second steps of dehydrogenation occurred on both the singlet and triplet states, and the lowest energy route is Ni + CT{sub 4} → {sup 1}COM → {sup 1}TS1 → {sup 3}IM1 → {sup 3}TS2 → {sup 3}IM2. The third and fourth steps of dehydrogenation occurred on both the singlet and quintet states, and the minimum energy reaction pathway appeared to be IM3 → {sup 1}TS4 → {sup 5}IM4 → {sup 5}TS5 → {sup 5}IM5 → {sup 5}pro + T{sub 2}. The fourth step of dehydrogenation TNiCT → T{sub 2}NiC was the rate-determining step of the entire reaction with the rate constant of k{sub 2} = 2.8 × 10{sup 13} exp(−313,136/RT) (in cm{sup 3} mol{sup −1} s{sup −1}), and its activation energy barrier was calculated to be 51.8 kcal/mol. The Ni-catalyzed CH{sub 4} and CD{sub 4} cracking

Theoretical investigation of the selective dehydration and dehydrogenation of ethanol catalyzed by small molecules.

Science.gov (United States)

Wang, Yanqun; Tang, Yizhen; Shao, Youxiang

2017-09-01

Catalytic dehydration and dehydrogenation reactions of ethanol have been investigated systematically using the ab initio quantum chemistry methods The catalysts include water, hydrogen peroxide, formic acid, phosphoric acid, hydrogen fluoride, ammonia, and ethanol itself. Moreover, a few clusters of water and ethanol were considered to simulate the catalytic mechanisms in supercritical water and supercritical ethanol. The barriers for both dehydration and dehydrogenation can be reduced significantly in the presence of the catalysts. It is revealed that the selectivity of the catalytic dehydration and dehydrogenation depends on the acidity and basicity of the catalysts and the sizes of the clusters. The acidic catalyst prefers dehydration while the basic catalysts tend to promote dehydrogenation more effectively. The calculated water-dimer catalysis mechanism supports the experimental results of the selective oxidation of ethanol in the supercritical water. It is suggested that the solvent- and catalyst-free self-oxidation of the supercritical ethanol could be an important mechanism for the selective dehydrogenation of ethanol on the theoretical point of view. Copyright © 2017 Elsevier Inc. All rights reserved.

3-Sulfinopropionyl-coenzyme A (3SP-CoA) desulfinase from Advenella mimigardefordensis DPN7T: crystal structure and function of a desulfinase with an acyl-CoA dehydrogenase fold

Science.gov (United States)

Schürmann, Marc; Meijers, Rob; Schneider, Thomas R.; Steinbüchel, Alexander; Cianci, Michele

2015-01-01

3-Sulfinopropionyl-coenzyme A (3SP-CoA) desulfinase (AcdDPN7; EC 3.13.1.4) was identified during investigation of the 3,3′-dithiodipropionic acid (DTDP) catabolic pathway in the betaproteobacterium Advenella mimigardefordensis strain DPN7T. DTDP is an organic disulfide and a precursor for the synthesis of polythioesters (PTEs) in bacteria, and is of interest for biotechnological PTE production. AcdDPN7 catalyzes sulfur abstraction from 3SP-CoA, a key step during the catabolism of DTDP. Here, the crystal structures of apo AcdDPN7 at 1.89 Å resolution and of its complex with the CoA moiety from the substrate analogue succinyl-CoA at 2.30 Å resolution are presented. The apo structure shows that AcdDPN7 belongs to the acyl-CoA dehydrogenase superfamily fold and that it is a tetramer, with each subunit containing one flavin adenine dinucleotide (FAD) molecule. The enzyme does not show any dehydrogenase activity. Dehydrogenase activity would require a catalytic base (Glu or Asp residue) at either position 246 or position 366, where a glutamine and a glycine are instead found, respectively, in this desulfinase. The positioning of CoA in the crystal complex enabled the modelling of a substrate complex containing 3SP-CoA. This indicates that Arg84 is a key residue in the desulfination reaction. An Arg84Lys mutant showed a complete loss of enzymatic activity, suggesting that the guanidinium group of the arginine is essential for desulfination. AcdDPN7 is the first desulfinase with an acyl-CoA dehydrogenase fold to be reported, which underlines the versatility of this enzyme scaffold. PMID:26057676

Biochemical competition makes fatty-acid β-oxidation vulnerable to substrate overload.

Directory of Open Access Journals (Sweden)

Karen van Eunen

Full Text Available Fatty-acid metabolism plays a key role in acquired and inborn metabolic diseases. To obtain insight into the network dynamics of fatty-acid β-oxidation, we constructed a detailed computational model of the pathway and subjected it to a fat overload condition. The model contains reversible and saturable enzyme-kinetic equations and experimentally determined parameters for rat-liver enzymes. It was validated by adding palmitoyl CoA or palmitoyl carnitine to isolated rat-liver mitochondria: without refitting of measured parameters, the model correctly predicted the β-oxidation flux as well as the time profiles of most acyl-carnitine concentrations. Subsequently, we simulated the condition of obesity by increasing the palmitoyl-CoA concentration. At a high concentration of palmitoyl CoA the β-oxidation became overloaded: the flux dropped and metabolites accumulated. This behavior originated from the competition between acyl CoAs of different chain lengths for a set of acyl-CoA dehydrogenases with overlapping substrate specificity. This effectively induced competitive feedforward inhibition and thereby led to accumulation of CoA-ester intermediates and depletion of free CoA (CoASH. The mitochondrial [NAD⁺]/[NADH] ratio modulated the sensitivity to substrate overload, revealing a tight interplay between regulation of β-oxidation and mitochondrial respiration.

Cluster size selectivity in the product distribution of ethene dehydrogenation on niobium clusters.

Science.gov (United States)

Parnis, J Mark; Escobar-Cabrera, Eric; Thompson, Matthew G K; Jacula, J Paul; Lafleur, Rick D; Guevara-García, Alfredo; Martínez, Ana; Rayner, David M

2005-08-18

Ethene reactions with niobium atoms and clusters containing up to 25 constituent atoms have been studied in a fast-flow metal cluster reactor. The clusters react with ethene at about the gas-kinetic collision rate, indicating a barrierless association process as the cluster removal step. Exceptions are Nb8 and Nb10, for which a significantly diminished rate is observed, reflecting some cluster size selectivity. Analysis of the experimental primary product masses indicates dehydrogenation of ethene for all clusters save Nb10, yielding either Nb(n)C2H2 or Nb(n)C2. Over the range Nb-Nb6, the extent of dehydrogenation increases with cluster size, then decreases for larger clusters. For many clusters, secondary and tertiary product masses are also observed, showing varying degrees of dehydrogenation corresponding to net addition of C2H4, C2H2, or C2. With Nb atoms and several small clusters, formal addition of at least six ethene molecules is observed, suggesting a polymerization process may be active. Kinetic analysis of the Nb atom and several Nb(n) cluster reactions with ethene shows that the process is consistent with sequential addition of ethene units at rates corresponding approximately to the gas-kinetic collision frequency for several consecutive reacting ethene molecules. Some variation in the rate of ethene pick up is found, which likely reflects small energy barriers or steric constraints associated with individual mechanistic steps. Density functional calculations of structures of Nb clusters up to Nb(6), and the reaction products Nb(n)C2H2 and Nb(n)C2 (n = 1...6) are presented. Investigation of the thermochemistry for the dehydrogenation of ethene to form molecular hydrogen, for the Nb atom and clusters up to Nb6, demonstrates that the exergonicity of the formation of Nb(n)C2 species increases with cluster size over this range, which supports the proposal that the extent of dehydrogenation is determined primarily by thermodynamic constraints. Analysis of

Rhodium-Catalyzed Dehydrogenative Borylation of Cyclic Alkenes

Science.gov (United States)

Kondoh, Azusa; Jamison, Timothy F.

2010-01-01

A rhodium-catalyzed dehydrogenative borylation of cyclic alkenes is described. This reaction provides direct access to cyclic 1-alkenylboronic acid pinacol esters, useful intermediates in organic synthesis. Suzuki-Miyaura cross-coupling applications are also presented. PMID:20107646

The Antibiotic CJ-15,801 is an Antimetabolite which Hijacks and then Inhibits CoA Biosynthesis

Science.gov (United States)

van der Westhuyzen, Renier; Hammons, Justin C.; Meier, Jordan L.; Dahesh, Samira; Moolman, Wessel J. A.; Pelly, Stephen C.; Nizet, Victor; Burkart, Michael D.; Strauss, Erick

2012-01-01

SUMMARY The natural product CJ-15,801 is an inhibitor of Staphylococcus aureus, but not other bacteria. Its close structural resemblance to pantothenic acid, the vitamin precursor of coenzyme A (CoA), and its Michael acceptor moiety suggest that it irreversibly inhibits an enzyme involved in CoA biosynthesis or utilization. However, its mode of action and the basis for its specificity have not been elucidated to date. We demonstrate that CJ-15,801 is transformed by the uniquely selective S. aureus pantothenate kinase, the first CoA biosynthetic enzyme, into a substrate for the next enzyme, phosphopantothenoylcysteine synthetase, which is inhibited through formation of a tight-binding structural mimic of its native reaction intermediate. These findings reveal CJ-15,801 as a vitamin biosynthetic pathway antimetabolite with a mechanism similar to that of the sulfonamide antibiotics, and highlight CoA biosynthesis as a viable antimicrobial drug target. PMID:22633408

Structure of Mycobacterium tuberculosis phosphopantetheine adenylyltransferase in complex with the feedback inhibitor CoA reveals only one active-site conformation

Energy Technology Data Exchange (ETDEWEB)

Wubben, T.; Mesecar, A.D. (Purdue); (UIC)

2014-10-02

Phosphopantetheine adenylyltransferase (PPAT) catalyzes the penultimate step in the coenzyme A (CoA) biosynthetic pathway, reversibly transferring an adenylyl group from ATP to 4'-phosphopantetheine to form dephosphocoenzyme A (dPCoA). To complement recent biochemical and structural studies on Mycobacterium tuberculosis PPAT (MtPPAT) and to provide further insight into the feedback regulation of MtPPAT by CoA, the X-ray crystal structure of the MtPPAT enzyme in complex with CoA was determined to 2.11 {angstrom} resolution. Unlike previous X-ray crystal structures of PPAT-CoA complexes from other bacteria, which showed two distinct CoA conformations bound to the active site, only one conformation of CoA is observed in the MtPPAT-CoA complex.

Pantothenate kinase 1 is required to support the metabolic transition from the fed to the fasted state.

Directory of Open Access Journals (Sweden)

Roberta Leonardi

2010-06-01

Full Text Available Coenzyme A (CoA biosynthesis is regulated by the pantothenate kinases (PanK, of which there are four active isoforms. The PanK1 isoform is selectively expressed in liver and accounted for 40% of the total PanK activity in this organ. CoA synthesis was limited using a Pank1(-/- knockout mouse model to determine whether the regulation of CoA levels was critical to liver function. The elimination of PanK1 reduced hepatic CoA levels, and fasting triggered a substantial increase in total hepatic CoA in both Pank1(-/- and wild-type mice. The increase in hepatic CoA during fasting was blunted in the Pank1(-/- mouse, and resulted in reduced fatty acid oxidation as evidenced by abnormally high accumulation of long-chain acyl-CoAs, acyl-carnitines, and triglycerides in the form of lipid droplets. The Pank1(-/- mice became hypoglycemic during a fast due to impaired gluconeogenesis, although ketogenesis was normal. These data illustrate the importance of PanK1 and elevated liver CoA levels during fasting to support the metabolic transition from glucose utilization and fatty acid synthesis to gluconeogenesis and fatty acid oxidation. The findings also suggest that PanK1 may be a suitable target for therapeutic intervention in metabolic disorders that feature hyperglycemia and hypertriglyceridemia.

Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

Directory of Open Access Journals (Sweden)

Rasmus Bjerregaard Christensen

2016-01-01

Full Text Available We employ a semi-classical Langevin approach to study current-induced atomic dynamics in a partially dehydrogenated armchair graphene nanoribbon. All parameters are obtained from density functional theory. The dehydrogenated carbon dimers behave as effective impurities, whose motion decouples from the rest of carbon atoms. The electrical current can couple the dimer motion in a coherent fashion. The coupling, which is mediated by nonconservative and pseudo-magnetic current-induced forces, change the atomic dynamics, and thereby show their signature in this simple system. We study the atomic dynamics and current-induced vibrational instabilities using a simplified eigen-mode analysis. Our study illustrates how armchair nanoribbons can serve as a possible testbed for probing the current-induced forces.

Effect of alloying on carbon formation during ethane dehydrogenation

DEFF Research Database (Denmark)

Rovik, Anne; Kegnæs, Søren; Dahl, Søren

2009-01-01

The structure sensitivity of different transition metals in the hydrogenolysis, dehydrogenation, and coking reactions during ethane conversion has been investigated. The investigated metals, Ni, Ru, Rh, and Pd, are co-impregnated with Ag onto an inactive MgAl2O4 spinel support and tested in the c......The structure sensitivity of different transition metals in the hydrogenolysis, dehydrogenation, and coking reactions during ethane conversion has been investigated. The investigated metals, Ni, Ru, Rh, and Pd, are co-impregnated with Ag onto an inactive MgAl2O4 spinel support and tested...... in the conversion of ethane. A tendency is clear for all catalysts: In the first period of time 100% ethane is converted and roughly half of the carbon is converted into coke and deposited on the catalyst. The other half of the carbon is converted into methane. The active sites in the hydrogenolysis are blocked...... by coke during the initial period where after dehydrogenation of ethane is observed. It has previously been predicted in surface science studies that Ag covers the steps of certain transition metals. Here it is documented that the hydrogenolysis and coking reactions are significantly suppressed by co...

Integration of catalyst design and reactor engineering in paraffins dehydrogenation

Energy Technology Data Exchange (ETDEWEB)

Sanfilippo, D.; Miracca, I. [Snamprogetti S.p.A., S. Donato Milanese (Italy)

2005-07-01

Unfortunately, olefins are not a natural fossil resource. Their production requires sophisticated and costly technologies, highly demanding in terms of investments and energy. Dehydrogenations are applied industrially to light alkanes (propane to propylene for polymers and isobutane to iso-butylene for gasoline and polymers) as well as long linear ones (C{sub 10}-C{sub 14} to linear-alkyl-benzenes) and for the production of styrene from ethylbenzene. The light paraffins dehydrogenation sustains a network of technologies allowing an integrated approach to create value from Natural Gas. (orig.)

Light alkane (mixed feed) selective dehydrogenation using bi ...

African Journals Online (AJOL)

... refinery processes and their catalytic dehydrogenation gives corresponding alkenes. ... was prepared by sequentional impregnation method and characterized by BET, ... Optimum propene selectivity is about 48 %, obtained at 600 oC and ...

Iridium‐Catalyzed Dehydrogenative Decarbonylation of Primary Alcohols with the Liberation of Syngas

DEFF Research Database (Denmark)

Olsen, Esben Paul Krogh; Madsen, Robert

2012-01-01

A new iridium‐catalyzed reaction in which molecular hydrogen and carbon monoxide are cleaved from primary alcohols in the absence of any stoichiometric additives has been developed. The dehydrogenative decarbonylation was achieved with a catalyst generated in situ from [Ir(coe)2Cl]2 (coe=cyclooct......A new iridium‐catalyzed reaction in which molecular hydrogen and carbon monoxide are cleaved from primary alcohols in the absence of any stoichiometric additives has been developed. The dehydrogenative decarbonylation was achieved with a catalyst generated in situ from [Ir(coe)2Cl]2 (coe...... to excellent yields. Ethers, esters, imides, and aryl halides are stable under the reaction conditions, whereas olefins are partially saturated. The reaction is believed to proceed by two consecutive organometallic transformations that are catalyzed by the same iridium(I)–BINAP species. First, dehydrogenation...

Mechanism of MenE inhibition by acyl-adenylate analogues and discovery of novel antibacterial agents.

Science.gov (United States)

Matarlo, Joe S; Evans, Christopher E; Sharma, Indrajeet; Lavaud, Lubens J; Ngo, Stephen C; Shek, Roger; Rajashankar, Kanagalaghatta R; French, Jarrod B; Tan, Derek S; Tonge, Peter J

2015-10-27

MenE is an o-succinylbenzoyl-CoA (OSB-CoA) synthetase in the bacterial menaquinone biosynthesis pathway and is a promising target for the development of novel antibacterial agents. The enzyme catalyzes CoA ligation via an acyl-adenylate intermediate, and we have previously reported tight-binding inhibitors of MenE based on stable acyl-sulfonyladenosine analogues of this intermediate, including OSB-AMS (1), which has an IC50 value of ≤25 nM for Escherichia coli MenE. Herein, we show that OSB-AMS reduces menaquinone levels in Staphylococcus aureus, consistent with its proposed mechanism of action, despite the observation that the antibacterial activity of OSB-AMS is ∼1000-fold lower than the IC50 for enzyme inhibition. To inform the synthesis of MenE inhibitors with improved antibacterial activity, we have undertaken a structure-activity relationship (SAR) study stimulated by the knowledge that OSB-AMS can adopt two isomeric forms in which the OSB side chain exists either as an open-chain keto acid or a cyclic lactol. These studies revealed that negatively charged analogues of the keto acid form bind, while neutral analogues do not, consistent with the hypothesis that the negatively charged keto acid form of OSB-AMS is the active isomer. X-ray crystallography and site-directed mutagenesis confirm the importance of a conserved arginine for binding the OSB carboxylate. Although most lactol isomers tested were inactive, a novel difluoroindanediol inhibitor (11) with improved antibacterial activity was discovered, providing a pathway toward the development of optimized MenE inhibitors in the future.

Correlation of changes in rate of sterol synthesis with changes in HMG CoA reductase activity in cultured lens epithelial cells

International Nuclear Information System (INIS)

Cenedella, R.J.; Hitchener, W.R.

1986-01-01

In the present study, the authors correlated changes in HMG CoA reductase activity with changes in relative rates of sterol synthesis measured from either 3 H 2 O or 1- 14 C-acetate for bovine lens epithelial cells cultured in the presence or absence of lipoproteins. Enzyme activity and rates of incorporation of 3 H 2 O or 1- 14 C-acetate into digitonin precipitable sterols were measured in cells on the 4th day of subculture in DMEM containing 9% whole calf serum (WM) or 9% lipoprotein deficient serum (LDM). In three experiments, HMG CoA reductase activity (U/10 6 cells) averaged 2.2 +/- 0.1 times greater for cells grown in LDM than WM. Sterol synthesis averaged 3.0 +/- 0.4 times greater when measured with 3 H 2 O and 4.0 +/- 1.1 times greater when measured with 14 C-acetate. Thus, 3 H 2 O and 14 C-acetate appear to be comparable substrates for estimating changes in relative rates of sterol synthesis by cultured cells. The larger increases in rates of sterol synthesis than in reductase activity in response to decreased cholesterol could reflect stimulation at additional metabolic steps in the cholesterol pathway beyond mevalonic acid

Effects of carnitine and its congeners on eicosanoid discharge from rat cells: Implications for release of TNFα

NARCIS (Netherlands)

I.M. Garrelds (Ingrid); G.R. Elliott (G.); W.M. Pruimboom (Wanda); F.J. Zijlstra (Freek); I.L. Bonta

1993-01-01

textabstractTHE acyl carrier coenzyme A (CoA) is involved in fatty acid metabolism. The carnitine/CoA ratio is of particular importance in regulating the transport of long-chain fatty acids into mitochondria for oxidation. Also CoA has a role in the formation and breakdown of products from both the

Silver-Catalyzed Dehydrogenative Synthesis of Carboxylic Acids from Primary Alcohols

DEFF Research Database (Denmark)

Ghalehshahi, Hajar Golshadi; Madsen, Robert

2017-01-01

A simple silver-catalyzed protocol has been developed for the acceptorless dehydrogenation of primary alcohols into carboxylic acids and hydrogen gas. The procedure uses 2.5 % Ag2 CO3 and 2.5-3 equiv of KOH in refluxing mesitylene to afford the potassium carboxylate which is then converted...... into the acid with HCl. The reaction can be applied to a variety of benzylic and aliphatic primary alcohols with alkyl and ether substituents, and in some cases halide, olefin, and ester functionalities are also compatible with the reaction conditions. The dehydrogenation is believed to be catalyzed by silver...

Spectroscopic evidence for origins of size and support effects on selectivity of Cu nanoparticle dehydrogenation catalysts.

Science.gov (United States)

Witzke, M E; Dietrich, P J; Ibrahim, M Y S; Al-Bardan, K; Triezenberg, M D; Flaherty, D W

2017-01-03

Selective dehydrogenation catalysts that produce acetaldehyde from bio-derived ethanol can increase the efficiency of subsequent processes such as C-C coupling over metal oxides to produce 1-butanol or 1,3-butadiene or oxidation to acetic acid. Here, we use in situ X-ray absorption spectroscopy and steady state kinetics experiments to identify Cu δ+ at the perimeter of supported Cu clusters as the active site for esterification and Cu 0 surface sites as sites for dehydrogenation. Correlation of dehydrogenation and esterification selectivities to in situ measures of Cu oxidation states show that this relationship holds for Cu clusters over a wide-range of diameters (2-35 nm) and catalyst supports and reveals that dehydrogenation selectivities may be controlled by manipulating either.

Characterization and functional assay of a fatty acyl-CoA reductase gene in the scale insect, Ericerus pela Chavannes (Hemiptera: Coccoidae).

Science.gov (United States)

Hu, Yan-Hong; Chen, Xiao-Ming; Yang, Pu; Ding, Wei-Feng

2018-04-01

Ericerus pela Chavannes (Hemiptera: Coccoidae) is an economically important scale insect because the second instar males secrete a harvestable wax-like substance. In this study, we report the molecular cloning of a fatty acyl-CoA reductase gene (EpFAR) of E. pela. We predicted a 520-aa protein with the FAR family features from the deduced amino acid sequence. The EpFAR mRNA was expressed in five tested tissues, testis, alimentary canal, fat body, Malpighian tubules, and mostly in cuticle. The EpFAR protein was localized by immunofluorescence only in the wax glands and testis. EpFAR expression in High Five insect cells documented the recombinant EpFAR reduced 26-0:(S) CoA and to its corresponding alcohol. The data illuminate the molecular mechanism for fatty alcohol biosynthesis in a beneficial insect, E. pela. © 2017 Wiley Periodicals, Inc.

CHARACTERIZING THE INFRARED SPECTRA OF SMALL, NEUTRAL, FULLY DEHYDROGENATED POLYCYCLIC AROMATIC HYDROCARBONS

Energy Technology Data Exchange (ETDEWEB)

Mackie, C. J.; Peeters, E.; Cami, J. [Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7 (Canada); Bauschlicher, C. W. Jr., E-mail: mackie@strw.leidenuniv.nl [NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035 (United States)

2015-02-01

We present the results of a computational study to investigate the infrared spectroscopic properties of a large number of polycyclic aromatic hydrocarbon (PAH) molecules and their fully dehydrogenated counterparts. We constructed a database of fully optimized geometries for PAHs that is complete for eight or fewer fused benzene rings, thus containing 1550 PAHs and 805 fully dehydrogenated aromatics. A large fraction of the species in our database have clearly non-planar or curved geometries. For each species, we determined the frequencies and intensities of their normal modes using density functional theory calculations. Whereas most PAH spectra are fairly similar, the spectra of fully dehydrogenated aromatics are much more diverse. Nevertheless, these fully dehydrogenated species show characteristic emission features at 5.2 μm, 5.5 μm, and 10.6 μm; at longer wavelengths, there is a forest of emission features in the 16-30 μm range that appears as a structured continuum, but with a clear peak centered around 19 μm. We searched for these features in Spitzer-IRS spectra of various positions in the reflection nebula NGC 7023. We find a weak emission feature at 10.68 μm in all positions except that closest to the central star. We also find evidence for a weak 19 μm feature at all positions that is not likely due to C{sub 60}. We interpret these features as tentative evidence for the presence of a small population of fully dehydrogenated PAHs, and discuss our results in the framework of PAH photolysis and the formation of fullerenes.

A soluble fatty acyl-acyl carrier protein synthetase from the bioluminescent bacterium Vibrio harveyi.

Science.gov (United States)

Byers, D M; Holmes, C G

1990-01-01

An enzyme catalyzing the ligation of long chain fatty acids to bacterial acyl carrier protein (ACP) has been detected and partially characterized in cell extracts of the bioluminescent bacterium Vibrio harveyi. Acyl-ACP synthetase activity (optimal pH 7.5-8.0) required millimolar concentrations of ATP and Mg2+ and was slightly activated by Ca2+, but was inhibited at high ionic strength and by Triton X-100. ACP from either Escherichia coli (apparent Km = 20 microM) or V. harveyi was used as a substrate. Of the [14C]fatty acids tested as substrates (8-18 carbons), a preference for fatty acids less than or equal to 14 carbons in length was observed. Vibrio harveyi acyl-ACP synthetase appears to be a soluble hydrophilic enzyme on the basis of subcellular fractionation and Triton X-114 phase partition assay. The enzyme was not coinduced with luciferase activity or light emission in vivo during the late exponential growth phase in liquid culture. Acyl-ACP synthetase activity was also detected in extracts from the luminescent bacterium Vibrio fischeri, but not Photobacterium phosphoreum. The cytosolic nature and enzymatic properties of V. harveyi acyl-ACP synthetase indicate that it may have a different physiological role than the membrane-bound activity of E. coli, which has been implicated in phosphatidylethanolamine turnover. Acyl-ACP synthetase activity in V. harveyi could be involved in the intracellular activation and elongation of exogenous fatty acids that occurs in this species or in the reactivation of free myristic acid generated by luciferase.

Acyl-Lipid Metabolism

Science.gov (United States)

Li-Beisson, Yonghua; Shorrosh, Basil; Beisson, Fred; Andersson, Mats X.; Arondel, Vincent; Bates, Philip D.; Baud, Sébastien; Bird, David; DeBono, Allan; Durrett, Timothy P.; Franke, Rochus B.; Graham, Ian A.; Katayama, Kenta; Kelly, Amélie A.; Larson, Tony; Markham, Jonathan E.; Miquel, Martine; Molina, Isabel; Nishida, Ikuo; Rowland, Owen; Samuels, Lacey; Schmid, Katherine M.; Wada, Hajime; Welti, Ruth; Xu, Changcheng; Zallot, Rémi; Ohlrogge, John

2013-01-01

Acyl lipids in Arabidopsis and all other plants have a myriad of diverse functions. These include providing the core diffusion barrier of the membranes that separates cells and subcellular organelles. This function alone involves more than 10 membrane lipid classes, including the phospholipids, galactolipids, and sphingolipids, and within each class the variations in acyl chain composition expand the number of structures to several hundred possible molecular species. Acyl lipids in the form of triacylglycerol account for 35% of the weight of Arabidopsis seeds and represent their major form of carbon and energy storage. A layer of cutin and cuticular waxes that restricts the loss of water and provides protection from invasions by pathogens and other stresses covers the entire aerial surface of Arabidopsis. Similar functions are provided by suberin and its associated waxes that are localized in roots, seed coats, and abscission zones and are produced in response to wounding. This chapter focuses on the metabolic pathways that are associated with the biosynthesis and degradation of the acyl lipids mentioned above. These pathways, enzymes, and genes are also presented in detail in an associated website (ARALIP: http://aralip.plantbiology.msu.edu/). Protocols and methods used for analysis of Arabidopsis lipids are provided. Finally, a detailed summary of the composition of Arabidopsis lipids is provided in three figures and 15 tables. PMID:23505340

Friedel-Crafts Acylation with Amides

Science.gov (United States)

Raja, Erum K.; DeSchepper, Daniel J.; Nilsson Lill, Sten O.; Klumpp, Douglas A.

2012-01-01

Friedel-Crafts acylation has been known since the 1870s and it is an important organic synthetic reaction leading to aromatic ketone products. Friedel-Crafts acylation is usually done with carboxylic acid chlorides or anhydrides while amides are generally not useful substrates in these reactions. Despite being the least reactive carboxylic acid derivative, we have found a series of amides capable of providing aromatic ketones in good yields (55–96%, 17 examples). We propose a mechanism involving diminished C-N resonance through superelectrophilic activation and subsequent cleavage to acyl cations. PMID:22690740

Regulation of very-long acyl chain ceramide synthesis by acyl-CoA-binding protein

DEFF Research Database (Denmark)

Ferreira, Natalia Santos; Engelsby, Hanne; Neess, Ditte

2017-01-01

and cardiovascular diseases, as well as neurological disorders. Here we show that acyl-coenzyme A-binding protein (ACBP) potently facilitates very-long acyl chain ceramide synthesis. ACBP increases the activity of ceramide synthase 2 (CerS2) by more than 2-fold and CerS3 activity by 7-fold. ACBP binds very......-long-chain acyl-CoA esters, which is required for its ability to stimulate CerS activity. We also show that high-speed liver cytosol from wild-type mice activates CerS3 activity, whereas cytosol from ACBP knock-out mice does not. Consistently, CerS2 and CerS3 activities are significantly reduced in the testes...... of ACBP(-/-) mice, concomitant with a significant reduction in long- and very-long-chain ceramide levels. Importantly, we show that ACBP interacts with CerS2 and CerS3. Our data uncover a novel mode of regulation of very-long acyl chain ceramide synthesis by ACBP, which we anticipate is of crucial...

Facile Dehydrogenation of Ethane on the IrO2(110) Surface.

Science.gov (United States)

Bian, Yingxue; Kim, Minkyu; Li, Tao; Asthagiri, Aravind; Weaver, Jason F

2018-02-21

Realizing the efficient and selective conversion of ethane to ethylene is important for improving the utilization of hydrocarbon resources, yet remains a major challenge in catalysis. Herein, ethane dehydrogenation on the IrO 2 (110) surface is investigated using temperature-programmed reaction spectroscopy (TPRS) and density functional theory (DFT) calculations. The results show that ethane forms strongly bound σ-complexes on IrO 2 (110) and that a large fraction of the complexes undergo C-H bond cleavage during TPRS at temperatures below 200 K. Continued heating causes as much as 40% of the dissociated ethane to dehydrogenate and desorb as ethylene near 350 K, with the remainder oxidizing to CO x species. Both TPRS and DFT show that ethylene desorption is the rate-controlling step in the conversion of ethane to ethylene on IrO 2 (110) during TPRS. Partial hydrogenation of the IrO 2 (110) surface is found to enhance ethylene production from ethane while suppressing oxidation to CO x species. DFT predicts that hydrogenation of reactive oxygen atoms of the IrO 2 (110) surface effectively deactivates these sites as H atom acceptors, and causes ethylene desorption to become favored over further dehydrogenation and oxidation of ethane-derived species. The study reveals that IrO 2 (110) exhibits an exceptional ability to promote ethane dehydrogenation to ethylene near room temperature, and provides molecular-level insights for understanding how surface properties influence selectivity toward ethylene production.

Acyl-CoA-binding protein (ACBP) can mediate intermembrane acyl-CoA transport and donate acyl-CoA for beta-oxidation and glycerolipid synthesis

DEFF Research Database (Denmark)

Rasmussen, J T; Færgeman, Nils J.; Kristiansen, K

1994-01-01

The dissociation constants for octanoyl-CoA, dodecanoyl-CoA and hexadecanoyl-CoA binding to acyl-CoA-binding protein (ACBP) were determined by using titration microcalorimetry. The KD values obtained, (0.24 +/- 0.02) x 10(-6) M, (0.65 +/- 0.2) x 10(-8) M and (0.45 +/- 0.2) x 10(-13) M respectively......, were much lower than expected. ACBP was able to extract hexadecanoyl-CoA from phosphatidylcholine membranes immobilized on a nitrocellulose membrane. The acyl-CoA/ACBP complex formed was able to transport acyl-CoA to mitochondria or microsomes in suspension, or to microsomes immobilized...

Characterization of a structurally and functionally diverged acyl-acyl carrier protein desaturase from milkweed seed.

Science.gov (United States)

Cahoon, E B; Coughlan, S J; Shanklin, J

1997-04-01

A cDNA for a structurally variant acyl-acyl carrier protein (ACP) desaturase was isolated from milkweed (Asclepias syriaca) seed, a tissue enriched in palmitoleic (16:1delta9)* and cis-vaccenic (18:1delta11) acids. Extracts of Escherichia coli that express the milkweed cDNA catalyzed delta9 desaturation of acyl-ACP substrates, and the recombinant enzyme exhibited seven- to ten-fold greater specificity for palmitoyl (16:0)-ACP and 30-fold greater specificity for myristoyl (14:0)-ACP than did known delta9-stearoyl (18:0)-ACP desaturases. Like other variant acyl-ACP desaturases reported to date, the milkweed enzyme contains fewer amino acids near its N-terminus compared to previously characterized delta9-18:0-ACP desaturases. Based on the activity of an N-terminal deletion mutant of a delta9-18:0-ACP desaturase, this structural feature likely does not account for differences in substrate specificities.

Human carbonyl reductase 1 participating in intestinal first-pass drug metabolism is inhibited by fatty acids and acyl-CoAs.

Science.gov (United States)

Hara, Akira; Endo, Satoshi; Matsunaga, Toshiyuki; El-Kabbani, Ossama; Miura, Takeshi; Nishinaka, Toru; Terada, Tomoyuki

2017-08-15

Human carbonyl reductase 1 (CBR1), a member of the short-chain dehydrogenase/reductase (SDR) superfamily, reduces a variety of carbonyl compounds including endogenous isatin, prostaglandin E 2 and 4-oxo-2-nonenal. It is also a major non-cytochrome P450 enzyme in the phase I metabolism of carbonyl-containing drugs, and is highly expressed in the intestine. In this study, we found that long-chain fatty acids and their CoA ester derivatives inhibit CBR1. Among saturated fatty acids, myristic, palmitic and stearic acids were inhibitory, and stearic acid was the most potent (IC 50 9µM). Unsaturated fatty acids (oleic, elaidic, γ-linolenic and docosahexaenoic acids) and acyl-CoAs (palmitoyl-, stearoyl- and oleoyl-CoAs) were more potent inhibitors (IC 50 1.0-2.5µM), and showed high inhibitory selectivity to CBR1 over its isozyme CBR3 and other SDR superfamily enzymes (DCXR and DHRS4) with CBR activity. The inhibition by these fatty acids and acyl-CoAs was competitive with respect to the substrate, showing the K i values of 0.49-1.2µM. Site-directed mutagenesis of the substrate-binding residues of CBR1 suggested that the interactions between the fatty acyl chain and the enzyme's Met141 and Trp229 are important for the inhibitory selectivity. We also examined CBR1 inhibition by oleic acid in cellular levels: The fatty acid effectively inhibited CBR1-mediated 4-oxo-2-nonenal metabolism in colon cancer DLD1 cells and increased sensitivity to doxorubicin in the drug-resistant gastric cancer MKN45 cells that highly express CBR1. The results suggest a possible new food-drug interaction through inhibition of CBR1-mediated intestinal first-pass drug metabolism by dietary fatty acids. Copyright © 2017 Elsevier Inc. All rights reserved.

Pseudomonas aeruginosa with lasI quorum-sensing deficiency during corneal infection

DEFF Research Database (Denmark)

Zhu, H.; Bandara, R.; Conibear, T.C.

2004-01-01

To understand the importance of Pseudomonas aeruginosa quorum-sensing systems in the development of corneal infection, the genotypic characteristics and pathogenesis of seven ocular isolates with low-protease and acyl homoserine lactone (AHL) activity and quorum-sensing mutants of PAO1 deficient...

Improvement of the dehydrogenating kinetics of the Mg(NH{sub 2}){sub 2}/LiH materials by inducing LiBH{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Wang, Jingchuan, E-mail: wangjingchuan@caep.cn; Song, Jiangfeng; Chen, Changan; Luo, Deli

2016-12-15

Highlights: • This work indicates that inducing 10 wt.% LiBH{sub 4} into the Mg(NH{sub 2}){sub 2}/LiH mixture significantly improves the dehydrogenating kinetics. It has a near 40 times as large as the effect of the Ti{sub 3}Cr{sub 3}V{sub 4} nanoparticles catalyst under the 200 °C and 0.1 MPa dehydrogenating environment. • Based on diffusion model, the dehydrogenating kinetic curve was fitted for illuminating the mechanism of dehydrogenation improvement. • The mechanism is proposed that the eutectic reaction takes a big role in the catalysis process as the arising of nanorods inside of the matrix after several re-/dehydrogenation cycles. - Abstract: The lightweight high-capacity Li-Mg-N-H system is a promising candidate for the hydrogen energy storage materials. Nevertheless, the slow dehydrogenating process limits its application. This work is focusing on the effect of LiBH{sub 4} on the dehydrogenating kinetics of the Mg(NH{sub 2}){sub 2}/LiH mixture. It indicates that inducing 10 wt.% LiBH{sub 4} into the Mg(NH{sub 2}){sub 2}/LiH mixture significantly improves the dehydrogenating kinetics. As a result, it has a near 40 times as large as the effect of the Ti alloy nanoparticles catalyst, under the 200 °C and 0.1 MPa dehydrogenating environment. Based on our previous dehydrogenating kinetics model, the mechanism of this improving effect of LiBH{sub 4} is discussed as well, which shows that the eutectic reaction takes a big role in the catalysis process as the arising of nanorods inside of the matrix after several re-/dehydrogenation cycles.

Vulnerability to oxidative stress in vitro in pathophysiology of mitochondrial short-chain acyl-CoA dehydrogenase deficiency: response to antioxidants.

Directory of Open Access Journals (Sweden)

Zarazuela Zolkipli

Full Text Available OBJECTIVE: To elucidate the pathophysiology of SCAD deficient patients who have a unique neurological phenotype, among fatty acid oxidation disorders, with early developmental delay, CNS malformations, intractable seizures, myopathy and clinical signs suggesting oxidative stress. METHODS: We studied skin fibroblast cultures from patients homozygous for ACADS common variant c.625G>A (n = 10, compound heterozygous for c.625G>A/c.319C>T (n = 3 or homozygous for pathogenic c.319C>T (n = 2 and c.1138C>T (n = 2 mutations compared to fibroblasts from patients with carnitine palmitoyltransferase 2 (CPT2 (n = 5, mitochondrial trifunctional protein (MTP/long-chain L-3-hydroxyacyl-CoA dehydrogenase (LCHAD (n = 7, and medium-chain acyl-CoA dehydrogenase (MCAD deficiencies (n = 4 and normal controls (n = 9. All were exposed to 50 µM menadione at 37°C. Additional conditions included exposure to 39°C and/or hypoglycemia. Time to 100% cell death was confirmed with trypan blue dye exclusion. Experiments were repeated with antioxidants (Vitamins C and E or N-acetylcysteine, Bezafibrate or glucose and temperature rescue. RESULTS: The most significant risk factor for vulnerability to menadione-induced oxidative stress was the presence of a FAO defect. SCADD fibroblasts were the most vulnerable compared to other FAO disorders and controls, and were similarly affected, independent of genotype. Cell death was exacerbated by hyperthermia and/or hypoglycemia. Hyperthermia was a more significant independent risk factor than hypoglycemia. Rescue significantly prolonged survival. Incubation with antioxidants and Bezafibrate significantly increased viability of SCADD fibroblasts. INTERPRETATION: Vulnerability to oxidative stress likely contributes to neurotoxicity of SCADD regardless of ACADS genotype and is significantly exacerbated by hyperthermia. We recommend rigorous temperature control in SCADD patients during acute illness

Kinetic modeling of ethylbenzene dehydrogenation over hydrotalcite catalysts

KAUST Repository

Atanda, Luqman

2011-07-01

Kinetics of ethylbenzene dehydrogenation to styrene was investigated over a series of quaternary mixed oxides of Mg3Fe0.25Me0.25Al0.5 (Me=Co, Mn and Ni) catalysts prepared by calcination of hydrotalcite-like compounds and compared with commercial catalyst. The study was carried out in the absence of steam using a riser simulator at 400, 450, 500 and 550°C for reaction times of 5, 10, 15 and 20s. Mg3Fe0.25Mn0.25Al0.5 afforded the highest ethylbenzene conversion of 19.7% at 550°C. Kinetic parameters for the dehydrogenation process were determined using the catalyst deactivation function based on reactant conversion model. The apparent activation energies for styrene production were found to decrease as follows: E1-Ni>E1-Co>E1-Mn. © 2011 Elsevier B.V.

Light alkane (mixed feed selective dehydrogenation using bi-metallic zeolite supported catalyst

Directory of Open Access Journals (Sweden)

Zeeshan Nawaz

2009-12-01

Full Text Available Light alkanes are the important intermediates of many refinery processes and their catalytic dehydrogenation gives corresponding alkenes. The aim behind this experimentation is to investigate reaction behavior of mixed alkanes during direct catalytic dehydrogenation and emphasis has been given to enhance propene. Bi-metallic zeolite supported catalyst Pt-Sn/ZSM-5 was prepared by sequentional impregnation method and characterized by BET, EDS and XRD. Direct dehydrogenation reaction is highly endothermic and its conversion is thermodynamically limited. Results showed that the increase in temperature increases the conversion to some extent but there is no overall effect on selectivity of propene. Increase in time-on-stream (TOS remarkably improves propene selectivity at the expense of lower conversion. The performances of bi-metallic zeolite based catalyst largely affected by coke deposition. The presence of butane and ethane adversely affected propane conversion. Optimum propene selectivity is about 48 %, obtained at 600 oC and time-on-stream 10 h.

A New Homogeneous Catalyst for the Dehydrogenation of Dimethylamine Borane Starting with Ruthenium(III Acetylacetonate

Directory of Open Access Journals (Sweden)

Ebru Ünel Barın

2015-06-01

Full Text Available The catalytic activity of ruthenium(III acetylacetonate was investigated for the first time in the dehydrogenation of dimethylamine borane. During catalytic reaction, a new ruthenium(II species is formed in situ from the reduction of ruthenium(III and characterized using UV-Visible, Fourier transform infrared (FTIR, 1H NMR, and mass spectroscopy. The most likely structure suggested for the ruthenium(II species is mer-[Ru(N2Me43(acacH]. Mercury poisoning experiment indicates that the catalytic dehydrogenation of dimethylamine-borane is homogeneous catalysis. The kinetics of the catalytic dehydrogenation of dimethylamine borane starting with Ru(acac3 were studied depending on the catalyst concentration, substrate concentration and temperature. The hydrogen generation was found to be first-order with respect to catalyst concentration and zero-order regarding the substrate concentration. Evaluation of the kinetic data provides the activation parameters for the dehydrogenation reaction: the activation energy Ea = 85 ± 2 kJ·mol−1, the enthalpy of activation ∆H# = 82 ± 2 kJ·mol−1 and the entropy of activation; ∆S# = −85 ± 5 J·mol−1·K−1. The ruthenium(II catalyst formed from the reduction of ruthenium(III acetylacetonate provides 1700 turnovers over 100 hours in hydrogen generation from the dehydrogenation of dimethylamine borane before deactivation at 60 °C.

CoCoa: a software tool for estimating the coefficient of coancestry from multilocus genotype data.

Science.gov (United States)

Maenhout, Steven; De Baets, Bernard; Haesaert, Geert

2009-10-15

Phenotypic data collected in breeding programs and marker-trait association studies are often analyzed by means of linear mixed models. In these models, the covariance between the genetic background effects of all genotypes under study is modeled by means of pairwise coefficients of coancestry. Several marker-based coancestry estimation procedures allow to estimate this covariance matrix, but generally introduce a certain amount of bias when the examined genotypes are part of a breeding program. CoCoa implements the most commonly used marker-based coancestry estimation procedures and as such, allows to select the best fitting covariance structure for the phenotypic data at hand. This better model fit translates into an increased power and improved type I error control in association studies and an improved accuracy in phenotypic prediction studies. The presented software package also provides an implementation of the new Weighted Alikeness in State (WAIS) estimator for use in hybrid breeding programs. Besides several matrix manipulation tools, CoCoa implements two different bending heuristics, in case the inverse of an ill-conditioned coancestry matrix estimate is needed. The software package CoCoa is freely available at http://webs.hogent.be/cocoa. Source code, manual, binaries for 32 and 64-bit Linux systems and an installer for Microsoft Windows are provided. The core components of CoCoa are written in C++, while the graphical user interface is written in Java.

Dehydrogenation and concurrent isomerization of n-butenes on mixed tin and antimony oxide catalysts

Energy Technology Data Exchange (ETDEWEB)

Irvine, E.A.; Taylor, D.

1978-01-01

The dehydrogenation and concurrent isomerization of n-butenes on mixed tin and antimony oxide catalysts which had been outgassed at 698/sup 0/K were carried out in the presence of oxygen at 474/sup 0/K, and the initial approximately zero-order rates of 1,3-butadiene formation and rates of isomerization were used as a measure of catalytic activity to construct activity patterns as a function of catalyst composition. A comparison of the patterns with those for the isomerization of 3,3-dimethyl-1-butene and for the selective oxidation of propane on the same catalysts indicated that the dehydrogenation of 1-butene involves a m-allyl intermediate, but isomerization occurs through carbonium ion formation. For the cis- and trans-isomers, both reactions apparently occurred via a common allyl (but not m-allyl) intermediate. Dehydrogenation to butadiene decreased in the order 1-butene > cis-2-butene trans-2-butene and was maximum at 10% antimony for 1-butene and 21% antimony for 2-butene. Isomerization was always slower than dehydrogenation and showed two maEima, at 21 (or 27%) and at 75% antimony.

Improved Dehydrogenation Properties of 2LiNH2-MgH2 by Doping with Li3AlH6

Directory of Open Access Journals (Sweden)

Shujun Qiu

2017-01-01

Full Text Available Doping with additives in a Li-Mg-N-H system has been regarded as one of the most effective methods of improving hydrogen storage properties. In this paper, we prepared Li3AlH6 and evaluated its effect on the dehydrogenation properties of 2LiNH2-MgH2. Our studies show that doping with Li3AlH6 could effectively lower the dehydrogenation temperatures and increase the hydrogen content of 2LiNH2-MgH2. For example, 2LiNH2-MgH2-0.1Li3AlH6 can desorb 6.43 wt % of hydrogen upon heating to 300 °C, with the onset dehydrogenation temperature at 78 °C. Isothermal dehydrogenation testing indicated that 2LiNH2-MgH2-0.1Li3AlH6 had superior dehydrogenation kinetics at low temperature. Moreover, the release of byproduct NH3 was successfully suppressed. Measurement of the thermal diffusivity suggests that the enhanced dehydrogenation properties may be ascribed to the fact that doping with Li3AlH6 could improve the heat transfer for solid–solid reaction.

Multi-organ abnormalities and mTORC1 activation in zebrafish model of multiple acyl-CoA dehydrogenase deficiency.

Directory of Open Access Journals (Sweden)

Seok-Hyung Kim

2013-06-01

Full Text Available Multiple Acyl-CoA Dehydrogenase Deficiency (MADD is a severe mitochondrial disorder featuring multi-organ dysfunction. Mutations in either the ETFA, ETFB, and ETFDH genes can cause MADD but very little is known about disease specific mechanisms due to a paucity of animal models. We report a novel zebrafish mutant dark xavier (dxa(vu463 that has an inactivating mutation in the etfa gene. dxa(vu463 recapitulates numerous pathological and biochemical features seen in patients with MADD including brain, liver, and kidney disease. Similar to children with MADD, homozygote mutant dxa(vu463 zebrafish have a spectrum of phenotypes ranging from moderate to severe. Interestingly, excessive maternal feeding significantly exacerbated the phenotype. Homozygous mutant dxa(vu463 zebrafish have swollen and hyperplastic neural progenitor cells, hepatocytes and kidney tubule cells as well as elevations in triacylglycerol, cerebroside sulfate and cholesterol levels. Their mitochondria were also greatly enlarged, lacked normal cristae, and were dysfunctional. We also found increased signaling of the mechanistic target of rapamycin complex 1 (mTORC1 with enlarged cell size and proliferation. Treatment with rapamycin partially reversed these abnormalities. Our results indicate that etfa gene function is remarkably conserved in zebrafish as compared to humans with highly similar pathological, biochemical abnormalities to those reported in children with MADD. Altered mTORC1 signaling and maternal nutritional status may play critical roles in MADD disease progression and suggest novel treatment approaches that may ameliorate disease severity.

Study on excimer laser irradiation for controlled dehydrogenation and crystallization of boron doped hydrogenated amorphous/nanocrystalline silicon multilayers

International Nuclear Information System (INIS)

Gontad, F.; Conde, J.C.; Filonovich, S.; Cerqueira, M.F.; Alpuim, P.; Chiussi, S.

2013-01-01

We report on the excimer laser annealing (ELA) induced temperature gradients, allowing controlled crystallization and dehydrogenation of boron-doped a-Si:H/nc-Si:H multilayers. Depth of the dehydrogenation and crystallization process has been studied numerically and experimentally, showing that temperatures below the monohydride decomposition can be used and that significant changes of the doping profile can be avoided. Calculation of temperature profiles has been achieved through numerical modeling of the heat conduction differential equation. Increase in the amount of nano-crystals, but not in their size, has been demonstrated by Raman spectroscopy. Effective dehydrogenation and shape of the boron profile have been studied by time of flight secondary ion mass spectroscopy. The relatively low temperature threshold for dehydrogenation, below the monohydride decomposition temperature, has been attributed to both, the large hydrogen content of the original films and the partial crystallization during the ELA process. The results of this study show that UV-laser irradiation is an effective tool to improve crystallinity and dopant activation in p + -nc-Si:H films without damaging the substrate. - Highlights: • An efficient dehydrogenation is possible through excimer laser annealing. • 140 mJ/cm 2 is enough for dehydrogenation without significant changes in doping profile. • Fluences up to 300 mJ/cm 2 promote partial crystallization of the amorphous structures

Study on excimer laser irradiation for controlled dehydrogenation and crystallization of boron doped hydrogenated amorphous/nanocrystalline silicon multilayers

Energy Technology Data Exchange (ETDEWEB)

Gontad, F., E-mail: fran_gontad@yahoo.es [Applied Physics Department, University of Vigo, E.I. Industrial, Campus de As Lagoas, Marcosende, E-36310, Vigo (Spain); Conde, J.C. [Applied Physics Department, University of Vigo, E.I. Industrial, Campus de As Lagoas, Marcosende, E-36310, Vigo (Spain); Filonovich, S.; Cerqueira, M.F.; Alpuim, P. [Department of Physics, University of Minho, Campus de Azurém, 4800-058 Guimarães (Portugal); Chiussi, S. [Applied Physics Department, University of Vigo, E.I. Industrial, Campus de As Lagoas, Marcosende, E-36310, Vigo (Spain)

2013-06-01

We report on the excimer laser annealing (ELA) induced temperature gradients, allowing controlled crystallization and dehydrogenation of boron-doped a-Si:H/nc-Si:H multilayers. Depth of the dehydrogenation and crystallization process has been studied numerically and experimentally, showing that temperatures below the monohydride decomposition can be used and that significant changes of the doping profile can be avoided. Calculation of temperature profiles has been achieved through numerical modeling of the heat conduction differential equation. Increase in the amount of nano-crystals, but not in their size, has been demonstrated by Raman spectroscopy. Effective dehydrogenation and shape of the boron profile have been studied by time of flight secondary ion mass spectroscopy. The relatively low temperature threshold for dehydrogenation, below the monohydride decomposition temperature, has been attributed to both, the large hydrogen content of the original films and the partial crystallization during the ELA process. The results of this study show that UV-laser irradiation is an effective tool to improve crystallinity and dopant activation in p{sup +}-nc-Si:H films without damaging the substrate. - Highlights: • An efficient dehydrogenation is possible through excimer laser annealing. • 140 mJ/cm{sup 2} is enough for dehydrogenation without significant changes in doping profile. • Fluences up to 300 mJ/cm{sup 2} promote partial crystallization of the amorphous structures.

Electron transfer flavoprotein deficiency: Functional and molecular aspects

DEFF Research Database (Denmark)

Schiff, M; Froissart, R; Olsen, Rikke Katrine Jentoft

2006-01-01

Multiple acyl-CoA dehydrogenase deficiency (MADD) is a recessively inherited metabolic disorder that can be due to a deficiency of electron transfer flavoprotein (ETF) or its dehydrogenase (ETF-ubiquinone oxidoreductase). ETF is a mitochondrial matrix protein consisting of alpha- (30kDa) and beta......- (28kDa) subunits encoded by the ETFA and ETFB genes, respectively. In the present study, we have analysed tissue samples from 16 unrelated patients with ETF deficiency, and we report the results of ETF activity, Western blot analysis and mutation analysis. The ETF assay provides a reliable diagnostic...... tool to confirm ETF deficiency in patients suspected to suffer from MADD. Activity ranged from less than 1 to 16% of controls with the most severely affected patients disclosing the lowest activity values. The majority of patients had mutations in the ETFA gene while only two of them harboured...

Tailored ceria nanoparticles for CO2 mediated ethylbenzene dehydrogenation

NARCIS (Netherlands)

Kovacevic, M.

2016-01-01

Styrene production via ethylbenzene dehydrogenation (EBDH) is one of the ten most important petrochemical processes. Possessing highly reactive double bond which facilitates self-polymerization and polymerization with other monomers, styrene is the fourth utmost essential bulk monomer at present.

Age-dependent decline in acyl-ghrelin concentrations and reduced association of acyl-ghrelin and growth hormone in healthy older adults.

Science.gov (United States)

Nass, Ralf; Farhy, Leon S; Liu, Jianhua; Pezzoli, Suzan S; Johnson, Michael L; Gaylinn, Bruce D; Thorner, Michael O

2014-02-01

Acyl-ghrelin is thought to have both orexigenic effects and to stimulate GH release. A possible cause of the anorexia of aging is an age-dependent decrease in circulating acyl-ghrelin levels. The purpose of the study was to compare acyl-ghrelin and GH concentrations between healthy old and young adults and to examine the relationship of acyl-ghrelin and GH secretion in both age groups. Six healthy older adults (age 62-74 y, body mass index range 20.9-29 kg/m(2)) and eight healthy young men (aged 18-28 y, body mass index range 20.6-26.2 kg/m(2)) had frequent blood samples drawn for hormone measurements every 10 minutes for 24 hours. Ghrelin was measured in an in-house, two-site sandwich ELISA specific for full-length acyl-ghrelin. GH was measured in a sensitive assay (Immulite 2000), and GH peaks were determined by deconvolution analysis. The acyl-ghrelin/GH association was estimated from correlations between amplitudes of individual GH secretory events and the average acyl-ghrelin concentration in the 60-minute interval preceding each GH burst. Twenty-four-hour mean (±SEM) GH (0.48 ± 0.14 vs 2.2 ± 0.3 μg/L, P adults compared with young adults. Twenty-four-hour cortisol concentrations were higher in the old than the young adults (15.1 ± 1.0 vs 10.6 ± 0.9 μg/dL, respectively, P young adults (0.16 ± 0.12 vs 0.69 ± 0.04, P age-dependent decline in circulating acyl-ghrelin levels, which might play a role both in the decline of GH and in the anorexia of aging. Our data also suggest that with normal aging, endogenous acyl-ghrelin levels are less tightly linked to GH regulation.

An efficient strategy for designing ambipolar organic semiconductor material: Introducing dehydrogenated phosphorus atoms into pentacene core

Science.gov (United States)

Tang, Xiao-Dan

2017-09-01

The charge transport properties of phosphapentacene (P-PEN) derivatives were systematically explored by theoretical calculation. The dehydrogenated P-PENs have reasonable frontier molecular orbital energy levels to facilitate both electron and hole injection. The reduced reorganization energies of dehydrogenated P-PENs could be intimately connected to the bonding nature of phosphorus atoms. From the idea of homology modeling, the crystal structure of TIPSE-4P-2p is constructed and fully optimized. Fascinatingly, TIPSE-4P-2p shows the intrinsic property of ambipolar transport in both hopping and band models. Thus, introducing dehydrogenated phosphorus atoms into pentacene core could be an efficient strategy for designing ambipolar material.

Compared effects of missense mutations in Very-Long-Chain Acyl-CoA Dehydrogenase deficiency: Combined analysis by structural, functional and pharmacological approaches.

Science.gov (United States)

Gobin-Limballe, Stéphanie; McAndrew, Ryan P; Djouadi, Fatima; Kim, Jung-Ja; Bastin, Jean

2010-05-01

Very-Long-Chain Acyl-CoA Dehydrogenase deficiency (VLCADD) is an autosomal recessive disorder considered as one of the more common ss-oxidation defects, possibly associated with neonatal cardiomyopathy, infantile hepatic coma, or adult-onset myopathy. Numerous gene missense mutations have been described in these VLCADD phenotypes, but only few of them have been structurally and functionally analyzed, and the molecular basis of disease variability is still poorly understood. To address this question, we first analyzed fourteen disease-causing amino acid changes using the recently described crystal structure of VLCAD. The predicted effects varied from the replacement of amino acid residues lining the substrate binding cavity, involved in holoenzyme-FAD interactions or in enzyme dimerisation, predicted to have severe functional consequences, up to amino acid substitutions outside key enzyme domains or lying on near enzyme surface, with predicted milder consequences. These data were combined with functional analysis of residual fatty acid oxidation (FAO) and VLCAD protein levels in patient cells harboring these mutations, before and after pharmacological stimulation by bezafibrate. Mutations identified as detrimental to the protein structure in the 3-D model were generally associated to profound FAO and VLCAD protein deficiencies in the patient cells, however, some mutations affecting FAD binding or monomer-monomer interactions allowed a partial response to bezafibrate. On the other hand, bezafibrate restored near-normal FAO rates in some mutations predicted to have milder consequences on enzyme structure. Overall, combination of structural, biochemical, and pharmacological analysis allowed assessment of the relative severity of individual mutations, with possible applications for disease management and therapeutic approach. Copyright 2010 Elsevier B.V. All rights reserved.

Communication: Visualization and spectroscopy of defects induced by dehydrogenation in individual silicon nanocrystals

Science.gov (United States)

Kislitsyn, Dmitry A.; Mills, Jon M.; Kocevski, Vancho; Chiu, Sheng-Kuei; DeBenedetti, William J. I.; Gervasi, Christian F.; Taber, Benjamen N.; Rosenfield, Ariel E.; Eriksson, Olle; Rusz, Ján; Goforth, Andrea M.; Nazin, George V.

2016-06-01

We present results of a scanning tunneling spectroscopy (STS) study of the impact of dehydrogenation on the electronic structures of hydrogen-passivated silicon nanocrystals (SiNCs) supported on the Au(111) surface. Gradual dehydrogenation is achieved by injecting high-energy electrons into individual SiNCs, which results, initially, in reduction of the electronic bandgap, and eventually produces midgap electronic states. We use theoretical calculations to show that the STS spectra of midgap states are consistent with the presence of silicon dangling bonds, which are found in different charge states. Our calculations also suggest that the observed initial reduction of the electronic bandgap is attributable to the SiNC surface reconstruction induced by conversion of surface dihydrides to monohydrides due to hydrogen desorption. Our results thus provide the first visualization of the SiNC electronic structure evolution induced by dehydrogenation and provide direct evidence for the existence of diverse dangling bond states on the SiNC surfaces.

Experimental and Theoretical Mechanistic Investigation of the Iridium-Catalyzed Dehydrogenative Decarbonylation of Primary Alcohols

DEFF Research Database (Denmark)

Olsen, Esben Paul Krogh; Singh, Thishana; Harris, Pernille

2015-01-01

The mechanism for the iridium-BINAP catalyzed dehydrogenative decarbonylation of primary alcohols with the liberation of molecular hydrogen and carbon monoxide was studied experimentally and computationally. The reaction takes place by tandem catalysis through two catalytic cycles involving...... cycles. One carbon monoxide ligand was shown to remain coordinated to iridium throughout the reaction, and release of carbon monoxide was suggested to occur from a dicarbonyl complex. IrH2Cl(CO)(rac-BINAP) was also synthesized and detected in the dehydrogenation of benzyl alcohol. In the same experiment......, IrHCl2(CO)(rac-BINAP) was detected from the release of HCl in the dehydrogenation and subsequent reaction with IrCl(CO)(rac-BINAP). This indicated a substitution of chloride with the alcohol to form a square planar iridium alkoxo complex that could undergo a beta-hydride elimination. A KIE of 1...

Acylated flavone glycosides from Veronica

DEFF Research Database (Denmark)

Albach, Dirk C.; Grayer, Renée J.; Jensen, Søren Rosendal

2003-01-01

A survey of the flavonoid glycosides of selected taxa in the genus Veronica yielded two new acylated 5,6,7,3',4'-pentahydroxyflavone (6-hydroxyluteolin) glycosides and two rare allose-containing acylated 5,7,8,4'-tetrahydroxyflavone (isoscutellarein) glycosides. The new compounds were isolated from...

Vectorial acylation in Saccharomyces cerevisiae. Fat1p and fatty acyl-CoA synthetase are interacting components of a fatty acid import complex

DEFF Research Database (Denmark)

Zou, Zhiying; Tong, Fumin; Færgeman, Nils J.

2003-01-01

the growth defect in the faa1Delta fat1Delta strain indicating some essential functions of Fat1p cannot be performed by Faa4p. Chromosomally encoded FAA1 and FAT1 are not able to suppress the growth deficiencies of the fat1Delta faa1Delta and faa1Delta faa4Delta strains, respectively, indicating Faa1p...... as trap were active when tested using the yeast two-hybrid system. Third, co-expressed, differentially tagged Fat1p and Faa1p or Faa4p were co-immunoprecipitated. Collectively, these data support the hypothesis that fatty acid import by vectorial acylation in yeast requires a multiprotein complex, which...... consists of Fat1p and Faa1p or Faa4p....

Synthesis of benzimidazoles via iridium-catalyzed acceptorless dehydrogenative coupling.

Science.gov (United States)

Sun, Xiang; Lv, Xiao-Hui; Ye, Lin-Miao; Hu, Yu; Chen, Yan-Yan; Zhang, Xue-Jing; Yan, Ming

2015-07-21

Iridium-catalyzed acceptorless dehydrogenative coupling of tertiary amines and arylamines has been developed. A number of benzimidazoles were prepared in good yields. An iridium-mediated C-H activation mechanism is suggested. This finding represents a novel strategy for the synthesis of benzimidazoles.

Aerobic, Metal-Free, and Catalytic Dehydrogenative Coupling of Heterocycles: En Route to Hedgehog Signaling Pathway Inhibitors.

Science.gov (United States)

Bering, Luis; Paulussen, Felix M; Antonchick, Andrey P

2018-04-06

The nitrosonium ion-catalyzed dehydrogenative coupling of heteroarenes under mild reaction conditions is reported. The developed method utilizes ambient molecular oxygen as a terminal oxidant, and only water is produced as byproduct. Dehydrogenative coupling of heteroarenes translated into the rapid discovery of novel hedgehog signaling pathway inhibitors, emphasizing the importance of the developed methodology.

Combustion kinetics of the coke on deactivated dehydrogenation catalysts

NARCIS (Netherlands)

Luo, Sha; He, Songbo; Li, XianRu; Li, Jingqiu; Bi, Wenjun; Sun, Chenglin

2015-01-01

The coke combustion kinetics on the deactivated catalysts for long chain paraffin dehydrogenation was studied by the thermogravimetry and differential thermogravimetry (TG–DTG) technique. The amount and H/C mole ratio of the coke were determined by the TG and elemental analysis. And the

The Newborn Screening Paradox: Sensitivity vs. Overdiagnosis in VLCAD Deficiency

NARCIS (Netherlands)

Diekman, Eugene; de Sain-van der Velden, Monique; Waterham, Hans; Kluijtmans, Leo; Schielen, Peter; van Veen, Evert Ben; Ferdinandusse, Sacha; Wijburg, Frits; Visser, Gepke

2016-01-01

To improve the efficacy of newborn screening (NBS) for very long chain acyl-CoA dehydrogenase deficiency (VLCADD). Data on all dried blood spots collected by the Dutch NBS from October 2007 to 2010 (742.728) were included. Based solely on the C14:1 levels (cutoff ≥0.8 μmol/L), six newborns with

Diagnostic potential of stored dried blood spots for inborn errors of metabolism: a metabolic autopsy of medium-chain acyl-CoA dehydrogenase deficiency.

Science.gov (United States)

Kaku, Noriyuki; Ihara, Kenji; Hirata, Yuichiro; Yamada, Kenji; Lee, Sooyoung; Kanemasa, Hikaru; Motomura, Yoshitomo; Baba, Haruhisa; Tanaka, Tamami; Sakai, Yasunari; Maehara, Yoshihiko; Ohga, Shouichi

2018-05-02

It is estimated that 1-5% of sudden infant death syndrome (SIDS) cases might be caused by undiagnosed inborn errors of metabolism (IEMs); however, the postmortem identification of IEMs remains difficult. This study aimed to evaluate the usefulness of dried blood spots (DBSs) stored after newborn screening tests as a metabolic autopsy to determine the causes of death in infants and children who died suddenly and unexpectedly. Infants or toddlers who had suddenly died without a definite diagnosis between July 2008 and December 2012 at Kyushu University Hospital in Japan were enrolled in this study. Their Guthrie cards, which had been stored for several years at 4-8°C, were used for an acylcarnitine analysis by tandem mass spectrometry to identify inborn errors of metabolism. Fifteen infants and children who died at less than 2 years of age and for whom the cause of death was unknown were enrolled for the study. After correcting the C0 and C8 values assuming the hydrolysation of acylcarnitine in the stored DBSs, the corrected C8 value of one case just exceeded the cut-off level for medium-chain acyl-CoA dehydrogenase (MCAD) deficiency screening. Genetic and biochemical analyses confirmed this patient to have MCAD deficiency. DBSs stored after newborn screening tests are a promising tool for metabolic autopsy. The appropriate compensation of acylcarnitine data and subsequent genetic and biochemical analyses are essential for the postmortem diagnosis of inborn errors of metabolism. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Hydrogen bonding-mediated dehydrogenation in the ammonia borane combined graphene oxide systems

Science.gov (United States)

Kuang, Anlong; Liu, Taijuan; Kuang, Minquan; Yang, Ruifeng; Huang, Rui; Wang, Guangzhao; Yuan, Hongkuan; Chen, Hong; Yang, Xiaolan

2018-03-01

The dehydrogenation of ammonia borane (AB) adsorbed on three different graphene oxide (GO) sheets is investigated within the ab initio density functional theory. The energy barriers to direct combination the hydrogens of hydroxyl groups and the hydridic hydrogens of AB to release H2 are relatively high, indicating that the process is energetically unfavorable. Our theoretical study demonstrates that the dehydrogenation mechanism of the AB-GO systems has undergone two critical steps, first, there is the formation of the hydrogen bond (O-H-O) between two hydroxyl groups, and then, the hydrogen bond further react with the hydridic hydrogens of AB to release H2 with low reaction barriers.

Photoaffinity Labeling of Developing Jojoba Seed Microsomal Membranes with a Photoreactive Analog of Acyl-Coenzyme A (Acyl-CoA) (Identification of a Putative Acyl-CoA:Fatty Alcohol Acyltransferase.

Science.gov (United States)

Shockey, J. M.; Rajasekharan, R.; Kemp, J. D.

1995-01-01

Jojoba (Simmondsia chinensis, Link) is the only plant known that synthesizes liquid wax. The final step in liquid wax biosynthesis is catalyzed by an integral membrane enzyme, fatty acyl-coenzyme A (CoA):fatty alcohol acyltransferase, which transfers an acyl chain from acyl-CoA to a fatty alcohol to form the wax ester. To purify the acyltransferase, we have labeled the enzyme with a radioiodinated, photoreactive analog of acyl-CoA, 12-[N-(4-azidosalicyl)amino] dodecanoyl-CoA (ASD-CoA). This molecule acts as an inhibitor of acyltransferase activity in the dark and as an irreversible inhibitor upon exposure to ultraviolet light. Oleoyl-CoA protects enzymatic activity in a concentration-dependent manner. Photolysis of microsomal membranes with labeled ASD-CoA resulted in strong labeling of two polypeptides of 57 and 52 kD. Increasing concentrations of oleoyl-CoA reduced the labeling of the 57-kD polypeptide dramatically, whereas the labeling of the 52-kD polypeptide was much less responsive to oleoyl-CoA. Also, unlike the other polypeptide, the labeling of the 57-kD polypeptide was enhanced considerably when photolyzed in the presence of dodecanol. These results suggest that a 57-kD polypeptide from jojoba microsomes may be the acyl-CoA:fatty alcohol acyltransferase.

Analytische und Effektor-Studien von N-Acyl-Ethanolaminphosphaten

OpenAIRE

Ates, Ebru

2011-01-01

Bei N-Acyl-Ethanolaminphosphaten handelt es sich um eine bislang wenig untersuchte Klasse polarer Substanzen, deren Erforschung aufgrund ihrer strukturellen Analogie zu apolaren, physiologisch wirksamen N-Acyl-Ethanolaminen von Interesse ist. Zu bear-beiten waren analytische Fragestellungen, die auch synthetische Aufgaben beinhalteten, wie Methodenentwicklung und Versuche zur Erfassung von N-Acyl-Ethanolamin-phosphaten in ausgewählten Lebensmitteln sowie strukturelle Studien zur „Bioaktivität...

Dehydrogenation of Surface-Oxidized Mixtures of 2LiBH4 + Al/Additives (TiF3 or CeO2

Directory of Open Access Journals (Sweden)

Juan Luis Carrillo-Bucio

2017-11-01

Full Text Available Research for suitable hydrogen storage materials is an important ongoing subject. LiBH4–Al mixtures could be attractive; however, several issues must be solved. Here, the dehydrogenation reactions of surface-oxidized 2LiBH4 + Al mixtures plus an additive (TiF3 or CeO2 at two different pressures are presented. The mixtures were produced by mechanical milling and handled under welding-grade argon. The dehydrogenation reactions were studied by means of temperature programmed desorption (TPD at 400 °C and at 3 or 5 bar initial hydrogen pressure. The milled and dehydrogenated materials were characterized by scanning electron microscopy (SEM, X-ray diffraction (XRD, and Fourier transformed infrared spectroscopy (FT-IR The additives and the surface oxidation, promoted by the impurities in the welding-grade argon, induced a reduction in the dehydrogenation temperature and an increase in the reaction kinetics, as compared to pure (reported LiBH4. The dehydrogenation reactions were observed to take place in two main steps, with onsets at 100 °C and 200–300 °C. The maximum released hydrogen was 9.3 wt % in the 2LiBH4 + Al/TiF3 material, and 7.9 wt % in the 2LiBH4 + Al/CeO2 material. Formation of CeB6 after dehydrogenation of 2LiBH4 + Al/CeO2 was confirmed.

Endophilin-A1 BAR domain interaction with arachidonyl CoA.

Science.gov (United States)

Petoukhov, Maxim V; Weissenhorn, Winfried; Svergun, Dmitri I

2014-01-01

Endophilin-A1 belongs to the family of BAR domain containing proteins that catalyze membrane remodeling processes via sensing, inducing and stabilizing membrane curvature. We show that the BAR domain of endophilin-A1 binds arachidonic acid and molds its coenzyme A (CoA) activated form, arachidonyl-CoA into a defined structure. We studied low resolution structures of endophilin-A1-BAR and its complex with arachidonyl-CoA in solution using synchrotron small-angle X-ray scattering (SAXS). The free endophilin-A1-BAR domain is shown to be dimeric at lower concentrations but builds tetramers and higher order complexes with increasing concentrations. Extensive titration SAXS studies revealed that the BAR domain produces a homogenous complex with the lipid micelles. The structural model of the complexes revealed two arachidonyl-CoA micelles bound to the distal arms of an endophilin-A1-BAR dimer. Intriguingly, the radius of the bound micelles significantly decreases compared to that of the free micelles, and this structural result may provide hints on the potential biological relevance of the endophilin-A1-BAR interaction with arachidonyl CoA.

An Efficient, Mild and Solvent-Free Synthesis of Benzene Ring Acylated Harmalines

Directory of Open Access Journals (Sweden)

Sabira Begum

2009-12-01

Full Text Available A facile synthesis of a series of benzene ring acylated analogues of harmaline has been achieved by Friedel-Crafts acylation under solvent-free conditions at room temperature using acyl halides/acid anhydrides and AlCl3. The reaction afforded 10- and 12-acyl analogues of harmaline in good yield, along with minor quantities of N-acyl-tryptamines and 8-acyl analogues of N-acyltryptamines.

A Historical Cohort Study on the Efficacy of Glucocorticoids and Riboflavin Among Patients with Late-onset Multiple Acyl-CoA Dehydrogenase Deficiency.

Science.gov (United States)

Liu, Xin-Yi; Wang, Zhi-Qiang; Wang, Dan-Ni; Lin, Min-Ting; Wang, Ning

2016-01-20

Late-onset multiple acyl-CoA dehydrogenase deficiency (MADD) is the most common type of lipid storage myopathies in China. Most patients with late-onset MADD are well responsive to riboflavin. Up to now, these patients are often treated with glucocorticoids as the first-line drug because they are misdiagnosed as polymyositis without muscle biopsy or gene analysis. Although glucocorticoids seem to improve the fatty acid metabolism of late-onset MADD, the objective evaluation of their rationalization on this disorder and comparison with riboflavin treatment are unknown. We performed a historical cohort study on the efficacy of the two drugs among 45 patients with late-onset MADD, who were divided into glucocorticoids group and riboflavin group. Detailed clinical information of baseline and 1-month follow-up were collected. After 1-month treatment, a dramatic improvement of muscle strength was found in riboflavin group (P riboflavin group (P riboflavin group still presented high-level muscle enzymes and weak muscle strength after 1-month riboflavin treatment, meaning that 1-month treatment duration maybe insufficient and patients should keep on riboflavin supplement for a longer time. Our results provide credible evidences that the overall efficacy of riboflavin is superior to glucocorticoids, and a longer duration of riboflavin treatment is necessary for patients with late-onset MADD.

The role of peroxisomal fatty acyl-CoA beta-oxidation in bile acid biosynthesis

International Nuclear Information System (INIS)

Hayashi, H.; Miwa, A.

1989-01-01

The physiological role of the peroxisomal fatty acyl-CoA beta-oxidizing system (FAOS) is not yet established. We speculated that there might be a relationship between peroxisomal degradation of long-chain fatty acids in the liver and the biosynthesis of bile acids. This was investigated using [1- 14 C]butyric acid and [1- 14 C]lignoceric acid as substrates of FAOS in mitochondria and peroxisomes, respectively. The incorporation of [ 14 C]lignoceric acid into primary bile acids was approximately four times higher than that of [ 14 C]butyric acid (in terms of C-2 units). The pools of these two fatty acids in the liver were exceedingly small. The incorporations of radioactivity into the primary bile acids were strongly inhibited by administration of aminotriazole, which is a specific inhibitor of peroxisomal FAOS in vivo. Aminotriazole inhibited preferentially the formation of cholate, the major primary bile acid, from both [ 14 C]lignoceric acid and [ 14 C]butyric acid, rather than the formation of chenodeoxycholate. The former inhibition was about 70% and the latter was approximately 40-50%. In view of reports that cholate is biosynthesized from endogenous cholesterol, the above results indicate that peroxisomal FAOS may have an anabolic function, supplying acetyl CoA for bile acid biosynthesis

The role of peroxisomal fatty acyl-CoA beta-oxidation in bile acid biosynthesis

Energy Technology Data Exchange (ETDEWEB)

Hayashi, H.; Miwa, A. (Josai Univ., Saitama (Japan))

1989-11-01

The physiological role of the peroxisomal fatty acyl-CoA beta-oxidizing system (FAOS) is not yet established. We speculated that there might be a relationship between peroxisomal degradation of long-chain fatty acids in the liver and the biosynthesis of bile acids. This was investigated using (1-{sup 14}C)butyric acid and (1-{sup 14}C)lignoceric acid as substrates of FAOS in mitochondria and peroxisomes, respectively. The incorporation of ({sup 14}C)lignoceric acid into primary bile acids was approximately four times higher than that of ({sup 14}C)butyric acid (in terms of C-2 units). The pools of these two fatty acids in the liver were exceedingly small. The incorporations of radioactivity into the primary bile acids were strongly inhibited by administration of aminotriazole, which is a specific inhibitor of peroxisomal FAOS in vivo. Aminotriazole inhibited preferentially the formation of cholate, the major primary bile acid, from both ({sup 14}C)lignoceric acid and ({sup 14}C)butyric acid, rather than the formation of chenodeoxycholate. The former inhibition was about 70% and the latter was approximately 40-50%. In view of reports that cholate is biosynthesized from endogenous cholesterol, the above results indicate that peroxisomal FAOS may have an anabolic function, supplying acetyl CoA for bile acid biosynthesis.

2-methylbutyryl-CoA dehydrogenase deficiency associated with autism and mental retardation

DEFF Research Database (Denmark)

Kanavin, Oivind J; Woldseth, Berit; Jellum, Egil

2007-01-01

BACKGROUND: 2-methylbutyryl-CoA dehydrogenase deficiency or short/branched chain acyl-CoA dehydrogenase deficiency (SBCADD) is caused by a defect in the degradation pathway of the amino acid L-isoleucine. METHODS: We report a four-year-old mentally retarded Somali boy with autism and a history...... cases with SBCADD, both originating from Somalia and Eritrea, indicating that it is relatively prevalent in this population. Autism has not previously been described with mutations in this gene, thus expanding the clinical spectrum of SBCADD....

Kinetics on NiZn Bimetallic Catalysts for Hydrogen Evolution via Selective Dehydrogenation of Methylcyclohexane to Toluene

KAUST Repository

Shaikh Ali, Anaam

2017-01-18

Liquid organic chemical hydrides are effective hydrogen storage media for easy and safe transport. The chemical couple of methylcyclohexane (MCH) and toluene (TOL) has been considered one of the feasible cycles for a hydrogen carrier, but the selective dehydrogenation of MCH to TOL has been reported using only Pt-based noble metal catalysts. This study reports MCH dehydrogenation to TOL using supported NiZn as a selective, non-noble-metal catalyst. A combined experimental and computational study was conducted to provide insight into the site requirements and reaction mechanism for MCH dehydrogenation to TOL, which were compared with those for cyclohexane (CH) dehydrogenation to benzene (BZ). The kinetic measurements carried out at 300-360°C showed an almost zero order with respect to MCH pressure in the high-pressure region (≥10 kPa) and nearly a positive half order with respective to H pressure (≤40 kPa). These kinetic data for the dehydrogenation reaction paradoxically indicate that hydrogenation of a strongly chemisorbed intermediate originating from TOL is the rate-determining step. Density functional theory (DFT) calculation confirms that the dehydrogenated TOL species at the aliphatic (methyl) position group (CHCH) were strongly adsorbed on the surface, which must be hydrogenated to desorb as TOL. This hydrogen-assisted desorption mechanism explains the essential role of excess H present in the feed in maintaining the activity of the metallic surface for hydrogenation. The rate of the CH to BZ reaction was less sensitive to H pressure than that of MCH to TOL, which can be explained by the absence of a methyl group in the structure, which in turn reduces the binding energy of the adsorbed species. DFT suggests that the improved TOL selectivity by adding Zn to Ni was due to Zn atoms preferentially occupying low-coordination sites on the surface (the corner and edge sites), which are likely the unselective sites responsible for the C-C dissociation of the

Kinetics on NiZn Bimetallic Catalysts for Hydrogen Evolution via Selective Dehydrogenation of Methylcyclohexane to Toluene

KAUST Repository

Shaikh Ali, Anaam; Jedidi, Abdesslem; Anjum, Dalaver H.; Cavallo, Luigi; Takanabe, Kazuhiro

2017-01-01

Liquid organic chemical hydrides are effective hydrogen storage media for easy and safe transport. The chemical couple of methylcyclohexane (MCH) and toluene (TOL) has been considered one of the feasible cycles for a hydrogen carrier, but the selective dehydrogenation of MCH to TOL has been reported using only Pt-based noble metal catalysts. This study reports MCH dehydrogenation to TOL using supported NiZn as a selective, non-noble-metal catalyst. A combined experimental and computational study was conducted to provide insight into the site requirements and reaction mechanism for MCH dehydrogenation to TOL, which were compared with those for cyclohexane (CH) dehydrogenation to benzene (BZ). The kinetic measurements carried out at 300-360°C showed an almost zero order with respect to MCH pressure in the high-pressure region (≥10 kPa) and nearly a positive half order with respective to H pressure (≤40 kPa). These kinetic data for the dehydrogenation reaction paradoxically indicate that hydrogenation of a strongly chemisorbed intermediate originating from TOL is the rate-determining step. Density functional theory (DFT) calculation confirms that the dehydrogenated TOL species at the aliphatic (methyl) position group (CHCH) were strongly adsorbed on the surface, which must be hydrogenated to desorb as TOL. This hydrogen-assisted desorption mechanism explains the essential role of excess H present in the feed in maintaining the activity of the metallic surface for hydrogenation. The rate of the CH to BZ reaction was less sensitive to H pressure than that of MCH to TOL, which can be explained by the absence of a methyl group in the structure, which in turn reduces the binding energy of the adsorbed species. DFT suggests that the improved TOL selectivity by adding Zn to Ni was due to Zn atoms preferentially occupying low-coordination sites on the surface (the corner and edge sites), which are likely the unselective sites responsible for the C-C dissociation of the

Copper oxide as efficient catalyst for oxidative dehydrogenation of alcohols with air

DEFF Research Database (Denmark)

Poreddy, Raju; Engelbrekt, Christian; Riisager, Anders

2015-01-01

The oxidative dehydrogenation of alcohols to carbonyl compounds was studied using CuO nanoparticle catalysts prepared by solution synthesis in buffered media. CuO nanoparticles synthesized in N-cyclohexyl- 3-aminopropanesulfonic acid buffer showed high catalytic activity for the oxidation...... of benzylic, alicyclic and unsaturated alcohols to their corresponding carbonyl compounds with excellent selectivities. The observed trend in activity for conversion of substituted alcohols suggested a β-H elimination step to be involved, thus enabling a possible reaction mechanism for oxidative...... dehydrogenation of benzyl alcohols to be proposed. The use of CuO as an inexpensive and efficient heterogeneous catalyst under aerobic conditions provides a new noble metal-free and green reaction protocol for carbonyl compound synthesis....

OCTN3 is a mammalian peroxisomal membrane carnitine transporter

International Nuclear Information System (INIS)

Lamhonwah, Anne-Marie; Ackerley, Cameron A.; Tilups, Aina; Edwards, Vernon D.; Wanders, Ronald J.; Tein, Ingrid

2005-01-01

Carnitine is a zwitterion essential for the β-oxidation of fatty acids. The role of the carnitine system is to maintain homeostasis in the acyl-CoA pools of the cell, keeping the acyl-CoA/CoA pool constant even under conditions of very high acyl-CoA turnover, thereby providing cells with a critical source of free CoA. Carnitine derivatives can be moved across intracellular barriers providing a shuttle mechanism between mitochondria, peroxisomes, and microsomes. We now demonstrate expression and colocalization of mOctn3, the intermediate-affinity carnitine transporter (K m 20 μM), and catalase in murine liver peroxisomes by TEM using immunogold labelled anti-mOctn3 and anti-catalase antibodies. We further demonstrate expression of hOCTN3 in control human cultured skin fibroblasts both by Western blotting and immunostaining analysis using our specific anti-mOctn3 antibody. In contrast with two peroxisomal biogenesis disorders, we show reduced expression of hOCTN3 in human PEX 1 deficient Zellweger fibroblasts in which the uptake of peroxisomal matrix enzymes is impaired but the biosynthesis of peroxisomal membrane proteins is normal, versus a complete absence of hOCTN3 in human PEX 19 deficient Zellweger fibroblasts in which both the uptake of peroxisomal matrix enzymes as well as peroxisomal membranes are deficient. This supports the localization of hOCTN3 to the peroxisomal membrane. Given the impermeability of the peroxisomal membrane and the key role of carnitine in the transport of different chain-shortened products out of peroxisomes, there appears to be a critical need for the intermediate-affinity carnitine/organic cation transporter, OCTN3, on peroxisomal membranes now shown to be expressed in both human and murine peroxisomes. This Octn3 localization is in keeping with the essential role of carnitine in peroxisomal lipid metabolism

Plasma levels of acylated ghrelin in patients with functional dyspepsia

Science.gov (United States)

Kim, Yeon Soo; Lee, Joon Seong; Lee, Tae Hee; Cho, Joo Young; Kim, Jin Oh; Kim, Wan Jung; Kim, Hyun Gun; Jeon, Seong Ran; Jeong, Hoe Su

2012-01-01

AIM: To investigate the relationship between plasma acylated ghrelin levels and the pathophysiology of functional dyspepsia. METHODS: Twenty-two female patients with functional dyspepsia and twelve healthy volunteers were recruited for the study. The functional dyspepsia patients were each diagnosed based on the Rome III criteria. Eligible patients completed a questionnaire concerning the severity of 10 symptoms. Plasma acylated ghrelin levels before and after a meal were determined in the study participants using a commercial human acylated enzyme immunoassay kit; electrogastrograms were performed for 50 min before and after a standardized 10-min meal containing 265 kcal. RESULTS: There were no significant differences in plasma acylated ghrelin levels between healthy volunteers and patients with functional dyspepsia. However, in patients with functional dyspepsia, there was a negative correlation between fasting plasma acylated ghrelin levels and the sum score of epigastric pain (r = -0.427, P = 0.047) and a positive correlation between the postprandial/fasting plasma acylated ghrelin ratio and the sum score of early satiety (r = 0.428, P =0.047). Additionally, there was a negative correlation between fasting acylated ghrelin plasma levels and fasting normogastria (%) (r = -0.522, P = 0.013). Interestingly, two functional dyspepsia patients showed paradoxically elevated plasma acylated ghrelin levels after the meal. CONCLUSION: Abnormal plasma acylated ghrelin levels before or after a meal may be related to several of the dyspeptic symptoms seen in patients with functional dyspepsia. PMID:22611317

Medium-chain acyl-CoA dehydrogenase (MCAD) mutations identified by MS/MS-based prospective screening of newborns differ from those observed in patients with clinical symptoms

DEFF Research Database (Denmark)

Andresen, B S; Dobrowolski, S F; O'Reilly, L

2001-01-01

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is the most frequently diagnosed mitochondrial beta-oxidation defect, and it is potentially fatal. Eighty percent of patients are homozygous for a common mutation, 985A-->G, and a further 18% have this mutation in only one disease allele. In a...

Erbium trifluoromethanesulfonate-catalyzed Friedel–Crafts acylation using aromatic carboxylic acids as acylating agents under monomode-microwave irradiation

DEFF Research Database (Denmark)

Tran, Phuong Hoang; Hansen, Poul Erik; Nguyen, Hai Truong

2015-01-01

Erbium trifluoromethanesulfonate is found to be a good catalyst for the Friedel–Crafts acylation of arenes containing electron-donating substituents using aromatic carboxylic acids as the acylating agents under microwave irradiation. An effective, rapid and waste-free method allows the preparation...... of a wide range of aryl ketones in good yields and in short reaction times with minimum amounts of waste...

Genetics Home Reference: short/branched chain acyl-CoA dehydrogenase deficiency

Science.gov (United States)

... unclear why some people with SBCAD deficiency develop health problems and others do not. Doctors suggest that in some cases, signs and symptoms may be triggered by infections, prolonged periods without food (fasting), or an increased amount of protein-rich foods ...

Biotin augments acetyl CoA carboxylase 2 gene expression in the hypothalamus, leading to the suppression of food intake in mice.

Science.gov (United States)

Sone, Hideyuki; Kamiyama, Shin; Higuchi, Mutsumi; Fujino, Kaho; Kubo, Shizuka; Miyazawa, Masami; Shirato, Saya; Hiroi, Yuka; Shiozawa, Kota

2016-07-29

It is known that biotin prevents the development of diabetes by increasing the functions of pancreatic beta-cells and improving insulin sensitivity in the periphery. However, its anti-obesity effects such as anorectic effects remain to be clarified. Acetyl CoA carboxylase (ACC), a biotin-dependent enzyme, has two isoforms (ACC1 and ACC2) and serves to catalyze the reaction of acetyl CoA to malonyl CoA. In the hypothalamus, ACC2 increases the production of malonyl CoA, which acts as a satiety signal. In this study, we investigated whether biotin increases the gene expression of ACC2 in the hypothalamus and suppresses food intake in mice administered excessive biotin. Food intake was significantly decreased by biotin, but plasma regulators of appetite, including glucose, ghrelin, and leptin, were not affected. On the other hand, biotin notably accumulated in the hypothalamus and enhanced ACC2 gene expression there, but it did not change the gene expression of ACC1, malonyl CoA decarboxylase (a malonyl CoA-degrading enzyme), and AMP-activated protein kinase α-2 (an ACC-inhibitory enzyme). These findings strongly suggest that biotin potentiates the suppression of appetite by upregulating ACC2 gene expression in the hypothalamus. This effect of biotin may contribute to the prevention of diabetes by biotin treatment. Copyright © 2016 Elsevier Inc. All rights reserved.

Activation of Exogenous Fatty Acids to Acyl-Acyl Carrier Protein Cannot Bypass FabI Inhibition in Neisseria*

Science.gov (United States)

Yao, Jiangwei; Bruhn, David F.; Frank, Matthew W.; Lee, Richard E.; Rock, Charles O.

2016-01-01

Neisseria is a Gram-negative pathogen with phospholipids composed of straight chain saturated and monounsaturated fatty acids, the ability to incorporate exogenous fatty acids, and lipopolysaccharides that are not essential. The FabI inhibitor, AFN-1252, was deployed as a chemical biology tool to determine whether Neisseria can bypass the inhibition of fatty acid synthesis by incorporating exogenous fatty acids. Neisseria encodes a functional FabI that was potently inhibited by AFN-1252. AFN-1252 caused a dose-dependent inhibition of fatty acid synthesis in growing Neisseria, a delayed inhibition of growth phenotype, and minimal inhibition of DNA, RNA, and protein synthesis, showing that its mode of action is through inhibiting fatty acid synthesis. Isotopic fatty acid labeling experiments showed that Neisseria encodes the ability to incorporate exogenous fatty acids into its phospholipids by an acyl-acyl carrier protein-dependent pathway. However, AFN-1252 remained an effective antibacterial when Neisseria were supplemented with exogenous fatty acids. These results demonstrate that extracellular fatty acids are activated by an acyl-acyl carrier protein synthetase (AasN) and validate type II fatty acid synthesis (FabI) as a therapeutic target against Neisseria. PMID:26567338

Mechanistic insights into the oxidative dehydrogenation of amines to nitriles in continuous flow

DEFF Research Database (Denmark)

Corker, Emily C.; Ruiz-Martínez, Javier; Riisager, Anders

2015-01-01

The oxidative dehydrogenation of various aliphatic amines to their corresponding nitrile compounds using RuO2/Al2O3 catalysts in air was successfully applied to a continuous flow reaction. Conversions of amines (up to >99%) and yields of nitriles (up to 77%) varied depending on reaction conditions...... and the amine utilised. The presence of water was found to be important for the activity and stability of the RuO2/Al2O3 catalyst. The Hammett relationship and in situ infrared spectroscopy were applied to divulge details about the catalytic mechanism of the oxidative dehydrogenation of amines over RuO2/Al2O3...

Biochemical characterization of recombinant cinnamoyl CoA reductase 1 (Ll-CCRH1) from Leucaena leucocephala.

Science.gov (United States)

Sonawane, Prashant; Vishwakarma, Rishi Kishore; Khan, Bashir M

2013-07-01

Recombinant cinnamoyl CoA reductase 1 (Ll-CCRH1) protein from Leucaena leucocephala was overexpressed in Escherichia coli BL21 (DE3) strain and purified to apparent homogeneity. Optimum pH for forward and reverse reaction was found to be 6.5 and 7.8 respectively. The enzyme was most stable around pH 6.5 at 25°C for 90 min. The enzyme showed Kcat/Km for feruloyl, caffeoyl, sinapoyl, coumaroyl CoA, coniferaldehyde and sinapaldehyde as 4.6, 2.4, 2.3, 1.7, 1.9 and 1.2 (×10(6) M(-1) s(-1)), respectively, indicating affinity of enzyme for feruloyl CoA over other substrates and preference of reduction reaction over oxidation. Activation energy, Ea for various substrates was found to be in the range of 20-50 kJ/mol. Involvement of probable carboxylate ion, histidine, lysine or tyrosine at the active site of enzyme was predicted by pH activity profile. SAXS studies of protein showed radius 3.04 nm and volume 49.25 nm(3) with oblate ellipsoid shape. Finally, metal ion inhibition studies revealed that Ll-CCRH1 is a metal independent enzyme. Copyright © 2013 Elsevier B.V. All rights reserved.

Rapid PMR determination of hydrogen in titanium hydride and dehydrogenated titanium powders

International Nuclear Information System (INIS)

Il'enko, V.S.; Demidenko, L.M.

1987-01-01

Proton magnetic resonance (PMR) enables determining hydrogen quantitatively in titanium hydride and dehydrogenated titanium powders without destroying the specimen and is also more informative than high-temperature extraction methods. PMR provides data on the electron-nuclear interactions and the activation energies for hydrogen diffusion while also providing conclusions on the forms and positives of the hydrogen in the lattice and the binding to the metal atoms. The authors have developed a rapid method for determining hydrogen in titanium hydride and dehydrogenated titanium powders which reduces the analysis time and improves the metrological characteristics. The authors use a YaMR-5535 spectrometer working at 40 MHz upgraded for use with hydrogen in solids. The authors used specimens of mass about 2 g ground to 0.1 mm powder

Improved magnetic properties and fracture strength of NdFeB by dehydrogenation

Energy Technology Data Exchange (ETDEWEB)

Yan, M. [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China)]. E-mail: mse_yanmi@dial.zju.edu.cn; Yu, L.Q. [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Wu, J.M. [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Cui, X.G. [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China)

2006-11-15

Effects of the dehydrogenation of the hydrogen decrepitated (HD) powders on the magnetic properties and the fracture strength of sintered NdFeB magnets were studied. It was found that the lattice parameters and the crystal phase of NdFeB changed significantly with the various hydrogen contents of the resultant HD powders due to the different degrees of dehydrogenation. The magnetic properties and fracture strength increased with decreasing hydrogen content, reaching the maximum increases of 200% for both intrinsic coercivity and bending strength, which can be ascribed to the improved microstructure of the sintered NdFeB magnets. The hydrogen remaining in the HD powders diffused out and affected drastically the grain and grain boundaries by the hydrogen out-take channel during the subsequent sintering process.

Improved magnetic properties and fracture strength of NdFeB by dehydrogenation

International Nuclear Information System (INIS)

Yan, M.; Yu, L.Q.; Wu, J.M.; Cui, X.G.

2006-01-01

Effects of the dehydrogenation of the hydrogen decrepitated (HD) powders on the magnetic properties and the fracture strength of sintered NdFeB magnets were studied. It was found that the lattice parameters and the crystal phase of NdFeB changed significantly with the various hydrogen contents of the resultant HD powders due to the different degrees of dehydrogenation. The magnetic properties and fracture strength increased with decreasing hydrogen content, reaching the maximum increases of 200% for both intrinsic coercivity and bending strength, which can be ascribed to the improved microstructure of the sintered NdFeB magnets. The hydrogen remaining in the HD powders diffused out and affected drastically the grain and grain boundaries by the hydrogen out-take channel during the subsequent sintering process

Late-onset form of beta-electron transfer flavoprotein deficiency

DEFF Research Database (Denmark)

Curcoy, A; Olsen, Rikke Katrine Jentoft; Ribes, A

2003-01-01

Multiple acyl-CoA-dehydrogenase deficiency (MADD) or glutaric aciduria type II (GAII) are a group of metabolic disorders due to deficiency of either electron transfer flavoprotein (ETF) or electron transfer flavoprotein ubiquinone oxidoreductase (ETF-QO). We report the clinical features...... and biochemical and molecular genetic analyses of a patient with a mild late-onset form of GAII due to beta-ETF deficiency. Biochemical data showed an abnormal urine organic acid profile, low levels of free carnitine, increased levels of C(10:1n-6), and C(14:1n-9) in plasma, and decreased oxidation of [9,10-3H......]palmitate and [9,10-3H]myristate in fibroblasts, suggesting MAD deficiency. In agreement with these findings, mutational analysis of the ETF/ETFDH genes demonstrated an ETFB missense mutation 124T>C in exon 2 leading to replacement of cysteine-42 with arginine (C42R), and a 604_606AAG deletion in exon 6...

In vivo efficacy of acyl CoA: diacylglycerol acyltransferase (DGAT) 1 inhibition in rodent models of postprandial hyperlipidemia.

Science.gov (United States)

King, Andrew J; Segreti, Jason A; Larson, Kelly J; Souers, Andrew J; Kym, Philip R; Reilly, Regina M; Collins, Christine A; Voorbach, Martin J; Zhao, Gang; Mittelstadt, Scott W; Cox, Bryan F

2010-07-10

Postprandial serum triglyceride concentrations have recently been identified as a major, independent risk factor for future cardiovascular events. As a result, postprandial hyperlipidemia has emerged as a potential therapeutic target. The purpose of this study was two-fold. Firstly, to describe and characterize a standardized model of postprandial hyperlipidemia in multiple rodent species; and secondly, apply these rodent models to the evaluation of a novel class of pharmacologic agent; acyl CoA:diacylglycerol acyltransferase (DGAT) 1 inhibitors. Serum triglycerides were measured before and for 4h after oral administration of a standardized volume of corn oil, to fasted C57BL/6, ob/ob, apoE(-/-) and CD-1 mice; Sprague-Dawley and JCR/LA-cp rats; and normolipidemic and hyperlipidemic hamsters. Intragastric administration of corn oil increased serum triglycerides in all animals evaluated, however the magnitude and time-course of the postprandial triglyceride excursion varied. The potent and selective DGAT-1 inhibitor A-922500 (0.03, 0.3 and 3 mg/kg, p.o.), dose-dependently attenuated the maximal postprandial rise in serum triglyceride concentrations in all species tested. At the highest dose of DGAT-1 inhibitor, the postprandial triglyceride response was abolished. This study provides a comprehensive characterization of the time-course of postprandial hyperlipidemia in rodents. In addition, the ability of DGAT-1 inhibitors to attenuate postprandial hyperlipidemia in multiple rodent models, including those that feature insulin resistance, is documented. Exaggerated postprandial hyperlipidemia is inherent to insulin-resistant states in humans and contributes to the substantially elevated cardiovascular risk observed in these patients. Therefore, by attenuating postprandial hyperlipidemia, DGAT-1 inhibition may represent a novel therapeutic approach to reduce cardiovascular risk. Copyright 2010 Elsevier B.V. All rights reserved.

Biosynthesis of plasmalogens by the microsomal fraction of Fischer R-3259 sarcoma. Influence of specific 2-acyl chains on the desaturation of 1-alkyl-2-acyl-sn-gycero-3-phosphoethanolamine

Energy Technology Data Exchange (ETDEWEB)

Wykle, R.L.; Schremmer, J.M.

1979-08-07

In the Fischer R-3259 sarcoma, ethanolamine plasmalogens are synthesized from 1-akyl-2-acyl-sn-glycero-3-phosphoethanolamine by a microsomal desaturase that inserts a ..delta../sup 1/ double bond in the alkyl chain. In the present study, a series of 1-(1-/sup 14/C)hexadecyl-2-acyl-GPE substrates containing specific acyl groups ranging from C/sub 2/ /sub 0/ to C/sub 20/ /sub 4/ at the 2 position were prepared and tested as substrates for the microsomal ..delta../sup 1/-alkyl desaturase. The microsomal preparations contained an acyl hydrolase that removed the C/sub 2/ /sub 0/, C/sub 4/ /sub 0/, and C/sub 7/ /sub 0/ acyl groups from the 2 position. By inhibiting the hydrolase with diisopropyl fluorophosphate, it was possible to test conversion of the unaltered substrates to plasmalogens. The alkyl desaturase exhibited little discrimination among the specific acyl derivatives tested. The highest rate of desaturation was obtained with 1-(1-/sup 14/C)-hexadecyl-2-acyl-GPE synthesized in situ in the microsomes via acylation of 1-(1-/sup 14/C)hexadecyl-GPE; this rate was threefold that observed with exogenously acylated substrates. The 1-(1-/sup 14/C)hexadecyl-2-acyl-GPE synthesized in situ contained highly unsaturated acyl groups; no selectivity of the desaturase for specific acyl chains was detected when the different molecular species of 1-(1-/sup 14/C)alkyl-2-acyl-GPE and 1-(1-/sup 14/C)alk-1'-eyl-2-acyl-GPE were compared. The short-chain substrates, being moe hydrophilic, mimicked the chromatographic behavior of 1-alkyl-GPE, yet they did not resemble the lyso compound in its higher conversion to plasmalogens. Thus, despite their similar R/sub f/ values, the packing of the short-chain acyl homologues in the membrane may be quite different from that of the lyso compound. Binding of 1-hexadecyl-2-acyl-GPE and 1-hexadecyl-GPE to microsomal membranes was similar.

Flexible DAQ card for detector systems utilizing the CoaXPress communication standard

International Nuclear Information System (INIS)

Neue, G.; Hejtmánek, M.; Marčišovský, M.; Voleš, P.

2015-01-01

This work concerns the design and construction of a flexible FPGA based data acquisition system aimed for particle detectors. The interface card as presented was designed for large area detectors with millions of individual readout channels. Flexibility was achieved by partitioning the design into multiple PCBs, creating a set of modular blocks, allowing the creation of a wide variety of configurations by simply stacking functional PCBs together. This way the user can easily toggle the polarity of the high voltage bias supply or switch the downstream interface from CoaXPress to PCIe or stream directly HDMI. We addressed the issues of data throughput, data buffering, bias voltage generation, trigger timing and fine tuning of the whole readout chain enabling a smooth data transmission. On the current prototype, we have wire-bonded a MediPix2 MXR quad and connected it to a XILINX FPGA. For the downstream interface, we implemented the CoaXPress communication protocol, which enables us to stream data at 3.125 Gbps to a standard PC

OleA Glu117 is key to condensation of two fatty-acyl coenzyme A substrates in long-chain olefin biosynthesis

Energy Technology Data Exchange (ETDEWEB)

Jensen, Matthew R.; Goblirsch, Brandon R.; Christenson, James K.; Esler, Morgan A.; Mohamed, Fatuma A.; Wackett, Lawrence P.; Wilmot, Carrie M. (UMM)

2017-10-12

In the interest of decreasing dependence on fossil fuels, microbial hydrocarbon biosynthesis pathways are being studied for renewable, tailored production of specialty chemicals and biofuels. One candidate is long-chain olefin biosynthesis, a widespread bacterial pathway that produces waxy hydrocarbons. Found in three- and four-gene clusters, oleABCD encodes the enzymes necessary to produce cis-olefins that differ by alkyl chain length, degree of unsaturation, and alkyl chain branching. The first enzyme in the pathway, OleA, catalyzes the Claisen condensation of two fatty acyl-coenzyme A (CoA) molecules to form a β-keto acid. In this report, the mechanistic role of Xanthomonas campestris OleA Glu117 is investigated through mutant enzymes. Crystal structures were determined for each mutant as well as their complex with the inhibitor cerulenin. Complemented by substrate modeling, these structures suggest that Glu117 aids in substrate positioning for productive carbon–carbon bond formation. Analysis of acyl-CoA substrate hydrolysis shows diminished activity in all mutants. When the active site lacks an acidic residue in the 117 position, OleA cannot form condensed product, demonstrating that Glu117 has a critical role upstream of the essential condensation reaction. Profiling of pH dependence shows that the apparent pKa for Glu117 is affected by mutagenesis. Taken together, we propose that Glu117 is the general base needed to prime condensation via deprotonation of the second, non-covalently bound substrate during turnover. This is the first example of a member of the thiolase superfamily of condensing enzymes to contain an active site base originating from the second monomer of the dimer.

THE MATHEMATICAL MODEL DEVELOPMENT OF THE ETHYLBENZENE DEHYDROGENATION PROCESS KINETICS IN A TWO-STAGE ADIABATIC CONTINUOUS REACTOR

Directory of Open Access Journals (Sweden)

V. K. Bityukov

2015-01-01

Full Text Available The article is devoted to the mathematical modeling of the kinetics of ethyl benzene dehydrogenation in a two-stage adiabatic reactor with a catalytic bed functioning on continuous technology. The analysis of chemical reactions taking place parallel to the main reaction of styrene formation has been carried out on the basis of which a number of assumptions were made proceeding from which a kinetic scheme describing the mechanism of the chemical reactions during the dehydrogenation process was developed. A mathematical model of the dehydrogenation process, describing the dynamics of chemical reactions taking place in each of the two stages of the reactor block at a constant temperature is developed. The estimation of the rate constants of direct and reverse reactions of each component, formation and exhaustion of the reacted mixture was made. The dynamics of the starting material concentration variations (ethyl benzene batch was obtained as well as styrene formation dynamics and all byproducts of dehydrogenation (benzene, toluene, ethylene, carbon, hydrogen, ect.. The calculated the variations of the component composition of the reaction mixture during its passage through the first and second stages of the reactor showed that the proposed mathematical description adequately reproduces the kinetics of the process under investigation. This demonstrates the advantage of the developed model, as well as loyalty to the values found for the rate constants of reactions, which enable the use of models for calculating the kinetics of ethyl benzene dehydrogenation under nonisothermal mode in order to determine the optimal temperature trajectory of the reactor operation. In the future, it will reduce energy and resource consumption, increase the volume of produced styrene and improve the economic indexes of the process.

Understanding Acyl Chain and Glycerolipid Metabolism in Plants

Energy Technology Data Exchange (ETDEWEB)

Ohlrogge, John B.

2013-11-05

Progress is reported in these areas: acyl-editing in initial eukaryotic lipid assembly in soybean seeds; identification and characterization of two Arabidopsis thaliana lysophosphatidyl acyltransferases with preference for lysophosphatidylethanolamine; and characterization and subcellular distribution of lysolipid acyl transferase activity of pea leaves.

Microstructures and Dehydrogenation Properties of Ball-milled MgH2-K2Ti6O13-Ni Composite Systems

Directory of Open Access Journals (Sweden)

ZHANG Jian

2016-11-01

Full Text Available The K2Ti6O13 whisker separate-doped and K2Ti6O13 whisker and Ni powder multi-doped MgH2 hydrogen storage composite systems were prepared by mechanical milling method. The microstructures and dehydrogenation properties of the prepared samples were characterized by some testing methods such as X-ray diffraction (XRD, scanning electron microscope (SEM and differential scanning calorimeter (DSC. The results show that the K2Ti6O13 whisker not only plays the roles in refining the MgH2 crystalline grain, but also inhibit the agglomeration of MgH2 particles in K2Ti6O13 whisker separate-doped system, which results in the decreased dehydrogenation temperature of MgH2 matrix. When the mass ratio of K2Ti6O13 to MgH2 is 3:7, the improvement effect on dehydrogenation properties of MgH2 is the most remarkable. As compared with pure ball-milled MgH2, the dehydrogenation temperature of MgH2 in K2Ti6O13 whisker separate-doped system is decreased by nearly 75℃. For K2Ti6O13 whisker and Ni powder multi-dopedsystem, the dehydrogenation temperature of MgH2 matrix is further decreased compared to K2Ti6O13 whisker separate-doped one due to the dual effects of refined MgH2 crystalline grain by K2Ti6O13 whisker and destabilized MgH2 lattice by Ni solution. As compared with pure ball-milled MgH2, the dehydrogenation temperature of MgH2 in K2Ti6O13 whisker and Ni powder multi-doped system is decreased by nearly 87℃.

Dehydrogenation of Light Alkanes over Supported Pt Catalysts

OpenAIRE

Wu, Jason

2015-01-01

The production of light alkenes comprises a 250 million ton per year industry due to their extensive use in the production of plastics, rubbers, fuel blending agents, and chemical intermediates. While steam cracking and fluid catalytic cracking of petroleum crude oils are the most common methods for obtaining light alkenes, rising oil prices and low selectivities toward specific alkenes have driven the search for a more economical and efficient process. Catalytic dehydrogenation of light alka...

A comparative DFT study on the dehydrogenation of methanol on Rh(100) and Rh(110)

Science.gov (United States)

Zhang, Minhua; Wu, Xingyu; Yu, Yingzhe

2018-04-01

Numerous density functional theory calculations have been performed to investigate the complete mechanisms of methanol dehydrogenation on Rh(100) and Rh(110) surfaces. The adsorption properties of relevant species were discussed in details. In addition, a comprehensive reaction network including four reaction pathways was built and analyzed. It is found that the initial Osbnd H bond scission of CH3OH seems to be more favorable than Csbnd H bond cleavage on both Rh(100) and Rh(110) surfaces from the perspective of activation barriers. It is also concluded that path1 (CH3OH → CH3O → CH2O → CHO → CO) is the predominant pathway on both Rh(100) and Rh (110) surfaces. On the whole, in most of the dehydrogenation reactions investigated, the energy barriers on Rh(100) are lower than those on Rh (110). Remarkable differences in the activity and predominant reaction pathway on Rh(100), Rh(110) and Rh(111) indicate that the dehydrogenation of methanol might be structure-sensitive.

Production of high-octane, unleaded motor fuel by alkylation of isobutane with isoamylenes obtained by dehydrogenation of isopentane

Energy Technology Data Exchange (ETDEWEB)

Hutson, T. Jr.; Hann, P.D.

1981-01-31

A process combination, with inter-cooperation, for producing high-octane alkylates comprising (a) dehydrogenating isopentane to isopentenes (amylenes), (b) introducing the mixture of said amylenes and unconverted isopentane into an HF alkylation unit for reaction with fresh or recycled isobutane, (c) separating the alkylation products into high octane alkylates, isopentane (for recycling to the dehydrogenation reactor) and isobutane (for recycling to the alkylation reactor).

Impaired rate of microsomal fatty acid elongation in undernourished neonatal rat brain

International Nuclear Information System (INIS)

Yeh, Y.Y.

1986-01-01

Hypomyelination caused by undernourishment in characterized by low concentrations of myelin lipids and marked reduction in lignocerate (C/sub 24:0/) and nervonate (C/sub 24:1/) moiety of cerebroside and sulfatide. Since microsomal elongation is the major source of long chain (22 to 24 carbons) fatty acids in the brain, the effect of neonatal undernourishment on acyl elongation was investigated. Undernourishment of suckling rats were induced after birth by restricting maternal dietary intake to 40% of that consumed by dams fed ad libitum. Neonates suckled by the normally fed dams served as controls. Microsomal elongation was measured as nmol from [2- 14 C] malonyl CoA incorporated/h per mg of protein. At 19 days of age, rates of behenoyl CoA (C/sub 22:0/) and erucoyl CoA (C/sub 22:1/) elongation in whole brain of undernourished neonates were 30-40% lower than that of the control, whereas the elongation rates of acyl CoA 16, 18 and 20 carbons in length either saturated or monounsaturated were similar in both groups. Undernourishment had no effect on cytoplasmic de novo fatty acid synthesis from acetyl CoA. If there are multiple elongation factors, the results indicate that the depressed activity of elongating enzyme(s) for C/sub 22:0/ and C/sub 22:1/ is an important contributing factor in lowering S/sub 24:0/ and C/sub 24:1/ content in cerebroside and sulfatide. This impairment may be a specific lesion leading to hypomyelination in undernourished rats

The influence of ball-milling time on the dehydrogenation properties of the NaAlH4-MgH2 composite

NARCIS (Netherlands)

Bendyna, J.K.; Dyjak, S.M.; Notten, P.H.L.

2015-01-01

The recently developed NaAlH4eMgH2 composite shows improved hydrogen-storage properties compared to MgH2 and NaAlH4. However, the dehydrogenation reaction rates are still too limited, hampering practical applications. Mechanical ball milling is broadly used to improve the dehydrogenation reaction

Rapid Hydrogen Shift Reactions in Acyl Peroxy Radicals

DEFF Research Database (Denmark)

Knap, Hasse Christian; Jørgensen, Solvejg

2017-01-01

-shift with X = 6, 7, 8, or 9) in the hydroperoxy acyl peroxy radicals, this H-shift is a reversible reaction and it scrambles between two peroxides, hydroperoxy acyl peroxy and peroxy peroxoic acid radicals. The forward reaction rate constants of the 1,X-OOH H-shift reactions are estimated to be above 103 s–1...... with transition state theory corrected with Eckart quantum tunnelling correction. The ratio between the forward and reverse reaction rate constant of the 1,X-OOH H-shift reactions is around ∼105. Therefore, the equilibrium is pushed toward the production of peroxy peroxoic acid radicals. These very fast 1,X-OOH H......We have used quantum mechanical chemical calculations (CCSD(T)-F12a/cc-pVDZ-F12//M06-2X/aug-cc-pVTZ) to investigate the hydrogen shift (H-shift) reactions in acyl peroxy and hydroperoxy acyl peroxy radicals. We have focused on the H-shift reactions from a hydroperoxy group (OOH) (1,X-OOH H...

Striving towards improved Friedel-Crafts acylation catalysts

International Nuclear Information System (INIS)

Scott, N.M.; Deacon, G.B.

1998-01-01

Full text: Lanthanum, ytterbium and scandium salts of trifluoromethanesulfonic acid have been shown to act as promising Lewis acid catalysts for the Friedel-Craft acylation reactions. In our study catalytic acylation of anisole by acetic anhydride in nitroethane was investigated. Yields were determined after extraction of para-methoxyacetophenone from the reaction mixture by G.L.C using the external standardisation method. Anhydrous lanthanoid tris-triflate salts [Ln(O 3 SCF 3 ) 3 , Ln La, Y, Nd, Eu and Yb] were initially investigated as catalysts. Ytterbium tris-triflate was found to be the most effective giving ∼90% of the acylation product. The hydrated lanthanide tris-nitrate salts [Ln(NO 3 ) 3 .nH 2 O, Ln = La, Nd, Eu and Yb] were also investigated using in situ dehydration with acetic anhydride. These were found to have low solubility in the reaction mixture and gave poor yields of para-methoxyacetophenone. The formation of side products was suggested by the low total recovery of anisole and para-methoxyacetophenone. The blocking of coordination sites of these catalysts by tetraglyme resulted in a 50% reduction in acylation activity compared with the simple salt. Addition of Li(O 3 SCF 3 ) to Ln(O 3 SCF 3 ) 3 catalysts (ratio of 4:1)had only a slight accelerating effect on the Friedel-Crafts acylation reaction and the yield was only marginally greater than that in the absence of the added salt. In contrast Li(ClO 4 ) dramatically decreased reaction times and improved the yield of para-methoxyace-tophenone, as recently reported

Oxidative dehydrogenation of ethane on rare-earth oxide-based catalysts

Energy Technology Data Exchange (ETDEWEB)

Buyevskaya, O.; Baerns, M. [Institut fuer Angewandte Chemie Berlin-Adlershof e.V., Berlin (Germany)

1998-12-31

Results on the oxidative dehydrogenation of ethane on rare-earth oxide (REO) based catalysts (Na-P-Sm-O, Sm-Sr(Ca)-O, La-Sr-O and Nd-Sr-O) are described. Oxygen adsorption was found to be a key factor which determines the activity of this type of catalysts. Continuous flow experiments in the presence of catalysts which reveal strong oxygen adsorption showed that the reaction mixture is ignited resulting in an enhanced heat generation at the reactor inlet. The heat produced by the oxidative reactions was sufficient under the conditions chosen for the endothermic thermal pyrolysis which takes place preferentially in the gas phase. Ignition of the reaction mixture is an important catalyst function. Contrary to non-catalytic oxidative dehydrogenation, reaction temperatures above 700 C could be achieved without significant external heat input. Ethylene yields of up to 34-45% (S=66-73%) were obtained on REO-based catalysts under non-isothermal conditions (T{sub max}=810-865 C) at contact times in the order of 30 to 40 ms. (orig.)

Cost-effectiveness analysis of universal newborn screening for medium chain acyl-CoA dehydrogenase deficiency in France.

Science.gov (United States)

Hamers, Françoise F; Rumeau-Pichon, Catherine

2012-06-08

Five diseases are currently screened on dried blood spots in France through the national newborn screening programme. Tandem mass spectrometry (MS/MS) is a technology that is increasingly used to screen newborns for an increasing number of hereditary metabolic diseases. Medium chain acyl-CoA dehydrogenase deficiency (MCADD) is among these diseases. We sought to evaluate the cost-effectiveness of introducing MCADD screening in France. We developed a decision model to evaluate, from a societal perspective and a lifetime horizon, the cost-effectiveness of expanding the French newborn screening programme to include MCADD. Published and, where available, routine data sources were used. Both costs and health consequences were discounted at an annual rate of 4%. The model was applied to a French birth cohort. One-way sensitivity analyses and worst-case scenario simulation were performed. We estimate that MCADD newborn screening in France would prevent each year five deaths and the occurrence of neurological sequelae in two children under 5 years, resulting in a gain of 128 life years or 138 quality-adjusted life years (QALY). The incremental cost per year is estimated at €2.5 million, down to €1 million if this expansion is combined with a replacement of the technology currently used for phenylketonuria screening by MS/MS. The resulting incremental cost-effectiveness ratio (ICER) is estimated at €7 580/QALY. Sensitivity analyses indicate that while the results are robust to variations in the parameters, the model is most sensitive to the cost of neurological sequelae, MCADD prevalence, screening effectiveness and screening test cost. The worst-case scenario suggests an ICER of €72 000/QALY gained. Although France has not defined any threshold for judging whether the implementation of a health intervention is an efficient allocation of public resources, we conclude that the expansion of the French newborn screening programme to MCADD would appear to be cost

Caveolar fatty acids and acylation of caveolin-1.

Directory of Open Access Journals (Sweden)

Qian Cai

Full Text Available Caveolae are cholesterol and sphingolipids rich subcellular domains on plasma membrane. Caveolae contain a variety of signaling proteins which provide platforms for signaling transduction. In addition to enriched with cholesterol and sphingolipids, caveolae also contain a variety of fatty acids. It has been well-established that acylation of protein plays a pivotal role in subcellular location including targeting to caveolae. However, the fatty acid compositions of caveolae and the type of acylation of caveolar proteins remain largely unknown. In this study, we investigated the fatty acids in caveolae and caveolin-1 bound fatty acids.Caveolae were isolated from Chinese hamster ovary (CHO cells. The caveolar fatty acids were extracted with Folch reagent, methyl esterificated with BF3, and analyzed by gas chromatograph-mass spectrometer (GC/MS. The caveolin-1 bound fatty acids were immunoprecipitated by anti-caveolin-1 IgG and analyzed with GC/MS.In contrast to the whole CHO cell lysate which contained a variety of fatty acids, caveolae mainly contained three types of fatty acids, 0.48 µg palmitic acid, 0.61 µg stearic acid and 0.83 µg oleic acid/caveolae preparation/5 × 10(7 cells. Unexpectedly, GC/MS analysis indicated that caveolin-1 was not acylated by myristic acid; instead, it was acylated by palmitic acid and stearic acid.Caveolae contained a special set of fatty acids, highly enriched with saturated fatty acids, and caveolin-1 was acylated by palmitic acid and stearic acid. The unique fatty acid compositions of caveolae and acylation of caveolin-1 may be important for caveolae formation and for maintaining the function of caveolae.

The hexanoyl-CoA precursor for cannabinoid biosynthesis is formed by an acyl-activating enzyme in Cannabis sativa trichomes.

Science.gov (United States)

Stout, Jake M; Boubakir, Zakia; Ambrose, Stephen J; Purves, Randy W; Page, Jonathan E

2012-08-01

The psychoactive and analgesic cannabinoids (e.g. Δ(9) -tetrahydrocannabinol (THC)) in Cannabis sativa are formed from the short-chain fatty acyl-coenzyme A (CoA) precursor hexanoyl-CoA. Cannabinoids are synthesized in glandular trichomes present mainly on female flowers. We quantified hexanoyl-CoA using LC-MS/MS and found levels of 15.5 pmol g(-1) fresh weight in female hemp flowers with lower amounts in leaves, stems and roots. This pattern parallels the accumulation of the end-product cannabinoid, cannabidiolic acid (CBDA). To search for the acyl-activating enzyme (AAE) that synthesizes hexanoyl-CoA from hexanoate, we analyzed the transcriptome of isolated glandular trichomes. We identified 11 unigenes that encoded putative AAEs including CsAAE1, which shows high transcript abundance in glandular trichomes. In vitro assays showed that recombinant CsAAE1 activates hexanoate and other short- and medium-chained fatty acids. This activity and the trichome-specific expression of CsAAE1 suggest that it is the hexanoyl-CoA synthetase that supplies the cannabinoid pathway. CsAAE3 encodes a peroxisomal enzyme that activates a variety of fatty acid substrates including hexanoate. Although phylogenetic analysis showed that CsAAE1 groups with peroxisomal AAEs, it lacked a peroxisome targeting sequence 1 (PTS1) and localized to the cytoplasm. We suggest that CsAAE1 may have been recruited to the cannabinoid pathway through the loss of its PTS1, thereby redirecting it to the cytoplasm. To probe the origin of hexanoate, we analyzed the trichome expressed sequence tag (EST) dataset for enzymes of fatty acid metabolism. The high abundance of transcripts that encode desaturases and a lipoxygenase suggests that hexanoate may be formed through a pathway that involves the oxygenation and breakdown of unsaturated fatty acids. © 2012 National Research Council of Canada. The Plant Journal © 2012 Blackwell Publishing Ltd.

Clear relationship between ETF/ETFDH genotype and phenotype in patients with multiple acyl-CoA dehydrogenation deficiency

DEFF Research Database (Denmark)

Olsen, Rikke K J; Andresen, Brage S; Christensen, Ernst

2003-01-01

activity, we have investigated the molecular genetic basis for disease development in nine patients representing the phenotypic spectrum of MADD. We report the genomic structures of the ETFA, ETFB, and ETFDH genes and the identification and characterization of seven novel and three previously reported...... disease-causing mutations. Our molecular genetic investigations of these nine patients are consistent with three clinical forms of MADD showing a clear relationship between the nature of the mutations and the severity of disease. Interestingly, our data suggest that homozygosity for two null mutations...... mutation identified in a patient with type III disease showed that the residual activity of the mutant enzyme could be rescued up to 59% of that of wild-type activity when ETFB-D128N-transformed E. coli cells were grown at low temperature. This indicates that the effect of the ETF/ETFDH genotype...

Adsorption and dehydrogenation of ammonia at the V{sub 2}O{sub 5}(010) surface: DFT cluster studies

Energy Technology Data Exchange (ETDEWEB)

Gruber, Mathis; Hermann, Klaus [Fritz-Haber-Institut der MPG, Berlin (Germany)

2008-07-01

Transition metal oxide catalysts are widely used for selective oxidation reactions. However, in many cases details of the catalytic reaction mechanisms are still under discussion. One prominent example is the ammoxidation of propylene to acrylonitrile at transition metal oxide surfaces (SOHIO process). This catalytic reaction includes, amongst other steps, the adsorption and dehydrogenation of NH{sub x}, x<4, at the catalyst surface. We have performed theoretical studies on these reaction steps where the catalyst is simulated by a finite section of the V{sub 2}O{sub 5}(010) surface. The calculations use density-functional theory combined with clusters modeling the surface and adsorbate system. Calculations for the clean V{sub 2}O{sub 5}(010) surface show that binding energies of the H atom are always significantly larger than of the NH{sub x} species. Further, the substrate is found to lower corresponding dehydrogenation energies compared with values for the gas phase reaction. However, the lowering is too small to make dehydrogenation likely to happen under ammoxidation reaction conditions. This suggests that surface defects such as oxygen vacancies become important for the reaction. Therefore, the role of oxygen vacancies for the dehydrogenation of NH{sub x} is discussed in detail.

Theoretical Study of Palladium Membrane Reactor Performance During Propane Dehydrogenation Using CFD Method

Directory of Open Access Journals (Sweden)

Kamran Ghasemzadeh

2017-04-01

Full Text Available This study presents a 2D-axisymmetric computational fluid dynamic (CFD model to investigate the performance Pd membrane reactor (MR during propane dehydrogenation process for hydrogen production. The proposed CFD model provided the local information of temperature and component concentration for the driving force analysis. After investigation of mesh independency of CFD model, the validation of CFD model results was carried out by other modeling data and a good agreement between CFD model results and theoretical data was achieved. Indeed, in the present model, a tubular reactor with length of 150 mm was considered, in which the Pt-Sn-K/Al2O3 as catalyst were filled in reaction zone. Hence, the effects of the important operating parameter (reaction temperature on the performances of membrane reactor (MR were studied in terms of propane conversion and hydrogen yield. The CFD results showed that the suggested MR system during propane dehydrogenation reaction presents higher performance with respect to once obtained in the conventional reactor (CR. In particular, by applying Pd membrane, was found that propane conversion can be increased from 41% to 49%. Moreover, the highest value of propane conversion (X = 91% was reached in case of Pd-Ag MR. It was also established that the feed flow rate of the MR is to be the one of the most important factors defining efficiency of the propane dehydrogenation process.

Synthesis of bis- and tris(indolylmethanes catalyzed by an inorganic nano-sized catalyst followed by dehydrogenation to hyperconjugated products

Directory of Open Access Journals (Sweden)

Khorshidi Alireza

2016-01-01

Full Text Available A set of bis- and tris(indolylmethanes were prepared and dehydrogenated to their hyperconjugated products in a one-pot fashion. Nano-sized-SO3H functionalized mesoporous KIT-6 coated on magnetite nanoparticles (Fe3O4@SiO2@KIT-6-OSO3H was used as an efficient catalyst in the first step of synthesis, and dehydrogenation was performed by using (NH42S2O8 after removal of the catalyst. The catalyst was fully characterized by Fourier transform infrared spectroscopy (FT-IR, transmission electron microscopy (TEM and X-ray powder diffraction (XRD, as well as nitrogen adsorption-desorption isotherms. The bis- and tris(indolylmethanes were studied by UV-Vis spectroscopy before and after dehydrogenation, and effect of the ambient parameters on their spectra was investigated. It was found that bis- and tris(indolylmethanes have no considerable absorption in the visible range and what makes them colorful is partial dehydrogenation due to exposure to air. Our catalyst as a new combination of known materials, showed superiority in terms of yield, time, and mild reaction conditions in comparison with previous reports.

Saccharomyces cerevisiae Atf1p is an alcohol acetyltransferase and a thioesterase in vitro.

Science.gov (United States)

Nancolas, Bethany; Bull, Ian D; Stenner, Richard; Dufour, Virginie; Curnow, Paul

2017-06-01

The alcohol-O-acyltransferases are bisubstrate enzymes that catalyse the transfer of acyl chains from an acyl-coenzyme A (CoA) donor to an acceptor alcohol. In the industrial yeast Saccharomyces cerevisiae this reaction produces acyl esters that are an important influence on the flavour of fermented beverages and foods. There is also a growing interest in using acyltransferases to produce bulk quantities of acyl esters in engineered microbial cell factories. However, the structure and function of the alcohol-O-acyltransferases remain only partly understood. Here, we recombinantly express, purify and characterize Atf1p, the major alcohol acetyltransferase from S. cerevisiae. We find that Atf1p is promiscuous with regard to the alcohol cosubstrate but that the acyltransfer activity is specific for acetyl-CoA. Additionally, we find that Atf1p is an efficient thioesterase in vitro with specificity towards medium-chain-length acyl-CoAs. Unexpectedly, we also find that mutating the supposed catalytic histidine (H191) within the conserved HXXXDG active site motif only moderately reduces the thioesterase activity of Atf1p. Our results imply a role for Atf1p in CoA homeostasis and suggest that engineering Atf1p to reduce the thioesterase activity could improve product yields of acetate esters from cellular factories. © 2017 The Authors. Yeast published by John Wiley & Sons, Ltd. © 2017 The Authors. Yeast published by John Wiley & Sons, Ltd.

Regioselective Acylation of Diols and Triols: The Cyanide Effect.

Science.gov (United States)

Peng, Peng; Linseis, Michael; Winter, Rainer F; Schmidt, Richard R

2016-05-11

Central topics of carbohydrate chemistry embrace structural modifications of carbohydrates and oligosaccharide synthesis. Both require regioselectively protected building blocks that are mainly available via indirect multistep procedures. Hence, direct protection methods targeting a specific hydroxy group are demanded. Dual hydrogen bonding will eventually differentiate between differently positioned hydroxy groups. As cyanide is capable of various kinds of hydrogen bonding and as it is a quite strong sterically nondemanding base, regioselective O-acylations should be possible at low temperatures even at sterically congested positions, thus permitting formation and also isolation of the kinetic product. Indeed, 1,2-cis-diols, having an equatorial and an axial hydroxy group, benzoyl cyanide or acetyl cyanide as an acylating agent, and DMAP as a catalyst yield at -78 °C the thermodynamically unfavorable axial O-acylation product; acyl migration is not observed under these conditions. This phenomenon was substantiated with 3,4-O-unproteced galacto- and fucopyranosides and 2,3-O-unprotected mannopyranosides. Even for 3,4,6-O-unprotected galactopyranosides as triols, axial 4-O-acylation is appreciably faster than O-acylation of the primary 6-hydroxy group. The importance of hydrogen bonding for this unusual regioselectivity could be confirmed by NMR studies and DFT calculations, which indicate favorable hydrogen bonding of cyanide to the most acidic axial hydroxy group supported by hydrogen bonding of the equatorial hydroxy group to the axial oxygen. Thus, the "cyanide effect" is due to dual hydrogen bonding of the axial hydroxy group which enhances the nucleophilicity of the respective oxygen atom, permitting an even faster reaction for diols than for mono-ols. In contrast, fluoride as a counterion favors dual hydrogen bonding to both hydroxy groups leading to equatorial O-acylation.

Heterogeneous catalytic oxidative dehydrogenation of ethylbenzene to styrene with carbon dioxide

Energy Technology Data Exchange (ETDEWEB)

Badstube, T.; Papp, H. [Leipzig Univ. (Germany). Inst. fuer Technische Chemie; Kustrowski, P.; Dziembaj, R. [Jagiellonian Univ., Crakow (Poland). Faculty of Chemistry

1998-12-31

Alkaline promoted active carbon supported iron catalysts are very active in the oxidative dehydrogenation of ethylbenzene to styrene in the presence of carbon dioxide. The best results were obtained at 550 C for a Li-promoted catalyst with a conversion of ethylbenzene of 75% and a selectivity towards styrene of nearly 95%. These results are better than those obtained with industrial catalysts which perform the dehydrogenation process with an excess of water. The main product of the dehydrogenation reaction with CO{sub 2} was styrene, but the following by-products were detected - benzene and toluene. The selectivity towards toluene was always higher than towards benzene. We observed also the formation of carbon monoxide and water, which were produced with a constant molar ratio of about 0.8. The weight of the catalysts increased up to 20% during the reaction due to deposition of carbon. Using a too large excess of CO{sub 2} (CO{sub 2}/EB>10) was harmful for the styrene yield. The most favorable molar ratio of CO{sub 2} to EB was 10:1. No correlation between the molar ratios of reactants and the amount of deposited coke on the surface of catalysts was observed. The highest catalytic activity showed iron loaded D-90 catalysts which were promoted with alkali metals in a molar ratio of 1:10. Iron, nickel and cobalt loaded carbonized PPAN, PC, inorganic supports like Al{sub 2}O{sub 3}, SiO{sub 2}/ZrO{sub 2} or TiO{sub 2} respectively and commercial iron catalysts applied for styrene production did not show comparable catalytic activity in similar conditions. (orig.)

ENHANCEMENT OF EQUILIBRIUMSHIFT IN DEHYDROGENATION REACTIONS USING A NOVEL MEMBRANE REACTOR; FINAL

International Nuclear Information System (INIS)

Shamsuddin Ilias, Ph.d., P.E.; Franklin G. King, D.Sc.

2001-01-01

With the advances in new inorganic materials and processing techniques, there has been renewed interest in exploiting the benefits of membranes in many industrial applications. Inorganic and composite membranes are being considered as potential candidates for use in membrane-reactor configuration for effectively increasing reaction rate, selectivity and yield of equilibrium limited reactions. To investigate the usefulness of a palladium-ceramic composite membrane in a membrane reactor-separator configuration, we investigated the dehydrogenation of cyclohexane by equilibrium shift. A two-dimensional pseudo-homogeneous reactor model was developed to study the dehydrogenation of cyclohexane by equilibrium shift in a tubular membrane reactor. Radial diffusion was considered to account for the concentration gradient in the radial direction due to permeation through the membrane. For a dehydrogenation reaction, the feed stream to the reaction side contained cyclohexane and argon, while the separation side used argon as the sweep gas. Equilibrium conversion for dehydrogenation of cyclohexane is 18.7%. The present study showed that 100% conversion could be achieved by equilibrium shift using Pd-ceramic membrane reactor. For a feed containing cyclohexane and argon of 1.64 x 10(sup -6) and 1.0 x 10(sup -3) mol/s, over 98% conversion could be readily achieved. The dehydrogenation of cyclohexane was also experimentally investigated in a palladium-ceramic membrane reactor. The Pd-ceramic membrane was fabricated by electroless deposition of palladium on ceramic substrate. The performance of Pd-ceramic membrane was compared with a commercially available hydrogen-selective ceramic membrane. From limited experimental data it was observed that by appropriate choice of feed flow rate and sweep gas rate, the conversion of cyclohexane to benzene and hydrogen can increased to 56% at atmospheric pressure and 200 C in a Pd-ceramic membrane reactor. In the commercial ceramic membrane

N-acyl phosphatidylethanolamines affect the lateral distribution of cholesterol in membranes

DEFF Research Database (Denmark)

Térová, B.; Slotte, J.P.; Petersen, G.

2005-01-01

-acyl-POPE) or N-acyl-dipalmitoyl-sn-glycero-3-phosphatidylethanolamine (N-acyl-DPPE), and how the molecules interacted with cholesterol. The gel ¿ liquid crystalline transition temperature of sonicated N-acyl phosphatidylethanolamine vesicles in water correlated positively with the number of palmitic acyl chains...... in the molecules. Based on diphenylhexatriene steady state anisotropy measurements, the presence of 33 mol% cholesterol in the membranes removed the phase transition from N-oleoyl-POPE bilayers, but failed to completely remove it from N-palmitoyl-DPPE and N-palmitoyl-POPE bilayers, suggesting rather weak...... interaction of cholesterol with the N-saturated NAPEs. The rate of cholesterol desorption from mixed monolayers containing N-palmitoyl-DPPE and cholesterol (1:1 molar ratio) was much higher compared to cholesterol/DPPE binary monolayers, suggesting a weak cholesterol interaction with N-palmitoyl-DPPE also...

Kinetic properties and inhibition of Trypanosoma cruzi 3-hydroxy-3-methylglutaryl CoA reductase

DEFF Research Database (Denmark)

Hurtado-Guerrrero, Ramón; Pena Diaz, Javier; Montalvetti, Andrea

2002-01-01

A detailed kinetic analysis of the recombinant soluble enzyme 3-hydroxy-3-methylglutaryl CoA reductase (HMGR) from Trypanosoma cruzi has been performed. The enzyme catalyzes the normal anabolic reaction and the reductant is NADPH. It also catalyzes the oxidation of mevalonate but at a lower propo...

2-methylbutyryl-CoA dehydrogenase deficiency associated with autism and mental retardation: a case report

DEFF Research Database (Denmark)

Kanavin, Øjvind; Woldseth, Berit; Jellum, Egil

2007-01-01

previously reported cases with SBCADD, both originating from Somalia and Eritrea, indicating that it is relatively prevalent in this population. Autism has not previously been described with mutations in this gene, thus expanding the clinical spectrum of SBCADD. PMID: 17883863 [PubMed - in process]......ABSTRACT: BACKGROUND: 2-methylbutyryl-CoA dehydrogenase deficiency or short/branched chain acyl-CoA dehydrogenase deficiency (SBCADD) is caused by a defect in the degradation pathway of the amino acid L-isoleucine. METHODS: We report a four-year-old mentally retarded Somali boy with autism...

Xenobiotic/medium chain fatty acid: CoA ligase - a critical review on its role in fatty acid metabolism and the detoxification of benzoic acid and aspirin.

Science.gov (United States)

van der Sluis, Rencia; Erasmus, Elardus

2016-10-01

Activation of fatty acids by the acyl-CoA synthetases (ACSs) is the vital first step in fatty acid metabolism. The enzymatic and physiological characterization of the human xenobiotic/medium chain fatty acid: CoA ligases (ACSMs) has been severely neglected even though xenobiotics, such as benzoate and salicylate, are detoxified through this pathway. This review will focus on the nomenclature and substrate specificity of the human ACSM ligases; the biochemical and enzymatic characterization of ACSM1 and ACSM2B; the high sequence homology of the ACSM2 genes (ACSM2A and ACSM2B) as well as what is currently known regarding disease association studies. Several discrepancies exist in the current literature that should be taken note of. For example, the single nucleotide polymorphisms (SNPs) reported to be associated with aspirin metabolism and multiple risk factors of metabolic syndrome are incorrect. Kinetic data on the substrate specificity of the human ACSM ligases are non-existent and currently no data exist on the influence of SNPs on the enzyme activity of these ligases. One of the biggest obstacles currently in the field is that glycine conjugation is continuously studied as a one-step process, which means that key regulatory factors of the two individual steps remain unknown.

Imaging sequential dehydrogenation of methanol on Cu(110) with a scanning tunneling microscope.

Science.gov (United States)

Kitaguchi, Y; Shiotari, A; Okuyama, H; Hatta, S; Aruga, T

2011-05-07

Adsorption of methanol and its dehydrogenation on Cu(110) were studied by using a scanning tunneling microscope (STM). Upon adsorption at 12 K, methanol preferentially forms clusters on the surface. The STM could induce dehydrogenation of methanol sequentially to methoxy and formaldehyde. This enabled us to study the binding structures of these products in a single-molecule limit. Methoxy was imaged as a pair of protrusion and depression along the [001] direction. This feature is fully consistent with the previous result that it adsorbs on the short-bridge site with the C-O axis tilted along the [001] direction. The axis was induced to flip back and forth by vibrational excitations with the STM. Two configurations were observed for formaldehyde, whose structures were proposed based on their characteristic images and motions.

Oxidative dehydrogenation of aqueous ethanol on a carbon supported platinum catalyst

NARCIS (Netherlands)

Tillaart, van den J.A.A.; Kuster, B.F.M.; Marin, G.B.M.M.

1994-01-01

The kinetics of the selective oxidative dehydrogenation of ethanol to ethanal over a platinum on graphite catalyst with oxygen in water was investigated in a three-phase continuous stirred tank reactor by variation of temp., pH and reactant concns. No effect of the pH on the disappearance rate of

Oxidative dehydrogenation of ethylbenzene using nitrous oxide over vanadia-magnesia catalysts

NARCIS (Netherlands)

Shiju, N.R.; Anilkumar, M.; Gokhale, S.P.; Rao, B.S.; Satyanarayana, C.V.V.

2011-01-01

A series of V-Mg-O catalysts with different loadings of vanadia were prepared by the wet impregnation method and the effect of the local structure of these catalysts on the oxidative dehydrogenation of ethylbenzene with N2O was investigated. High styrene selectivity (97%) was obtained at 773 K. The

Dehydrogenation of Ethylbenzene with Carbon Dioxide as Soft Oxidant over Supported Vanadium-Antimony Oxide Catalyst

Energy Technology Data Exchange (ETDEWEB)

Hong, Do Young; Vislovskiy, Vladislav P.; Yoo, Jin S.; Chang, Jong San [Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); Park, Sang Eon [Inha University, Incheon (Korea, Republic of); Park, Min Seok [Mongolia International University, Ulaanbaatar (Mongolia)

2005-11-15

This work presents that carbon dioxide, which is a main contributor to the global warming effect, could be utilized as a selective oxidant in the oxidative dehydrogenation of ethylbenzene. The dehydrogenation of ethylbenzene over alumina-supported vanadium-antimony oxide catalyst has been studied under different atmospheres such as inert nitrogen, steam, oxygen or carbon dioxide as diluent or oxidant. Among them, the addition of carbon dioxide gave the highest styrene yield (up to 82%) and styrene selectivity (up to 97%) along with stable activity. Carbon dioxide could play a beneficial role of a selective oxidant in the improvement of the catalytic behavior through the oxidative pathway.

Non-Precious Bimetallic Catalysts for Selective Dehydrogenation of an Organic Chemical Hydride System

KAUST Repository

Shaikh Ali, Anaam; Jedidi, Abdesslem; Cavallo, Luigi; Takanabe, Kazuhiro

2015-01-01

Methylcyclohexane (MCH)-Toluene (TOL) chemical hydride cycles as a hydrogen carrier system is successful with the selective dehydrogenation reaction of MCH to TOL, which has been achieved only using precious Pt-based catalysts. Herein, we report

Central and peripheral des-acyl ghrelin regulates body temperature in rats.

Science.gov (United States)

Inoue, Yoshiyuki; Nakahara, Keiko; Maruyama, Keisuke; Suzuki, Yoshiharu; Hayashi, Yujiro; Kangawa, Kenji; Murakami, Noboru

2013-01-04

In the present study using rats, we demonstrated that central and peripheral administration of des-acyl ghrelin induced a decrease in the surface temperature of the back, and an increase in the surface temperature of the tail, although the effect of peripheral administration was less marked than that of central administration. Furthermore, these effects of centrally administered des-acyl ghrelin could not be prevented by pretreatment with [D-Lys3]-GHRP-6 GH secretagogue receptor 1a (GHS-R1a) antagonists. Moreover, these actions of des-acyl ghrelin on body temperature were inhibited by the parasympathetic nerve blocker methylscopolamine but not by the sympathetic nerve blocker timolol. Using immunohistochemistry, we confirmed that des-acyl ghrelin induced an increase of cFos expression in the median preoptic nucleus (MnPO). Additionally, we found that des-acyl ghrelin dilated the aorta and tail artery in vitro. These results indicate that centrally administered des-acyl ghrelin regulates body temperature via the parasympathetic nervous system by activating neurons in the MnPO through interactions with a specific receptor distinct from the GHS-R1a, and that peripherally administered des-acyl ghrelin acts on the central nervous system by passing through the blood-brain barrier, whereas it exerts a direct action on the peripheral vascular system. Copyright © 2012 Elsevier Inc. All rights reserved.

Reprogramming Acyl Carrier Protein Interactions of an Acyl-CoA Promiscuous trans-Acyltransferase

DEFF Research Database (Denmark)

Ye, Zhixia; Musiol-Kroll, Ewa Maria; Weber, Tilmann

2014-01-01

Protein interactions between acyl carrier proteins (ACPs) and trans-acting acyltransferase domains (trans-ATs) are critical for regioselective extender unit installation by many polyketide synthases, yet little is known regarding the specificity of these interactions, particularly for trans-ATs w...

Acyl-CoA binding protein and epidermal barrier function

DEFF Research Database (Denmark)

Bloksgaard, Maria; Neess, Ditte; Færgeman, Nils J

2014-01-01

The acyl-CoA binding protein (ACBP) is a 10kDa intracellular protein expressed in all eukaryotic species and mammalian tissues investigated. It binds acyl-CoA esters with high specificity and affinity and is thought to act as an intracellular transporter of acyl-CoA esters between different...... includes tousled and greasy fur, development of alopecia and scaling of the skin with age. Furthermore, epidermal barrier function is compromised causing a ~50% increase in transepidermal water loss relative to that of wild type mice. Lipidomic analyses indicate that this is due to significantly reduced...

Structural properties of pepsin-solubilized collagen acylated by lauroyl chloride along with succinic anhydride

International Nuclear Information System (INIS)

Li, Conghu; Tian, Zhenhua; Liu, Wentao; Li, Guoying

2015-01-01

The structural properties of pepsin-solubilized calf skin collagen acylated by lauroyl chloride along with succinic anhydride were investigated in this paper. Compared with native collagen, acylated collagen retained the unique triple helix conformation, as determined by amino acid analysis, circular dichroism and X-ray diffraction. Meanwhile, the thermostability of acylated collagen using thermogravimetric measurements was enhanced as the residual weight increased by 5%. With the temperature increased from 25 to 115 °C, the secondary structure of native and acylated collagens using Fourier transform infrared spectroscopy measurements was destroyed since the intensity of the major amide bands decreased and the positions of the major amide bands shifted to lower wavenumber, respectively. Meanwhile, two-dimensional correlation spectroscopy revealed that the most sensitive bands for acylated and native collagens were amide I and II bands, respectively. Additionally, the corresponding order of the groups between native and acylated collagens was different and the correlation degree for acylated collagen was weaker than that of native collagen, suggesting that temperature played a small influence on the conformation of acylated collagen, which might be concluded that the hydrophobic interaction improved the thermostability of collagen. - Highlights: • Acylated collagen retained the unique triple helix conformation. • Acylated collagen had stronger thermostability than native collagen. • Amide I was the most sensitive band to the temperature for acylated collagen. • Amide II was the most sensitive band to the temperature for native collagen. • Auto-peak at 1680 cm −1 for acylated collagen disappeared at higher temperature

Fatty acyl-CoA reductases of birds

Directory of Open Access Journals (Sweden)

Hellenbrand Janine

2011-12-01

Full Text Available Abstract Background Birds clean and lubricate their feathers with waxes that are produced in the uropygial gland, a holocrine gland located on their back above the tail. The type and the composition of the secreted wax esters are dependent on the bird species, for instance the wax ester secretion of goose contains branched-chain fatty acids and unbranched fatty alcohols, whereas that of barn owl contains fatty acids and alcohols both of which are branched. Alcohol-forming fatty acyl-CoA reductases (FAR catalyze the reduction of activated acyl groups to fatty alcohols that can be esterified with acyl-CoA thioesters forming wax esters. Results cDNA sequences encoding fatty acyl-CoA reductases were cloned from the uropygial glands of barn owl (Tyto alba, domestic chicken (Gallus gallus domesticus and domestic goose (Anser anser domesticus. Heterologous expression in Saccharomyces cerevisiae showed that they encode membrane associated enzymes which catalyze a NADPH dependent reduction of acyl-CoA thioesters to fatty alcohols. By feeding studies of transgenic yeast cultures and in vitro enzyme assays with membrane fractions of transgenic yeast cells two groups of isozymes with different properties were identified, termed FAR1 and FAR2. The FAR1 group mainly synthesized 1-hexadecanol and accepted substrates in the range between 14 and 18 carbon atoms, whereas the FAR2 group preferred stearoyl-CoA and accepted substrates between 16 and 20 carbon atoms. Expression studies with tissues of domestic chicken indicated that FAR transcripts were not restricted to the uropygial gland. Conclusion The data of our study suggest that the identified and characterized avian FAR isozymes, FAR1 and FAR2, can be involved in wax ester biosynthesis and in other pathways like ether lipid synthesis.

Fatty acyl-CoA reductases of birds

Science.gov (United States)

2011-01-01

Background Birds clean and lubricate their feathers with waxes that are produced in the uropygial gland, a holocrine gland located on their back above the tail. The type and the composition of the secreted wax esters are dependent on the bird species, for instance the wax ester secretion of goose contains branched-chain fatty acids and unbranched fatty alcohols, whereas that of barn owl contains fatty acids and alcohols both of which are branched. Alcohol-forming fatty acyl-CoA reductases (FAR) catalyze the reduction of activated acyl groups to fatty alcohols that can be esterified with acyl-CoA thioesters forming wax esters. Results cDNA sequences encoding fatty acyl-CoA reductases were cloned from the uropygial glands of barn owl (Tyto alba), domestic chicken (Gallus gallus domesticus) and domestic goose (Anser anser domesticus). Heterologous expression in Saccharomyces cerevisiae showed that they encode membrane associated enzymes which catalyze a NADPH dependent reduction of acyl-CoA thioesters to fatty alcohols. By feeding studies of transgenic yeast cultures and in vitro enzyme assays with membrane fractions of transgenic yeast cells two groups of isozymes with different properties were identified, termed FAR1 and FAR2. The FAR1 group mainly synthesized 1-hexadecanol and accepted substrates in the range between 14 and 18 carbon atoms, whereas the FAR2 group preferred stearoyl-CoA and accepted substrates between 16 and 20 carbon atoms. Expression studies with tissues of domestic chicken indicated that FAR transcripts were not restricted to the uropygial gland. Conclusion The data of our study suggest that the identified and characterized avian FAR isozymes, FAR1 and FAR2, can be involved in wax ester biosynthesis and in other pathways like ether lipid synthesis. PMID:22151413

Diacylglycerol Acyltransferase 1 Is Regulated by Its N-Terminal Domain in Response to Allosteric Effectors.

Science.gov (United States)

Caldo, Kristian Mark P; Acedo, Jeella Z; Panigrahi, Rashmi; Vederas, John C; Weselake, Randall J; Lemieux, M Joanne

2017-10-01

Diacylglycerol acyltransferase 1 (DGAT1) is an integral membrane enzyme catalyzing the final and committed step in the acyl-coenzyme A (CoA)-dependent biosynthesis of triacylglycerol (TAG). The biochemical regulation of TAG assembly remains one of the least understood areas of primary metabolism to date. Here, we report that the hydrophilic N-terminal domain of Brassica napus DGAT1 (BnaDGAT1 1-113 ) regulates activity based on acyl-CoA/CoA levels. The N-terminal domain is not necessary for acyltransferase activity and is composed of an intrinsically disordered region and a folded segment. We show that the disordered region has an autoinhibitory function and a dimerization interface, which appears to mediate positive cooperativity, whereas the folded segment of the cytosolic region was found to have an allosteric site for acyl-CoA/CoA. Under increasing acyl-CoA levels, the binding of acyl-CoA with this noncatalytic site facilitates homotropic allosteric activation. Enzyme activation, on the other hand, is prevented under limiting acyl-CoA conditions (low acyl-CoA-to-CoA ratio), whereby CoA acts as a noncompetitive feedback inhibitor through interaction with the same folded segment. The three-dimensional NMR solution structure of the allosteric site revealed an α-helix with a loop connecting a coil fragment. The conserved amino acid residues in the loop interacting with CoA were identified, revealing details of this important regulatory element for allosteric regulation. Based on these results, a model is proposed illustrating the role of the N-terminal domain of BnaDGAT1 as a positive and negative modulator of TAG biosynthesis. © 2017 American Society of Plant Biologists. All Rights Reserved.

Thermodynamics of ligand binding to acyl-coenzyme A binding protein studied by titration calorimetry

DEFF Research Database (Denmark)

Færgeman, Nils J.; Sigurskjold, B W; Kragelund, B B

1996-01-01

Ligand binding to recombinant bovine acyl-CoA binding protein (ACBP) was examined using isothermal microcalorimetry. Microcalorimetric measurements confirm that the binding affinity of acyl-CoA esters for ACBP is strongly dependent on the length of the acyl chain with a clear preference for acyl-...

Synergistic effect of Ti and F co-doping on dehydrogenation properties of MgH2 from first-principles calculations

International Nuclear Information System (INIS)

Zhang, J.; Huang, Y.N.; Mao, C.; Peng, P.

2012-01-01

Highlights: ► The co-incorporation of Ti and F into MgH 2 lattice is energetically favorable. ► The incorporated Ti and F in MgH 2 preferably generate TiH 2 and MgF 2 , respectively. ► The synergistic effect of Ti and F is superior to that of pure Ti. ► The weakened interactions of Mg–H explain enhanced dehydrogenation properties. - Abstract: The energetic and electronic properties of MgH 2 co-doped with Ti and F are investigated using first-principles calculations based on density functional theory. The calculation results show that incorporation of Ti combined with F atoms into MgH 2 lattice is energetically favorable relative to single incorporation of Ti atom. After dehydrogenation, the co-doped Ti and F in MgH 2 preferably generate TiH 2 and MgF 2 , respectively. Comparatively, the combined effect of Ti and F in improving the dehydrogenation properties of MgH 2 is superior to that of pure Ti. These results provide a reasonable explanation for experimental observations. Analysis of electronic structures suggests the enhanced dehydrogenation properties of doped MgH 2 can be attributed to the weakened bonding interactions between Mg and H due to foreign species doping.

Isolated Poly(3-Hydroxybutyrate) (PHB) Granules Are Complex Bacterial Organelles Catalyzing Formation of PHB from Acetyl Coenzyme A (CoA) and Degradation of PHB to Acetyl-CoA▿

OpenAIRE

Uchino, Keiichi; Saito, Terumi; Gebauer, Birgit; Jendrossek, Dieter

2007-01-01

Poly(3-hydroxybutyrate) (PHB) granules isolated in native form (nPHB granules) from Ralstonia eutropha catalyzed formation of PHB from 14C-labeled acetyl coenzyme A (CoA) in the presence of NADPH and concomitantly released CoA, revealing that PHB biosynthetic proteins (acetoacetyl-CoA thiolase, acetoacetyl-CoA reductase, and PHB synthase) are present and active in isolated nPHB granules in vitro. nPHB granules also catalyzed thiolytic cleavage of PHB in the presence of added CoA, resulting in...

Dehydrogenation of Isobutane with Carbon Dioxide over SBA-15-Supported Vanadium Oxide Catalysts

Directory of Open Access Journals (Sweden)

Chunling Wei

2016-10-01

Full Text Available A series of vanadia catalysts supported on SBA-15 (V/SBA with a vanadia (V content ranging from 1% to 11% were prepared by an incipient wetness method. Their catalytic behavior in the dehydrogenation of isobutane to isobutene with CO2 was examined. The catalysts were characterized by N2 adsorption, X-ray diffraction (XRD, scanning electron microscopy (SEM, Raman spectroscopy, and temperature-programmed reduction (TPR. It was found that these catalysts were effective for the dehydrogenation reaction, and the catalytic activity is correlated with the amount of dispersed vanadium species on the SBA-15 support. The 7% V/SBA catalyst shows the highest activity, which gives 40.8% isobutane conversion and 84.8% isobutene selectivity. The SBA-15-supported vanadia exhibits higher isobutane conversion and isobutene selectivity than the MCM-41-supported one.

Development of packed bed membrane reactor for the oxidative dehydrogenation of propane

NARCIS (Netherlands)

Kotanjac, Zeljko

2009-01-01

In this research, a reactor concept for the oxidative dehydrogenation of propane was studied. First a literature survey was performed, to investigate which are the best catalyst systems and best operating conditions that result in the largest propylene yield. In the kinetic study of ODHP over a

Lactic acid and hydrogen from glycerol via acceptorless dehydrogenation using homogeneous catalysts

NARCIS (Netherlands)

Bottari, Giovanni; Barta, Katalin

2015-01-01

Acceptorless dehydrogenation of alcohols has emerged as a powerful methodology for the valorization of biomass derived platform chemicals and building blocks. In this review we provide a short overview of the advantages and possible product outcomes of this method. The main focus will be devoted to

Oxidative activation of dihydropyridine amides to reactive acyl donors

DEFF Research Database (Denmark)

Funder, Erik Daa; Trads, Julie Brender; Gothelf, Kurt Vesterager

2015-01-01

Amides of 1,4-dihydropyridine (DHP) are activated by oxidation for acyl transfer to amines, alcohols and thiols. In the reduced form the DHP amide is stable towards reaction with amines at room temperature. However, upon oxidation with DDQ the acyl donor is activated via a proposed pyridinium...

Acyl carrier proteins from sunflower (Helianthus annuus L.) seeds and their influence on FatA and FatB acyl-ACP thioesterase activities.

Science.gov (United States)

Aznar-Moreno, Jose A; Venegas-Calerón, Mónica; Martínez-Force, Enrique; Garcés, Rafael; Salas, Joaquín J

2016-08-01

The kinetics of acyl-ACP thioesterases from sunflower importantly changed when endogenous ACPs were used. Sunflower FatB was much more specific towards saturated acyl-ACPs when assayed with them. Acyl carrier proteins (ACPs) are small (~9 kDa), soluble, acidic proteins involved in fatty acid synthesis in plants and bacteria. ACPs bind to fatty acids through a thioester bond, generating the acyl-ACP lipoproteins that are substrates for fatty acid synthase (FAS) complexes, and that are required for fatty acid chain elongation, acting as important intermediates in de novo fatty acid synthesis in plants. Plants, usually express several ACP isoforms with distinct functionalities. We report here the cloning of three ACPs from developing sunflower seeds: HaACP1, HaACP2, and HaACP3. These proteins were plastidial ACPs expressed strongly in seeds, and as such they are probably involved in the synthesis of sunflower oil. The recombinant sunflower ACPs were expressed in bacteria but they were lethal to the prokaryote host. Thus, they were finally produced using the GST gene fusion system, which allowed the apo-enzyme to be produced and later activated to the holo form. Radiolabelled acyl-ACPs from the newly cloned holo-ACP forms were also synthesized and used to characterize the activity of recombinant sunflower FatA and FatB thioesterases, important enzymes in plant fatty acids synthesis. The activity of these enzymes changed significantly when the endogenous ACPs were used. Thus, FatA importantly increased its activity levels, whereas FatB displayed a different specificity profile, with much high activity levels towards saturated acyl-CoA derivatives. All these data pointed to an important influence of the ACP moieties on the activity of enzymes involved in lipid synthesis.

Acyl Meldrum's acid derivatives: application in organic synthesis

Science.gov (United States)

Janikowska, K.; Rachoń, J.; Makowiec, S.

2014-07-01

This review is focused on an important class of Meldrum's acid derivatives commonly known as acyl Meldrum's acids. The preparation methods of these compounds are considered including the recently proposed and rather rarely used ones. The chemical properties of acyl Meldrum's acids are described in detail, including thermal stability and reactions with various nucleophiles. The possible mechanisms of these transformations are analyzed. The bibliography includes 134 references.

EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2014. Scientific Opinion on Dietary Reference Values for pantothenic acid

DEFF Research Database (Denmark)

Tetens, Inge

2014-01-01

Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies (NDA) derived Dietary Reference Values (DRVs) for pantothenic acid. Pantothenic acid is a water-soluble vitamin, which is a component of coenzyme A (CoA) and acyl-carrier proteins. Pantothenic...

Brown-Vialetto-Van Laere and Fazio Londe syndrome is associated with a riboflavin transporter defect mimicking mild MADD: a new inborn error of metabolism with potential treatment

NARCIS (Netherlands)

Bosch, A.M.; Abeling, N.G.G.M.; Ijlst, L.; Knoester, H.; van der Pol, W.L.; Stroomer, A.E.M.; Wanders, R.J.; Visser, G.; Wijburg, F.A.; Duran, M.; Waterham, H.R.

2011-01-01

We report on three patients (two siblings and one unrelated) presenting in infancy with progressive muscle weakness and paralysis of the diaphragm. Metabolic studies revealed a profile of plasma acylcarnitines and urine organic acids suggestive of a mild form of the multiple acyl-CoA dehydrogenation

Incorporation of catalytic dehydrogenation into fischer-tropsch synthesis to significantly reduce carbon dioxide emissions

Science.gov (United States)

Huffman, Gerald P.

2012-11-13

A new method of producing liquid transportation fuels from coal and other hydrocarbons that significantly reduces carbon dioxide emissions by combining Fischer-Tropsch synthesis with catalytic dehydrogenation is claimed. Catalytic dehydrogenation (CDH) of the gaseous products (C1-C4) of Fischer-Tropsch synthesis (FTS) can produce large quantities of hydrogen while converting the carbon to multi-walled carbon nanotubes (MWCNT). Incorporation of CDH into a FTS-CDH plant converting coal to liquid fuels can eliminate all or most of the CO.sub.2 emissions from the water-gas shift (WGS) reaction that is currently used to elevate the H.sub.2 level of coal-derived syngas for FTS. Additionally, the FTS-CDH process saves large amounts of water used by the WGS reaction and produces a valuable by-product, MWCNT.

Rivastigmine Improves Appetite by Increasing the Plasma Acyl/Des-Acyl Ghrelin Ratio and Cortisol in Alzheimer Disease

Directory of Open Access Journals (Sweden)

Yoshiko Furiya

2018-03-01

Full Text Available Background: Weight loss accelerates cognitive decline and increases mortality in patients with dementia. While acetylcholinesterase (AChE inhibitors are known to cause appetite loss, we sometimes encounter patients in whom switching from donepezil (AChE inhibitor to rivastigmine (AChE and butyrylcholinesterase [BuChE] inhibitor improves appetite. Since BuChE inactivates ghrelin, a potent orexigenic hormone, we speculated that rivastigmine improves appetite by inhibiting BuChE-mediated ghrelin inactivation. Methods: The subjects were patients with mild to moderate Alzheimer disease treated with either rivastigmine patch (n = 11 or donepezil (n = 11 for 6 months. Before and after treatment, we evaluated appetite (0, decreased; 1, slightly decreased; 2, normal; 3, slightly increased; 4, increased, cognitive function, and blood biochemical variables, including various hormones. Results: Rivastigmine treatment significantly improved appetite (from 1.6 ± 0.5 to 2.6 ± 0.7, whereas donepezil treatment did not (from 2.0 ± 0.0 to 1.8 ± 0.4. Simultaneously, rivastigmine, but not donepezil, significantly decreased the serum cholinesterase activity (from 304.3 ± 60.5 to 246.8 ± 78.5 IU/L and increased the cortisol level (from 11.86 ± 3.12 to 14.61 ± 3.29 μg/dL and the acyl/des-acyl ghrelin ratio (from 4.03 ± 2.96 to 5.28 ± 2.72. The levels of leptin, insulin, total ghrel­in, and cognitive function were not significantly affected by either treatment. Conclusions: Our results suggest that compared with donepezil, rivastigmine has the advantage of improving appetite by increasing the acyl/des-acyl ghrelin ratio and cortisol level, thereby preventing weight loss.

A Historical Cohort Study on the Efficacy of Glucocorticoids and Riboflavin Among Patients with Late-onset Multiple Acyl-CoA Dehydrogenase Deficiency

Institute of Scientific and Technical Information of China (English)

Xin-Yi Liu; Zhi-Qiang Wang; Dan-Ni Wang; Min-Ting Lin; Ning Wang

2016-01-01

Background:Late-onset multiple acyl-CoA dehydrogenase deficiency (MADD) is the most common type of lipid storage myopathies in China.Most patients with late-onset MADD are well responsive to riboflavin.Up to now,these patients are often treated with glucocorticoids as the first-line drug because they are misdiagnosed as polymyositis without muscle biopsy or gene analysis.Although glucocorticoids seem to improve the fatty acid metabolism of late-onset MADD,the objective evaluation of their rationalization on this disorder and comparison with riboflavin treatment are unknown.Methods:We performed a historical cohort study on the efficacy of the two drugs among 45 patients with late-onset MADD,who were divided into glucocorticoids group and riboflavin group.Detailed clinical information of baseline and 1-month follow-up were collected.Results:After 1-month treatment,a dramatic improvement of muscle strength was found in riboflavin group (P ＜ 0.05).There was no significant difference in muscle enzymes between the two groups.Significantly,the number of patients with full recovery in glucocorticoids group was less than the number in riboflavin group (P ＜ 0.05).On the other hand,almost half of the patients in riboflavin group still presented high-level muscle enzymes and weak muscle strength after 1-month riboflavin treatment,meaning that 1-month treatment duration maybe insufficient and patients should keep on riboflavin supplement for a longer time.Conclusions:Our results provide credible evidences that the overall efficacy of riboflavin is superior to glucocorticoids,and a longer duration of riboflavin treatment is necessary for patients with late-onset MADD.

Cost-effectiveness analysis of universal newborn screening for medium chain acyl-CoA dehydrogenase deficiency in France

Directory of Open Access Journals (Sweden)

Hamers Françoise F

2012-06-01

Full Text Available Abstract Background Five diseases are currently screened on dried blood spots in France through the national newborn screening programme. Tandem mass spectrometry (MS/MS is a technology that is increasingly used to screen newborns for an increasing number of hereditary metabolic diseases. Medium chain acyl-CoA dehydrogenase deficiency (MCADD is among these diseases. We sought to evaluate the cost-effectiveness of introducing MCADD screening in France. Methods We developed a decision model to evaluate, from a societal perspective and a lifetime horizon, the cost-effectiveness of expanding the French newborn screening programme to include MCADD. Published and, where available, routine data sources were used. Both costs and health consequences were discounted at an annual rate of 4%. The model was applied to a French birth cohort. One-way sensitivity analyses and worst-case scenario simulation were performed. Results We estimate that MCADD newborn screening in France would prevent each year five deaths and the occurrence of neurological sequelae in two children under 5 years, resulting in a gain of 128 life years or 138 quality-adjusted life years (QALY. The incremental cost per year is estimated at €2.5 million, down to €1 million if this expansion is combined with a replacement of the technology currently used for phenylketonuria screening by MS/MS. The resulting incremental cost-effectiveness ratio (ICER is estimated at €7 580/QALY. Sensitivity analyses indicate that while the results are robust to variations in the parameters, the model is most sensitive to the cost of neurological sequelae, MCADD prevalence, screening effectiveness and screening test cost. The worst-case scenario suggests an ICER of €72 000/QALY gained. Conclusions Although France has not defined any threshold for judging whether the implementation of a health intervention is an efficient allocation of public resources, we conclude that the expansion of the French

Low plasma lecithin : cholesterol acyltransferase and lipid transfer protein activities in growth hormone deficient and acromegalic men: role in altered high density lipoproteins

NARCIS (Netherlands)

Beentjes, JAM; van Tol, A; Sluiter, WJ; Dullaart, RPF

2000-01-01

Growth hormone (GH) deficiency and acromegaly may be associated with increased cardiovascular risk. Little is known about alterations in high density lipoproteins (HDL) in these conditions. Lecithin:cholesterol acyl transferase (LCAT) has the ability to esterify free cholesterol (FC) in HDL.

Synthesis and Evaluation of Nanostructured Gold-Iron Oxide Catalysts for the Oxidative Dehydrogenation of Cyclohexane

Science.gov (United States)

Wu, Peng

Shape-controlled iron oxide and gold-iron oxide catalysts with a cubic inverse spinel structure were studied in this thesis for the oxidative dehydrogenation of cyclohexane. The structure of iron oxide and gold-iron oxide catalysts has no major impact on their oxidative dehydrogenation activity. However, the product selectivity is influenced. Both cyclohexene and benzene are formed on bare iron oxide nanoshapes, while benzene is the only dehydrogenation product in the presence of gold. The selectivity of benzene over CO2 depends strongly on the stability of the iron oxide support and the gold-support interaction. The highest benzene yield has been observed on gold-iron oxide octahedra. {111}-bound nanooctahedra are highly stable in reaction conditions at 300 °C, while {100}-bound nanocubes start to sinter above 250 °C. The highest benzene yield has been observed on gold-iron oxide nanooctahedra, which are likely to have gold atoms, and few-atom gold clusters strongly-bound on their surface. Cationic gold appears to be the active site for benzene formation. An all-organic method to prepare Au-FeOx nano-catalysts is needed due to the inconvenience of the half-organic, half-inorganic synthesis process discussed above. Several methods from the literature to prepare gold-iron oxide nanocomposites completely in organic solvents were reviewed and followed. FeOx Au synthesis procedures in literatures are initially designed for a Au content of over 70%. This approach was tried here to prepare composites with a much lower Au content (2-5 atom. %). Heat treatment is required to bond Au and FeOx NPs in the organic-phase syntheses. Au-FeOx-4 was obtained as a selective catalyst for the ODH of cyclohexane. A Audelta+ peak is observed in the UV-Vis spectrum of sample Au-FeOx-4. This different Au delta+ form may be cationic Au nano-clusters interacting with the FeOx support. It has been demonstrated that cationic gold is responsible for dehydrogenation behavior. Furthermore, the

Evidence for marsh mallow (Malva parviflora) toxicosis causing myocardial disease and myopathy in four horses.

Science.gov (United States)

Bauquier, J; Stent, A; Gibney, J; Jerrett, I; White, J; Tennent-Brown, B; Pearce, A; Pitt, J

2017-05-01

long chain acyl CoA dehydrogenase deficiency. © 2016 EVJ Ltd.

Lipopolysaccharides with acylation defects potentiate TLR4 signaling and shape T cell responses.

Directory of Open Access Journals (Sweden)

Anna Martirosyan

Full Text Available Lipopolysaccharides or endotoxins are components of Gram-negative enterobacteria that cause septic shock in mammals. However, a LPS carrying hexa-acyl lipid A moieties is highly endotoxic compared to a tetra-acyl LPS and the latter has been considered as an antagonist of hexa-acyl LPS-mediated TLR4 signaling. We investigated the relationship between the structure and the function of bacterial LPS in the context of human and mouse dendritic cell activation. Strikingly, LPS with acylation defects were capable of triggering a strong and early TLR4-dependent DC activation, which in turn led to the activation of the proteasome machinery dampening the pro-inflammatory cytokine secretion. Upon activation with tetra-acyl LPS both mouse and human dendritic cells triggered CD4(+ T and CD8(+ T cell responses and, importantly, human myeloid dendritic cells favored the induction of regulatory T cells. Altogether, our data suggest that LPS acylation controlled by pathogenic bacteria might be an important strategy to subvert adaptive immunity.

1,5-Anhydro-D-fructose: regioselective acylation with fatty acids

DEFF Research Database (Denmark)

Lundt, Inge; Andersen, Søren Møller; Marcussen, Jan

1999-01-01

Regioselective acylation of 1,5-anhydro-D-fructose was performed with dodecanoic acid to give 1,5-anhydro-6-O-dodecanoyl-D-fructose, chemically in 50% yield and enzymatically in quantitative yield. Quantitative conversions were also obtained using hexadecanoic and octadecanoic acids as acyl donors...

Acyl transfer from membrane lipids to peptides is a generic process.

Science.gov (United States)

Dods, Robert H; Bechinger, Burkhard; Mosely, Jackie A; Sanderson, John M

2013-11-15

The generality of acyl transfer from phospholipids to membrane-active peptides has been probed using liquid chromatography-mass spectrometry analysis of peptide-lipid mixtures. The peptides examined include melittin, magainin II, PGLa, LAK1, LAK3 and penetratin. Peptides were added to liposomes with membrane lipid compositions ranging from pure phosphatidylcholine (PC) to mixtures of PC with phosphatidylethanolamine, phosphatidylserine or phosphatidylglycerol. Experiments were typically conducted at pH7.4 at modest salt concentrations (90 mM NaCl). In favorable cases, lipidated peptides were further characterized by tandem mass spectrometry methods to determine the sites of acylation. Melittin and magainin II were the most reactive peptides, with significant acyl transfer detected under all conditions and membrane compositions. Both peptides were lipidated at the N-terminus by transfer from PC, phosphatidylethanolamine, phosphatidylserine or phosphatidylglycerol, as well as at internal sites: lysine for melittin; serine and lysine for magainin II. Acyl transfer could be detected within 3h of melittin addition to negatively charged membranes. The other peptides were less reactive, but for each peptide, acylation was found to occur in at least one of the conditions examined. The data demonstrate that acyl transfer is a generic process for peptides bound to membranes composed of diacylglycerophospholipids. Phospholipid membranes cannot therefore be considered as chemically inert toward peptides and by extension proteins. © 2013. Published by Elsevier Ltd. All rights reserved.

Catalytic mechanism of the dehydrogenation of ethylbenzene over Fe–Co/Mg(Al)O derived from hydrotalcites

KAUST Repository

Tope, Balkrishna B.

2011-11-01

Catalytic mechanism of ethylbenzene dehydrogenation over Fe-Co/Mg(Al)O derived from hydrotalcites has been studied based on the XAFS and XPS catalyst characterization and the FTIR measurements of adsorbed species. Fe-Co/Mg(Al)O showed synergy, whereas Fe-Ni/Mg(Al)O showed no synergy, in the dehydrogenation of ethylbenzene. Ni species were stably incorporated as Ni2+ in the regular sites in periclase and spinel structure in the Fe-Ni/Mg(Al)O. Contrarily, Co species exists as a mixture of Co3+/Co2+ in the Fe-Co/Mg(Al)O and was partially isolated from the regular sites in the structures with increasing the Co content. Co addition enhanced Lewis acidity of Fe3+ active sites by forming Fe3+-O-Co 3+/2+(1/1) bond, resulting in an increase in the activity. FTIR of ethylbenzene adsorbed on the Fe-Co/Mg(Al)O clearly showed formations of C-O bond and π-adsorbed aromatic ring. This suggests that ethylbenzene was strongly adsorbed on the Fe3+ acid sites via π-bonding and the dehydrogenation was initiated by α-H+ abstraction from ethyl group on Mg2+-O2- basic sites, followed by C-O-Mg bond formation. The α-H+ abstraction by O2-(-Mg 2+) was likely followed by β-H abstraction, leading to the formations of styrene and H2. Such catalytic mechanism by the Fe 3+ acid-O2-(-Mg2+) base couple and the Fe 3+/Fe2+ reduction-oxidation cycle was further assisted by Co3+/Co2+, leading to a good catalytic activity for the dehydrogenation of ethylbenzene. © 2011 Elsevier B.V. All rights reserved.

De novo fatty acid biosynthesis and elongation in very long-chain acyl-CoA dehydrogenase-deficient mice supplemented with odd or even medium-chain fatty acids.

Science.gov (United States)

Tucci, Sara; Behringer, Sidney; Spiekerkoetter, Ute

2015-11-01

An even medium-chain triglyceride (MCT)-based diet is the mainstay of treatment in very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency (VLCADD). Previous studies with magnetic resonance spectroscopy have shown an impact of MCT on the average fatty acid chain length in abdominal fat. We therefore assume that medium-chain fatty acids (MCFAs) are elongated and accumulate in tissue as long-chain fatty acids. In this study, we explored the hepatic effects of long-term supplementation with MCT or triheptanoin, an odd-chain C7-based triglyceride, in wild-type and VLCAD-deficient (VLCAD(-/-) ) mice after 1 year of supplementation as compared with a control diet. The de novo biosynthesis and elongation of fatty acids, and peroxisomal β-oxidation, were quantified by RT-PCR. This was followed by a comprehensive analysis of hepatic and cardiac fatty acid profiles by GC-MS. Long-term application of even and odd MCFAs strongly induced de novo biosynthesis and elongation of fatty acids in both wild-type and VLCAD(-/-) mice, leading to an alteration of the hepatic fatty acid profiles. We detected de novo-synthesized and elongated fatty acids, such as heptadecenoic acid (C17:1n9), eicosanoic acid (C20:1n9), erucic acid (C22:1n9), and mead acid (C20:3n9), that were otherwise completely absent in mice under control conditions. In parallel, the content of monounsaturated fatty acids was massively increased. Furthermore, we observed strong upregulation of peroxisomal β-oxidation in VLCAD(-/-) mice, especially when they were fed an MCT diet. Our data raise the question of whether long-term MCFA supplementation represents the most efficient treatment in the long term. Studies on the hepatic toxicity of triheptanoin are still ongoing. © 2015 FEBS.

Acyl Chain Preference in Foam Cell Formation from Mouse Peritoneal Macrophages.

Science.gov (United States)

Fujiwara, Yuko; Hama, Kotaro; Tsukahara, Makoto; Izumi-Tsuzuki, Ryosuke; Nagai, Toru; Ohe-Yamada, Mihoko; Inoue, Keizo; Yokoyama, Kazuaki

2018-01-01

Macrophage foam cells play critical roles in the initiation and development of atherosclerosis by synthesizing and accumulating cholesteryl ester (CE) in lipid droplets. However, in analyzing lipid metabolism in foam cell formation, studies have focused on the sterol group, and little research has been done on the acyl chains. Therefore, we adapted a model system using liposomes containing particular acyl chains and examined the effect of various acyl chains on foam cell formation. Of the phosphatidylserine (PS) liposomes tested containing PS, phosphatidylcholine, and cholesterol, we found that unsaturated (C18:1), but not saturated (C16:0 and C18:0), PS liposomes induced lipid droplet formation, indicating that foam cell formation depends on the nature of the acyl chain of the PS liposomes. Experiments on the uptake and accumulation of cholesterol from liposomes by adding [ 14 C]cholesterol suggested that foam cell formation could be induced only when cholesterol was converted to CE in the case of C18:1 PS liposomes. Both microscopic observations and metabolic analysis suggest that cholesterol incorporated into either C16:0 or C18:0 PS liposomes may stay intact after being taken in by endosomes. The [ 14 C]C18:1 fatty acyl chain in the C18:1 PS liposome was used to synthesize CE and triacylglycerol (TG). Interestingly, the [ 14 C]C16:0 in the C18:1 PS liposome was metabolized to sphingomyelin rather than being incorporated into either CE or TG, which could be because of enzymatic acyl chain selectivity. In conclusion, our results indicate that the acyl chain preference of macrophages could have some impact on their progression to foam cells.

Green synthesis of Ni-Nb oxide catalysts for low-temperature oxidative dehydrogenation of ethane

KAUST Repository

Zhu, Haibo; Rosenfeld, Devon C.; Anjum, Dalaver H.; Caps, Valerie; Basset, Jean-Marie

2015-01-01

The straightforward solid-state grinding of a mixture of Ni nitrate and Nb oxalate crystals led to, after mild calcination (T<400°C), nanostructured Ni-Nb oxide composites. These new materials efficiently catalyzed the oxidative dehydrogenation (ODH

Study of the niobium dehydrogenation process by transmission electron microscopy

International Nuclear Information System (INIS)

Bulhoes, I.A.M.; Akune, K.

1983-01-01

The evolution of the micro-structure of Nb-H, during the dehydrogenation process through thermal treatment, has been studied by Transmission Electron Microscopy. The results are used in order to interpret the variation of the line resolution of Electron Channeling Pattern (ECP) of Nb-H as a function of isochronous annealing temperature. It is concluded that the improvement of the ECP line resolution is enhanced of β hydrate in Nb. (Author) [pt

Dehydrogenation of light alkanes over rhenium catalysts on conventional and mesoporous MFI supports

DEFF Research Database (Denmark)

Rovik, Anne Krogh; Hagen, Anke; Schmidt, I.

2006-01-01

Recently, Re/HZSM-5 (Si/Al = 15) was shown to be an efficient catalyst for ethane dehydrogenation and aromatization at 823 K and atmospheric pressure. In this reaction, the major initial products were benzene, toluene and xylene (BTX), but increasing amounts of ethene were produced with time...

Controlling reaction pathways for alcohol dehydration and dehydrogenation over FeSBA-15 catalysts

NARCIS (Netherlands)

Guan, Y.; Li, Y.; Santen, van R.A.; Hensen, E.J.M.; Li, Can

2007-01-01

The iron location in FeSBA-15 strongly influences the selectivity to dehydrogenation and dehydration in ethanol conversion. At low iron loading, Fe is present as isolated species in the amorphous silica phase. At higher loading additional aggregated forms of iron oxide exist. Isolated species in the

Fatty Acyl Chains of Mycobacterium marinum Lipooligosaccharides

Science.gov (United States)

Rombouts, Yoann; Alibaud, Laeticia; Carrère-Kremer, Séverine; Maes, Emmanuel; Tokarski, Caroline; Elass, Elisabeth; Kremer, Laurent; Guérardel, Yann

2011-01-01

We have recently established the fine structure of the glycan backbone of lipooligosaccharides (LOS-I to LOS-IV) isolated from Mycobacterium marinum, a close relative of Mycobacterium tuberculosis. These studies culminated with the description of an unusual terminal N-acylated monosaccharide that confers important biological functions to LOS-IV, such as macrophage activation, that may be relevant to granuloma formation. It was, however, also suggested that the lipid moiety was required for LOSs to exert their immunomodulatory activity. Herein, using highly purified LOSs from M. marinum, we have determined through a combination of mass spectrometric and NMR techniques, the structure and localization of the fatty acids composing the lipid moiety. The occurrence of two distinct polymethyl-branched fatty acids presenting specific localizations is consistent with the presence of two highly related polyketide synthases (Pks5 and Pks5.1) in M. marinum and presumably involved in the synthesis of these fatty acyl chains. In addition, a bioinformatic search permitted us to identify a set of enzymes potentially involved in the biosynthesis or transfer of these lipids to the LOS trehalose unit. These include MMAR_2343, a member of the Pap (polyketide-associated protein) family, that acylates trehalose-based glycolipids in M. marinum. The participation of MMAR_2343 to LOS assembly was demonstrated using a M. marinum mutant carrying a transposon insertion in the MMAR_2343 gene. Disruption of MMAR_2343 resulted in a severe LOS breakdown, indicating that MMAR_2343, hereafter designated PapA4, fulfills the requirements for LOS acylation and assembly. PMID:21803773

Role of lecithin-cholesterol acyltransferase in the metabolism of oxidized phospholipids in plasma: studies with platelet-activating factor-acetyl hydrolase-deficient plasma.

Science.gov (United States)

Subramanian, V S; Goyal, J; Miwa, M; Sugatami, J; Akiyama, M; Liu, M; Subbaiah, P V

1999-07-09

To determine the relative importance of platelet-activating factor-acetylhydrolase (PAF-AH) and lecithin-cholesterol acyltransferase (LCAT) in the hydrolysis of oxidized phosphatidylcholines (OXPCs) to lyso-phosphatidylcholine (lyso-PC), we studied the formation and metabolism of OXPCs in the plasma of normal and PAF-AH-deficient subjects. Whereas the loss of PC following oxidation was similar in the deficient and normal plasmas, the formation of lyso-PC was significantly lower, and the accumulation of OXPC was higher in the deficient plasma. Isolated LDL from the PAF-AH-deficient subjects was more susceptible to oxidation, and stimulated adhesion molecule synthesis in endothelial cells, more than the normal LDL. Oxidation of 16:0-[1-14C]-18:2 PC, equilibrated with plasma PC, resulted in the accumulation of labeled short- and long-chain OXPCs, in addition to the labeled aqueous products. The formation of the aqueous products decreased by 80%, and the accumulation of short-chain OXPC increased by 110% in the deficient plasma, compared to the normal plasma, showing that PAF-AH is predominantly involved in the hydrolysis of the truncated OXPCs. Labeled sn-2-acyl group from the long-chain OXPC was not only hydrolyzed to free fatty acid, but was preferentially transferred to diacylglycerol, in both the normal and deficient plasmas. In contrast, the acyl group from unoxidized PC was transferred only to cholesterol, showing that the specificity of LCAT is altered by OXPC. It is concluded that, while PAF-AH carries out the hydrolysis of mainly truncated OXPCs, LCAT hydrolyzes and transesterifies the long-chain OXPCs.

Effects of Al{sub 2}O{sub 3} phase and Cl component on dehydrogenation of propane

Energy Technology Data Exchange (ETDEWEB)

Liu, Jie; Liu, Changcheng; Ma, Aizeng; Rong, Junfeng; Da, Zhijian, E-mail: dazhijianripp@163.com; Zheng, Aiguo; Qin, Ling

2016-04-15

Graphical abstract: - Highlights: • Comparative study of Al{sub 2}O{sub 3} phase on dehydrogenation of propane was implemented. • Pore structures and acid properties of Pt-Al{sub 2}O{sub 3} are correlated to the activities. • Pt-θ-Al{sub 2}O{sub 3} with abundant Cl content shows the highest activity and stability. - Abstract: The effects of two Al{sub 2}O{sub 3} phases, γ- and θ-Al{sub 2}O{sub 3}, and Cl component on the performances of Pt-Al{sub 2}O{sub 3} catalysts in the dehydrogenation of propane were investigated in this work. The catalysts were systematically characterized by various techniques, such as scanning transmission electron microscopy (STEM), temperature-programmed desorption with ammonia as probe molecules (NH{sub 3}-TPD) and temperature-programmed oxidation (TPO). The characterizations and catalytic results show that: (i) the pore structures and acid properties of the two Al{sub 2}O{sub 3} phases can change the quantity, location and property of the carbon deposition, (ii) the existence of Cl plays a significant role on the agglomeration of Pt particles and carbon deposition, which further influence the catalytic performances of Pt-Al{sub 2}O{sub 3} catalysts with different support phases for propane dehydrogenation.

The R117A variant of the Escherichia coli transacylase FabD synthesizes novel acyl-(acyl carrier proteins).

Science.gov (United States)

Marcella, Aaron M; Barb, Adam W

2017-12-01

The commercial impact of fermentation systems producing novel and biorenewable chemicals will flourish with the expansion of enzymes engineered to synthesize new molecules. Though a small degree of natural variability exists in fatty acid biosynthesis, the molecular space accessible through enzyme engineering is fundamentally limitless. Prokaryotic fatty acid biosynthesis enzymes build carbon chains on a functionalized acyl carrier protein (ACP) that provides solubility, stability, and a scaffold for interactions with the synthetic enzymes. Here, we identify the malonyl-coenzyme A (CoA)/holo-ACP transacylase (FabD) from Escherichia coli as a platform enzyme for engineering to diversify microbial fatty acid biosynthesis. The FabD R117A variant produced novel ACP-based primer and extender units for fatty acid biosynthesis. Unlike the wild-type enzyme that is highly specific for malonyl-CoA to produce malonyl-ACP, the R117A variant synthesized acetyl-ACP, succinyl-ACP, isobutyryl-ACP, 2-butenoyl-ACP, and β-hydroxybutyryl-ACP among others from holo-ACP and the corresponding acyl-CoAs with specific activities from 3.7 to 120 nmol min -1  mg -1 . FabD R117A maintained K M values for holo-ACP (~ 40 μM) and displayed small changes in K M for acetoacetyl-CoA (110 ± 30 μM) and acetyl-CoA (200 ± 70 μM) when compared to malonyl-CoA (80 ± 30 μM). FabD R117A represents a novel catalyst that synthesizes a broad range of acyl-acyl-ACPs.

Isolated 2-methylbutyrylglycinuria caused by short/branched-chain acyl-CoA dehydrogenase deficiency: identification of a new enzyme defect, resolution of its molecular basis, and evidence for distinct acyl-CoA dehydrogenases in isoleucine and valine metabolism

NARCIS (Netherlands)

Andresen, B. S.; Christensen, E.; Corydon, T. J.; Bross, P.; Pilgaard, B.; Wanders, R. J.; Ruiter, J. P.; Simonsen, H.; Winter, V.; Knudsen, I.; Schroeder, L. D.; Gregersen, N.; Skovby, F.

2000-01-01

Acyl-CoA dehydrogenase (ACAD) defects in isoleucine and valine catabolism have been proposed in clinically diverse patients with an abnormal pattern of metabolites in their urine, but they have not been proved enzymatically or genetically, and it is unknown whether one or two ACADs are involved. We

Engineered Production of Short-Chain Acyl-Coenzyme A Esters in Saccharomyces cerevisiae

DEFF Research Database (Denmark)

Krink-Koutsoubelis, Nicolas; Loechner, Anne C.; Lechner, Anna

2018-01-01

Short-chain acyl-coenzyme A esters serve as intermediate compounds in fatty acid biosynthesis, and the production of polyketides, biopolymers and other value-added chemicals. S. cerevisiae is a model organism that has been utilized for the biosynthesis of such biologically and economically valuable...... compounds. However, its limited repertoire of short-chain acyl-CoAs effectively prevents its application as a production host for a plethora of natural products. Therefore, we introduced biosynthetic metabolic pathways to five different acyl-CoA esters into S. cerevisiae. Our engineered strains provide......-CoA at 0.5 μM; and isovaleryl-CoA, n-butyryl-CoA, and n-hexanoyl-CoA at 6 μM each. The acyl-CoAs produced in this study are common building blocks of secondary metabolites and will enable the engineered production of a variety of natural products in S. cerevisiae. By providing this toolbox of acyl...

Mutations in COA3 cause isolated complex IV deficiency associated with neuropathy, exercise intolerance, obesity, and short stature

DEFF Research Database (Denmark)

Ostergaard, Elsebet; Weraarpachai, Woranontee; Ravn, Kirstine Johanne Theresia

2015-01-01

BACKGROUND: We investigated a subject with an isolated cytochrome c oxidase (COX) deficiency presenting with an unusual phenotype characterised by neuropathy, exercise intolerance, obesity, and short stature. METHODS AND RESULTS: Blue-native polyacrylamide gel electrophoresis (BN-PAGE) analysis s...

Purification of specific structured lipids by distillation: Effects on acyl migration

DEFF Research Database (Denmark)

Xu, Xuebing; Skands, A.; Adler-Nissen, Jens

2001-01-01

The cause and effects of acyl migration during the purification of specific structured lipids by distillation were studied in a conventional batch deodorizer with stripping steam. The mixture of specific structured lipids produced by lipase-catalyzed acidolysis between rapeseed oil and capric acid...... influenced the rate of acyl migration, and their combinations made the effect more severe. However, diacylglycerols were found to be the main reason for acyl migration. In the distillation of the specific structured lipid product mixture, distillation temperature and time were the main factors to determine...... the degree of acyl migration and the extent of separation of free fatty acids. The results indicate that more efficient separation technology should be used to improve the quality of the purified structured lipids. in order to reduce the distillation temperature, vacuum should be made as low as possible...

Metabolism of 1-acyl-2-acetyl-sn-glycero-3-phosphocholine in the human neutrophil

International Nuclear Information System (INIS)

Triggiani, M.; D'Souza, D.M.; Chilton, F.H.

1991-01-01

The biosynthesis of 1-acyl-2-acetyl-sn-glycero-3-phosphocholine (1-acyl-2-acetyl-GPC) together with that of 1-alkyl-2-acetyl-GPC (platelet-activating factor) has been demonstrated in a variety of inflammatory cells and tissues. It has been hypothesized that the relative proportion of these phospholipids produced upon cell activation may be influenced by their rates of catabolism. We studied the catabolism of 1-acyl-2-acetyl-GPC in resting and activated human neutrophils and compared it to that of 1-alkyl-2-acetyl-GPC. Neutrophils rapidly catabolize both 1-alkyl-2-acetyl-GPC and 1-acyl-2-acetyl-GPC; however, the rate of catabolism of 1-acyl-2-acetyl-GPC is approximately 2-fold higher than that of 1-alkyl-2-acetyl-GPC. In addition, most of 1-acyl-2-acetyl-GPC is catabolized through a pathway different from that of 1-alkyl-2-acetyl-GPC. The main step in the catabolism of 1-acyl-2-acetyl-GPC is the removal of the long chain at the sn-1 position; the long chain residue is subsequently incorporated either into triglycerides or into phosphatidylcholine. The 1-lyso-2-acetyl-GPC formed in this reaction is then further degraded to glycerophosphocholine, choline, or phosphocholine. 1-Acyl-2-acetyl-GPC is also catabolized, to a lesser extent, through deacetylation at the sn-2 position and reacylation with a long chain fatty acid. Stimulation of neutrophils by A23187 results in a higher rate of catabolism of 1-acyl-2-acetyl-GPC by increasing both the removal of the long chain at the sn-1 position and the deacetylation-reacylation at the sn-2 position. In a broken cell preparation, the cytosolic fraction of the neutrophil was shown to contain an enzyme activity which cleaved the sn-1 position of 1-acyl-2-acetyl-GPC and 1-acyl-2-lyso-GPC but not of 1,2-diacyl-GPC

Both acyl and des-acyl ghrelin regulate adiposity and glucose metabolism via central nervous system ghrelin receptors.

Science.gov (United States)

Heppner, Kristy M; Piechowski, Carolin L; Müller, Anne; Ottaway, Nickki; Sisley, Stephanie; Smiley, David L; Habegger, Kirk M; Pfluger, Paul T; Dimarchi, Richard; Biebermann, Heike; Tschöp, Matthias H; Sandoval, Darleen A; Perez-Tilve, Diego

2014-01-01

Growth hormone secretagogue receptors (GHSRs) in the central nervous system (CNS) mediate hyperphagia and adiposity induced by acyl ghrelin (AG). Evidence suggests that des-AG (dAG) has biological activity through GHSR-independent mechanisms. We combined in vitro and in vivo approaches to test possible GHSR-mediated biological activity of dAG. Both AG (100 nmol/L) and dAG (100 nmol/L) significantly increased inositol triphosphate formation in human embryonic kidney-293 cells transfected with human GHSR. As expected, intracerebroventricular infusion of AG in mice increased fat mass (FM), in comparison with the saline-infused controls. Intracerebroventricular dAG also increased FM at the highest dose tested (5 nmol/day). Chronic intracerebroventricular infusion of AG or dAG increased glucose-stimulated insulin secretion (GSIS). Subcutaneously infused AG regulated FM and GSIS in comparison with saline-infused control mice, whereas dAG failed to regulate these parameters even with doses that were efficacious when delivered intracerebroventricularly. Furthermore, intracerebroventricular dAG failed to regulate FM and induce hyperinsulinemia in GHSR-deficient (Ghsr(-/-)) mice. In addition, a hyperinsulinemic-euglycemic clamp suggests that intracerebroventricular dAG impairs glucose clearance without affecting endogenous glucose production. Together, these data demonstrate that dAG is an agonist of GHSR and regulates body adiposity and peripheral glucose metabolism through a CNS GHSR-dependent mechanism.

Copper(II)/amine synergistically catalyzed enantioselective alkylation of cyclic N-acyl hemiaminals with aldehydes.

Science.gov (United States)

Sun, Shutao; Mao, Ying; Lou, Hongxiang; Liu, Lei

2015-07-07

The first catalytic asymmetric alkylation of N-acyl quinoliniums with aldehydes has been described. A copper/amine synergistic catalytic system has been developed, allowing the addition of functionalized aldehydes to a wide range of electronically varied N-acyl quinoliniums in good yields with excellent enantiocontrol. The synergistic catalytic system was also effective for N-acyl dihydroisoquinoliniums and β-caboliniums, demonstrating the general applicability of the protocol in the enantioselective alkylation of diverse cyclic N-acyl hemiaminals.

Thioesterase activity and acyl-CoA/fatty acid cross-talk of hepatocyte nuclear factor-4{alpha}.

Science.gov (United States)

Hertz, Rachel; Kalderon, Bella; Byk, Tamara; Berman, Ina; Za'tara, Ghadeer; Mayer, Raphael; Bar-Tana, Jacob

2005-07-01

Hepatocyte nuclear factor-4alpha (HNF-4alpha) activity is modulated by natural and xenobiotic fatty acid and fatty acyl-CoA ligands as a function of their chain length, unsaturation, and substitutions. The acyl-CoA site of HNF-4alpha is reported here to consist of the E-F domain, to bind long-chain acyl-CoAs but not the respective free acids, and to catalyze the hydrolysis of bound fatty acyl-CoAs. The free acid pocket, previously reported in the x-ray structure of HNF-4alpha E-domain, entraps fatty acids but excludes acyl-CoAs. The acyl-CoA and free acid sites are distinctive and noncongruent. Free fatty acid products of HNF-4alpha thioesterase may exchange with free acids entrapped in the fatty acid pocket of HNF-4alpha. Cross-talk between the acyl-CoA and free fatty acid binding sites is abrogated by high affinity, nonhydrolyzable acyl-CoA ligands of HNF-4alpha that inhibit its thioesterase activity. Hence, HNF-4alpha transcriptional activity is controlled by its two interrelated acyl ligands and two binding sites interphased in tandem by the thioesterase activity. The acyl-CoA/free-acid and receptor/enzyme duality of HNF-4alpha extends the paradigm of nuclear receptors.

Characterization of Lipid A Variants by Energy-Resolved Mass Spectrometry: Impact of Acyl Chains

Science.gov (United States)

Crittenden, Christopher M.; Akin, Lucas D.; Morrison, Lindsay J.; Trent, M. Stephen; Brodbelt, Jennifer S.

2017-06-01

Lipid A molecules consist of a diglucosamine sugar core with a number of appended acyl chains that vary in their length and connectivity. Because of the challenging nature of characterizing these molecules and differentiating between isomeric species, an energy-resolved MS/MS strategy was undertaken to track the fragmentation trends and map genealogies of product ions originating from consecutive cleavages of acyl chains. Generalizations were developed based on the number and locations of the primary and secondary acyl chains as well as variations in preferential cleavages arising from the location of the phosphate groups. Secondary acyl chain cleavage occurs most readily for lipid A species at the 3' position, followed by primary acyl chain fragmentation at both the 3' and 3 positions. In the instances of bisphosphorylated lipid A variants, phosphate loss occurs readily in conjunction with the most favorable primary and secondary acyl chain cleavages. [Figure not available: see fulltext.

Size and Site Dependence of the Catalytic Activity of Iridium Clusters toward Ethane Dehydrogenation.

Science.gov (United States)

Ge, Yingbin; Jiang, Hao; Kato, Russell; Gummagatta, Prasuna

2016-12-01

This research focuses on optimizing transition metal nanocatalyst immobilization and activity to enhance ethane dehydrogenation. Ethane dehydrogenation, catalyzed by thermally stable Ir n (n = 8, 12, 18) atomic clusters that exhibit a cuboid structure, was studied using the B3LYP method with triple-ζ basis sets. Relativistic effects and dispersion corrections were included in the calculations. In the dehydrogenation reaction Ir n + C 2 H 6 → H-Ir n -C 2 H 5 → (H) 2 -Ir n -C 2 H 4 , the first H-elimination is the rate-limiting step, primarily because the reaction releases sufficient heat to facilitate the second H-elimination. The catalytic activity of the Ir clusters strongly depends on the Ir cluster size and the specific catalytic site. Cubic Ir 8 is the least reactive toward H-elimination in ethane: Ir 8 + C 2 H 6 → H-Ir 8 -C 2 H 5 has a large (65 kJ/mol) energy barrier, whereas Ir 12 (3 × 2 × 2 cuboid) and Ir 18 (3 × 3 × 2 cuboid) lower this energy barrier to 22 and 3 kJ/mol, respectively. The site dependence is as prominent as the size effect. For example, the energy barrier for the Ir 18 + C 2 H 6 → H-Ir 18 -C 2 H 5 reaction is 3, 48, and 71 kJ/mol at the corner, edge, or face-center sites of the Ir 18 cuboid, respectively. Energy release due to Ir cluster insertion into an ethane C-H bond facilitates hydrogen migration on the Ir cluster surface, and the second H-elimination of ethane. In an oxygen-rich environment, oxygen molecules may be absorbed on the Ir cluster surface. The oxygen atoms bonded to the Ir cluster surface may slightly increase the energy barrier for H-elimination in ethane. However, the adsorption of oxygen and its reaction with H atoms on the Ir cluster releases sufficient heat to yield an overall thermodynamically favored reaction: Ir n + C 2 H 6 + 1 / 2 O 2 → Ir n + C 2 H 4 + H 2 O. These results will be useful toward reducing the energy cost of ethane dehydrogenation in industry.

Cholinesterase catalyzed hydrolysis of O-acyl derivatives of serotonin

International Nuclear Information System (INIS)

Makhaeva, G.F.; Suvorov, N.N.; Ginodman, L.N.; Antonov, V.K.; AN SSSR, Moscow. Inst. Bioorganicheskoj Khimii)

1977-01-01

Hydrolysis of O acyl serotonin derivatives containing the residues of monocarbon dicarbon and amino acids under the effect of horse serum butyryl cholinesterase and bull erythrocytic acetylcholinesterase has been studied. It has been established, that acetylcholinesterase hydrolizes O acetylserotonin only; butyrylcholinesterase hydrolizes all the compounds investigated, except for 5,5'-terephthaloildioxytriptamine. The kinetic parameters of hydrolysis were determined. O acyl serotonin derivatives turned out good substrates of butylrylcholinesterase; serotonin and 5.5'-terephtaloildioxytriptamine are effective competitine inhibitors of the enzyme. Estimating of resistance of O acyl serotonin derivatines to blood cholinesterase effect under physiological conditions shows that the compounds investigated with the exception of 5,5'-terephthaloildioxytriptamine must be quickly hydrolyzed under butyrylcholinesterase action. 5,5'-terephthaloildioxytriptamine is suggested as a radioprotective preparation with the prolonged effect, which agrees with the biological test results

Identification of four new mutations in the short-chain acyl-CoA dehydrogenase (SCAD) gene in two patients

DEFF Research Database (Denmark)

Gregersen, N; Winter, V S; Corydon, M J

1998-01-01

We have shown previously that a variant allele of the short-chain acyl-CoA dehydrogenase ( SCAD ) gene, 625G-->A, is present in homozygous form in 7% of control individuals and in 60% of 135 patients with elevated urinary excretion of ethylmalonic acid (EMA). We have now characterized three disease......-causing mutations (confirmed by lack of enzyme activity after expression in COS-7 cells) and a new susceptibility variant in the SCAD gene of two patients with SCAD deficiency, and investigated their frequency in patients with elevated EMA excretion. The first SCAD-deficient patient was a compound heterozygote...... for two mutations, 274G-->T and 529T-->C. These mutations were not present in 98 normal control alleles, but the 529T-->C mutation was found in one allele among 133 patients with elevated EMA excretion. The second patient carried a 1147C-->T mutation and the 625G-->A polymorphism in one allele...

Concentrations of long-chain acyl-acyl carrier proteins during fatty acid synthesis by chloroplasts isolated from pea (Pisum sativum), safflower (Carthamus tinctoris), and amaranthus (Amaranthus lividus) leaves

International Nuclear Information System (INIS)

Roughan, G.; Nishida, I.

1990-01-01

Fatty acid synthesis from [1-14C]acetate by chloroplasts isolated from peas and amaranthus was linear for at least 15 min, whereas incorporation of the tracer into long-chain acyl-acyl carrier protein (ACP) did not increase after 2-3 min. When reactions were transferred to the dark after 3-5 min, long-chain acyl-ACPs lost about 90% of their radioactivity and total fatty acids retained all of theirs. Half-lives of the long-chain acyl-ACPs were estimated to be 10-15 s. Concentrations of palmitoyl-, stearoyl-, and oleoyl-ACP as indicated by equilibrium labeling during steady-state fatty acid synthesis, ranged from 0.6-1.1, 0.2-0.7, and 0.4-1.6 microM, respectively, for peas and from 1.6-1.9, 1.3-2.6, and 0.6-1.4 microM, respectively, for amaranthus. These values are based on a chloroplast volume of 47 microliters/mg chlorophyll and varied according to the mode of the incubation. A slow increase in activity of the fatty acid synthetase in safflower chloroplasts resulted in long-chain acyl-ACPs continuing to incorporate labeled acetate for 10 min. Upon re-illumination following a dark break, however, both fatty acid synthetase activity and acyl-ACP concentrations increased very rapidly. Palmitoyl-ACP was present at concentrations up to 2.5 microM in safflower chloroplasts, whereas those of stearoyl- and oleoyl-ACPs were in the lower ranges measured for peas. Acyl-ACPs were routinely separated from extracts of chloroplasts that had been synthesising long-chain fatty acids from labeled acetate by a minor modification of the method of Mancha et al. The results compared favorably with those obtained using alternative analytical methods such as adsorption to filter paper and partition chromatography on silicic acid columns

12-Oxo-Phytodienoic Acid Accumulation during Seed Development Represses Seed Germination in Arabidopsis[C][W][OA

Science.gov (United States)

Dave, Anuja; Hernández, M. Luisa; He, Zhesi; Andriotis, Vasilios M.E.; Vaistij, Fabián E.; Larson, Tony R.; Graham, Ian A.

2011-01-01

Arabidopsis thaliana COMATOSE (CTS) encodes an ABC transporter involved in peroxisomal import of substrates for β-oxidation. Various cts alleles and mutants disrupted in steps of peroxisomal β-oxidation have previously been reported to exhibit a severe block on seed germination. Oxylipin analysis on cts, acyl CoA oxidase1 acyl CoA oxidase2 (acx1 acx2), and keto acyl thiolase2 dry seeds revealed that they contain elevated levels of 12-oxo-phytodienoic acid (OPDA), jasmonic acid (JA), and JA-Ile. Oxylipin and transcriptomic analysis showed that accumulation of these oxylipins occurs during late seed maturation in cts. Analysis of double mutants generated by crossing cts with mutants in the JA biosynthesis pathway indicate that OPDA, rather than JA or JA-Ile, contributes to the block on germination in cts seeds. We found that OPDA was more effective at inhibiting wild-type germination than was JA and that this effect was independent of CORONATINE INSENSITIVE1 but was synergistic with abscisic acid (ABA). Consistent with this, OPDA treatment increased ABA INSENSITIVE5 protein abundance in a manner that parallels the inhibitory effect of OPDA and OPDA+ABA on seed germination. These results demonstrate that OPDA acts along with ABA to regulate seed germination in Arabidopsis. PMID:21335376

Bio-production of Baccatin III, an Important Precursor of Paclitaxel by a Cost-Effective Approach.

Science.gov (United States)

Lin, Shu-Ling; Wei, Tao; Lin, Jun-Fang; Guo, Li-Qiong; Wu, Guang-Pei; Wei, Jun-Bin; Huang, Jia-Jun; Ouyang, Ping-Lan

2018-07-01

Natural production of anti-cancer drug taxol from Taxus has proved to be environmentally unsustainable and economically unfeasible. Currently, bioengineering the biosynthetic pathway of taxol is an attractive alternative production approach. 10-deacetylbaccatin III-10-O-acetyl transferase (DBAT) was previously characterized as an acyltransferase, using 10-deacetylbaccatin III (10-DAB) and acetyl CoA as natural substrates, to form baccatin III in the taxol biosynthesis. Here, we report that other than the natural acetyl CoA (Ac-CoA) substrate, DBAT can also utilize vinyl acetate (VA), which is commercially available at very low cost, acylate quickly and irreversibly, as acetyl donor in the acyl transfer reaction to produce baccatin III. Furthermore, mutants were prepared via a semi-rational design in this work. A double mutant, I43S/D390R was constructed to combine the positive effects of the different single mutations on catalytic activity, and its catalytic efficiency towards 10-DAB and VA was successfully improved by 3.30-fold, compared to that of wild-type DBAT, while 2.99-fold higher than the catalytic efficiency of WT DBAT towards 10-DAB and Ac-CoA. These findings can provide a promising economically and environmentally friendly method for exploring novel acyl donors to engineer natural product pathways.

Acylation of salmon calcitonin modulates in vitro intestinal peptide flux through membrane permeability enhancement

DEFF Research Database (Denmark)

Trier, Sofie; Linderoth, Lars; Bjerregaard, Simon

2015-01-01

hypothesize that tailoring the acylation may be used to optimize intestinal translocation. This work aims to characterize acylated analogues of the therapeutic peptide salmon calcitonin (sCT), which lowers blood calcium, by systematically increasing acyl chain length at two positions, in order to elucidate...... to be optimal, as elongating the chain causes greater binding to the cell membrane but similar permeability, and we speculate that increasing the chain length further may decrease the permeability. In conclusion, acylated sCT acts as its own in vitro intestinal permeation enhancer, with reversible effects...... on Caco-2 cells, indicating that acylation of sCT may represent a promising tool to increase intestinal permeability without adding oral permeation enhancers....

Plant Acyl-CoA:Lysophosphatidylcholine Acyltransferases (LPCATs) Have Different Specificities in Their Forward and Reverse Reactions*

Science.gov (United States)

Lager, Ida; Yilmaz, Jenny Lindberg; Zhou, Xue-Rong; Jasieniecka, Katarzyna; Kazachkov, Michael; Wang, Peng; Zou, Jitao; Weselake, Randall; Smith, Mark A.; Bayon, Shen; Dyer, John M.; Shockey, Jay M.; Heinz, Ernst; Green, Allan; Banas, Antoni; Stymne, Sten

2013-01-01

Acyl-CoA:lysophosphatidylcholine acyltransferase (LPCAT) enzymes have central roles in acyl editing of phosphatidylcholine (PC). Plant LPCAT genes were expressed in yeast and characterized biochemically in microsomal preparations of the cells. Specificities for different acyl-CoAs were similar for seven LPCATs from five different species, including species accumulating hydroxylated acyl groups in their seed oil, with a preference for C18-unsaturated acyl-CoA and low activity with palmitoyl-CoA and ricinoleoyl (12-hydroxyoctadec-9-enoyl)-CoA. We showed that Arabidopsis LPCAT1 and LPCAT2 enzymes catalyzed the acylation and de-acylation of both sn positions of PC, with a preference for the sn-2 position. When acyl specificities of the Arabidopsis LPCATs were measured in the reverse reaction, sn-2-bound oleoyl, linoleoyl, and linolenoyl groups from PC were transferred to acyl-CoA to a similar extent. However, a ricinoleoyl group at the sn-2-position of PC was removed 4–6-fold faster than an oleoyl group in the reverse reaction, despite poor utilization in the forward reaction. The data presented, taken together with earlier published reports on in vivo lipid metabolism, support the hypothesis that plant LPCAT enzymes play an important role in regulating the acyl-CoA composition in plant cells by transferring polyunsaturated and hydroxy fatty acids produced on PC directly to the acyl-CoA pool for further metabolism or catabolism. PMID:24189065

Identification of N-acyl-fumonisin B1 as new cytotoxic metabolites of fumonisin mycotoxins.

Science.gov (United States)

Harrer, Henning; Laviad, Elad L; Humpf, Hans Ulrich; Futerman, Anthony H

2013-03-01

Fumonisins are mycotoxins produced by Fusarium species. The predominant derivative, fumonisin B1 (FB1), occurs in food and feed and is of health concern due to its hepatotoxic and carcinogenic effects. However, the role of FB1 metabolites on the mechanism of the toxicity, the inhibition of the ceramide synthesis, is unknown. The aim of this study was to identify new fumonisin metabolites and to evaluate their cytotoxic potential. MS, molecular biology, and in vitro enzyme assays were used to investigate fumonisin metabolism in mammalian cells overexpressing human ceramide synthase (CerS) genes. N-acyl-FB1 derivatives were detected as new metabolites in cultured cells at levels of up to 10 pmol/mg of protein. The N-acylation of FB1 and hydrolyzed FB1 was analyzed in several cell lines, including cells overexpressing CerS. The acyl-chain length of the N-acyl fumonisins depends on the CerS isoform acylating them. The N-acyl fumonisins are more cytotoxic than the parent fumonisin B1. The identification of N-acyl fumonisins with various acyl chain lengths together with the observed cytotoxicity of these compounds is a new aspect of fumonisin-related toxicity. Therefore, these new metabolites might play an important role in the mode of action of fumonisins. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Increased superoxide accumulation in pyruvate dehydrogenase complex deficient fibroblasts.

Science.gov (United States)

Glushakova, Lyudmyla G; Judge, Sharon; Cruz, Alex; Pourang, Deena; Mathews, Clayton E; Stacpoole, Peter W

2011-11-01

The pyruvate dehydrogenase complex (PDC) oxidizes pyruvate to acetyl CoA and is critically important in maintaining normal cellular energy homeostasis. Loss-of-function mutations in PDC give rise to congenital lactic acidosis and to progressive cellular energy failure. However, the subsequent biochemical consequences of PDC deficiency that may contribute to the clinical manifestations of the disorder are poorly understood. We postulated that altered flux through PDC would disrupt mitochondrial electron transport, resulting in oxidative stress. Compared to cells from 4 healthy subjects, primary cultures of skin fibroblasts from 9 patients with variable mutations in the gene encoding the alpha subunit (E1α) of pyruvate dehydrogenase (PDA1) demonstrated reduced growth and viability. Superoxide (O(2)(.-)) from the Qo site of complex III of the electron transport chain accumulated in these cells and was associated with decreased activity of manganese superoxide dismutase. The expression of uncoupling protein 2 was also decreased in patient cells, but there were no significant changes in the expression of cellular markers of protein or DNA oxidative damage. The expression of hypoxia transcription factor 1 alpha (HIF1α) also increased in PDC deficient fibroblasts. We conclude that PDC deficiency is associated with an increase in O(2)(.-) accumulation coupled to a decrease in mechanisms responsible for its removal. Increased HIF1α expression may contribute to the increase in glycolytic flux and lactate production in PDC deficiency and, by trans-activating pyruvate dehydrogenase kinase, may further suppress residual PDC activity through phosphorylation of the E1α subunit. Copyright © 2011 Elsevier Inc. All rights reserved.

LOCATION OF ACYL GROUPS ON TWO PARTLY ACYLATED GLYCOLIPIDS FROM STRAINS OF USTILAGO (SMUT FUNGI),

Science.gov (United States)

erythritol from Ustilago sp. (probably U. nuda (Jens.) Rostr. = U. tritici (Pers.) Rostr.) PRL-627 were acetalated with methyl vinyl ether, deacylated...Partly acylated ustilagic acids 8 (from Ustilago maydis (DC) Corda (= U. zeae Unger) PRL-119), consisting of partially esterified beta-cellobiosyl

Stomach regulates energy balance via acylated ghrelin and desacyl ghrelin

OpenAIRE

Asakawa, A; Inui, A; Fujimiya, M; Sakamaki, R; Shinfuku, N; Ueta, Y; Meguid, M M; Kasuga, M

2005-01-01

Background/Aims: The gastric peptide ghrelin, an endogenous ligand for growth-hormone secretagogue receptor, has two major molecular forms: acylated ghrelin and desacyl ghrelin. Acylated ghrelin induces a positive energy balance, while desacyl ghrelin has been reported to be devoid of any endocrine activities. The authors examined the effects of desacyl ghrelin on energy balance.

Study of the performance of vanadium based catalysts prepared by grafting in the oxidative dehydrogenation of propane

Energy Technology Data Exchange (ETDEWEB)

Santacesaria, E.; Carotenuto, G.; Tesser, R.; Di Serio, M. [Naples Univ. (Italy). Dept. of Chemistry

2011-07-01

The oxidative dehydrogenation (ODH) of propane has been investigated by using many different vanadia based catalysts, prepared by grafting technique and containing variable amounts of active phase supported on SiO{sub 2} previously coated, by grafting in three different steps, with multilayer of TiO{sub 2}. A depth catalytic screening, conducted in a temperature range of 400-600 C, at atmospheric pressure and in a range of residence time W/F=0.08-0.33 ghmol{sub -1}, has shown that the vanadium oxide catalysts on TiO{sub 2}-SiO{sub 2} support, prepared by grafting have good performances in the ODH of propane. In particular, a preliminary study has demonstrated that higher selectivities can be obtained employing catalysts having a well dispersed active phase that can be achieved with a V{sub 2}O{sub 5} content lower than 10%{sub w}t. It is well known that, in the case of redox catalysts, an increase of the selectivity can be achieved not only by using an adequate catalytic system but also via engineering routes like decoupling catalytic steps of reduction and re-oxidation. In fact it has been observed that by operating in dehydrogenating mode, on the same catalysts, a higher selectivity is obtained although the catalyst is poisoned by the formation of coke on the surface. As consequence of the results obtained in dehydrogenation, in this work has been explored the possibility to feed low amounts of oxygen, below the stoichiometric level with the aim to keep clean the surface from coke but maintaining high the selectivity, because, dehydrogenation reaction prevails. In this work, the behavior of catalysts containing different amounts of V2O5 has been studied in the propane-propene reaction by using different ratios C{sub 3}H{sub 8}/O{sub 2} included in the range 0-2. (orig.)

Identification and quantification of intermediates of unsaturated fatty acid metabolism in plasma of patients with fatty acid oxidation disorders

NARCIS (Netherlands)

Onkenhout, W.; Venizelos, V.; van der Poel, P. F.; van den Heuvel, M. P.; Poorthuis, B. J.

1995-01-01

The free fatty acid and total fatty acid profiles in plasma of nine patients with medium-chain acyl-CoA dehydrogenase (MCAD) deficiency, two with very-long-chain acyl-CoA dehydrogenase (VLCAD) deficiency and two with mild-type multiple acyl-CoA dehydrogenase (MAD-m) deficiency, were analyzed by gas

Acylated flavonol tri- and tetraglycosides in the flavonoid metabolome of Cladrastis kentukea (Leguminosae).

Science.gov (United States)

Kite, Geoffrey C; Rowe, Emily R; Lewis, Gwilym P; Veitch, Nigel C

2011-04-01

The foliar metabolome of Cladrastis kentukea (Leguminosae) contains a complex mixture of flavonoids including acylated derivatives of the 3-O-rhamnosyl(1→2)[rhamnosyl(1→6)]-galactosides of kaempferol and quercetin and their 7-O-rhamnosides, together with an array of non-acylated kaempferol and quercetin di-, tri- and tetraglycosides. Thirteen of the acylated flavonoids, 12 of which had not been reported previously, were characterised by spectroscopic and chemical methods. Eight of these were the four isomers of kaempferol 3-O-α-l-rhamnopyranosyl(1→2)[α-l-rhamnopyranosyl(1→6)]-(3/4-O-E/Z-p-coumaroyl-β-d-galactopyranoside) and their 7-O-α-l-rhamnopyranosides, and three were isomers of quercetin 3-O-α-l-rhamnopyranosyl(1→2)[α-l-rhamnopyranosyl(1→6)]-(3/4-O-E/Z-p-coumaroyl-β-d-galactopyranoside) - the remaining 4Z isomer was identified by LC-UV-MS analysis of a crude extract. The final two acylated flavonoids characterised by NMR were the 3E and 4E isomers of kaempferol 3-O-α-l-rhamnopyranosyl(1→2)[α-l-rhamnopyranosyl(1→6)]-(3/4-O-E-feruloyl-β-d-galactopyranoside)-7-O-α-l-rhamnopyranoside while the 3Z and 4Z isomers were again detected by LC-UV-MS. Using the observed fragmentation behaviour of the isolated compounds following a variety of MS experiments, a further 18 acylated flavonoids were given tentative structures by LC-MS analysis of a crude extract. Acylated flavonoids were absent from the flowers of C. kentukea, which contained an array of non-acylated kaempferol and quercetin glycosides. Immature fruits contained kaempferol 3-O-α-rhamnopyranosyl(1→2)[α-rhamnopyranosyl(1→6)]-β-galactopyranoside and its 7-O-α-rhamnopyranoside as the major flavonoids with acylated flavonoids, different from those in the leaves, only present as minor constituents. The presence of acylated flavonoids distinguishes the foliar flavonoid metabolome of C. kentukea from that of a closely related legume, Styphnolobium japonicum, which contains a similar

A new and selective cycle for dehydrogenation of linear and cyclic alkanes under mild conditions using a base metal

Science.gov (United States)

Solowey, Douglas P.; Mane, Manoj V.; Kurogi, Takashi; Carroll, Patrick J.; Manor, Brian C.; Baik, Mu-Hyun; Mindiola, Daniel J.

2017-11-01

Selectively converting linear alkanes to α-olefins under mild conditions is a highly desirable transformation given the abundance of alkanes as well as the use of olefins as building blocks in the chemical community. Until now, this reaction has been primarily the remit of noble-metal catalysts, despite extensive work showing that base-metal alkylidenes can mediate the reaction in a stoichiometric fashion. Here, we show how the presence of a hydrogen acceptor, such as the phosphorus ylide, when combined with the alkylidene complex (PNP)Ti=CHtBu(CH3) (PNP=N[2-P(CHMe2)2-4-methylphenyl]2-), catalyses the dehydrogenation of cycloalkanes to cyclic alkenes, and linear alkanes with chain lengths of C4 to C8 to terminal olefins under mild conditions. This Article represents the first example of a homogeneous and selective alkane dehydrogenation reaction using a base-metal titanium catalyst. We also propose a unique mechanism for the transfer dehydrogenation of hydrocarbons to olefins and discuss a complete cycle based on a combined experimental and computational study.

Journal of Chemical Sciences

Indian Academy of Sciences (India)

0006741

impact of sugar and fatty acid on the bioactivity of N-fatty acyl-L-tyrosine derivatives. Metal free ... mediated oxidative dehydrogenation and ring opening of lactam in ... presence of a catalytic amount of triphenylphosphine in CH2Cl2 at ambient temperature in .... Cover picture: High energy density materials. For details, see ...

Dehydrogenation of propane in the presence of carbon dioxide over chromium and gallium oxides catalysts

Energy Technology Data Exchange (ETDEWEB)

Lapidus, A.L.; Agafonov, Yu.A.; Gaidai, N.A.; Nekrasov, N.V.; Menshova, M.V.; Kunusova, R.M. [Russian Academy of Sciences, Moscow (Russian Federation). N.D. Zelinsky Inst. of Organic Chemistry

2011-07-01

Effective chromium and gallium oxides supported catalysts were prepared and tested in longduration experiments for propane dehydrogenation in the presence of CO{sub 2}. The optimal concentrations of active metals were found. It was shown that the activity, selectivity and stability of chromium oxides catalysts were higher than these parameters for gallium ones. Mechanism of propane oxidative dehydrogenation was studied over both catalysts using unstationary and spectroscopic methods. The employment of these methods allowed to establish the differences in process mechanism. It was shown that surface hydroxides took participation in propene formation over Cr-catalysts and hydrides - over Ga-ones. Propane and carbon dioxide participated in the reaction from the adsorbed state over both catalysts but they were differed by the adsorption capacity of the reaction components: CO2 was tied more firmly than C{sub 3}H{sub 6} over both catalysts, CO{sub 2} and C{sub 3}H{sub 6} were tied more strongly with Cr-catalysts than with Ga-ones. It was shown that CO{sub 2} took active participation in reverse watergas shift reaction and in oxidation of catalyst surface over chromium oxides catalysts. The main role of CO{sub 2} in propane dehydrogenation over gallium catalysts consisted in a decrease of coke formation. Step-schemes of propene and cracking products formation were proposed on the basis of literature and obtained data: via the redox mechanism over Cr-catalysts and through a heterolytic dissociation reaction pathway over Ga-ones. (orig.)

Oxidative dehydrogenation of the 2-aminomethylpyridine (EDTA) ruthenium (III) complex

International Nuclear Information System (INIS)

Toma, H.E.; Tsurumaki, M.

1990-01-01

The oxidative dehydrogenation of the 2-aminomethylpyridine (ampy) ligand coordinated to the (EDTA)RU(III) complex was investigated based on cyclic voltammetry, spectoelectrochemistry and stopped-flow kinetic measurements in aqueous solution. The reaction mechanism is consistent with the deprotonation of the ampy ligand (pk a =7.48), followed by a reversible one-electron transfer step. The intermediate species generated at this step undergoes a metal-induced electron transfer process, with k=227 s -1 , converting into the corresponding 2-iminomethylpyridine complex. (author) [pt

In-situ TEM on (de)hydrogenation of Pd at 0.5–4.5 bar hydrogen pressure and 20–400°C

International Nuclear Information System (INIS)

Yokosawa, Tadahiro; Alan, Tuncay; Pandraud, Gregory; Dam, Bernard; Zandbergen, Henny

2012-01-01

We have developed a nanoreactor, sample holder and gas system for in-situ transmission electron microscopy (TEM) of hydrogen storage materials up to at least 4.5 bar. The MEMS-based nanoreactor has a microheater, two electron-transparent windows and a gas inlet and outlet. The holder contains various O-rings to have leak-tight connections with the nanoreactor. The system was tested with the (de)hydrogenation of Pd at pressures up to 4.5 bar. The Pd film consisted of islands being 15 nm thick and 50–500 nm wide. In electron diffraction mode we observed reproducibly a crystal lattice expansion and shrinkage owing to hydrogenation and dehydrogenation, respectively. In selected-area electron diffraction and bright/dark-field modes the (de)hydrogenation of individual Pd particles was followed. Some Pd islands are consistently hydrogenated faster than others. When thermally cycled, thermal hysteresis of about 10–16 °C between hydrogen absorption and desorption was observed for hydrogen pressures of 0.5–4.5 bar. Experiments at 0.8 bar and 3.2 bar showed that the (de)hydrogenation temperature is not affected by the electron beam. This result shows that this is a fast method to investigate hydrogen storage materials with information at the nanometer scale. -- Highlights: ► In-situ TEM experiments up to 4.5 bar. ► In-situ TEM on a hydrogen storage material at pressures used in practice. ► No electron beam effect on (de)hydrogenation. ► In-situ TEM allows for fast screening of hydrogen storage materials.

Environmentally benign synthesis of amides and ureas via catalytic dehydrogenation coupling of volatile alcohols and amines in a Pd-Ag membrane reactor

KAUST Repository

Chen, Tao

2016-05-31

In this study, we report the direct synthesis of amides and ureas via the catalytic dehydrogenation of volatile alcohols and amines using the Milstein catalyst in a Pd-Ag/ceramic membrane reactor. A series of amides and ureas, which could not be synthesized in an open system by catalytic dehydrogenation coupling, were obtained in moderate to high yields via catalytic dehydrogenation of volatile alcohols and amines. This process could be monitored by the hydrogen produced. Compared to the traditional method of condensation, this catalytic system avoids the stoichiometric pre-activation or in situ activation of reagents, and is a much cleaner process with high atom economy. This methodology, only possible by employing the Pd-Ag/ceramic membrane reactor, not only provides a new environmentally benign synthetic approach of amides and ureas, but is also a potential method for hydrogen storage.

Environmentally benign synthesis of amides and ureas via catalytic dehydrogenation coupling of volatile alcohols and amines in a Pd-Ag membrane reactor

KAUST Repository

Chen, Tao; Zeng, Gaofeng; Lai, Zhiping; Huang, Kuo-Wei

2016-01-01

In this study, we report the direct synthesis of amides and ureas via the catalytic dehydrogenation of volatile alcohols and amines using the Milstein catalyst in a Pd-Ag/ceramic membrane reactor. A series of amides and ureas, which could not be synthesized in an open system by catalytic dehydrogenation coupling, were obtained in moderate to high yields via catalytic dehydrogenation of volatile alcohols and amines. This process could be monitored by the hydrogen produced. Compared to the traditional method of condensation, this catalytic system avoids the stoichiometric pre-activation or in situ activation of reagents, and is a much cleaner process with high atom economy. This methodology, only possible by employing the Pd-Ag/ceramic membrane reactor, not only provides a new environmentally benign synthetic approach of amides and ureas, but is also a potential method for hydrogen storage.

In-situ TEM on (de)hydrogenation of Pd at 0.5-4.5 bar hydrogen pressure and 20-400°C.

Science.gov (United States)

Yokosawa, Tadahiro; Alan, Tuncay; Pandraud, Gregory; Dam, Bernard; Zandbergen, Henny

2012-01-01

We have developed a nanoreactor, sample holder and gas system for in-situ transmission electron microscopy (TEM) of hydrogen storage materials up to at least 4.5 bar. The MEMS-based nanoreactor has a microheater, two electron-transparent windows and a gas inlet and outlet. The holder contains various O-rings to have leak-tight connections with the nanoreactor. The system was tested with the (de)hydrogenation of Pd at pressures up to 4.5 bar. The Pd film consisted of islands being 15 nm thick and 50-500 nm wide. In electron diffraction mode we observed reproducibly a crystal lattice expansion and shrinkage owing to hydrogenation and dehydrogenation, respectively. In selected-area electron diffraction and bright/dark-field modes the (de)hydrogenation of individual Pd particles was followed. Some Pd islands are consistently hydrogenated faster than others. When thermally cycled, thermal hysteresis of about 10-16°C between hydrogen absorption and desorption was observed for hydrogen pressures of 0.5-4.5 bar. Experiments at 0.8 bar and 3.2 bar showed that the (de)hydrogenation temperature is not affected by the electron beam. This result shows that this is a fast method to investigate hydrogen storage materials with information at the nanometer scale. Copyright © 2011 Elsevier B.V. All rights reserved.

Molecular analysis of virulent genes (coa and spa) of staphylococcus aureus involved in natural cases of bovine mastitis

International Nuclear Information System (INIS)

Khan, A.; Javed, M.T.; Mahmood, F.; Hussain, R.

2013-01-01

The present study was undertaken to determine the distribution and genotypic characteristics of Staphylococcus aureus isolates recovered from naturally occurring mastitis in cattle and buffaloes. For this purpose a total of 1445 lactating cattle (653) and buffaloes (792) present at two experimental livestock farms Okara (Bahadarnagar) and Sahiwal (Qadiarabad), in and around district Faisalabad and slaughtered at an abattoir due to low milk yield and were screened for mastitis. California Mastitis Test (CMT) was used to detect sub clinical mastitis. The positive quarter milk samples were collected for culturing of S. aureus isolates. taphylococcus aureus isolates were identified on the basis of growth features, biochemical characteristics, coagulase test and as well as amplification of coagulase (coa) and spa (spa-X) genes specific to its virulence. S. aureus isolates (n=265) were characterized by Polymerase chain reaction to determine the frequency of coagulase (coa) and spa (spa-X) genes. From these isolates the amplification of the coagulase (coa) gene yielded three different PCR products approximately 204bp to 490bp while spa (spa-X) gene produced five different products ranging in size from 190bp to 320bp. PCR revealed that from all the coagulase positive S. aureus isolates 261(98.5%) had spa (spa-X) gene. The results of the present study indicated that S. aureus isolates recovered from bovine mastitis were genetically different within and among the various herds which may provide essential and valuable strategies to control staphylococcal infections in future. (author)

Molecular analysis of virulent genes (coa and spa) of staphylococcus aureus involved in natural cases of bovine mastitis

Energy Technology Data Exchange (ETDEWEB)

Khan, A.; Javed, M. T.; Mahmood, F. [University of Agriculture, Faisalabad (Pakistan). Dept. of Pathology; Hussain, R. [The Islamia Univ. of Bahawalpur, Pakistan (Pakistan). Dept. of Veterinary and Animal Sciences

2013-12-15

The present study was undertaken to determine the distribution and genotypic characteristics of Staphylococcus aureus isolates recovered from naturally occurring mastitis in cattle and buffaloes. For this purpose a total of 1445 lactating cattle (653) and buffaloes (792) present at two experimental livestock farms Okara (Bahadarnagar) and Sahiwal (Qadiarabad), in and around district Faisalabad and slaughtered at an abattoir due to low milk yield and were screened for mastitis. California Mastitis Test (CMT) was used to detect sub clinical mastitis. The positive quarter milk samples were collected for culturing of S. aureus isolates. taphylococcus aureus isolates were identified on the basis of growth features, biochemical characteristics, coagulase test and as well as amplification of coagulase (coa) and spa (spa-X) genes specific to its virulence. S. aureus isolates (n=265) were characterized by Polymerase chain reaction to determine the frequency of coagulase (coa) and spa (spa-X) genes. From these isolates the amplification of the coagulase (coa) gene yielded three different PCR products approximately 204bp to 490bp while spa (spa-X) gene produced five different products ranging in size from 190bp to 320bp. PCR revealed that from all the coagulase positive S. aureus isolates 261(98.5%) had spa (spa-X) gene. The results of the present study indicated that S. aureus isolates recovered from bovine mastitis were genetically different within and among the various herds which may provide essential and valuable strategies to control staphylococcal infections in future. (author)

The influence of surface oxygen and hydroxyl groups on the dehydrogenation of ethylene, acetic acid and hydrogenated vinyl acetate on pure Pd(1 0 0): A DFT study

Energy Technology Data Exchange (ETDEWEB)

Huang, Yanping [Key Laboratory for Green Chemical Technology of Ministry of Education, R& D Center for Petrochemical Technology, Tianjin University, Tianjin (China); Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072 (China); Dong, Xiuqin [Key Laboratory for Green Chemical Technology of Ministry of Education, R& D Center for Petrochemical Technology, Tianjin University, Tianjin (China); Yu, Yingzhe, E-mail: yzhyu@tju.edu.cn [Key Laboratory for Green Chemical Technology of Ministry of Education, R& D Center for Petrochemical Technology, Tianjin University, Tianjin (China); Zhang, Minhua, E-mail: mhzhangtj@163.com [Key Laboratory for Green Chemical Technology of Ministry of Education, R& D Center for Petrochemical Technology, Tianjin University, Tianjin (China)

2016-12-01

Highlights: • All dehydrogenation reactions in vinyl acetate synthesis on Pd(1 0 0) were studied. • The energy barriers of the transition state of the three reactions were calculated. • The influence of surface Os and OHs on all dehydrogenation actions was discussed. - Abstract: On the basis of a Langmuir–Hinshelwood-type mechanism, the dehydrogenation of ethylene, acetic acid and hydrogenated vinyl acetate (VAH) on pure Pd(1 0 0) with surface oxygen atoms (Os) and hydroxyl groups (OHs) was studied with density functional theory (DFT) method. Our calculation results show that both Os and OHs can consistently reduce the activation energies of dehydrogenation of ethylene, acetic acid and VAH to some degree with only one exception that OHs somehow increase the activation energy of VAH. Based on Langmuir–Hinshelwood mechanism, the three dehydrogenation reactions in presence of surface Os and OHs are almost consistently favored, compared with the corresponding processes on clean Pd(1 0 0) surfaces, and thus a Langmuir–Hinshelwood-type mechanism may not be excluded beforehand when investigating the microscopic performance of the oxygen-assisted vinyl acetate synthesis on Pd(1 0 0) catalysts.

Application of Heterogeneous Copper Catalyst in a Continuous Flow Process: Dehydrogenation of Cyclohexanol

Science.gov (United States)

Glin´ski, Marek; Ulkowska, Urszula; Iwanek, Ewa

2016-01-01

In this laboratory experiment, the synthesis of a supported solid catalyst (Cu/SiO2) and its application in the dehydrogenation of cyclohexanol performed under flow conditions was studied. The experiment was planned for a group of two or three students for two 6 h long sessions. The copper catalyst was synthesized using incipient wetness…

Non-Precious Bimetallic Catalysts for Selective Dehydrogenation of an Organic Chemical Hydride System

KAUST Repository

Shaikh Ali, Anaam

2015-07-06

Methylcyclohexane (MCH)-Toluene (TOL) chemical hydride cycles as a hydrogen carrier system is successful with the selective dehydrogenation reaction of MCH to TOL, which has been achieved only using precious Pt-based catalysts. Herein, we report improved selectivity using non-precious metal nickel-based bimetallic catalysts, where the second metal occupies the unselective step sites.

CoaSim: A Flexible Environment for Simulating Genetic Data under Coalescent Models

DEFF Research Database (Denmark)

Mailund; Schierup, Mikkel Heide; Pedersen, Christian Nørgaard Storm

2005-01-01

get insight into these. Results We have created the CoaSim application as a flexible environment for Monte various types of genetic data under equilibrium and non-equilibrium coalescent variety of applications. Interaction with the tool is through the Guile version scripting language. Scheme scripts......Background Coalescent simulations are playing a large role in interpreting large scale intra- polymorphism surveys and for planning and evaluating association studies. Coalescent of data sets under different models can be compared to the actual data to test different evolutionary factors and thus...

Synthesis of carbon-supported copper catalyst and its catalytic performance in methanol dehydrogenation

Energy Technology Data Exchange (ETDEWEB)

Shelepova, Ekaterina V. [Boreskov Institute of Catalysis SB RAS, pr. Ac. Lavrentieva, 5, Novosibirsk, 630090 (Russian Federation); National Research Tomsk Polytechnic University, Lenin av., 30, Tomsk, 634050 (Russian Federation); Vedyagin, Aleksey A., E-mail: vedyagin@catalysis.ru [Boreskov Institute of Catalysis SB RAS, pr. Ac. Lavrentieva, 5, Novosibirsk, 630090 (Russian Federation); National Research Tomsk Polytechnic University, Lenin av., 30, Tomsk, 634050 (Russian Federation); Ilina, Ludmila Yu.; Nizovskii, Alexander I. [Boreskov Institute of Catalysis SB RAS, pr. Ac. Lavrentieva, 5, Novosibirsk, 630090 (Russian Federation); Tsyrulnikov, Pavel G. [Institute of Hydrocarbon Processing SB RAS, Neftezavodskaya st., 54, Omsk, 644040 (Russian Federation)

2017-07-01

Highlights: • Carbon-supported copper catalyst was studied in dehydrogenation of methanol. • Reduction temperature affected size of Cu particles and Cu{sup 0}/Cu{sup 2+} ratio. • Reduction at 400 °C was required to obtain high methyl formate yield. - Abstract: Carbon-supported copper catalyst was prepared by incipient wetness impregnation of Sibunit with an aqueous solution of copper nitrate. Copper loading was 5 wt.%. Temperature of reductive pretreatment was varied within a range of 200–400 °C. The samples were characterized by transmission electron microscopy, X-ray diffraction analysis, X-ray photoelectron and X-ray absorption spectroscopies. Catalytic activity of the samples was studied in a reaction of methanol dehydrogenation. Silica-based catalyst with similar copper loading was used as a reference. It was found that copper is distributed over the surface of support in the form of metallic and partially oxidized particles of about 12–17 nm in size. Diminished interaction of copper with support was supposed to be responsible for high catalytic activity.

Chromium downregulates the expression of Acetyl CoA Carboxylase 1 gene in lipogenic tissues of domestic goats: a potential strategy for meat quality improvement.

Science.gov (United States)

Najafpanah, Mohammad Javad; Sadeghi, Mostafa; Zali, Abolfazl; Moradi-Shahrebabak, Hossein; Mousapour, Hojatollah

2014-06-15

Acetyl CoA Carboxylase 1 (ACC1) is a biotin-dependent enzyme that catalyzes the carboxylation of Acetyl CoA to form Malonyl CoA, the key intermediate metabolite in fatty acid synthesis. In this study, the mRNA expression of the ACC1 gene was evaluated in four different tissues (liver, visceral fat, subcutaneous fat, and longissimus muscle) of the domestic goat (Capra hircus) kids feeding on four different levels of trivalent chromium (0, 0.5, 1, and 1.5mg/day) as food supplementation. RT-qPCR technique was used for expression analyses and heat shock protein 90 gene (HSP-90) was considered as reference gene for data normalization. Our results revealed that 1.5mg/day chromium significantly reduced the expression of the ACC1 gene in liver, visceral fat, and subcutaneous fat tissues, but not in longissimus muscles (Pmeat quality in domestic animals. Copyright © 2014 Elsevier B.V. All rights reserved.

Study of vanadium based mesoporous silicas for oxidative dehydrogenation of propane and n-butane

Czech Academy of Sciences Publication Activity Database

Bulánek, R.; Kalužová, A.; Setnička, M.; Zukal, Arnošt; Čičmanec, P.; Mayerová, Jana

2012-01-01

Roč. 179, č. 1 (2012), s. 149-158 ISSN 0920-5861 R&D Projects: GA ČR GAP106/10/0196 Institutional research plan: CEZ:AV0Z40400503 Keywords : vanadium * oxidative dehydrogenation * mesoporous silicas Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.980, year: 2012

The Acylation State of Surface Lipoproteins of Mollicute Acholeplasma laidlawii*

Science.gov (United States)

Serebryakova, Marina V.; Demina, Irina A.; Galyamina, Maria A.; Kondratov, Ilya G.; Ladygina, Valentina G.; Govorun, Vadim M.

2011-01-01

Acylation of the N-terminal Cys residue is an essential, ubiquitous, and uniquely bacterial posttranslational modification that allows anchoring of proteins to the lipid membrane. In Gram-negative bacteria, acylation proceeds through three sequential steps requiring lipoprotein diacylglyceryltransferase, lipoprotein signal peptidase, and finally lipoprotein N-acyltransferase. The apparent lack of genes coding for recognizable homologs of lipoprotein N-acyltransferase in Gram-positive bacteria and Mollicutes suggests that the final step of the protein acylation process may be absent in these organisms. In this work, we monitored the acylation state of eight major lipoproteins of the mollicute Acholeplasma laidlawii using a combination of standard two-dimensional gel electrophoresis protein separation, blotting to nitrocellulose membranes, and MALDI-MS identification of modified N-terminal tryptic peptides. We show that for each A. laidlawii lipoprotein studied a third fatty acid in an amide linkage on the N-terminal Cys residue is present, whereas diacylated species were not detected. The result thus proves that A. laidlawii encodes a lipoprotein N-acyltransferase activity. We hypothesize that N-acyltransferases encoded by genes non-homologous to N-acyltransferases of Gram-negative bacteria are also present in other mollicutes and Gram-positive bacteria. PMID:21540185

Exploring Cooperative Effects in Oxidative NHC Catalysis: Regioselective Acylation of Carbohydrates.

Science.gov (United States)

Cramer, David L; Bera, Srikrishna; Studer, Armido

2016-05-23

The utility of oxidative NHC catalysis for both the regioselective and chemoselective functionalization of carbohydrates is explored. Chiral NHCs allow for the highly regioselective oxidative esterification of various carbohydrates using aldehydes as acylation precursors. The transformation was also shown to be amenable to both cis/trans diol isomers, free amino groups, and selective for specific sugar epimers in competition experiments. Efficiency and regioselectivity of the acylation can be improved upon using two different NHC catalysts that act cooperatively. The potential of the method is documented by the regioselective acylation of an amino-linked neodisaccharide. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Toward Green Acylation of (Heteroarenes: Palladium-Catalyzed Carbonylation of Olefins to Ketones

Directory of Open Access Journals (Sweden)

Jie Liu

2017-11-01

Full Text Available Green Friedel–Crafts acylation reactions belong to the most desired transformations in organic chemistry. The resulting ketones constitute important intermediates, building blocks, and functional molecules in organic synthesis as well as for the chemical industry. Over the past 60 years, advances in this topic have focused on how to make this reaction more economically and environmentally friendly by using green acylating conditions, such as stoichiometric acylations and catalytic homogeneous and heterogeneous acylations. However, currently well-established methodologies for their synthesis either produce significant amounts of waste or proceed under harsh conditions, limiting applications. Here, we present a new protocol for the straightforward and selective introduction of acyl groups into (hetero­arenes without directing groups by using available olefins with inexpensive CO. In the presence of commercial palladium catalysts, inter- and intramolecular carbonylative C–H functionalizations take place with good regio- and chemoselectivity. Compared to classical Friedel–Crafts chemistry, this novel methodology proceeds under mild reaction conditions. The general applicability of this methodology is demonstrated by the direct carbonylation of industrial feedstocks (ethylene and diisobutene as well as of natural products (eugenol and safrole. Furthermore, synthetic applications to drug molecules are showcased.

Acute aerobic exercise differentially alters acylated ghrelin and perceived fullness in normal-weight and obese individuals.

Science.gov (United States)

Heden, Timothy D; Liu, Ying; Park, Youngmin; Dellsperger, Kevin C; Kanaley, Jill A

2013-09-01

Adiposity alters acylated ghrelin concentrations, but it is unknown whether adiposity alters the effect of exercise and feeding on acylated ghrelin responses. Therefore, the purpose of this study was to determine whether adiposity [normal-weight (NW) vs. obese (Ob)] influences the effect of exercise and feeding on acylated ghrelin, hunger, and fullness. Fourteen NW and 14 Ob individuals completed two trials in a randomized counterbalanced fashion, including a prior exercise trial (EX) and a no exercise trial (NoEX). During the EX trial, the participants performed 1 h of treadmill walking (55-60% peak O2 uptake) during the evening, 12 h before a 4-h standardized mixed meal test. Frequent blood samples were taken and analyzed for acylated ghrelin, and a visual analog scale was used to assess perceived hunger and fullness. In NW individuals, EX, compared with NoEX, reduced fasting acylated ghrelin concentrations by 18% (P = 0.03), and, in response to feeding, the change in acylated ghrelin (P = 0.02) was attenuated by 39%, but perceived hunger and fullness were unaltered. In Ob individuals, despite no changes in fasting or postprandial acylated ghrelin concentrations with EX, postprandial fullness was attenuated by 46% compared with NoEX (P = 0.05). In summary, exercise performed the night before a meal suppresses acylated ghrelin concentrations in NW individuals without altering perceived hunger or fullness. In Ob individuals, despite no changes in acylated ghrelin concentrations, EX reduced the fullness response to the test meal. Acylated ghrelin and perceived fullness responses are differently altered by acute aerobic exercise in NW and Ob individuals.

Room-Temperature Alternative to the Arbuzov Reaction: The Reductive Deoxygenation of Acyl Phosphonates

OpenAIRE

Kedrowski, Sean M. A.; Dougherty, Dennis A.

2010-01-01

The reductive deoxygenation of acyl phosphonates using a Wolff−Kishner-like sequence is described. This transformation allows direct access to alkyl phosphonates from acyl phosphonates at room temperature. The method can be combined with acyl phosphonate synthesis into a one pot, four-step procedure for the conversion of carboxylic acids into alkyl phosphonates. The methodology works well for a variety of aliphatic acids and shows a functional group tolerance similar to that of other hydrazon...

Studies on acylation of lysolecithin in chicken intestine

International Nuclear Information System (INIS)

Lokesh, B.R.; Madhava Rao, A.; Murthy, S.K.

1976-01-01

The enzymatic acylation of lysolecithin to lecithin is shown to occur in the brush border-free particulate fraction of the small intestines of neonatal chicken. It requires ATP, coenzyme A and Mg 2+ or Mn 2+ for maximal activity. The system is specific for oleic acid. The fatty acid composition at the α-position of lysolecithin does not seem to influence the rate of acylation. The fatty acid incorporated into lysolecithin is shown to occupy exclusively, the β-position. [ 32 P]lecithin and [1- 14 C]oleic acid has been used as tracers in the studies. (author)

Quantum chemical study of penicillin: Reactions after acylation

Science.gov (United States)

Li, Rui; Feng, Dacheng; Zhu, Feng

The density functional theory methods were used on the model molecules of penicillin to determine the possible reactions after their acylation on ?-lactamase, and the results were compared with sulbactam we have studied. The results show that, the acylated-enzyme tetrahedral intermediate can evolves with opening of ?-lactam ring as well as the thiazole ring; the thiazole ring-open products may be formed via ?-lactam ring-open product or from tetrahedral intermediate directly. Those products, in imine or enamine form, can tautomerize via hydrogen migration. In virtue of the water-assisted, their energy barriers are obviously reduced.

Identification of unusual phospholipid fatty acyl compositions of Acanthamoeba castellanii.

Directory of Open Access Journals (Sweden)

Marta Palusinska-Szysz

Full Text Available Acanthamoeba are opportunistic protozoan pathogens that may lead to sight-threatening keratitis and fatal granulomatous encephalitis. The successful prognosis requires early diagnosis and differentiation of pathogenic Acanthamoeba followed by aggressive treatment regimen. The plasma membrane of Acanthamoeba consists of 25% phospholipids (PL. The presence of C20 and, recently reported, 28- and 30-carbon fatty acyl residues is characteristic of amoeba PL. A detailed knowledge about this unusual PL composition could help to differentiate Acanthamoeba from other parasites, e.g. bacteria and develop more efficient treatment strategies. Therefore, the detailed PL composition of Acanthamoeba castellanii was investigated by 31P nuclear magnetic resonance spectroscopy, thin-layer chromatography, gas chromatography, high performance liquid chromatography and liquid chromatography-mass spectrometry. Normal and reversed phase liquid chromatography coupled with mass spectrometric detection was used for detailed characterization of the fatty acyl composition of each detected PL. The most abundant fatty acyl residues in each PL class were octadecanoyl (18∶0, octadecenoyl (18∶1 Δ9 and hexadecanoyl (16∶0. However, some selected PLs contained also very long fatty acyl chains: the presence of 28- and 30-carbon fatty acyl residues was confirmed in phosphatidylethanolamine (PE, phosphatidylserine, phosphatidic acid and cardiolipin. The majority of these fatty acyl residues were also identified in PE that resulted in the following composition: 28∶1/20∶2, 30∶2/18∶1, 28∶0/20∶2, 30∶2/20∶4 and 30∶3/20∶3. The PL of amoebae are significantly different in comparison to other cells: we describe here for the first time unusual, very long chain fatty acids with Δ5-unsaturation (30∶35,21,24 and 30∶221,24 localized exclusively in specific phospholipid classes of A. castellanii protozoa that could serve as specific biomarkers for the presence of

Diacylglycerol Acyltransferase-2 (DGAT2) and Monoacylglycerol Acyltransferase-2 (MGAT2) Interact to Promote Triacylglycerol Synthesis*

Science.gov (United States)

Jin, Youzhi; McFie, Pamela J.; Banman, Shanna L.; Brandt, Curtis; Stone, Scot J.

2014-01-01

Acyl CoA:1,2-diacylglycerol acyltransferase (DGAT)-2 is an integral membrane protein that catalyzes triacylglycerol (TG) synthesis using diacylglycerol and fatty acyl CoA as substrates. DGAT2 resides in the endoplasmic reticulum (ER), but when cells are incubated with fatty acids, DGAT2 interacts with lipid droplets presumably to catalyze localized TG synthesis for lipid droplet expansion. Previous studies have shown that DGAT2 interacts with proteins that synthesize its fatty acyl CoA substrates. In this study, we provide additional evidence that DGAT2 is present in a protein complex. Using a chemical cross-linker, disuccinimidyl suberate (DSS), we demonstrated that DGAT2 formed a dimer and was also part of a protein complex of ∼650 kDa, both in membranes and on lipid droplets. Using co-immunoprecipitation experiments and an in situ proximity ligation assay, we found that DGAT2 interacted with monoacylglycerol acyltransferase (MGAT)-2, an enzyme that catalyzes the synthesis of diacylglycerol. Deletion mutagenesis showed that the interaction with MGAT2 was dependent on the two transmembrane domains of DGAT2. No significant interaction of DGAT2 with lipin1, another enzyme that synthesizes diacylglycerol, could be detected. When co-expressed in cells, DGAT2 and MGAT2 co-localized in the ER and on lipid droplets. Co-expression also resulted in increased TG storage compared with expression of DGAT2 or MGAT2 alone. Incubating McArdle rat hepatoma RH7777 cells with 2-monoacylglycerol caused DGAT2 to translocate to lipid droplets. This also led to the formation of large cytosolic lipid droplets, characteristic of DGAT2, but not DGAT1, and indicated that DGAT2 can utilize monoacylglycerol-derived diacylglycerol. These findings suggest that the interaction of DGAT2 and MGAT2 serves to channel lipid substrates efficiently for TG biosynthesis. PMID:25164810

Rhenium-catalyzed dehydrogenative olefination of C(sp(3))-H bonds with hypervalent iodine(III) reagents.

Science.gov (United States)

Gu, Haidong; Wang, Congyang

2015-06-07

A dehydrogenative olefination of C(sp(3))-H bonds is disclosed here, by merging rhenium catalysis with an alanine-derived hypervalent iodine(III) reagent. Thus, cyclic and acyclic ethers, toluene derivatives, cycloalkanes, and nitriles are all successfully alkenylated in a regio- and stereoselective manner.

Cis–Trans Configuration of Coumaric Acid Acylation Affects the Spectral and Colorimetric Properties of Anthocyanins

Directory of Open Access Journals (Sweden)

Gregory T. Sigurdson

2018-03-01

Full Text Available The color expression of anthocyanins can be affected by a variety of environmental factors and structural characteristics. Anthocyanin acylation (type and number of acids is known to be key, but the influence of acyl isomers (with unique stereochemistries remains to be explored. The objective of this study was to investigate the effects of cis–trans configuration of the acylating group on the spectral and colorimetric properties of anthocyanins. Petunidin-3-rutinoside-5-glucoside (Pt-3-rut-5-glu and Delphinidin-3-rutinoside-5-glucoside (Dp-3-rut-5-glu and their cis and trans coumaroylated derivatives were isolated from black goji and eggplant, diluted in pH 1–9 buffers, and analyzed spectrophotometrically (380–700 nm and colorimetrically (CIELAB during 72 h of storage (25 °C, dark. The stereochemistry of the acylating group strongly impacted the spectra, color, and stability of the Dp and Pt anthocyanins. Cis acylated pigments exhibited the greatest λmax in all pH, as much as 66 nm greater than their trans counterparts, showing bluer hues. Cis acylation seemed to reduce hydration across pH, increasing color intensity, while trans acylation generally improved color retention over time. Dp-3-cis-p-cou-rut-5-glu exhibited blue hues even in pH 5 (C*ab = 10, hab = 256° where anthocyanins are typically colorless. Cis or trans double bond configurations of the acylating group affected anthocyanin spectral and stability properties.

Unravelling The Mechanism of Basic Aqueous Methanol Dehydrogenation Catalyzed By Ru-PNP Pincer Complexes

DEFF Research Database (Denmark)

Alberico, Elisabetta; Lennox, Alastair J. J.; Vogt, Lydia K.

2016-01-01

Ruthenium PNP complex 1a (RuH(CO)Cl(HN(C2H4Pi-Pr2)2)) represents a state-of-the-art catalyst for low-temperature (methanol dehydrogenation to H2 and CO2. Herein, we describe an investigation that combines experiment, spectroscopy, and theory to provide a mechanistic rationale...

Effects of ghrelin and des-acyl ghrelin on neurogenesis of the rat fetal spinal cord

International Nuclear Information System (INIS)

Sato, Miho; Nakahara, Keiko; Goto, Shintaro; Kaiya, Hiroyuki; Miyazato, Mikiya; Date, Yukari; Nakazato, Masamitsu; Kangawa, Kenji; Murakami, Noboru

2006-01-01

Expressions of the growth hormone secretagogue receptor (GHS-R) mRNA and its protein were confirmed in rat fetal spinal cord tissues by RT-PCR and immunohistochemistry. In vitro, over 3 nM ghrelin and des-acyl ghrelin induced significant proliferation of primary cultured cells from the fetal spinal cord. The proliferating cells were then double-stained using antibodies against the neuronal precursor marker, nestin, and the cell proliferation marker, 5-bromo-2'-deoxyuridine (BrdU), and the nestin-positive cells were also found to be co-stained with antibody against GHS-R. Furthermore, binding studies using [ 125 I]des-acyl ghrelin indicated the presence of a specific binding site for des-acyl ghrelin, and confirmed that the binding was displaced with unlabeled des-acyl ghrelin or ghrelin. These results indicate that ghrelin and des-acyl ghrelin induce proliferation of neuronal precursor cells that is both dependent and independent of GHS-R, suggesting that both ghrelin and des-acyl ghrelin are involved in neurogenesis of the fetal spinal cord

Ni–Ta–O mixed oxide catalysts for the low temperature oxidative dehydrogenation of ethane to ethylene

KAUST Repository

Zhu, Haibo; Rosenfeld, Devon C.; Anjum, Dalaver H.; Sangaru, Shiv; Saih, Youssef; Ould-Chikh, Samy; Basset, Jean-Marie

2015-01-01

The "wet" sol-gel and "dry" solid-state methods were used to prepare Ni-Ta-O mixed oxide catalysts. The resulting Ni-Ta oxides exhibit high activity and selectivity for the low temperature oxidative dehydrogenation of ethane to ethylene. The Ta

Acyl Meldrum's acid derivatives: application in organic synthesis

International Nuclear Information System (INIS)

Janikowska, K; Rachoń, J; Makowiec, S

2014-01-01

This review is focused on an important class of Meldrum's acid derivatives commonly known as acyl Meldrum's acids. The preparation methods of these compounds are considered including the recently proposed and rather rarely used ones. The chemical properties of acyl Meldrum's acids are described in detail, including thermal stability and reactions with various nucleophiles. The possible mechanisms of these transformations are analyzed. The bibliography includes 134 references

Long-chain acyl-CoA-dependent regulation of gene expression in bacteria, yeast and mammals

DEFF Research Database (Denmark)

Black, P N; Færgeman, Nils J.; DiRusso, C C

2000-01-01

). Both repression and activation are dependent upon the function of either of the acyl-CoA synthetases Faa1p or Faa4p. In mammals, purified hepatocyte nuclear transcription factor 4alpha (HNF-4alpha) like E. coli FadR, binds long chain acyl-CoA directly. Coexpression of HNF-4alpha and acyl-CoA synthetase...

Non-isothermal synergetic catalytic effect of TiF{sub 3} and Nb{sub 2}O{sub 5} on dehydrogenation high-energy ball milled MgH{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Zhang, Tiebang, E-mail: tiebangzhang@nwpu.edu.cn; Hou, Xiaojiang; Hu, Rui; Kou, Hongchao; Li, Jinshan

2016-11-01

MgH{sub 2}-M (M = TiF{sub 3} or Nb{sub 2}O{sub 5} or both of them) composites prepared by high-energy ball milling are used in this work to illustrate the dehydrogenation behavior of MgH{sub 2} with the addition of catalysts. The phase compositions, microstructures, particle morphologies and distributions of MgH{sub 2} with catalysts have been evaluated. The non-isothermal synergetic catalytic-dehydrogenation effect of TiF{sub 3} and Nb{sub 2}O{sub 5} evaluated by differential scanning calorimetry gives the evidences that the addition of catalysts is an effective strategy to destabilize MgH{sub 2} and reduce hydrogen desorption temperatures and activation energies. Depending on additives, the desorption peak temperatures of catalyzed MgH{sub 2} reduce from 417 °C to 341 °C for TiF{sub 3} and from 417 °C to 336 °C for Nb{sub 2}O{sub 5}, respectively. The desorption peak temperature reaches as low as 310 °C for MgH{sub 2} catalyzed by TiF{sub 3} coupling with Nb{sub 2}O{sub 5}. The non-isothermal synergetic catalytic effect of TiF{sub 3} and Nb{sub 2}O{sub 5} is mainly attributed to electronic exchange reactions with hydrogen molecules, which improve the recombination of hydrogen atoms during dehydrogenation process of MgH{sub 2}. - Highlights: • Catalytic surface for MgH{sub 2} is achieved by high-energy ball milling. • Non-isothermal dehydrogenation behavior of MgH{sub 2} with TiF{sub 3} and/or Nb{sub 2}O{sub 5} is illustrated. • Dehydrogenation activation energies of synergetic catalyzed MgH{sub 2} are obtained. • Synergetic catalytic-dehydrogenation mechanism of TiF{sub 3} and Nb{sub 2}O{sub 5} is proposed.

Role of acylCoA binding protein in acylCoA transport, metabolism and cell signaling

DEFF Research Database (Denmark)

Knudsen, J; Jensen, M V; Hansen, J K

1999-01-01

and pool formation and therefore also for the function of LCAs as metabolites and regulators of cellular functions [1]. The major factors controlling the free concentration of cytosol long chain acylCoA ester (LCA) include ACBP [2], sterol carrier protein 2 (SCP2) [3] and fatty acid binding protein (FABP...

Chromium oxide over activated carbons as catalyst for oxidative dehydrogenation of isobutane

International Nuclear Information System (INIS)

Cardenas, Agobardo; Acero Fabio N; Diaz, Jose de J

2007-01-01

The functional groups at the surface of an activated carbon Norit ROX 08 were modified through reaction with nitric acid, 8.8% 0 2 in N 2 and H 2 . the modified carbons were impregnated with a CrO 3 aqueous solution and used in the oxidative dehydrogenation of isobutane to isobutene (ODH). The formation of isobutene was observed at 443 k, with a maximum selectivity of 85% and a yield of 9%

Des-acyl ghrelin prevents heatstroke-like symptoms in rats exposed to high temperature and high humidity.

Science.gov (United States)

Inoue, Yoshiyuki; Hayashi, Yujiro; Kangawa, Kenji; Suzuki, Yoshihiro; Murakami, Noboru; Nakahara, Keiko

2016-02-26

We have shown previously that des-acyl ghrelin decreases body temperature in rats through activation of the parasympathetic nervous system. Here we investigated whether des-acyl ghrelin ameliorates heatstroke in rats exposed to high temperature. Peripheral administration of des-acyl ghrelin significantly attenuated hyperthermia induced by exposure to high-temperature (35°C) together with high humidity (70-80%). Although biochemical analysis revealed that exposure to high temperature significantly increased hematocrit and the serum levels of aspartate amino transferase (AST), alanine transaminase (ALT), blood urea nitrogen (BUN), creatinine and electrolytes (Na(+), K(+), Cl(-)), most of these heatstroke-associated reactions were significantly reduced by treatment with des-acyl ghrelin. The level of des-acyl ghrelin in plasma was also found to be significantly increased under high-temperature conditions. These results suggest that des-acyl ghrelin could be useful for preventing heatstroke under high temperature condition. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Analysis of glomerulosclerosis and atherosclerosis in lecithin cholesterol acyltransferase-deficient mice.

Science.gov (United States)

Lambert, G; Sakai, N; Vaisman, B L; Neufeld, E B; Marteyn, B; Chan, C C; Paigen, B; Lupia, E; Thomas, A; Striker, L J; Blanchette-Mackie, J; Csako, G; Brady, J N; Costello, R; Striker, G E; Remaley, A T; Brewer, H B; Santamarina-Fojo, S

2001-05-04

To evaluate the biochemical and molecular mechanisms leading to glomerulosclerosis and the variable development of atherosclerosis in patients with familial lecithin cholesterol acyl transferase (LCAT) deficiency, we generated LCAT knockout (KO) mice and cross-bred them with apolipoprotein (apo) E KO, low density lipoprotein receptor (LDLr) KO, and cholesteryl ester transfer protein transgenic mice. LCAT-KO mice had normochromic normocytic anemia with increased reticulocyte and target cell counts as well as decreased red blood cell osmotic fragility. A subset of LCAT-KO mice accumulated lipoprotein X and developed proteinuria and glomerulosclerosis characterized by mesangial cell proliferation, sclerosis, lipid accumulation, and deposition of electron dense material throughout the glomeruli. LCAT deficiency reduced the plasma high density lipoprotein (HDL) cholesterol (-70 to -94%) and non-HDL cholesterol (-48 to -85%) levels in control, apoE-KO, LDLr-KO, and cholesteryl ester transfer protein-Tg mice. Transcriptome and Western blot analysis demonstrated up-regulation of hepatic LDLr and apoE expression in LCAT-KO mice. Despite decreased HDL, aortic atherosclerosis was significantly reduced (-35% to -99%) in all mouse models with LCAT deficiency. Our studies indicate (i) that the plasma levels of apoB containing lipoproteins rather than HDL may determine the atherogenic risk of patients with hypoalphalipoproteinemia due to LCAT deficiency and (ii) a potential etiological role for lipoproteins X in the development of glomerulosclerosis in LCAT deficiency. The availability of LCAT-KO mice characterized by lipid, hematologic, and renal abnormalities similar to familial LCAT deficiency patients will permit future evaluation of LCAT gene transfer as a possible treatment for glomerulosclerosis in LCAT-deficient states.

Acylated flavonol glycosides from Larix needles

NARCIS (Netherlands)

Niemann, Gerard J.

2006-01-01

Kaempferol-3-p-coumarylglucoside (KCG) was isolated from ether fractions of acetone-extracted freeze-dried needles of all larch species investigated. In each case, KCG was found as one of the main flavonoids, whereas often a variety of closely related, acylated flavonoids was present in either

A simple, effective, green method for regioselective 3-acylation of unprotected indoles

DEFF Research Database (Denmark)

Tran, Phuong Huong; Tran, Hai N.; Hansen, Poul Erik

2015-01-01

A fast and green method is developed for regioselective acylation of indoles in the 3-position without the need for protection of the NH position. The method is based on Friedel-Crafts acylation using acid anhydrides. The method has been optimized, and Y(OTf)3 in catalytic amounts is found...

Hydrogen peroxide modified Mg-Al-O oxides supported Pt-Sn catalysts for paraffin dehydrogenation

NARCIS (Netherlands)

Lai, Y.; He, Songbo; Luo, S.; Bi, W.; Li, XianRu; Sun, Chenglin; Seshan, Kulathuiyer

2015-01-01

In this work, a new method to prepare Mg–Al–O oxide by co-precipitation method with addition of H2O2 was developed. The application of Mg–Al–O as a support of Pt–Sn catalysts for paraffin dehydrogenation was investigated. Characterization results indicated that modification of H2O2 (i) enlarged the

Commelinid Monocotyledon Lignins Are Acylated by p-Coumarate1[OPEN

Science.gov (United States)

Free, Heather C.A.; Smith, Bronwen G.

2018-01-01

Commelinid monocotyledons are a monophyletic clade differentiated from other monocotyledons by the presence of cell wall-bound ferulate and p-coumarate. The Poaceae, or grass family, is a member of this group, and most of the p-coumarate in the cell walls of this family acylates lignin. Here, we isolated and examined lignified cell wall preparations from 10 species of commelinid monocotyledons from nine families other than Poaceae, including species from all four commelinid monocotyledon orders (Poales, Zingiberales, Commelinales, and Arecales). We showed that, as in the Poaceae, lignin-linked p-coumarate occurs exclusively on the hydroxyl group on the γ-carbon of lignin unit side chains, mostly on syringyl units. Although the mechanism of acylation has not been studied directly in these species, it is likely to be similar to that in the Poaceae and involve BAHD acyl-coenzyme A:monolignol transferases. PMID:29724771

An in vitro fatty acylation assay reveals a mechanism for Wnt recognition by the acyltransferase Porcupine.

Science.gov (United States)

Asciolla, James J; Miele, Matthew M; Hendrickson, Ronald C; Resh, Marilyn D

2017-08-18

Wnt proteins are a family of secreted signaling proteins that play key roles in regulating cell proliferation in both embryonic and adult tissues. Production of active Wnt depends on attachment of palmitoleate, a monounsaturated fatty acid, to a conserved serine by the acyltransferase Porcupine (PORCN). Studies of PORCN activity relied on cell-based fatty acylation and signaling assays as no direct enzyme assay had yet been developed. Here, we present the first in vitro assay that accurately recapitulates PORCN-mediated fatty acylation of a Wnt substrate. The critical feature is the use of a double disulfide-bonded Wnt peptide that mimics the two-dimensional structure surrounding the Wnt acylation site. PORCN-mediated Wnt acylation was abolished when the Wnt peptide was treated with DTT, and did not occur with a linear (non-disulfide-bonded) peptide, or when the double disulfide-bonded Wnt peptide contained Ala substituted for the Ser acylation site. We exploited this in vitro Wnt acylation assay to provide direct evidence that the small molecule LGK974, which is in clinical trials for managing Wnt-driven tumors, is a bona fide PORCN inhibitor whose IC 50 for inhibition of Wnt fatty acylation in vitro closely matches that for inhibition of Wnt signaling. Side-by-side comparison of PORCN and Hedgehog acyltransferase (HHAT), two enzymes that attach 16-carbon fatty acids to secreted proteins, revealed that neither enzyme will accept the other's fatty acyl-CoA or peptide substrates. These findings illustrate the unique enzyme-substrate selectivity exhibited by members of the membrane-bound O -acyl transferase family. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Ni–Ta–O mixed oxide catalysts for the low temperature oxidative dehydrogenation of ethane to ethylene

KAUST Repository

Zhu, Haibo

2015-09-01

The "wet" sol-gel and "dry" solid-state methods were used to prepare Ni-Ta-O mixed oxide catalysts. The resulting Ni-Ta oxides exhibit high activity and selectivity for the low temperature oxidative dehydrogenation of ethane to ethylene. The Ta/(Ni + Ta) atomic ratios (varying from 0 to 0.11 in "wet" sol-gel method, and from 0 to 0.20 in "dry" solid-state method) as well as the preparation methods used in the synthesis, play important roles in controlling catalyst structure, activity, selectivity and stability in the oxidative dehydrogenation of ethane. Electron microscopy characterizations (TEM, EELS mapping, and HAADF-STEM) clearly demonstrate that the Ta atoms are inserted into NiO crystal lattice, resulting in the formation of a new Ni-Ta oxide solid solution. More Ta atoms are found to be located at the lattice sites of crystal surface in sol-gel catalyst. While, a small amount of thin layer of Ta2O5 clusters are detected in solid-state catalyst. Further characterization by XRD, N2 adsorption, SEM, H2-TPR, XPS, and Raman techniques reveal different properties of these two Ni-Ta oxides. Due to the different properties of the Ni-Ta oxide catalysts prepared by two distinct approaches, they exhibit different catalytic behaviors in the ethane oxidative dehydrogenation reaction at low temperature. Thus, the catalytic performance of Ni-Ta-O mixed oxide catalysts can be systematically modified and tuned by selecting a suitable synthesis method, and then varying the Ta content. ©2015 Elsevier Inc. All rights reserved.

A Novel 3-Sulfinopropionyl Coenzyme A (3SP-CoA) Desulfinase from Advenella mimigardefordensis Strain DPN7T Acting as a Key Enzyme during Catabolism of 3,3′-Dithiodipropionic Acid Is a Member of the Acyl-CoA Dehydrogenase Superfamily

Science.gov (United States)

Schürmann, Marc; Deters, Anika; Wübbeler, Jan Hendrik

2013-01-01

3-Sulfinopropionyl coenzyme A (3SP-CoA) desulfinase (AcdDPN7) is a new desulfinase that catalyzes the sulfur abstraction from 3SP-CoA in the betaproteobacterium Advenella mimigardefordensis strain DPN7T. During investigation of a Tn5::mob-induced mutant defective in growth on 3,3′-dithiodipropionate (DTDP) and also 3-sulfinopropionate (3SP), the transposon insertion was mapped to an open reading frame with the highest homology to an acyl-CoA dehydrogenase (Acd) from Burkholderia phenoliruptrix strain BR3459a (83% identical and 91% similar amino acids). An A. mimigardefordensis Δacd mutant was generated and verified the observed phenotype of the Tn5::mob-induced mutant. For enzymatic studies, AcdDPN7 was heterologously expressed in Escherichia coli BL21(DE3)/pLysS by using pET23a::acdDPN7. The purified protein is yellow and contains a noncovalently bound flavin adenine dinucleotide (FAD) cofactor, as verified by high-performance liquid chromatography–electrospray ionization mass spectrometry (HPLC-ESI-MS) analyses. Size-exclusion chromatography revealed a native molecular mass of about 173 kDa, indicating a homotetrameric structure (theoretically 179 kDa), which is in accordance with other members of the acyl-CoA dehydrogenase superfamily. In vitro assays unequivocally demonstrated that the purified enzyme converted 3SP-CoA into propionyl-CoA and sulfite (SO32−). Kinetic studies of AcdDPN7 revealed a Vmax of 4.19 μmol min−1 mg−1, an apparent Km of 0.013 mM, and a kcat/Km of 240.8 s−1 mM−1 for 3SP-CoA. However, AcdDPN7 is unable to perform a dehydrogenation, which is the usual reaction catalyzed by members of the acyl-CoA dehydrogenase superfamily. Comparison to other known desulfinases showed a comparably high catalytic efficiency of AcdDPN7 and indicated a novel reaction mechanism. Hence, AcdDPN7 encodes a new desulfinase based on an acyl-CoA dehydrogenase (EC 1.3.8.x) scaffold. Concomitantly, we identified the gene product that is responsible for

In situ electrochemical XRD study of (de)hydrogenation of MgyTi100-y thin films

NARCIS (Netherlands)

Vermeulen, P.; Wondergem, H.J.; Graat, P.C.J.; Borsa, D.M.; Schreuders, H.; Dam, B.; Griessen, R.; Notten, P.H.L.

2008-01-01

X-ray diffraction and electrochemical (de)hydrogenation were performed in situ to monitor the symmetry of the unit cells of MgyTi100-y thin film alloys (with 70 to 90 at.% Mg) along the pressure composition isotherms at room temperature. The diffraction patterns show that the crystal structures of

Tailored Formation of N-Doped Nanoarchitectures by Diffusion-Controlled on-Surface (Cyclo)-Dehydrogenation of Heteroaromatics

Czech Academy of Sciences Publication Activity Database

Pinardi, A. L.; Otero-Irurueta, G.; Palacio, I.; Martinez, J. I.; Sánchez-Sánchez, C.; Tello, M.; Rogero, C.; Cossaro, A.; Preobrajenski, A.; Gomez-Lor, B.; Jančařík, Andrej; Stará, Irena G.; Starý, Ivo; Lopez, M. F.; Méndez, J.; Martin-Gago, J. A.

2013-01-01

Roč. 7, č. 4 (2013), s. 3676-3684 ISSN 1936-0851 R&D Projects: GA ČR(CZ) GAP207/10/2207 Institutional support: RVO:61388963 Keywords : surface-assisted dehydrogenation * dibenzo[5]helicene * N-doped nanographene * heteroaromatic polymer Subject RIV: CC - Organic Chemistry Impact factor: 12.033, year: 2013

Attempts to Synthesize 3-acyl-4-hydroxycoumarins from Meldrum’s acid -- and Related Chemistry

OpenAIRE

Ye, Fengbin; Tropp, Kristin; Yu, Yiting

2007-01-01

We start our synthetic work with the acylation of Meldrum’s acid to get three different 5-acyl Meldrum’s acids. These compounds are attacked by various nucleophiles containing different hetero atoms to obtain β-ketoesters, β-ketoamides and the corresponding β-keto-phosphorus compounds respectively. New β-ketoamides could be synthesized and characterized. The reaction of acylated Meldrum’s acid and diphenylphosphine did not lead to the expected β-keto-phosphide compound, but the resulting prod...

Significance of β-dehydrogenation in ethanol electro-oxidation on platinum doped with Ru, Rh, Pd, Os and Ir.

Science.gov (United States)

Sheng, Tian; Lin, Wen-Feng; Hardacre, Christopher; Hu, P

2014-07-14

In the exploration of highly efficient direct ethanol fuel cells (DEFCs), how to promote the CO2 selectivity is a key issue which remains to be solved. Some advances have been made, for example, using bimetallic electrocatalysts, Rh has been found to be an efficient additive to platinum to obtain high CO2 selectivity experimentally. In this work, the mechanism of ethanol electrooxidation is investigated using the first principles method. It is found that CH3CHOH* is the key intermediate during ethanol electrooxidation and the activity of β-dehydrogenation is the rate determining factor that affects the completeness of ethanol oxidation. In addition, a series of transition metals (Ru, Rh, Pd, Os and Ir) are alloyed on the top layer of Pt(111) in order to analyze their effects. The elementary steps, α-, β-C-H bond and C-C bond dissociations, are calculated on these bimetallic M/Pt(111) surfaces and the formation potential of OH* from water dissociation is also calculated. We find that the active metals increase the activity of β-dehydrogenation but lower the OH* formation potential resulting in the active site being blocked. By considering both β-dehydrogenation and OH* formation, Ru, Os and Ir are identified to be unsuitable for the promotion of CO2 selectivity and only Rh is able to increase the selectivity of CO2 in DEFCs.

The influence of water on the oxygen-silver interaction and on the oxidative dehydrogenation of methanol

NARCIS (Netherlands)

Lefferts, Leon; Van Ommen, Jan G.; Ross, Julian R H

1988-01-01

Experiments carried out using temperature-programmed desorption and reduction could detect no interaction between water and silver at 200 °C. However, separate experiments on the effect of water on the oxidative dehydrogenation of methanol over a silver catalyst showed that water affected the

Accumulation of N-acyl-ethanolamine phospholipids in rat brains during post-decapitative ischemia

DEFF Research Database (Denmark)

Moesgaard, B.; Hansen, Harald S.; Jaroszewski, J.W.

1999-01-01

-phospho(N-acyl)-ethanolamine (NAPE(PLAS)), respectively, by spiking with authentic materials. Additionally, the identification was verified by thin-layer chromatography, which also showed the accumulation of N-acyl-ethanolamine phospholipids. The use of K-EDTA instead of the commonly used Cs...

Surface characterizations of TiH{sub 2} powders before and after dehydrogenation

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yeguang [School of Aeronautics & Astronautics, Sichuan University, Chengdu, 610065 (China); Wang, Chunming; Liu, Yang; Liu, Shaopeng; Xiao, Sufen [College of Materials Science and Engineering, Sichuan University, Chengdu, 610065 (China); Chen, Yungui, E-mail: ygchen60@aliyun.com [School of Aeronautics & Astronautics, Sichuan University, Chengdu, 610065 (China); College of Materials Science and Engineering, Sichuan University, Chengdu, 610065 (China)

2017-07-15

Highlights: • Oxides characteristics of TiH{sub 2} and HDH-Ti are investigated by XPS depth profiles. • The relative contents of TiO{sub 2}, Ti{sub 2}O{sub 3} and TiO are lower after dehydrogenation. • The decrease of Ti{sub 2}O{sub 3} is more remarkable followed by TiO{sub 2}, TiO after dehydrogenation. • The H atoms of TiH{sub 2} react preferentially with Ti{sub 2}O{sub 3} followed by TiO{sub 2}, TiO. - Abstract: The oxide film of TiH{sub 2} and HDH-Ti powder are investigated using X-ray photoelectron spectroscopy (XPS). The XPS depth profiles indicate that there exists mainly Ti{sup 2+}, Ti{sup 3+}, Ti{sup 4+} and Ti{sup 0} on TiH{sub 2} and HDH-Ti surface. The intensities of Ti 2p decrease for Ti{sup 4+}, first increase and then decrease for Ti{sup 3+} and Ti{sup 2+}, and increase all the time for Ti{sup 0} in the surface layer of TiH{sub 2} and HDH-Ti with the sputtering depth increasing. The relative fractions of TiO{sub 2}, Ti{sub 2}O{sub 3} and TiO for the Ti 2p of TiH{sub 2} and HDH-Ti first decrease and then slow down with the sputtering depth increasing. Meanwhile, the relative fractions of TiO{sub 2} and TiO of HDH-Ti are lower than that of TiH{sub 2} after the sputtering depth of about 5 nm, and the fraction of Ti{sub 2}O{sub 3} of HDH-Ti is always lower that of TiH{sub 2}. In addition, the decrease of Ti{sub 2}O{sub 3} is much pronounced, followed by TiO{sub 2} and TiO before and after dehydrogenation when the sputtering depth is more than 5 nm. The XPS depth profiles and calculation results suggest that the release of H atoms removes the part of oxygen on TiH{sub 2} surface, which results in the thinner oxide layer and low oxygen content of HDH-Ti powder.

Plasma levels of acylated and total ghrelin in pediatric patients with chronic kidney disease.

Science.gov (United States)

Naufel, Maria Fernanda Soares; Bordon, Milena; de Aquino, Talita Marques; Ribeiro, Eliane Beraldi; de Abreu Carvalhaes, João Tomás

2010-12-01

This cross-sectional study set out to compare total and acyl ghrelin levels in children with mild chronic kidney disease (CKD) undergoing conservative treatment (n = 19) with children with end-stage renal disease (ESRD) undergoing hemodialysis (n = 24), and with healthy controls (n = 20). The relationship between ghrelin levels and parameters of renal function, nutritional status, and selective hormones were investigated. ESRD patients had higher total ghrelin levels than those with mild CKD or control individuals. However, acyl ghrelin did not differ between groups, indicating that the excess circulating ghrelin was desacylated. Since desacyl ghrelin has been shown to inhibit appetite, increased levels might contribute to protein-energy wasting in pediatric renal patients. When all 43 renal patients were combined, multiple regression analysis found age and glomerular filtration rate (GFR) to be significant negative predictors of total ghrelin. Acyl ghrelin was influenced negatively by age and positively by energy intake. Acyl to total ghrelin ratio related positively to GFR and energy intake. The results indicate that total but not acyl ghrelin is influenced by low GFR in children with CKD and suggests that ghrelin activation may be impaired in these patients. Since energy intake is a positive predictor of acyl ghrelin, the physiological control of ghrelin secretion appears to be altered in pediatric renal patients.

Enantioselective N-Heterocyclic Carbene Catalysis via the Dienyl Acyl Azolium.

Science.gov (United States)

Gillard, Rachel M; Fernando, Jared E M; Lupton, David W

2018-04-16

Herein we report the enantioselective N-heterocyclic carbene catalyzed (4+2) annulation of the dienyl acyl azolium with enolates. The reaction exploits readily accessible acyl fluorides and TMS enol ethers to give a range of highly enantio- and diastereo-enriched cyclohexenes (most >97:3 er and >20:1 dr). The reaction was found to require high nucleophilicity NHC catalysts with mechanistic studies supporting a stepwise 1,6-addition/β-lactonization. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oxidative Dehydrogenation of n-Butenes to 1,3-Butadiene over Bismuth Molybdate and Ferrite Catalysts: A Review

KAUST Repository

Hong, Eunpyo; Park, Jung-Hyun; Shin, Chae-Ho

2015-01-01

1,3-Butadiene, an important raw material for a variety of chemical products, can be produced via the oxidative dehydrogenation (ODH) of n-butenes over multicomponent oxide catalysts based on bismuth molybdates and ferrites. In this review, the basic

Oxidative dehydrogenation of ethane over vanadium supported on mesoporous materials of M41S family

Czech Academy of Sciences Publication Activity Database

Čapek, J.; Adam, J.; Grygar, Tomáš; Bulánek, R.; Vradman, L.; Košová-Kučerová, G.; Čičmanec, P.; Knotek, P.

2008-01-01

Roč. 342, 1-2 (2008), s. 99-106 ISSN 0926-860X Grant - others:GA ČR(CZ) GP104/07/P038 Program:GP Institutional research plan: CEZ:AV0Z40320502 Keywords : oxidative dehydrogenation * ethane * vanadium * mesoporous materials Subject RIV: CA - Inorganic Chemistry Impact factor: 3.190, year: 2008

Synthesis of O-[11C]acetyl CoA, O-[11C]acetyl-L-carnitine, and L-[11C]carnitine labelled in specific positions, applied in PET studies on rhesus monkey

International Nuclear Information System (INIS)

Jacobson, Gunilla B.; Watanabe, Yasuyoshi; Valind, Sven; Kuratsune, Hirohiko; Laangstroem, Bengt

1997-01-01

The syntheses of L-carnitine, O-acetyl CoA, and O-acetyl-L-carnitine labelled with 11 C at the 1- or 2-position of the acetyl group or the N-methyl position of carnitine, using the enzymes acetyl CoA synthetase and carnitine acetyltransferase, are described. With a total synthesis time of 45 min, O-[1- 11 C]acetyl CoA and O-[2- 11 C]acetyl CoA was obtained in 60-70% decay-corrected radiochemical yield, and O-[1- 11 C]acetyl-L-carnitine and O-[2- 11 C]acetyl-L-carnitine in 70-80% yield, based on [1- 11 C]acetate or [2- 11 C]acetate, respectively. By an N-methylation reaction with [ 11 C]methyl iodide, L-[methyl- 11 C]carnitine was obtained within 30 min, and O-acetyl-L-[methyl- 11 C]carnitine within 40 min, giving a decay-corrected radiochemical yield of 60% and 40-50%, respectively, based on [ 11 C]methyl iodide. Initial data of the kinetics of the different 11 C-labelled L-carnitine and acetyl-L-carnitines in renal cortex of anaesthetized monkey (Macaca mulatta) are presented

Characterization of acyl-coenzyme A:diacylglycerol acyltransferase (DGAT) enzyme of human small intestine.

Science.gov (United States)

Hiramine, Yasushi; Tanabe, Toshizumi

2011-06-01

Acyl-coenzyme A:diacylglycerol acyltransferase (DGAT) enzyme plays a significant role in dietary triacylglycerol (TAG) absorption in the small intestine. However, the characteristics of human intestinal DGAT enzyme have not been examined in detail. The aim of our study was to characterize the human intestinal DGAT enzyme by examining acyl-CoA specificity, temperature dependency, and selectivity for 1,2-diacylglycerol (DAG) or 1,3-DAG. We detected DGAT activity of human intestinal microsome and found that the acyl-CoA specificity and temperature dependency of intestinal DGAT coincided with those of recombinant human DGAT1. To elucidate the selectivity of human intestinal DGAT to 1,2-DAG or 1,3-DAG, we conducted acyl-coenzyme A:monoacylglycerol acyltransferase assays using 1- or 2-monoacylglycerol (MAG) as substrates. When 2-MAG was used as acyl acceptor, both 1,2-DAG and TAG were generated; however, when 1-MAG was used, 1,3-DAG was predominantly observed and little TAG was detected. These findings suggest that human small intestinal DGAT, which is mainly encoded by DGAT1, utilizes 1,2-DAG as the substrate to form TAG. This study will contribute to understand the lipid absorption profile in the small intestine.

Promoting effect of active carbons on methanol dehydrogenation on sodium carbonate - hydrogen spillover

OpenAIRE

Su, S.; Prairie, M.; Renken, A.

1993-01-01

Methanol dehydrogenation to formaldehyde was conducted in a fixed-bed flow reactor with sodium carbonate catalyst mixed with active carbons or transition metals. The additives promoted the reaction rate at 880-970 K without modifying formaldehyde selectivity. This effect increases with increasing carbon content in the carbon-carbonate mixture. Activation energy of methanol conversion is the same for the mixture and the carbonate alone. Temperature-programmed desorption experiments showed that...

Adsorption and diffusion of H and NH{sub x} as key steps of the NH{sub x} dehydrogenation reaction at the V{sub 2}O{sub 5} (010) surface

Energy Technology Data Exchange (ETDEWEB)

Gruber, Mathis; Hermann, Klaus [Fritz-Haber-Institut der MPG, und Sfb 546, Berlin (Germany)

2009-07-01

Various selective oxidation reactions as the selective catalytic reduction (SCR) of NO{sub x} or the ammoxidation of propane/propene to acrylonitrile are processed on vanadium based metal-oxide catalysts in the presence of ammonia. In the reactions the intermediates NH{sub 2}, NH{sub 3}, and NH{sub 4} are involved indicating that the adsorption and dehydrogenation of NH{sub x}, x < 4, are important steps. We have performed theoretical studies of corresponding reaction steps where the catalyst is simulated by a finite section of the V{sub 2}O{sub 5} (010) surface. The calculations apply density-functional theory combined with clusters modeling the adsorbate system. The substrate lowers corresponding dehydrogenation energies considerably compared with values for the gas phase reaction. However, the lowering is too small to make dehydrogenation of NH{sub 3} likely to happen. Our results on the role of oxygen vacancies for the dehydrogenation indicate that such surface defects become important for the reaction. Besides the energetics also the diffusion at the surface influences the reaction. A nudged elastic band (NEB) routine has been implemented to evaluate diffusion paths and barriers. Hydrogen diffusion on the surface will be discussed and additional examples for NH{sub x} diffusion will be shown. Based on these results possible reaction scenarios for the dehydrogenation reaction will be presented.

Homozygosity for a severe novel medium-chain acyl-CoA dehydrogenase (MCAD) mutation IVS3-1G > C that leads to introduction of a premature termination codon by complete missplicing of the MCAD mRNA and is associated with phenotypic diversity ranging from sudden neonatal death to asymptomatic status

DEFF Research Database (Denmark)

Korman, Stanley H; Gutman, Alisa; Brooks, Rivka

2004-01-01

Virtually all patients with medium-chain acyl-CoA dehydrogenase deficiency (MCADD) are homozygous or compound heterozygous for the 985A > G mutation, which limits the study of a possible genotype/phenotype correlation. A newborn Palestinian infant died suddenly on the second day of life. A previo...

Suppression of acyl migration in enzymatic production of structured lipids through temperature programming

DEFF Research Database (Denmark)

Yang, Tiankui; Fruekilde, Maj-Britt; Xu, Xuebing

2005-01-01

Acyl migration in the glycerol backbone often leads to the increase of by-products in the enzymatic production of specific structured lipids. Acyl migration is a thermodynamic process and is very difficult to stop fully in actual reactions. The objective of this study was to investigate...

Reaction of tantalum-alkyne complexes with isocyanates or acyl cyanides

International Nuclear Information System (INIS)

Kataoka, Yasutaka; Oguchi, Yoshiyuki; Yoshizumi, Kazuyuki; Miwatashi, Seiji; Takai, Kazuhiko; Utimoto, Kiitiro

1992-01-01

Treatment of alkynes with low-valent tantalum derived from TiCl 5 and zinc produces tantalum-alkyne complexes (not isolated), which react in situ with phenyl isocyanate (or butyl isocyanate) to give (E)-α, β-unsaturated amides stereoselectively. The tantalum-alkyne complexes also react with acyl cyanides in the presence of BF 3 ·OEt 2 to give α-cyanohydrins. In both reactions, filtration of the reaction mixture containing the tantalum-alkyne complexes before addition of isocyanates (or acyl cyanides) is indispensable to obtain good yields. (author)

Thermophilic Coenzyme B12-Dependent Acyl Coenzyme A (CoA) Mutase from Kyrpidia tusciae DSM 2912 Preferentially Catalyzes Isomerization of (R)-3-Hydroxybutyryl-CoA and 2-Hydroxyisobutyryl-CoA.

Science.gov (United States)

Weichler, Maria-Teresa; Kurteva-Yaneva, Nadya; Przybylski, Denise; Schuster, Judith; Müller, Roland H; Harms, Hauke; Rohwerder, Thore

2015-07-01

The recent discovery of a coenzyme B12-dependent acyl-coenzyme A (acyl-CoA) mutase isomerizing 3-hydroxybutyryl- and 2-hydroxyisobutyryl-CoA in the mesophilic bacterium Aquincola tertiaricarbonis L108 (N. Yaneva, J. Schuster, F. Schäfer, V. Lede, D. Przybylski, T. Paproth, H. Harms, R. H. Müller, and T. Rohwerder, J Biol Chem 287:15502-15511, 2012, http://dx.doi.org/10.1074/jbc.M111.314690) could pave the way for a complete biosynthesis route to the building block chemical 2-hydroxyisobutyric acid from renewable carbon. However, the enzyme catalyzes only the conversion of the stereoisomer (S)-3-hydroxybutyryl-CoA at reasonable rates, which seriously hampers an efficient combination of mutase and well-established bacterial poly-(R)-3-hydroxybutyrate (PHB) overflow metabolism. Here, we characterize a new 2-hydroxyisobutyryl-CoA mutase found in the thermophilic knallgas bacterium Kyrpidia tusciae DSM 2912. Reconstituted mutase subunits revealed highest activity at 55°C. Surprisingly, already at 30°C, isomerization of (R)-3-hydroxybutyryl-CoA was about 7,000 times more efficient than with the mutase from strain L108. The most striking structural difference between the two mutases, likely determining stereospecificity, is a replacement of active-site residue Asp found in strain L108 at position 117 with Val in the enzyme from strain DSM 2912, resulting in a reversed polarity at this binding site. Overall sequence comparison indicates that both enzymes descended from different prokaryotic thermophilic methylmalonyl-CoA mutases. Concomitant expression of PHB enzymes delivering (R)-3-hydroxybutyryl-CoA (beta-ketothiolase PhaA and acetoacetyl-CoA reductase PhaB from Cupriavidus necator) with the new mutase in Escherichia coli JM109 and BL21 strains incubated on gluconic acid at 37°C led to the production of 2-hydroxyisobutyric acid at maximal titers of 0.7 mM. Measures to improve production in E. coli, such as coexpression of the chaperone MeaH and repression of

Acute effect of exercise intensity and duration on acylated ghrelin and hunger in men.

Science.gov (United States)

Broom, David R; Miyashita, Masashi; Wasse, Lucy K; Pulsford, Richard; King, James A; Thackray, Alice E; Stensel, David J

2017-03-01

Acute exercise transiently suppresses the orexigenic gut hormone acylated ghrelin, but the extent to which exercise intensity and duration determine this response is not fully understood. The effects of manipulating exercise intensity and duration on acylated ghrelin concentrations and hunger were examined in two experiments. In experiment one, nine healthy males completed three, 4-h conditions (control, moderate-intensity running (MOD) and vigorous-intensity running (VIG)), with an energy expenditure of ~2.5 MJ induced in both MOD (55-min running at 52% peak oxygen uptake (V.O 2peak )) and VIG (36-min running at 75% V.O 2peak ). In experiment two, nine healthy males completed three, 9-h conditions (control, 45-min running (EX45) and 90-min running (EX90)). Exercise was performed at 70% V.O 2peak In both experiments, participants consumed standardised meals, and acylated ghrelin concentrations and hunger were quantified at predetermined intervals. In experiment one, delta acylated ghrelin concentrations were lower than control in MOD (ES = 0.44, P = 0.01) and VIG (ES = 0.98, P Hunger ratings were similar across the conditions (P = 0.35). In experiment two, delta acylated ghrelin concentrations were lower than control in EX45 (ES = 0.77, P Hunger ratings were lower than control in EX45 (ES = 0.20, P = 0.01) and EX90 (ES = 0.27, P = 0.001); EX45 and EX90 were similar (ES = 0.07, P = 0.34). Hunger and delta acylated ghrelin concentrations remained suppressed at 1.5 h in EX90 but not EX45. In conclusion, exercise intensity, and to a lesser extent duration, are determinants of the acylated ghrelin response to acute exercise. © 2017 Society for Endocrinology.

Modification by SiO2 of Alumina Support for Light Alkane Dehydrogenation Catalysts

Directory of Open Access Journals (Sweden)

Giyjaz E. Bekmukhamedov

2016-10-01

Full Text Available Due to the continuously rising demand for C3–C5 olefins it is important to improve the performance of catalysts for dehydrogenation of light alkanes. In this work the effect of modification by SiO2 on the properties of the alumina support and the chromia-alumina catalyst was studied. SiO2 was introduced by impregnation of the support with a silica sol. To characterize the supports and the catalysts the following techniques were used: low-temperature nitrogen adsorption; IR-spectroscopy; magic angle spinning 29Si nuclear magnetic resonance; temperature programmed desorption and reduction; UV-Vis-, Raman- and electron paramagnetic resonance (EPR-spectroscopy. It was shown that the modifier in amounts of 2.5–7.5 wt % distributed on the support surface in the form of SiOx-islands diminishes the interaction between the alumina support and the chromate ions (precursor of the active component. As a result, polychromates are the compounds predominantly stabilized on the surface of the modified support; under thermal activation of the catalyst and are reduced to the amorphous Cr2O3. This in turn leads to an increase in the activity of the catalyst in the dehydrogenation of isobutane.

Interaction of gamma-glutamyltranspeptidase with clofibryl-S-acyl-glutathione in vitro and in vivo in rat.

Science.gov (United States)

Grillo, M P; Benet, L Z

2001-08-01

Clofibric acid (CA) is metabolized to chemically reactive acylating products that can transacylate glutathione to form clofibryl-S-acyl-glutathione (CA-SG) in vitro and in vivo. We investigated the first step in the degradation of CA-SG to the mercapturic acid conjugate, clofibryl-S-acyl-N-acetylcysteine (CA-SNAC), which is catalyzed by gamma-glutamyltranspeptidase (gamma-GT). After gamma-GT mediated cleavage of glutamate from CA-SG, the product clofibryl-S-acyl-cysteinylglycine (CA-S-CG) should undergo an intramolecular rearrangement reaction [Tate, S. S. (1975) FEBS Lett. 54, 319-322] to form clofibryl-N-acyl-cysteinylglycine (CA-N-CG). We performed in vitro studies incubating CA-SG with gamma-GT to determine the products formed, and in vivo studies examining the products excreted in urine after dosing rats with CA-SG or CA. Thus, CA-SG (0.1 mM) was incubated with gamma-GT (0.1 unit/mL) in buffer (pH 7.4, 25 degrees C) and analyzed for products formed by reversed-phase HPLC and electrospray mass spectrometry (ESI/MS). Results showed that CA-SG is degraded completely after 6 h of incubation leading to the formation of two products, CA-N-CG and its disulfide, with no detection of CA-S-CG thioester. After 36 h of incubation, only the disulfide remained in the incubation. Treatment of the disulfide with dithiothreitol led to the reappearance of CA-N-CG. ESI/LC/MS analysis of urine (16 h) extracts of CA-SG-dosed rats (200 mg/kg, iv) showed that CA-SG is degraded to CA-N-CG, CA-N-acyl-cysteine (CA-N-C) and their respective S-methylated products. The mercapturic acid conjugate (CA-SNAC) was found as a minor product. Analysis of urine extracts from CA-dosed rats (200 mg/kg, ip) resulted in the detection of clofibryl-N-acyl-cysteine (CA-N-C), but no evidence for the formation of CA-SNAC was obtained. These in vitro and in vivo experiments indicate that gamma-GT mediated degradation of clofibryl-S-acyl-glutathione leads primarily to the formation and excretion of clofibryl-N-acyl

The first three years of screening for medium chain acyl-CoA dehydrogenase deficiency (MCADD by newborn screening ontario

Directory of Open Access Journals (Sweden)

Fisher Lawrence

2010-11-01

Full Text Available Abstract Background Medium chain acyl-CoA dehydrogenase deficiency (MCADD is a disorder of mitochondrial fatty acid oxidation and is one of the most common inborn errors of metabolism. Identification of MCADD via newborn screening permits the introduction of interventions that can significantly reduce associated morbidity and mortality. This study reports on the first three years of newborn screening for MCADD in Ontario, Canada. Methods Newborn Screening Ontario began screening for MCADD in April 2006, by quantification of acylcarnitines (primarily octanoylcarnitine, C8 in dried blood spots using tandem mass spectrometry. Babies with positive screening results were referred to physicians at one of five regional Newborn Screening Treatment Centres, who were responsible for diagnostic evaluation and follow-up care. Results From April 2006 through March 2009, approximately 439 000 infants were screened for MCADD in Ontario. Seventy-four infants screened positive, with a median C8 level of 0.68 uM (range 0.33-30.41 uM. Thirty-one of the screen positive infants have been confirmed to have MCADD, while 36 have been confirmed to be unaffected. Screening C8 levels were higher among infants with MCADD (median 8.93 uM compared to those with false positive results (median 0.47 uM. Molecular testing was available for 29 confirmed cases of MCADD, 15 of whom were homozygous for the common c.985A > G mutation. Infants homozygous for the common mutation tended to have higher C8 levels (median 12.13 uM relative to compound heterozygotes for c.985A > G and a second detectable mutation (median 2.01 uM. Eight confirmed mutation carriers were identified among infants in the false positive group. The positive predictive value of a screen positive for MCADD was 46%. The estimated birth prevalence of MCADD in Ontario is approximately 1 in 14 000. Conclusions The birth prevalence of MCADD and positive predictive value of the screening test were similar to those

Targeted Lipidomics in Drosophila melanogaster Identifies Novel 2-Monoacylglycerols and N-acyl Amides

Science.gov (United States)

Takacs, Sara M.; Stuart, Jordyn M.; Basnet, Arjun; Raboune, Siham; Widlanski, Theodore S.; Doherty, Patrick; Bradshaw, Heather B.

2013-01-01

Lipid metabolism is critical to coordinate organ development and physiology in response to tissue-autonomous signals and environmental cues. Changes to the availability and signaling of lipid mediators can limit competitiveness, adaptation to environmental stressors, and augment pathological processes. Two classes of lipids, the N-acyl amides and the 2-acyl glycerols, have emerged as important signaling molecules in a wide range of species with important signaling properties, though most of what is known about their cellular functions is from mammalian models. Therefore, expanding available knowledge on the repertoire of these lipids in invertebrates will provide additional avenues of research aimed at elucidating biosynthetic, metabolic, and signaling properties of these molecules. Drosophila melanogaster is a commonly used organism to study intercellular communication, including the functions of bioactive lipids. However, limited information is available on the molecular identity of lipids with putative biological activities in Drosophila. Here, we used a targeted lipidomics approach to identify putative signaling lipids in third instar Drosophila larvae, possessing particularly large lipid mass in their fat body. We identified 2-linoleoyl glycerol, 2-oleoyl glycerol, and 45 N-acyl amides in larval tissues, and validated our findings by the comparative analysis of Oregon-RS, Canton-S and w1118 strains. Data here suggest that Drosophila represent another model system to use for the study of 2-acyl glycerol and N-acyl amide signaling. PMID:23874457

Oxidative Dehydrogenation of n-​Butane: Activity and Kinetics Over VOx​/Al2O3 Catalysts

NARCIS (Netherlands)

Madaan, N.; Haufe, R.; Shiju, N.R.; Rothenberg, G.

2014-01-01

The catalytic activity of a VOx/Al2O3 catalyst for the oxidative dehydrogenation of n-​butane is investigated. The effects of reaction temp., oxygen to n-​butane ratio and GHSV on the catalytic performance are examd. and optimized. Interestingly, this simple catalyst gives good conversion and

The oxidative dehydrogenation of methanol to formaldehyde over silver catalysts in relation to the oxygen-silver interaction

NARCIS (Netherlands)

Lefferts, Leonardus; van Ommen, J.G.; Ross, J.R.H.

1986-01-01

The properties of silver in the oxidative dehydrogenation of methanol were studied in a flow reactor under near industrial conditions. The influences of temperature, concentration of both reactants, gas velocity, space velocity, the form of the silver catalyst and surface composition of the catalyst

Acylated ghrelin concentrations are markedly decreased during pregnancy in mothers with and without gestational diabetes: relationship with cholinesterase.

Science.gov (United States)

Tham, Elaine; Liu, Jianhua; Innis, Sheila; Thompson, David; Gaylinn, Bruce D; Bogarin, Roberto; Haim, Alon; Thorner, Michael O; Chanoine, Jean-Pierre

2009-05-01

Acylated (octanoylated) ghrelin stimulates food intake and growth hormone secretion and is deacylated into desacyl ghrelin by butyrylcholinesterase. Acylated and desacyl ghrelin both promote adipogenesis. Ghrelin concentrations decrease with hyperglycemia and hyperinsulinism. We hypothesized that 1) acylated ghrelin increases during pregnancy, contributing positively to energy balance, but is lower in women with gestational diabetes and 2) butyrylcholinesterase activity is inversely correlated with acylated ghrelin concentrations. In a first group of subjects, using two-site sandwich ghrelin assays that specifically detect full-length forms, we investigated women with and without gestational diabetes (n = 14/group) during pregnancy and after delivery. We examined whether changes in ghrelin during a test meal were correlated with changes in pituitary growth hormone [assessed through calculation of the area under the curve (AUC) during the test meal]. In postpartum subjects, the percent of total ghrelin that is acylated was four to five times higher than previously observed using single antibody assays. During pregnancy, acylated ghrelin concentrations (mean +/- SE) were lower compared with the postpartum period throughout the meal (AUC 1.2 +/- 0.2 vs. 10.2 +/- 1.9 ng.ml(-1).90 min(-1), P < 0.001). In the postpartum, acylated ghrelin and growth hormone were positively correlated (r = 0.50, P = 0.007). Desacyl (but not acylated) ghrelin was increased in subjects with gestational diabetes during and after pregnancy (AUC 15.4 +/- 1.9 vs. 8.6 +/- 1.2 ng.ml(-1).90 min(-1), P = 0.005). In a second group of subjects (n = 13), acylated ghrelin was similarly suppressed during pregnancy. Circulating octanoate concentrations (3.1 +/- 0.5 vs. 4.5 +/- 0.6 microg/ml, P = 0.029) and cholinesterase activity (705 +/- 33 vs. 1,013 +/- 56 U/ml, P < 0.001) were lower during pregnancy compared with the postpartum period. In conclusion, acylated ghrelin markedly decreases during pregnancy

Veronica: Acylated flavone glycosides as chemosystematic markers

DEFF Research Database (Denmark)

Albach, Dirk C.; Grayer, Renée J.; Kite, Geoffrey C.

2005-01-01

HPLC/DAD and LCeMS of an extract of Veronica spicata subgenus Pseudolysimachium, Plantaginaceae) revealed the presence of six 6-hydroxyluteolin glycosides acylated with phenolic acids, three of which are new compounds and which we called spicosides. A flavonoid survey of seven more species...

Spectroscopic characterization of the on-surface induced (cyclo) dehydrogenation of a N-heteroaromatic compound on noble metal surfaces

Czech Academy of Sciences Publication Activity Database

Palacio, I.; Pinardi, A. L.; Martínez, J. I.; Preobrajenski, A.; Cossaro, A.; Jančařík, Andrej; Stará, Irena G.; Starý, Ivo; Méndez, J.; Martín-Gago, J.A.; López, M.F.

2017-01-01

Roč. 19, č. 33 (2017), s. 22454-22461 ISSN 1463-9076 Institutional support: RVO:61388963 Keywords : dibenzohelicene * on-surface (cyclo)dehydrogenation * spectroscopic characterization Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry Impact factor: 4.123, year: 2016

Proghrelin peptides: Desacyl ghrelin is a powerful inhibitor of acylated ghrelin, likely to impair physiological effects of acyl ghrelin but not of obestatin A study of pancreatic polypeptide secretion from mouse islets

DEFF Research Database (Denmark)

Kumar, Rajesh; Salehi, Albert; Rehfeld, Jens F

2010-01-01

Proghrelin, produced by the ghrelin (A-like) cells of the gastric mucosa, gives rise to cleavage products, including desacyl ghrelin, acyl ghrelin and obestatin. The products are thought to be secreted concomitantly. In an earlier study we found acyl ghrelin and obestatin, but not desacyl ghrelin...

CH{sub 4} dehydrogenation on Cu(1 1 1), Cu@Cu(1 1 1), Rh@Cu(1 1 1) and RhCu(1 1 1) surfaces: A comparison studies of catalytic activity

Energy Technology Data Exchange (ETDEWEB)

Zhang, Riguang; Duan, Tian [Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Ling, Lixia [Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Research Institute of Special Chemicals, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Wang, Baojun, E-mail: wangbaojun@tyut.edu.cn [Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China)

2015-06-30

Highlights: • Adsorbed Rh atom on Cu catalyst exhibits better catalytic activity for CH{sub 4} dehydrogenation. • The adsorbed Rh atom is the reaction active center for CH{sub 4} dehydrogenation. • The morphology of Cu substrate has negligible effect on CH{sub 4} dehydrogenation. - Abstract: In the CVD growth of graphene, the reaction barriers of the dehydrogenation for hydrocarbon molecules directly decide the graphene CVD growth temperature. In this study, density functional theory method has been employed to comparatively probe into CH{sub 4} dehydrogenation on four types of Cu(1 1 1) surface, including the flat Cu(1 1 1) surface (labeled as Cu(1 1 1)) and the Cu(1 1 1) surface with one surface Cu atom substituted by one Rh atom (labeled as RhCu(1 1 1)), as well as the Cu(1 1 1) surface with one Cu or Rh adatom (labeled as Cu@Cu(1 1 1) and Rh@Cu(1 1 1), respectively). Our results show that the highest barrier of the whole CH{sub 4} dehydrogenation process is remarkably reduced from 448.7 and 418.4 kJ mol{sup −1} on the flat Cu(1 1 1) and Cu@Cu(1 1 1) surfaces to 258.9 kJ mol{sup −1} on RhCu(1 1 1) surface, and to 180.0 kJ mol{sup −1} on Rh@Cu(1 1 1) surface, indicating that the adsorbed or substituted Rh atom on Cu catalyst can exhibit better catalytic activity for CH{sub 4} complete dehydrogenation; meanwhile, since the differences for the highest barrier between Cu@Cu(1 1 1) and Cu(1 1 1) surfaces are smaller, the catalytic behaviors of Cu@Cu(1 1 1) surface are very close to the flat Cu(1 1 1) surface, suggesting that the morphology of Cu substrate does not obviously affect the dehydrogenation of CH{sub 4}, which accords with the reported experimental observations. As a result, the adsorbed or substituted Rh atom on Cu catalyst exhibit a better catalytic activity for CH{sub 4} dehydrogenation compared to the pure Cu catalyst, especially on Rh-adsorbed Cu catalyst, we can conclude that the potential of synthesizing high-quality graphene with the

Kinetics of acyl transfer reactions in organic media catalysed by Candida antarctica lipase B.

Science.gov (United States)

Martinelle, M; Hult, K

1995-09-06

The acyl transfer reactions catalysed by Candida antartica lipase B in organic media followed a bi-bi ping-pong mechanism, with competitive substrate inhibition by the alcohols used as acyl acceptors. The effect of organic solvents on Vm and Km was investigated. The Vm values in acetonitrile was 40-50% of those in heptane. High Km values in acetonitrile compared to those in heptane could partly be explained by an increased solvation of the substrates in acetonitrile. Substrate solvation caused a 10-fold change in substrate specificity, defined as (Vm/Km)ethyl octanoate/(Vm/Km)octanoic acid, going from heptane to acetonitrile. Deacylation was the rate determining step for the acyl transfer in heptane with vinyl- and ethyl octanoate as acyl donors and (R)-2-octanol as acyl acceptor. With 1-octanol, a rate determining deacylation step in heptane was indicated using the same acyl donors. Using 1-octanol as acceptor in heptane, S-ethyl thiooctanoate had a 25- to 30-fold lower Vm/Km value and vinyl octanoate a 4-fold higher Vm/Km value than that for ethyl octanoate. The difference showed to be a Km effect for vinyl octanoate and mainly a Km effect for S-ethyl thiooctanoate. The Vm values of the esterification of octanoic acid with different alcohols was 10-30-times lower than those for the corresponding transesterification of ethyl octanoate. The low activity could be explained by a low pH around the enzyme caused by the acid or a withdrawing of active enzyme by nonproductive binding by the acid.

Dehydrogenation of ethane to ethylene via radical pathways enhanced by alkali metal based catalyst in oxysteam condition

KAUST Repository

Takanabe, Kazuhiro; Shahid, Salman

2016-01-01

The dehydrogenation of ethane to ethylene in the presence of oxygen and water was conducted using Na2WO4/SiO2 catalyst at high temperatures. At 923 K, the conversion rate without water was proportional to ethane pressure and a half order of oxygen

Plant fatty acyl reductases: enzymes generating fatty alcohols for protective layers with potential for industrial applications.

Science.gov (United States)

Rowland, Owen; Domergue, Frédéric

2012-09-01

Primary fatty alcohols are found throughout the biological world, either in free form or in a combined state. They are common components of plant surface lipids (i.e. cutin, suberin, sporopollenin, and associated waxes) and their absence can significantly perturb these essential barriers. Fatty alcohols and/or derived compounds are also likely to have direct functions in plant biotic and abiotic interactions. An evolutionarily related set of alcohol-forming fatty acyl reductases (FARs) is present in all kingdoms of life. Plant microsomal and plastid-associated FAR enzymes have been characterized, acting on acyl-coenzymeA (acyl-CoA) or acyl-acyl carrier protein (acyl-ACP) substrates, respectively. FARs have distinct substrate specificities both with regard to chain length and chain saturation. Fatty alcohols and wax esters, which are a combination of fatty alcohol and fatty acid, have a variety of commercial applications. The expression of FARs with desired specificities in transgenic microbes or oilseed crops would provide a novel means of obtaining these valuable compounds. In the present review, we report on recent progress in characterizing plant FAR enzymes and in understanding the biological roles of primary fatty alcohols, as well as describe the biotechnological production and industrial uses of fatty alcohols. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Fat and Sugar Metabolism During Exercise in Patients With Metabolic Myopathy

Science.gov (United States)

2017-08-31

Metabolism, Inborn Errors; Lipid Metabolism, Inborn Errors; Carbohydrate Metabolism, Inborn Errors; Long-Chain 3-Hydroxyacyl-CoA Dehydrogenase Deficiency; Glycogenin-1 Deficiency (Glycogen Storage Disease Type XV); Carnitine Palmitoyl Transferase 2 Deficiency; VLCAD Deficiency; Medium-chain Acyl-CoA Dehydrogenase Deficiency; Multiple Acyl-CoA Dehydrogenase Deficiency; Carnitine Transporter Deficiency; Neutral Lipid Storage Disease; Glycogen Storage Disease Type II; Glycogen Storage Disease Type III; Glycogen Storage Disease Type IV; Glycogen Storage Disease Type V; Muscle Phosphofructokinase Deficiency; Phosphoglucomutase 1 Deficiency; Phosphoglycerate Mutase Deficiency; Phosphoglycerate Kinase Deficiency; Phosphorylase Kinase Deficiency; Beta Enolase Deficiency; Lactate Dehydrogenase Deficiency; Glycogen Synthase Deficiency

pHP-Tethered N-Acyl Carbamate: A Photocage for Nicotinamide.

Science.gov (United States)

Salahi, Farbod; Purohit, Vatsal; Ferraudi, Guillermo; Stauffacher, Cynthia; Wiest, Olaf; Helquist, Paul

2018-05-04

The synthesis of a new photocaged nicotinamide having an N-acyl carbamate linker and a p-hydroxyphenacyl (pHP) chromophore is described. The photophysical and photochemical studies showed an absorption maximum at λ = 330 nm and a quantum yield for release of 11% that are dependent upon both pH and solvent. While the acyl carbamate releases nicotinamide efficiently, a simpler amide linker was inert to photocleavage. This photocaged nicotinamide has significant advantages with respect to quantum yield, absorbance wavelength, rate of release, and solubility that make it the first practical example of a photocaged amide.

Lipid storage myopathies.

Science.gov (United States)

Bruno, Claudio; Dimauro, Salvatore

2008-10-01

The aim of this review is to provide an update on disorders of lipid metabolism affecting skeletal muscle exclusively or predominantly and to summarize recent clinical, genetic, and therapeutic studies in this field. Over the past 5 years, new clinical phenotypes and genetic loci have been described, unusual pathogenic mechanisms have been elucidated, and novel pharmacological approaches have been developed. At least one genetic defect responsible for the myopathic form of CoQ10 deficiency has been identified, causing a disorder that is allelic with the late-onset riboflavine-responsive form of multiple acyl-coenzyme A dehydrogenation deficiency. Novel mechanisms involved in the lipolytic breakdown of cellular lipid depots have been described and have led to the identification of genes and mutations responsible for multisystemic neutral lipid storage disorders, characterized by accumulation of triglyceride in multiple tissues, including muscle. Defects in lipid metabolism can affect either the mitochondrial transport and oxidation of exogenous fatty acid or the catabolism of endogenous triglycerides. These disorders impair energy production and almost invariably involve skeletal muscle, causing progressive myopathy with muscle weakness, or recurrent acute episodes of rhabdomyolysis triggered by exercise, fasting, or infections. Clinical and genetic characterization of these disorders has important implications both for accurate diagnostic approach and for development of therapeutic strategies.

Ground-State Distortion in N-Acyl-tert-butyl-carbamates (Boc) and N-Acyl-tosylamides (Ts): Twisted Amides of Relevance to Amide N-C Cross-Coupling.

Science.gov (United States)

Szostak, Roman; Shi, Shicheng; Meng, Guangrong; Lalancette, Roger; Szostak, Michal

2016-09-02

Amide N-C(O) bonds are generally unreactive in cross-coupling reactions employing low-valent transition metals due to nN → π*C═O resonance. Herein we demonstrate that N-acyl-tert-butyl-carbamates (Boc) and N-acyl-tosylamides (Ts), two classes of acyclic amides that have recently enabled the development of elusive amide bond N-C cross-coupling reactions with organometallic reagents, are intrinsically twisted around the N-C(O) axis. The data have important implications for the design of new amide cross-coupling reactions with the N-C(O) amide bond cleavage as a key step.

Kinetics and Mechanism of the Reaction of Coherently Synchronized Oxidation and Dehydrogenation of Cyclohexane by Hydrogen Peroxide

Directory of Open Access Journals (Sweden)

Aghamammadova S.

2016-01-01

Based on this experimental researches, the complex reaction, consisting of parallel-sequential oxidation and dehydrogenation reactions, which are coherently synchronized, proceeds during the process of cyclohexane oxidation with biomimetic catalyst. Depending on the reaction parameters it is possible to deliberately adjust the direction of oxidation reaction and reaction rate.

NHE1 deficiency in liver: Implications for non-alcoholic fatty liver disease

Energy Technology Data Exchange (ETDEWEB)

Prasad, Vikram, E-mail: prasadvm@ucmail.uc.edu [Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine (United States); Chirra, Shivani [Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine (United States); Kohli, Rohit [Department of Gastroenterology, Hepatology, and Nutrition, Cincinnati Children’s Hospital, University of Cincinnati, Cincinnati, OH 45267 (United States); Shull, Gary E. [Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine (United States)

2014-07-25

Highlights: • FXR, PGC1α and PPARγ levels are upregulated in NHE1 deficient livers. • NHE1 deficiency downregulates expression of pro-lipogenic genes in liver. • Chronic exposure to high-fat diet upregulates hepatic NHE1 expression. • Loss of NHE1 better preserves hepatic insulin signaling in high-fat diet-fed mice. - Abstract: Non-alcoholic fatty liver disease NAFLD is closely associated with the dysregulation of lipid homeostasis. Diet-induced hepatic steatosis, which can initiate NAFLD progression, has been shown to be dramatically reduced in mice lacking the electroneutral Na{sup +}/H{sup +} exchanger NHE1 (Slc9a1). In this study, we investigated if NHE1 deficiency had effects in liver that could contribute to the apparent protection against aberrant lipid accumulation. RT-PCR and immunoblot analyses of wild-type and NHE1-null livers revealed an expression profile that strongly suggested attenuation of both de novo lipogenesis and hepatic stellate cell activation, which is implicated in liver fibrosis. This included upregulation of the farnesoid X receptor FXR, peroxisome proliferator-activated receptor PPARγ, its co-activator PGC1α, and sestrin 2, an antioxidant protein involved in hepatic metabolic homeostasis. Furthermore, expression levels of the pro-lipogenic liver X receptor LXRα, and acetyl CoA carboxylases 1 and 2 were downregulated. These changes were associated with evidence of reduced cellular stress, which persisted even upon exposure to a high-fat diet, and the better preservation of insulin signaling, as evidenced by protein kinase B/Akt phosphorylation (Ser473). These results indicate that NHE1 deficiency may protect against NAFLD pathogenesis, which is significant given the availability of highly specific NHE1 inhibitors.

NHE1 deficiency in liver: Implications for non-alcoholic fatty liver disease

International Nuclear Information System (INIS)

Prasad, Vikram; Chirra, Shivani; Kohli, Rohit; Shull, Gary E.

2014-01-01

Highlights: • FXR, PGC1α and PPARγ levels are upregulated in NHE1 deficient livers. • NHE1 deficiency downregulates expression of pro-lipogenic genes in liver. • Chronic exposure to high-fat diet upregulates hepatic NHE1 expression. • Loss of NHE1 better preserves hepatic insulin signaling in high-fat diet-fed mice. - Abstract: Non-alcoholic fatty liver disease NAFLD is closely associated with the dysregulation of lipid homeostasis. Diet-induced hepatic steatosis, which can initiate NAFLD progression, has been shown to be dramatically reduced in mice lacking the electroneutral Na + /H + exchanger NHE1 (Slc9a1). In this study, we investigated if NHE1 deficiency had effects in liver that could contribute to the apparent protection against aberrant lipid accumulation. RT-PCR and immunoblot analyses of wild-type and NHE1-null livers revealed an expression profile that strongly suggested attenuation of both de novo lipogenesis and hepatic stellate cell activation, which is implicated in liver fibrosis. This included upregulation of the farnesoid X receptor FXR, peroxisome proliferator-activated receptor PPARγ, its co-activator PGC1α, and sestrin 2, an antioxidant protein involved in hepatic metabolic homeostasis. Furthermore, expression levels of the pro-lipogenic liver X receptor LXRα, and acetyl CoA carboxylases 1 and 2 were downregulated. These changes were associated with evidence of reduced cellular stress, which persisted even upon exposure to a high-fat diet, and the better preservation of insulin signaling, as evidenced by protein kinase B/Akt phosphorylation (Ser473). These results indicate that NHE1 deficiency may protect against NAFLD pathogenesis, which is significant given the availability of highly specific NHE1 inhibitors

Process economics and safety considerations for the oxidative dehydrogenation of ethane using the M1 catalyst

Energy Technology Data Exchange (ETDEWEB)

Baroi, Chinmoy; Gaffney, Anne M.; Fushimi, Rebecca

2017-12-01

Olefins or unsaturated hydrocarbons play a vital role as feedstock for many industrially significant processes. Ethylene is the simplest olefin and a key raw material for consumer products. Oxidative Dehydrogenation (ODH) is one of the most promising new routes for ethylene production that can offer a significant advantage in energy efficiency over the conventional steam pyrolysis process. This study is focused on the ODH chemistry using the mixed metal oxide MoVTeNbOx catalysts, generally referred to as M1 for the key phase known to be active for dehydrogenation. Using performance results from the patent literature a series of process simulations were conducted to evaluate the effect of feed composition on operating costs, profitability and process safety. The key results of this study indicate that the ODH reaction can be made safer and more profitable without use of an inert diluent and furthermore by replacing O2 with CO2 as an oxidant. Modifications of the M1 catalyst composition in order to adopt these changes are discussed.

Generation of fatty acids by an acyl esterase in the bioluminescent system of Photobacterium phosphoreum

International Nuclear Information System (INIS)

Carey, L.M.; Rodriguez, A.; Meighen, E.

1984-01-01

The fatty acid reductase complex from Photobacterium phosphoreum has been discovered to have a long chain ester hydrolase activity associated with the 34K protein component of the complex. This protein has been resolved from the other components (50K and 58K) of the fatty acid reductase complex with a purity of > 95% and found to catalyze the transfer of acyl groups from acyl-CoA primarily to thiol acceptors with a low level of transfer to glycerol and water. Addition of the 50K protein of the complex caused a dramatic change in specificity increasing the transfer to oxygen acceptors. The acyl-CoA hydrolase activity increased almost 10-fold, and hence free fatty acids can be generated by the 34K protein when it is present in the fatty acid reductase complex. Hydrolysis of acyl-S-mercaptoethanol and acyl-1-glycerol and the ATP-dependent reduction of the released fatty acids to aldehyde for the luminescent reaction were also demonstrated for the reconstituted fatty acid reductase complex, raising the possibility that the immediate source of fatty acids for this reaction in vivo could be the membrane lipids and/or the fatty acid synthetase system

The development of a decision analytic model of changes in mean deviation in people with glaucoma: the COA model.

Science.gov (United States)

Kymes, Steven M; Lambert, Dennis L; Lee, Paul P; Musch, David C; Siegfried, Carla J; Kotak, Sameer V; Stwalley, Dustin L; Fain, Joel; Johnson, Chris; Gordon, Mae O

2012-07-01

To create and validate a statistical model predicting progression of primary open-angle glaucoma (POAG) assessed by loss of visual field as measured in mean deviation (MD) using 3 landmark studies of glaucoma progression and treatment. A Markov decision analytic model using patient level data described longitudinal MD changes over 7 years. Patient-level data from the Collaborative Initial Glaucoma Treatment Study (n = 607), the Ocular Hypertension Treatment Study (OHTS; n = 148; only those who developed POAG in the first 5 years of OHTS) and Advanced Glaucoma Intervention Study (n = 591), the COA model. We developed a Markov model with transition matrices stratified by current MD, age, race, and intraocular pressure categories and used a microsimulation approach to estimate change in MD over 7 years. Internal validation compared model prediction for 7 years to actual MD for COA participants. External validation used a cohort of glaucoma patients drawn from university clinical practices. Change in visual field as measured in MD in decibels (dB). Regressing the actual MD against the predicted produced an R(2) of 0.68 for the right eye and 0.63 for the left. The model predicted ending MD for right eyes of 65% of participants and for 63% of left eyes within 3 dB of actual results at 7 years. In external validation the model had an R(2) of 0.79 in the right eye and 0.77 in the left at 5 years. The COA model is a validated tool for clinicians, patients, and health policy makers seeking to understand longitudinal changes in MD in people with glaucoma. Copyright © 2012 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Association of acylated cationic decapeptides with dipalmitoylphosphatidylserine-dipalmitoyl- phosphatidylcholine lipid membranes

DEFF Research Database (Denmark)

Pedersen, T. B.; Sabra, Mads Christian; Frokjaer, Sven

2001-01-01

decapeptides that are N-terminally linked with C-2, C-8, and C-14 acyl chains contain four basic histidine residues in their identical amino acid sequence. A binding model, based on changes in the intrinsic fluorescent properties of the peptides upon association with the DPPC-DPPS membranes, is used...... DPPC-DPPS lipid mixture. The extent of peptide association deduced from the heat capacity measurements suggests a strong binding and membrane insertion of the C-14 acylated peptide in accordance with the fluorescence measurements....

Selectivity in the oxidative dehydrogenation of butene on zinc-iron oxide catalyst

Energy Technology Data Exchange (ETDEWEB)

Kung, H.H.; Kundalkar, B.; Kung, M.C.; Cheng, W.H.

1980-02-21

Adsorption, temperature-programed desorption, and pulse reaction studies of cis-2-butene and butadiene on spinel zinc ferrite by previously described methods provided evidence that the selectivity for oxidative dehydrogenation of butenes increases when zinc is added to the iron oxide catalyst because selective oxidation and complete oxidation proceed on separate sites, as they do on pure iron; because the density of sites for selective oxidation is higher and the density of sites for complete combustion is lower than on pure iron oxide; and because the activity of the combustion sites is lower.

Synthesis and characterization of conventional and mesoporous Ga-MFI for ethane dehydrogenation

DEFF Research Database (Denmark)

Leth, Karen Thrane; Rovik, Anne Krogh; Holm, Martin Spangsberg

2008-01-01

difference being the morphology of the crystals. The catalytic properties of the samples were tested in ethane dehydrogenation at 823 K and at atmospheric pressure. The two Ga-MFI samples differ greatly in conversion of ethane, as a result of their difference in porosity, and it is found that the conversion...... is reported for tetrahedral Ga incorporated in the MFI structure and it is shown that absorbed water molecules have an important impact on the Ga-71 electric field gradients and thereby on the quantitative evaluation of the Ga-71 MAS NMR intensities....

Effect of heterologous expression of acyl-CoA-binding protein on acyl-CoA level and composition in yeast

DEFF Research Database (Denmark)

Mandrup, S; Jepsen, R; Skøtt, H

1993-01-01

We have expressed a bovine synthetic acyl-CoA-binding protein (ACBP) gene in yeast (Saccharomyces cerevisiae) under the control of the GAL1 promoter. The heterologously expressed bovine ACBP constituted up to 6.4% of total cellular protein and the processing was identical with that of native bovi...

Diacylglycerol acyltransferase-2 (DGAT2) and monoacylglycerol acyltransferase-2 (MGAT2) interact to promote triacylglycerol synthesis.

Science.gov (United States)

Jin, Youzhi; McFie, Pamela J; Banman, Shanna L; Brandt, Curtis; Stone, Scot J

2014-10-10

Acyl CoA:1,2-diacylglycerol acyltransferase (DGAT)-2 is an integral membrane protein that catalyzes triacylglycerol (TG) synthesis using diacylglycerol and fatty acyl CoA as substrates. DGAT2 resides in the endoplasmic reticulum (ER), but when cells are incubated with fatty acids, DGAT2 interacts with lipid droplets presumably to catalyze localized TG synthesis for lipid droplet expansion. Previous studies have shown that DGAT2 interacts with proteins that synthesize its fatty acyl CoA substrates. In this study, we provide additional evidence that DGAT2 is present in a protein complex. Using a chemical cross-linker, disuccinimidyl suberate (DSS), we demonstrated that DGAT2 formed a dimer and was also part of a protein complex of ∼ 650 kDa, both in membranes and on lipid droplets. Using co-immunoprecipitation experiments and an in situ proximity ligation assay, we found that DGAT2 interacted with monoacylglycerol acyltransferase (MGAT)-2, an enzyme that catalyzes the synthesis of diacylglycerol. Deletion mutagenesis showed that the interaction with MGAT2 was dependent on the two transmembrane domains of DGAT2. No significant interaction of DGAT2 with lipin1, another enzyme that synthesizes diacylglycerol, could be detected. When co-expressed in cells, DGAT2 and MGAT2 co-localized in the ER and on lipid droplets. Co-expression also resulted in increased TG storage compared with expression of DGAT2 or MGAT2 alone. Incubating McArdle rat hepatoma RH7777 cells with 2-monoacylglycerol caused DGAT2 to translocate to lipid droplets. This also led to the formation of large cytosolic lipid droplets, characteristic of DGAT2, but not DGAT1, and indicated that DGAT2 can utilize monoacylglycerol-derived diacylglycerol. These findings suggest that the interaction of DGAT2 and MGAT2 serves to channel lipid substrates efficiently for TG biosynthesis. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Mild and Highly Efficient Copper(I Inspired Acylation of Alcohols and Polyols

Directory of Open Access Journals (Sweden)

Enoch A. Mensah

2017-01-01

Full Text Available A new and highly efficient method mediated by tetrakis(acetonitrilecopper(I triflate for activating both simple and highly hindered anhydrides in the acylation of alcohols and polyols is described. This new acylation method is mild and mostly proceeds at room temperature with low catalyst loading. The method is versatile and has been extended to a wide variety of different alcohol substrates to afford the corresponding ester products in good to excellent yields.

Handling of human short-chain acyl-CoA dehydrogenase (SCAD) variant proteins in transgenic mice

DEFF Research Database (Denmark)

Kragh, Peter M; Pedersen, Christina B; Schmidt, Stine P

2007-01-01

Abstract To investigate the in vivo handling of human short-chain acyl-CoA dehydrogenase (SCAD) variant proteins, three transgenic mouse lines were produced by pronuclear injection of cDNA encoding the wild-type, hSCAD-wt, and two disease causing folding variants hSCAD-319C > T and hSCAD-625G > A....... The transgenic mice were mated with an SCAD-deficient mouse strain (BALB/cByJ) and, in the second generation, three mouse lines were obtained without endogenous SCAD expression but harboring hSCAD-wt, hSCAD-319C > T, and hSCAD-625G > A transgenes, respectively. All three lines had expression of the transgene...... developed for any of the lines transgenic for the hSCAD folding variants. The indicated remarkable efficiency of the mouse protein quality control system in the degradation of SCAD folding variants should be further substantiated and investigated, since it might indicate ways to prevent disease...

Synthesis of 1-isopropyl-3-acyl-5-methyl-benzimidazolone Derivatives and Their Antimicrobial Activity

Directory of Open Access Journals (Sweden)

Shaopeng Wei

2013-03-01

Full Text Available A series of N-acylated analogues of 1-isopropyl-3-acyl-5-methyl-benzimidazolone were synthesized. Bioassay results indicated that analogues 5-07 and 5-19 exhibited the most potency against Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Analogues 5-02, 5-07, 5-12, 5-15, 5-19, 5-20 and 5-25 could effectively inhibit the spore germination of Botrytis cinerea. The relationship between structure and their antimicrobial activity (SAR has also been discussed according to aliphatic acids and aromatic acids derivatives, respectively. This implied that the N-acylated derivatives of 5-methyl-benzimidazolone might be potential antimicrobial agents.

Synthesis of O-[{sup 11}C]acetyl CoA, O-[{sup 11}C]acetyl-L-carnitine, and L-[{sup 11}C]carnitine labelled in specific positions, applied in PET studies on rhesus monkey

Energy Technology Data Exchange (ETDEWEB)

Jacobson, Gunilla B.; Watanabe, Yasuyoshi; Valind, Sven; Kuratsune, Hirohiko; Laangstroem, Bengt

1997-07-01

The syntheses of L-carnitine, O-acetyl CoA, and O-acetyl-L-carnitine labelled with {sup 11}C at the 1- or 2-position of the acetyl group or the N-methyl position of carnitine, using the enzymes acetyl CoA synthetase and carnitine acetyltransferase, are described. With a total synthesis time of 45 min, O-[1-{sup 11}C]acetyl CoA and O-[2-{sup 11}C]acetyl CoA was obtained in 60-70% decay-corrected radiochemical yield, and O-[1-{sup 11}C]acetyl-L-carnitine and O-[2-{sup 11}C]acetyl-L-carnitine in 70-80% yield, based on [1-{sup 11}C]acetate or [2-{sup 11}C]acetate, respectively. By an N-methylation reaction with [{sup 11}C]methyl iodide, L-[methyl-{sup 11}C]carnitine was obtained within 30 min, and O-acetyl-L-[methyl-{sup 11}C]carnitine within 40 min, giving a decay-corrected radiochemical yield of 60% and 40-50%, respectively, based on [{sup 11}C]methyl iodide. Initial data of the kinetics of the different {sup 11}C-labelled L-carnitine and acetyl-L-carnitines in renal cortex of anaesthetized monkey (Macaca mulatta) are presented.

Role of long-chain fatty acyl-CoA esters in the regulation of metabolism and in cell signalling

DEFF Research Database (Denmark)

Færgeman, Nils J.; Knudsen, J

1997-01-01

(Ki for acyl-CoA is 5 nM) indicates strongly that the free cytosolic acyl-CoA concentration is below 5 nM under these conditions. Only a limited number of the reported experiments on the effects of acyl-CoA on cellular functions and enzymes have been carried out at low physiological concentrations...

Liberdade e coação no direito de Kant

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Pinheiro, Celso de Moraes

2007-01-01

Full Text Available Kant divide a filosofia moral em duas partes: Ética e Teoria da Justiça. Cada uma é compota de diferentes descrições de deveres e direitos. A ética contém deveres e direitos internos, voluntários e não-coercitivos. A teoria da justiça contém deveres e direitos externos e coercitivos. Os dois tipos de deveres e direitos são definidos em sua relação um com o outro. O que distingue os deveres éticos, ou deveres de virtude, dos deveres jurídicos, é que a compulsão externa para o dever de virtude é baseado na livre coerção própria. Assim, a finalidade deste artigo é pesquisar a noção de dever, e a relação entre dever, liberdade e coação

Dual acylation and lipid raft association of Src-family protein tyrosine kinases are required for SDF-1/CXCL12-mediated chemotaxis in the Jurkat human T cell lymphoma cell line.

Science.gov (United States)

Zaman, Sabiha N; Resek, Mary E; Robbins, Stephen M

2008-10-01

Chemokines play pivotal roles in regulating a wide variety of biological processes by modulating cell migration and recruitment. Deregulation of chemokine signaling can alter cell recruitment, contributing to the pathogenic states associated with autoimmune disease, inflammatory disorders, and sepsis. During chemotaxis, lipid rafts and their resident signaling molecules have been demonstrated to partition to different parts of the cell. Herein, we investigated the role of lipid raft resident Src-family kinases (SFK) in stromal cell-derived factor 1/CXCL12-mediated chemotaxis. We have shown that Lck-deficient J.CaM 1.6 cells are defective in CXCL12-mediated chemotaxis in contrast to their parental counterpart, Jurkat cells. Ectopic expression of the SFK hematopoietic cell kinase (Hck) in J.CaM 1.6 cells reconstituted CXCL12 responsiveness. The requirement of lipid raft association of SFK was assessed using both isoforms of Hck: the dually acylated p59(Hck) isoform that is targeted to lipid rafts and the monoacylated p61(Hck) isoform that is nonraft-associated. We have shown using several gain and loss of acylation alleles that dual acylation of Hck was required for CXCL12-mediated chemotaxis in J.CaM 1.6 cells. These results highlight the importance of the unique microenvironment provided by lipid rafts and their specific contribution in providing specificity to CXCL12 signaling.

Density functional theory studies on the nano-scaled composites consisted of graphene and acyl hydrazone molecules

Science.gov (United States)

Ren, J. L.; Zhou, L.; Lv, Z. C.; Ding, C. H.; Wu, Y. H.; Bai, H. C.

2016-07-01

Graphene, which is the first obtained single atomic layer 2D materials, has drawn a great of concern in nano biotechnology due to the unique property. On one hand, acyl hydrazone compounds belonging to the Schif bases have aroused considerable attention in medicine, pharmacy, and analytical reagent. However, few understanding about the interaction between graphene and acyl hydrazone molecules is now available. And such investigations are much crucial for the applications of these new nano-scaled composites. The current work revealed theoretical investigations on the nano-scaled composites built by acyl hydrazone molecules loaded on the surface of graphene. The relative energy, electronic property and the interaction between the counterparts of graphene/acyl hydrazone composites are investigated based on the density functional theory calculations. According to the obtained adsorption energy, the formation of the nano-scaled composite from the isolated graphene and acyl hydrazone molecule is exothermic, and thus it is energetically favorable to form these nano composites in viewpoint of total energy change. The frontier molecular orbital for the nano composite is mainly distributed at the graphene part, leading to that the energy levels of the frontier molecular orbital of the nano composites are very close to that of isolated graphene. Moreover, the counterpart interaction for the graphene/acyl hydrazone composites is also explored based on the discussions of orbital hybridization, charge redistribution and Van der Waals interaction.

Turnover and metabolism of phosphatidylglycerol acyl moieties in E. coli

International Nuclear Information System (INIS)

Cooper, C.L.; Rock, C.O.

1987-01-01

Fatty acids synthesized in mutants (plsB) blocked in de novo phospholipid biosynthesis were preferentially transferred to phosphatidylglycerol (PtdGro). The ratio of phospholipid species labeled with 32 P and [ 3 H]acetate in the absence of glycerol-3-P acyltransferase activity indicated that [ 3 H]acetate incorporation into PtdGro was due to fatty acid turnover. The magnitude of the turnover process was difficult to estimate due to a significant contraction of the acetyl-CoA pool following the inhibition of phospholipid synthesis. A possible connection between PtdGro turnover and protein acylation was investigated in an E. coli strain containing a lipoprotein expression vector. Cells were prelabeled with [ 3 H]acetate and lipoprotein expression was induced concomitant with the addition of exogenous [ 14 C]-palmitate. [ 14 C] Palmitate was assimilated into the l-position of phosphatidylethanolamine and transferred to the amino terminus of the lipoprotein. In contrast, the ester-linked lipoprotein fatty acids and PtdGro were not enriched in carbon-14 implying a metabolic relationship between these two pools. The data suggest that turnover of PtdGro acyl moieties is related to protein acylation, but a direct link between the two processes remains to be established

A Thermal Dehydrogenative Diels–Alder Reaction of Styrenes for the Concise Synthesis of Functionalized Naphthalenes

Science.gov (United States)

Kocsis, Laura S.; Benedetti, Erica

2012-01-01

Functionalized naphthalenes are valuable building blocks in many important areas. A microwave-assisted, intramolecular dehydrogenative Diels-Alder reaction of styrenyl derivatives to provide cyclopenta[b]naphthalene substructures not previously accessible using existing synthetic methods is described. The synthetic utility of these uniquely functionalized naphthalenes was demonstrated by a single-step conversion of one of these cycloadducts to a fluorophore bearing a structural resemblance to Prodan. PMID:22913473

A thermal dehydrogenative Diels-Alder reaction of styrenes for the concise synthesis of functionalized naphthalenes.

Science.gov (United States)

Kocsis, Laura S; Benedetti, Erica; Brummond, Kay M

2012-09-07

Functionalized naphthalenes are valuable building blocks in many important areas. A microwave-assisted, intramolecular dehydrogenative Diels-Alder reaction of styrenyl derivatives to provide cyclopenta[b]naphthalene substructures not previously accessible using existing synthetic methods is described. The synthetic utility of these uniquely functionalized naphthalenes was demonstrated by a single-step conversion of one of these cycloadducts to a fluorophore bearing a structural resemblance to Prodan.

Altered regulation of lipid biosynthesis in a mutant of Arabidopsis deficient in chloroplast glycerol-3-phosphate acyltransferase activity

International Nuclear Information System (INIS)

Kunst, L.; Browse, J.; Somerville, C.

1988-01-01

The leaf membrane lipids of many plant species, including Arabidopsis thaliana (L.) Heynh., are synthesized by two complementary pathways that are associated with the chloroplast and the endoplasmic reticulum. By screening directly for alterations in lipid acyl-group composition, the authors have identified several mutants of Arabidopsis that lack the plastid pathway because of a deficiency in activity of the first enzyme in the plastid pathway of glycerolipid synthesis, acyl-ACP:sn-glycerol-3-phosphate acyltransferase. The lesion results in an increased synthesis of lipids by the cytoplasmic pathway that largely compensates for the loss of the plastid pathway and provides nearly normal amounts of all the lipids required for chloroplast biogenesis. However, the fatty acid composition of the leaf membrane lipids of the mutants is altered because the acyltransferases associated with the two pathways normally exhibit different substrate specificities. The remarkable flexibility of the system provides an insight into the nature of the regulatory mechanisms that allocate lipids for membrane biogenesis

Serum Levels of Acyl-Carnitines along the Continuum from Normal to Alzheimer's Dementia

Science.gov (United States)

Sapere, Nadia; La Marca, Giancarlo; Angiolillo, Antonella; Vitale, Michela; Corbi, Graziamaria; Scapagnini, Giovanni; Intrieri, Mariano; Russo, Claudio

2016-01-01

This study aimed to determine the serum levels of free L-carnitine, acetyl-L-carnitine and 34 acyl-L-carnitine in healthy subjects and in patients with or at risk of Alzheimer’s disease. Twenty-nine patients with probable Alzheimer’s disease, 18 with mild cognitive impairment of the amnestic type, 24 with subjective memory complaint and 46 healthy subjects were enrolled in the study, and the levels of carnitine and acyl-carnitines were measured by tandem mass spectrometry. The concentrations of acetyl-L-carnitine progressively decreased passing from healthy subjects group (mean±SD, 5.6±1.3 μmol/L) to subjective memory complaint (4.3±0.9 μmol/L), mild cognitive impairment (4.0±0.53 μmol/L), up to Alzheimer’s disease (3.5±0.6 μmol/L) group (p<0.001). The differences were significant for the comparisons: healthy subjects vs. subjective memory complaint, mild cognitive impairment or Alzheimer’s disease group; and subjective memory complaint vs. Alzheimer’s disease group. Other acyl-carnitines, such as malonyl-, 3-hydroxyisovaleryl-, hexenoyl-, decanoyl-, dodecanoyl-, dodecenoyl-, myristoyl-, tetradecenoyl-, hexadecenoyl-, stearoyl-, oleyl- and linoleyl-L-carnitine, showed a similar decreasing trend, passing from healthy subjects to patients at risk of or with Alzheimer’s disease. These results suggest that serum acetyl-L-carnitine and other acyl-L-carnitine levels decrease along the continuum from healthy subjects to subjective memory complaint and mild cognitive impairment subjects, up to patients with Alzheimer’s disease, and that the metabolism of some acyl-carnitines is finely connected among them. These findings also suggest that the serum levels of acetyl-L-carnitine and other acyl-L-carnitines could help to identify the patients before the phenotype conversion to Alzheimer’s disease and the patients who would benefit from the treatment with acetyl-L-carnitine. However, further validation on a larger number of samples in a longitudinal

Serum Levels of Acyl-Carnitines along the Continuum from Normal to Alzheimer's Dementia.

Directory of Open Access Journals (Sweden)

Adriana Cristofano

Full Text Available This study aimed to determine the serum levels of free L-carnitine, acetyl-L-carnitine and 34 acyl-L-carnitine in healthy subjects and in patients with or at risk of Alzheimer's disease. Twenty-nine patients with probable Alzheimer's disease, 18 with mild cognitive impairment of the amnestic type, 24 with subjective memory complaint and 46 healthy subjects were enrolled in the study, and the levels of carnitine and acyl-carnitines were measured by tandem mass spectrometry. The concentrations of acetyl-L-carnitine progressively decreased passing from healthy subjects group (mean±SD, 5.6±1.3 μmol/L to subjective memory complaint (4.3±0.9 μmol/L, mild cognitive impairment (4.0±0.53 μmol/L, up to Alzheimer's disease (3.5±0.6 μmol/L group (p<0.001. The differences were significant for the comparisons: healthy subjects vs. subjective memory complaint, mild cognitive impairment or Alzheimer's disease group; and subjective memory complaint vs. Alzheimer's disease group. Other acyl-carnitines, such as malonyl-, 3-hydroxyisovaleryl-, hexenoyl-, decanoyl-, dodecanoyl-, dodecenoyl-, myristoyl-, tetradecenoyl-, hexadecenoyl-, stearoyl-, oleyl- and linoleyl-L-carnitine, showed a similar decreasing trend, passing from healthy subjects to patients at risk of or with Alzheimer's disease. These results suggest that serum acetyl-L-carnitine and other acyl-L-carnitine levels decrease along the continuum from healthy subjects to subjective memory complaint and mild cognitive impairment subjects, up to patients with Alzheimer's disease, and that the metabolism of some acyl-carnitines is finely connected among them. These findings also suggest that the serum levels of acetyl-L-carnitine and other acyl-L-carnitines could help to identify the patients before the phenotype conversion to Alzheimer's disease and the patients who would benefit from the treatment with acetyl-L-carnitine. However, further validation on a larger number of samples in a longitudinal

Structural snapshots along the reaction pathway of Yersinia pestis RipA, a putative butyryl-CoA transferase

International Nuclear Information System (INIS)

Torres, Rodrigo; Lan, Benson; Latif, Yama; Chim, Nicholas; Goulding, Celia W.

2014-01-01

The crystal structures of Y. pestis RipA mutants were determined to provide insights into the CoA transferase reaction pathway. Yersinia pestis, the causative agent of bubonic plague, is able to survive in both extracellular and intracellular environments within the human host, although its intracellular survival within macrophages is poorly understood. A novel Y. pestis three-gene rip (required for intracellular proliferation) operon, and in particular ripA, has been shown to be essential for survival and replication in interferon γ-induced macrophages. RipA was previously characterized as a putative butyryl-CoA transferase proposed to yield butyrate, a known anti-inflammatory shown to lower macrophage-produced NO levels. RipA belongs to the family I CoA transferases, which share structural homology, a conserved catalytic glutamate which forms a covalent CoA-thioester intermediate and a flexible loop adjacent to the active site known as the G(V/I)G loop. Here, functional and structural analyses of several RipA mutants are presented in an effort to dissect the CoA transferase mechanism of RipA. In particular, E61V, M31G and F60M RipA mutants show increased butyryl-CoA transferase activities when compared with wild-type RipA. Furthermore, the X-ray crystal structures of E61V, M31G and F60M RipA mutants, when compared with the wild-type RipA structure, reveal important conformational changes orchestrated by a conserved acyl-group binding-pocket phenylalanine, Phe85, and the G(V/I)G loop. Binary structures of M31G RipA and F60M RipA with two distinct CoA substrate conformations are also presented. Taken together, these data provide CoA transferase reaction snapshots of an open apo RipA, a closed glutamyl-anhydride intermediate and an open CoA-thioester intermediate. Furthermore, biochemical analyses support essential roles for both the catalytic glutamate and the flexible G(V/I)G loop along the reaction pathway, although further research is required to fully

Structural snapshots along the reaction pathway of Yersinia pestis RipA, a putative butyryl-CoA transferase

Energy Technology Data Exchange (ETDEWEB)

Torres, Rodrigo; Lan, Benson; Latif, Yama; Chim, Nicholas [UC Irvine, 2212 Natural Sciences I, Irvine, CA 92697 (United States); Goulding, Celia W., E-mail: celia.goulding@uci.edu [UC Irvine, 2212 Natural Sciences I, Irvine, CA 92697 (United States); UC Irvine, 2302 Natural Sciences I, Irvine, CA 92697 (United States)

2014-04-01

The crystal structures of Y. pestis RipA mutants were determined to provide insights into the CoA transferase reaction pathway. Yersinia pestis, the causative agent of bubonic plague, is able to survive in both extracellular and intracellular environments within the human host, although its intracellular survival within macrophages is poorly understood. A novel Y. pestis three-gene rip (required for intracellular proliferation) operon, and in particular ripA, has been shown to be essential for survival and replication in interferon γ-induced macrophages. RipA was previously characterized as a putative butyryl-CoA transferase proposed to yield butyrate, a known anti-inflammatory shown to lower macrophage-produced NO levels. RipA belongs to the family I CoA transferases, which share structural homology, a conserved catalytic glutamate which forms a covalent CoA-thioester intermediate and a flexible loop adjacent to the active site known as the G(V/I)G loop. Here, functional and structural analyses of several RipA mutants are presented in an effort to dissect the CoA transferase mechanism of RipA. In particular, E61V, M31G and F60M RipA mutants show increased butyryl-CoA transferase activities when compared with wild-type RipA. Furthermore, the X-ray crystal structures of E61V, M31G and F60M RipA mutants, when compared with the wild-type RipA structure, reveal important conformational changes orchestrated by a conserved acyl-group binding-pocket phenylalanine, Phe85, and the G(V/I)G loop. Binary structures of M31G RipA and F60M RipA with two distinct CoA substrate conformations are also presented. Taken together, these data provide CoA transferase reaction snapshots of an open apo RipA, a closed glutamyl-anhydride intermediate and an open CoA-thioester intermediate. Furthermore, biochemical analyses support essential roles for both the catalytic glutamate and the flexible G(V/I)G loop along the reaction pathway, although further research is required to fully

Ultraviolet-Visible (UV-Vis) Microspectroscopic System Designed for the In Situ Characterization of the Dehydrogenation Reaction Over Platinum Supported Catalytic Microchannel Reactor.

Science.gov (United States)

Suarnaba, Emee Grace Tabares; Lee, Yi Fuan; Yamada, Hiroshi; Tagawa, Tomohiko

2016-11-01

An ultraviolet visible (UV-Vis) microspectroscopic system was designed for the in situ characterization of the activity of the silica supported platinum (Pt) catalyst toward the dehydrogenation of 1-methyl-1,4-cyclohexadiene carried out in a custom-designed catalytic microreactor cell. The in situ catalytic microreactor cell (ICMC) with inlet/outlet ports was prepared using quartz cover as the optical window to facilitate UV-Vis observation. A fabricated thermometric stage was adapted to the UV-Vis microspectrophotometer to control the reaction temperature inside the ICMC. The spectra were collected by focusing the UV-Vis beam on a 30 × 30 µm area at the center of ICMC. At 393 K, the sequential measurement of the spectra recorded during the reaction exhibited a broad absorption peak with maximum absorbance at 260 nm that is characteristic for gaseous toluene. This result indicates that the silica supported Pt catalyst is active towards the dehydrogenation of 1-methyl-1,4-cyclohexadiene at the given experimental conditions. The onset of coke formation was also detected based on the appearance of absorption bands at 300 nm. The UV-Vis microspectroscopic system developed can be used further in studying the mechanism of the dehydrogenation reaction. © The Author(s) 2016.

Lipase-catalyzed biodiesel synthesis with different acyl acceptors

Directory of Open Access Journals (Sweden)

Ognjanović Nevena D.

2008-01-01

Full Text Available Biodiesel is an alternative fuel for diesel engine that is environmentally acceptable. Conventionally, biodiesel is produced by transesterification of triglycerides and short alcohols in the presence of an acid or an alkaline catalyst. There are several problems associated with this kind of production that can be resolved by using lipase as the biocatalyst. The aim of the present work was to investigate novel acyl acceptors for biodiesel production. 2-Propanol and n-butanol have a less negative effect on lipase stability, and they also improve low temperature properties of the fuel. However, excess alcohol leads to inactivation of the enzyme, and glycerol, a major byproduct, can block the immobilized enzyme, resulting in low enzymatic activity. This problem was solved by using methyl acetate as acyl acceptor. Triacetylglycerol is produced instead of glycerol, and it has no negative effect on the activity of the lipase.

Proghrelin peptides: Desacyl ghrelin is a powerful inhibitor of acylated ghrelin, likely to impair physiological effects of acyl ghrelin but not of obestatin A study of pancreatic polypeptide secretion from mouse islets

DEFF Research Database (Denmark)

Kumar, Rajesh; Salehi, Albert; Rehfeld, Jens F

2010-01-01

Proghrelin, produced by the ghrelin (A-like) cells of the gastric mucosa, gives rise to cleavage products, including desacyl ghrelin, acyl ghrelin and obestatin. The products are thought to be secreted concomitantly. In an earlier study we found acyl ghrelin and obestatin, but not desacyl ghrelin......, to suppress the release of hormones from isolated islets of mouse and rat pancreas....

S-acylation of SOD1, CCS, and a stable SOD1-CCS heterodimer in human spinal cords from ALS and non-ALS subjects.

Science.gov (United States)

Antinone, Sarah E; Ghadge, Ghanashyam D; Ostrow, Lyle W; Roos, Raymond P; Green, William N

2017-01-25

Previously, we found that human Cu, Zn-superoxide dismutase (SOD1) is S-acylated (palmitoylated) in vitro and in amyotrophic lateral sclerosis (ALS) mouse models, and that S-acylation increased for ALS-causing SOD1 mutants relative to wild type. Here, we use the acyl resin-assisted capture (acyl-RAC) assay to demonstrate S-acylation of SOD1 in human post-mortem spinal cord homogenates from ALS and non-ALS subjects. Acyl-RAC further revealed that endogenous copper chaperone for SOD1 (CCS) is S-acylated in both human and mouse spinal cords, and in vitro in HEK293 cells. SOD1 and CCS formed a highly stable heterodimer in human spinal cord homogenates that was resistant to dissociation by boiling, denaturants, or reducing agents and was not observed in vitro unless both SOD1 and CCS were overexpressed. Cysteine mutations that attenuate SOD1 maturation prevented the SOD1-CCS heterodimer formation. The degree of S-acylation was highest for SOD1-CCS heterodimers, intermediate for CCS monomers, and lowest for SOD1 monomers. Given that S-acylation facilitates anchoring of soluble proteins to cell membranes, our findings suggest that S-acylation and membrane localization may play an important role in CCS-mediated SOD1 maturation. Furthermore, the highly stable S-acylated SOD1-CCS heterodimer may serve as a long-lived maturation intermediate in human spinal cord.

Dehydrogenation kinetics of pure and nickel-doped magnesium hydride investigated by in situ time-resolved powder X-ray diffraction

DEFF Research Database (Denmark)

Jensen, T.R.; Andreasen, A.; Vegge, Tejs

2006-01-01

The dehydrogenation kinetics of pure and nickel (Ni)-doped (2w/w%) magnesium hydride (MgH2) have been investigated by in situ time-resolved powder X-ray diffraction (PXD). Deactivated samples, i.e. air exposed, are investigated in order to focus on the effect of magnesium oxide (MgO) surface layers......, which might be unavoidable for magnesium (Mg)-based storage media for mobile applications. A curved position-sensitive detector covering 120 degrees in 20 and a rotating anode X-ray source provide a time resolution of 45 s and up to 90 powder pattems collected during an experiment under isothermal...... by the Johnson-Mehi-Avrami formalism in order to derive rate constants at different temperatures. The apparent activation energies for dehydrogenation of pure and Ni-doped magnesium hydride were E-A approximate to 300 and 250 kJ/mol, respectively. Differential scanning calorimetry gave, E-A = 270 k...

Simulation of the styrene production process via catalytic dehydrogenation of ethylbenzene using CHEMCAD® process simulator

OpenAIRE

Pérez-Sánchez, Amaury; Sánchez, Eddy Javier Pérez; Segura Silva, Rutdali María

2017-01-01

Abstract Background: Process simulation has been extensively used in recent years to design, evaluate or optimize processes, systems and specific operations of the chemical industry and its related disciplines. Currently, CHEMCAD® constitute one of the most used process simulators because of the great number of chemical and petrochemical processes that can be simulated. Method: The simulation of the production process of styrene via catalytic dehydrogenation of ethyl-benzene is carried ou...

The dehydrogenation performance and reaction mechanisms of Li{sub 3}AlH{sub 6} with TiF{sub 3} additive

Energy Technology Data Exchange (ETDEWEB)

Liu, Shu-Sheng [Materials and Thermochemistry Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Graduate School of Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Yao; Sun, Li-Xian; Zhang, Jian; Zhao, Jun-Ning [Materials and Thermochemistry Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Xu, Fen [Faculty of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian 116029 (China); Huang, Feng-Lei [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China)

2010-05-15

For Li{sub 3}AlH{sub 6} prepared by mechanical milling method, the dissociation reaction enthalpy and activation energy are calculated to be 22.1 kJ mol{sup -1} H{sub 2} and 133.7 {+-} 2.7 kJ mol{sup -1}, respectively. The dehydrogenation performance of Li{sub 3}AlH{sub 6} is greatly enhanced by TiF{sub 3} additive, especially in the kinetic behaviors. For the Li{sub 3}AlH{sub 6} + 10 mol% TiF{sub 3} sample, the starting temperature of dehydrogenation is obviously decreased by 60 C from that of pure Li{sub 3}AlH{sub 6} (190 C), and 3.0 wt.% H{sub 2} may be released within 1000 s at 120 C under an initial vacuum. With the amount of TiF{sub 3} increasing, the starting temperature decreases and the kinetics improves due to the decrease in the activation energy. The X-ray diffraction (XRD) together with thermogravimetric analysis (TGA) results show that there are three mechanochemical reactions involved during milling: i) Li{sub 3}AlH{sub 6} + TiF{sub 3} {yields} 3 LiF + Al + Ti + 3H{sub 2}, ii) Ti + H{sub 2} {yields} TiH{sub 2}, iii) 3 Al + Ti {yields} Al{sub 3}Ti. The in-situ formed Ti species (TiH{sub 2} and Al{sub 3}Ti) co-catalyze the thermal dehydrogenation of Li{sub 3}AlH{sub 6}. (author)

The effect of valinomycin in fibroblasts from patients with fatty acid oxidation disorders

International Nuclear Information System (INIS)

Ndukwe Erlingsson, Uzochi Chimdinma; Iacobazzi, Francesco; Liu, Aiping; Ardon, Orly; Pasquali, Marzia; Longo, Nicola

2013-01-01

Highlights: •Valinomycin can cause mitochondrial stress and stimulate fatty acid oxidation. •Cells with VLCAD deficiency fail to increase fatty acid oxidation in response to valinomycin. •Response to valinomycin can help in the diagnosis of VLCAD deficiency. -- Abstract: Disorders of the carnitine cycle and of the beta oxidation spiral impair the ability to obtain energy from fats at time of fasting and stress. This can result in hypoketotic hypoglycemia, cardiomyopathy, cardiac arrhythmia and other chronic medical problems. The in vitro study of fibroblasts from patients with these conditions is impaired by their limited oxidative capacity. Here we evaluate the capacity of valinomycin, a potassium ionophore that increases mitochondrial respiration, to increase the oxidation of fatty acids in cells from patients with inherited fatty acid oxidation defects. The addition of valinomycin to fibroblasts decreased the accumulation of the lipophilic cation tetraphenylphosphonium (TPP + ) at low concentrations due to the dissipation of the mitochondrial membrane potential. At higher doses, valinomycin increased TPP + accumulation due to the increased potassium permeability of the plasma membrane and subsequent cellular hyperpolarization. The incubation of normal fibroblasts with valinomycin increased [ 14 C]-palmitate oxidation (measured as [ 14 C]O 2 release) in a dose-dependent manner. By contrast, valinomycin failed to increase palmitate oxidation in fibroblasts from patients with very long chain acyl CoA dehydrogenase (VLCAD) deficiency. This was not observed in fibroblasts from patients heterozygous for this condition. These results indicate that valinomycin can increase fatty acid oxidation in normal fibroblasts and could be useful to differentiate heterozygotes from patients affected with VLCAD deficiency

Molecular Mechanisms of Insulin Resistance in Humans and Their Potential Links With Mitochondrial Dysfunction

OpenAIRE

Morino, Katsutaro; Petersen, Kitt Falk; Shulman, Gerald I.

2006-01-01

Recent studies using magnetic resonance spectroscopy have shown that decreased insulin-stimulated muscle glycogen synthesis due to a defect in insulin-stimulated glucose transport activity is a major factor in the pathogenesis of type 2 diabetes. The molecular mechanism underlying defective insulin-stimulated glucose transport activity can be attributed to increases in intramyocellular lipid metabolites such as fatty acyl CoAs and diacylglycerol, which in turn activate a serine/threonine kina...

Acyl-CoA-binding protein/diazepam-binding inhibitor gene and pseudogenes

DEFF Research Database (Denmark)

Mandrup, S; Hummel, R; Ravn, S

1992-01-01

Acyl-CoA-binding protein (ACBP) is a 10 kDa protein isolated from bovine liver by virtue of its ability to bind and induce the synthesis of medium-chain acyl-CoA esters. Surprisingly, it turned out to be identical to a protein named diazepam-binding Inhibitor (DBI) claimed to be an endogenous mod...... have molecularly cloned and characterized the ACBP/DBI gene family in rat. The rat ACBP/DBI gene family comprises one expressed gene and four processed pseudogenes of which one was shown to exist in two allelic forms. The expressed gene is organized into four exons and three introns...

40 CFR 721.10055 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts.

Science.gov (United States)

2010-07-01

...-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts. 721.10055 Section 721.10055 Protection of...-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts. (a) Chemical substance and...-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts (PMN P-03-46; CAS No. 136504-87-5) is subject to...

Metabolic alkene labeling and in vitro detection of histone acylation via the aqueous oxidative Heck reaction

NARCIS (Netherlands)

Ourailidou, Maria E; Dockerty, Paul; Witte, Martin; Poelarends, Gerrit J; Dekker, Frank J

2015-01-01

The detection of protein lysine acylations remains a challenge due to lack of specific antibodies for acylations with various chain lengths. This problem can be addressed by metabolic labeling techniques using carboxylates with reactive functionalities. Subsequent chemoselective reactions with a

Des-Acyl Ghrelin and Ghrelin O-Acyltransferase Regulate Hypothalamic-Pituitary-Adrenal Axis Activation and Anxiety in Response to Acute Stress

NARCIS (Netherlands)

Stark, R.; Santos, V.V.; Geenen, B.; Cabral, A.; Dinan, T.; Bayliss, J.A.; Lockie, S.H.; Reichenbach, A.; Lemus, M.B.; Perello, M.; Spencer, S.J.; Kozicz, L.T.; Andrews, Z.B.

2016-01-01

Ghrelin exists in two forms in circulation, acyl ghrelin and des-acyl ghrelin, both of which have distinct and fundamental roles in a variety of physiological functions. Despite this fact, a large proportion of papers simply measure and refer to plasma ghrelin without specifying the acylation

Monodisperse gold-palladium alloy nanoparticles and their composition-controlled catalysis in formic acid dehydrogenation under mild conditions.

Science.gov (United States)

Metin, Önder; Sun, Xiaolian; Sun, Shouheng

2013-02-07

Monodisperse 4 nm AuPd alloy nanoparticles with controlled composition were synthesized by co-reduction of hydrogen tetrachloroaurate(III) hydrate and palladium(II) acetylacetonate with a borane-morpholine complex in oleylamine. These NPs showed high activity (TOF = 230 h(-1)) and stability in catalyzing formic acid dehydrogenation and hydrogen production in water at 50 °C without any additives.

The kinetic and mechanistic aspects of the oxidative dehydrogenation of ethane over Li/Na/MgO catalysts

NARCIS (Netherlands)

Swaan, H.M.; Swaan, H.M.; Toebes, A.; Toebes, A.; van Ommen, J.G.; Seshan, Kulathuiyer; Ross, J.R.H.; Ross, J.R.H.

1992-01-01

Kinetic and mechanistic aspects of the oxidative dehydrogenation of ethane catalysed by Li/MgO and Li/Na/MgO have been investigated. Initial rate measurements at 600°C; revealed that the Li/MgO catalyst produced C2H4, CO2, CO and H2 by parallel reactions whereas the sodium-promoted catalyst produced

Synthesis and Bioactivity of Pyrazole Acyl Thiourea Derivatives

Directory of Open Access Journals (Sweden)

Jian Wu

2012-05-01

Full Text Available Sixteen novel pyrazole acyl thiourea derivatives 6 were synthesized from monomethylhydrazine (phenylhydrazine and ethyl acetoacetate. The key 5-chloro-3-methyl-1-substituted-1H-pyrazole-4-carbonyl chloride intermediates 4 were first generated in four steps through cyclization, formylation, oxidation and acylation. Thess were then reacted with ammonium thiocyanate in the presence of PEG-400 to afford 5-chloro-3-methyl-1-substituted-1H-pyrazole-4-carbonyl isothiocyanates 5. Subsequent reaction with fluorinated aromatic amines resulted in the formation of the title compounds. The synthesized compound were unequivocally characterized by IR, ¹H-NMR, ¹³C-NMR and elemental analysis and some of the synthesized compounds displayed good antifungal activities against Gibberella zeae, Fusarium oxysporum, Cytospora mandshurica and anti-TMV activity in preliminary antifungal activity tests.

Rate Parameter Distributions for Isobutane Dehydrogenation and Isobutene Dimerization and Desorption over HZSM-5

Directory of Open Access Journals (Sweden)

Trevor C. Brown

2013-11-01

Full Text Available Deconvolution of the evolved isobutene data obtained from temperature-programmed, low-pressure steady-state conversion of isobutane over HZSM-5 has yielded apparent activation energies for isobutane dehydrogenation, isobutene dimerization and desorption. Intrinsic activation energies and associated isobutane collision frequencies are also estimated. A combination of wavelet shrinkage denoising, followed by time-varying flexible least squares of the evolved mass-spectral abundance data over the temperature range 150 to 450 °C, provides accurate, temperature-dependent, apparent rate parameters. Intrinsic activation energies for isobutane dehydrogenation range from 86 to 235.2 kJ mol−1 (average = 150 ± 42 kJ mol−1 for isobutene dimerization from 48.3 to 267 kJ mol−1 (average = 112 ± 74 kJ mol−1 and for isobutene desorption from 64.4 to 97.8 kJ mol−1 (average = 77 ± 12 kJ mol−1. These wide ranges reflect the heterogeneity and acidity of the zeolite surface and structure. Seven distinct locations and sites, including Lewis and Brønsted acid sites can be identified in the profiles. Isobutane collision frequencies range from 10−0.4 to 1022.2 s−1 and are proportional to the accessibility of active sites, within the HZSM-5 micropores or on the external surface.

Role of Platinum Deposited on TiO2 in Photocatalytic Methanol Oxidation and Dehydrogenation Reactions

Directory of Open Access Journals (Sweden)

Luma M. Ahmed

2014-01-01

Full Text Available Titania modified nanoparticles have been prepared by the photodeposition method employing platinum particles on the commercially available titanium dioxide (Hombikat UV 100. The properties of the prepared photocatalysts were investigated by means of the Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, atomic force microscopy (AFM, and UV-visible diffuse spectrophotometry (UV-Vis. XRD was employed to determine the crystallographic phase and particle size of both bare and platinised titanium dioxide. The results indicated that the particle size was decreased with the increasing of platinum loading. AFM analysis showed that one particle consists of about 9 to 11 crystals. UV-vis absorbance analysis showed that the absorption edge shifted to longer wavelength for 0.5% Pt loading compared with bare titanium dioxide. The photocatalytic activity of pure and Pt-loaded TiO2 was investigated employing the photocatalytic oxidation and dehydrogenation of methanol. The results of the photocatalytic activity indicate that the platinized titanium dioxide samples are always more active than the corresponding bare TiO2 for both methanol oxidation and dehydrogenation processes. The loading with various platinum amounts resulted in a significant improvement of the photocatalytic activity of TiO2. This beneficial effect was attributed to an increased separation of the photogenerated electron-hole charge carriers.

THE EFFECTS OF EXERCISE ON FOOD INTAKE AND HUNGER: RELATIONSHIP WITH ACYLATED GHRELIN AND LEPTIN

Directory of Open Access Journals (Sweden)

Serife Vatansever-Ozen

2011-06-01

Full Text Available This study investigated the effects of a long bout of aerobic exercise on hunger and energy intake and circulating levels of leptin and acylated ghrelin. Ten healthy male subjects undertook two, 4 h trials in a randomized crossover design. In the exercise trial subjects ran for 105 min at 50% of maximal oxygen uptake and the last 15 min at 70% of maximal oxygen uptake followed by a 120 min rest period. In the control trial, subjects rested for 4 h. Subjects consumed a buffet test meal at 180 min during each trial. Hunger ratings, acylated ghrelin, leptin, glucose and insulin concentrations were measured at 0, 1, 2, 3 and 4 h. No differences were found at baseline values for hunger, acylated ghrelin, leptin, insulin and glucose for both trials (p > 0.05. The estimated energy expenditure of the exercise trial was 1550 ± 136 kcal. Exercise did not change subsequent absolute energy intake, but produced a significant decrease (p < 0.05 in relative energy intake. A two-way ANOVA revealed a significant (p < 0. 05 interaction effect for hunger and acylated ghrelin. In conclusion, this exercise regimen had a positive effect on reducing appetite which is related to reduced acylated ghrelin responses over time. This finding lends support for a role of exercise in weight management

Majority of cellular fatty acid acylated proteins are localized to the cytoplasmic surface of the plasma membrane

International Nuclear Information System (INIS)

Wilcox, C.A.; Olson, E.N.

1987-01-01

The BC 2 Hl muscle cell line was previously reported to contain a broad array of fatty acid acylated proteins. Palmitate was shown to be attached to membrane proteins posttranslationally through thiol ester linkages, whereas myristate was attached cotranslationally, or within seconds thereafter, to soluble and membrane-bound proteins through amide linkages. The temporal and subcellular differences between palmitate and myristate acylation suggested that these two classes of acyl proteins might follow different intracellular pathways to distinct subcellular membrane systems or organelles. In this study, the authors examined the subcellular localization of the major fatty acylated proteins in BC 4 Hl cells. Palmitate-containing proteins were localized to the plasma membrane, but only a subset of myristate-containing proteins was localized to this membrane fraction. The majority of acyl proteins were nonglycosylated and resistant to digestion with extracellular proteases, suggesting that they were not exposed to the external surface of the plasma membrane. Many proteins were, however, digested during incubation of isolated membranes with proteases, which indicates that these proteins were, however, digested during incubation of isolated membranes with proteases, which indicates that these proteins face the cytoplasm. Two-dimensional gel electrophoresis of proteins labeled with [ 3 H]palmitate and [ 3 H]myristate revealed that individual proteins were modified by only one of the two fatty acids and did not undergo both N-linked myristylation and ester-linked palmitylation. Together, these results suggest that the majority of cellular acyl proteins are routed to the cytoplasmic surface of the plasma membrane, and they raise the possibility that fatty acid acylation may play a role in intracellular sorting of nontransmembranous, nonglycosylated membrane proteins

[Metabolic myopathies].

Science.gov (United States)

Papazian, Óscar; Rivas-Chacón, Rafael

2013-09-06

To review the metabolic myopathies manifested only by crisis of myalgias, cramps and rigidity of the muscles with decreased voluntary contractions and normal inter crisis neurologic examination in children and adolescents. These metabolic myopathies are autosomic recessive inherited enzymatic deficiencies of the carbohydrates and lipids metabolisms. The end result is a reduction of intra muscle adenosine triphosphate, mainly through mitochondrial oxidative phosphorylation, with decrease of available energy for muscle contraction. The one secondary to carbohydrates intra muscle metabolism disorders are triggered by high intensity brief (fatty acids metabolism disorders are triggered by low intensity prolonged (> 10 min) exercises. The conditions in the first group in order of decreasing frequency are the deficiencies of myophosforilase (GSD V), muscle phosphofructokinase (GSD VII), phosphoglycerate mutase 1 (GSD X) and beta enolase (GSD XIII). The conditions in the second group in order of decreasing frequency are the deficiencies of carnitine palmitoyl transferase II and very long chain acyl CoA dehydrogenase. The differential characteristics of patients in each group and within each group will allow to make the initial presumptive clinical diagnosis in the majority and then to order only the necessary tests to achieve the final diagnosis. Treatment during the crisis includes hydration, glucose and alkalinization of urine if myoglobin in blood and urine are elevated. Prevention includes avoiding exercise which may induce the crisis and fasting. The prognosis is good with the exception of rare cases of acute renal failure due to hipermyoglobinemia because of severe rabdomyolisis.

Continuous recording of long-chain acyl-coenzyme A synthetase activity using fluorescently labeled bovine serum albumin

DEFF Research Database (Denmark)

Demant, Erland J.F.; Nystrøm, Birthe T.

2001-01-01

acyl-Coenzyme A, synthetase, activity assay, fluorescence recording, fatty acid probe, serum albumin, hydroxycoumarin, detergent, micelles, Pseudomonas fragi, rat liver microsomes......acyl-Coenzyme A, synthetase, activity assay, fluorescence recording, fatty acid probe, serum albumin, hydroxycoumarin, detergent, micelles, Pseudomonas fragi, rat liver microsomes...

Production of specific-structured lipids by enzymatic interesterification: elucidation of acyl migration by response surface design

DEFF Research Database (Denmark)

Xu, Xuebing; Skands, Anja; Høy, Carl-Erik

1998-01-01

Production of specific-structured lipids (SSL) by lipase-catalyzed interesterification has been attracting more and more attention recently. However, it was found that acyl migration occurs during the reaction and causes the production of by-products. In this paper, the elucidation of acyl...

Quantum Chemical Investigation on Photochemical Reactions of Nonanoic Acids at Air-Water Interface.

Science.gov (United States)

Xiao, Pin; Wang, Qian; Fang, Wei-Hai; Cui, Ganglong

2017-06-08

Photoinduced chemical reactions of organic compounds at the marine boundary layer have recently attracted significant experimental attention because this kind of photoreactions has been proposed to have substantial impact on local new particle formation and their photoproducts could be a source of secondary organic aerosols. In this work, we have employed first-principles density functional theory method combined with cluster models to systematically explore photochemical reaction pathways of nonanoic acids (NAs) to form volatile saturated and unsaturated C 9 and C 8 aldehydes at air-water interfaces. On the basis of the results, we have found that the formation of C 9 aldehydes is not initiated by intermolecular Norrish type II reaction between two NAs but by intramolecular T 1 C-O bond fission of NA generating acyl and hydroxyl radicals. Subsequently, saturated C 9 aldehydes are formed through hydrogenation reaction of acyl radical by another intact NA. Following two dehydrogenation reactions, unsaturated C 9 aldehydes are generated. In parallel, the pathway to C 8 aldehydes is initiated by T 1 C-C bond fission of NA, which generates octyl and carboxyl radicals; then, an octanol is formed through recombination reaction of octyl with hydroxyl radical. In the following, two dehydrogenation reactions result into an enol intermediate from which saturated C 8 aldehydes are produced via NA-assisted intermolecular hydrogen transfer. Finally, two dehydrogenation reactions generate unsaturated C 8 aldehydes. In these reactions, water and NA molecules are found to play important roles. They significantly reduce relevant reaction barriers. Our work has also explored oxygenation reactions of NA with molecular oxygen and radical-radical dimerization reactions.

Asymmetric Chemoenzymatic Reductive Acylation of Ketones by a Combined Iron-Catalyzed Hydrogenation-Racemization and Enzymatic Resolution Cascade

KAUST Repository

El-Sepelgy, Osama; Brzozowska, Aleksandra; Rueping, Magnus

2017-01-01

. By merging the iron-catalyzed redox reactions with enantioselective enzymatic acylations a wide range of benzylic, aliphatic and (hetero)aromatic ketones, as well as diketones, were reductively acylated. The corresponding products were isolated with high

Simulation of the styrene production process via catalytic dehydrogenation of ethylbenzene using CHEMCAD® process simulator

OpenAIRE

Amaury Pérez Sánchez; Eddy Javier Pérez Sánchez; Rutdali María Segura Silva

2017-01-01

Background: Process simulation has been extensively used in recent years to design, evaluate or optimize processes, systems and specific operations of the chemical industry and its related disciplines. Currently, CHEMCAD® constitute one of the most used process simulators because of the great number of chemical and petrochemical processes that can be simulated. Method: The simulation of the production process of styrene via catalytic dehydrogenation of ethyl-benzene is carried out by usin...

Catalytic performance of organically templated nano nickel incorporated-rice husk silica in hydroconversion of cyclohexene and dehydrogenation of ethanol

Directory of Open Access Journals (Sweden)

Salah A. Hassan

2013-06-01

Full Text Available Rice husk silica (RHS was extracted from local rice husk by acid digestion and burning at 650 °C. RHS-Ni catalyst was prepared by dissolving RHS in 1 N NaOH and titrating with 3 N HNO3 containing 10 wt.% Ni2+. The organic modifiers, either p-amino benzoic acid (A or p-phenylenediamine (PDA were incorporated in 5 wt.% and reduced in H2 flow. Investigation of the three catalysts, (RHS-NiR350, (RHS-Ni–AR350 and (RHS-Ni–PDAR350, confirmed good dispersion of Ni nanoparticles; all catalysts were amorphous. The BET surface areas increased in the order: (RHS-NiR350  150 °C, the backward dehydrogenation pathway was more favored, due to unavailability of H2; the process became structure-sensitive. In ethanol conversion, the prevailing dehydrogenation activity of organically modified catalyst samples was encouraged by improved homogeneous distribution of Ni nanoparticles and created micropre system.

Selective Acylation Enhances Membrane Charge Sensitivity of the Antimicrobial Peptide Mastoparan-X

DEFF Research Database (Denmark)

Etzerodt, Thomas Povl; Henriksen, Jonas Rosager; Rasmussen, Palle

2011-01-01

and positioning of the peptide in the membrane caused by either PA or OA acylation play a critical role in the fine-tuning of the effective charge of the peptide and thereby the fine-tuning of the peptide's selectivity between neutral and negatively charged lipid membranes. This finding is unique compared...... to previous reports where peptide acylation enhanced membrane affinity but also resulted in impaired selectivity. Our result may provide a method of enhancing selectivity of antimicrobial peptides toward bacterial membranes due to their high negative charge—a finding that should be investigated for other...

Phase behavior and nanoscale structure of phospholipid membranes incorporated with acylated C-14-peptides

DEFF Research Database (Denmark)

Pedersen, T.B.; Kaasgaard, Thomas; Jensen, M.O.

2005-01-01

The thermotropic phase behavior and lateral structure of dipalmitoylphosphatidylcholine (DPPC) lipid bilayers containing an acylated peptide has been characterized by differential scanning calorimetry (DSC) on vesicles and atomic force microscopy (AFM) on mica-supported bilayers. The acylated...... peptide, which is a synthetic decapeptide N-terminally linked to a C-14 acyl chain (C-14-peptide), is incorporated into DPPC bilayers in amounts ranging from 0-20 mol %. The calorimetric scans of the two-component system demonstrate a distinct influence of the C-14-peptide on the lipid bilayer...... gel phase DPPC bilayers, inserts preferentially into preexisting defect regions and has a noticeable influence on the organization of the surrounding lipids. The presence of the C-14-peptide gives rise to a laterally heterogeneous bilayer structure with coexisting lipid domains characterized by a 10...

Novel endogenous N-acyl amides activate TRPV1-4 receptors, BV-2 microglia, and are regulated in brain in an acute model of inflammation

Science.gov (United States)

Raboune, Siham; Stuart, Jordyn M.; Leishman, Emma; Takacs, Sara M.; Rhodes, Brandon; Basnet, Arjun; Jameyfield, Evan; McHugh, Douglas; Widlanski, Theodore; Bradshaw, Heather B.

2014-01-01

A family of endogenous lipids, structurally analogous to the endogenous cannabinoid, N-arachidonoyl ethanolamine (Anandamide), and called N-acyl amides have emerged as a family of biologically active compounds at TRP receptors. N-acyl amides are constructed from an acyl group and an amine via an amide bond. This same structure can be modified by changing either the fatty acid or the amide to form potentially hundreds of lipids. More than 70 N-acyl amides have been identified in nature. We have ongoing studies aimed at isolating and characterizing additional members of the family of N-acyl amides in both central and peripheral tissues in mammalian systems. Here, using a unique in-house library of over 70 N-acyl amides we tested the following three hypotheses: (1) Additional N-acyl amides will have activity at TRPV1-4, (2) Acute peripheral injury will drive changes in CNS levels of N-acyl amides, and (3) N-acyl amides will regulate calcium in CNS-derived microglia. Through these studies, we have identified 20 novel N-acyl amides that collectively activate (stimulating or inhibiting) TRPV1-4. Using lipid extraction and HPLC coupled to tandem mass spectrometry we showed that levels of at least 10 of these N-acyl amides that activate TRPVs are regulated in brain after intraplantar carrageenan injection. We then screened the BV2 microglial cell line for activity with this N-acyl amide library and found overlap with TRPV receptor activity as well as additional activators of calcium mobilization from these lipids. Together these data provide new insight into the family of N-acyl amides and their roles as signaling molecules at ion channels, in microglia, and in the brain in the context of inflammation. PMID:25136293

Oxidative Dehydrogenation of n-Butenes to 1,3-Butadiene over Bismuth Molybdate and Ferrite Catalysts: A Review

KAUST Repository

Hong, Eunpyo

2015-11-02

1,3-Butadiene, an important raw material for a variety of chemical products, can be produced via the oxidative dehydrogenation (ODH) of n-butenes over multicomponent oxide catalysts based on bismuth molybdates and ferrites. In this review, the basic concept, reaction mechanism, and catalysts typically used in an ODH reaction are discussed. © 2015, Springer Science+Business Media New York.

Moessbauer study on the formation process of Fe-K composition in iron-based catalyst for dehydrogenation of ethylbenzene

International Nuclear Information System (INIS)

Jiang Keyu; Zhao Zhenjie; Yang Xielong

2001-01-01

Fe-K spinel structure is the predecessor of active phase of potassium promoted iron-based catalyst for dehydrogenation of ethylbenzene. Moessbauer spectroscopy has been used to study the formation process of Fe-K spinel structure which depends on the catalyst composition and preparing condition. The results may prove useful for production of industrial catalyst

Influence of preparation conditions of hollow titania–nickel composite spheres on their catalytic activity for hydrolytic dehydrogenation of ammonia borane

Energy Technology Data Exchange (ETDEWEB)

Umegaki, Tetsuo, E-mail: umegaki.tetsuo@nihon-u.ac.jp [Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan); Ohashi, Takato [Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan); Xu, Qiang [National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan); Kojima, Yoshiyuki [Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan)

2014-04-01

Highlights: • We study influence of preparation conditions on activity of hollow titania–nickel composite spheres. • The activity for hydrolytic dehydrogenation of NH{sub 3}BH{sub 3} increases with increase of Ti + Ni content. • The activity depends on the amount of PS residue in the hollow spheres. - Abstract: The present work reports influence of preparation conditions of hollow titania–nickel composite spheres on their morphology and catalytic activity for hydrolytic dehydrogenation of ammonia borane (NH{sub 3}BH{sub 3}). The as-prepared hollow titania–nickel composite spheres were characterized by transmission electron microscopy (TEM). Catalytic activities of the hollow spheres for hydrolytic dehydrogenation of aqueous NaBH{sub 4}/NH{sub 3}BH{sub 3} solution improve with the decrease of Ti + Ni content. From the results of FTIR spectra and elemental analysis, the amount of residual polystyrene (PS) templates is able to be reduced by increasing aging time for the preparation, and the catalytic activity of the hollow spheres increases when the amount of residual PS templates decreases. The carbon content in the hollow spheres prepared with aging time = 24 h is 17.3 wt.%, and the evolution of 62 mL hydrogen is finished in about 22 min in the presence of the hollow spheres from aqueous NaBH{sub 4}/NH{sub 3}BH{sub 3} solution. The molar ratio of the hydrolytically generated hydrogen to the initial NH{sub 3}BH{sub 3} in the presence of the hollow spheres is 2.7.

Influence of vanadium oxidation states on the performance of V-Mg-Al mixed-oxide catalysts for the oxidative dehydrogenation of propane

International Nuclear Information System (INIS)

Schacht, L.; Navarrete, J.; Schacht, P.; Ramirez, M. A.

2010-01-01

V-Mg-Al mixed-oxide catalysts for oxidative dehydrogenation of propane were prepared by thermal decomposition of Mg-Al-layered double hydroxides with vanadium interlayer doping. The obtained catalysts were tested for the oxidative dehydrogenation of propane, obtaining good results in catalytic activity (conversion 16.55 % and selectivity 99.97 %) Results indicated that catalytic performance of these materials depends on how vanadium is integrated in the layered structure, which is determined by the Mg/Al ratio. Vanadium interlayer doping modifies the oxidation state of vanadium and consequently catalytic properties. Surface properties were studied by X-ray photoelectron spectroscopic and diffuse reflectance, UV-visible spectroscopy, and temperature programmed reduction. The analyses provided information about the oxidation state, before and after the reaction. From these results, it is suggested that selectivity to propylene and catalytic activity depend mainly of vanadium oxidation state. (Author)

Influence of vanadium oxidation states on the performance of V-Mg-Al mixed-oxide catalysts for the oxidative dehydrogenation of propane

Energy Technology Data Exchange (ETDEWEB)

Schacht, L. [IPN, Escuela Superior de Fisica y Matematicas, Departamento de Ciencia de Materiales, Av. IPN s/n, Edificio 9, Col. Lindavista, 07738 Mexico D. F. (Mexico); Navarrete, J.; Schacht, P.; Ramirez, M. A., E-mail: pschacha@imp.m [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D. F. (Mexico)

2010-07-01

V-Mg-Al mixed-oxide catalysts for oxidative dehydrogenation of propane were prepared by thermal decomposition of Mg-Al-layered double hydroxides with vanadium interlayer doping. The obtained catalysts were tested for the oxidative dehydrogenation of propane, obtaining good results in catalytic activity (conversion 16.55 % and selectivity 99.97 %) Results indicated that catalytic performance of these materials depends on how vanadium is integrated in the layered structure, which is determined by the Mg/Al ratio. Vanadium interlayer doping modifies the oxidation state of vanadium and consequently catalytic properties. Surface properties were studied by X-ray photoelectron spectroscopic and diffuse reflectance, UV-visible spectroscopy, and temperature programmed reduction. The analyses provided information about the oxidation state, before and after the reaction. From these results, it is suggested that selectivity to propylene and catalytic activity depend mainly of vanadium oxidation state. (Author)

Branched-chain amino acid restriction in Zucker-fatty rats improves muscle insulin sensitivity by enhancing efficiency of fatty acid oxidation and acyl-glycine export.

Science.gov (United States)

White, Phillip J; Lapworth, Amanda L; An, Jie; Wang, Liping; McGarrah, Robert W; Stevens, Robert D; Ilkayeva, Olga; George, Tabitha; Muehlbauer, Michael J; Bain, James R; Trimmer, Jeff K; Brosnan, M Julia; Rolph, Timothy P; Newgard, Christopher B

2016-07-01

A branched-chain amino acid (BCAA)-related metabolic signature is strongly associated with insulin resistance and predictive of incident diabetes and intervention outcomes. To better understand the role that this metabolite cluster plays in obesity-related metabolic dysfunction, we studied the impact of BCAA restriction in a rodent model of obesity in which BCAA metabolism is perturbed in ways that mirror the human condition. Zucker-lean rats (ZLR) and Zucker-fatty rats (ZFR) were fed either a custom control, low fat (LF) diet, or an isonitrogenous, isocaloric LF diet in which all three BCAA (Leu, Ile, Val) were reduced by 45% (LF-RES). We performed comprehensive metabolic and physiologic profiling to characterize the effects of BCAA restriction on energy balance, insulin sensitivity, and glucose, lipid and amino acid metabolism. LF-fed ZFR had higher levels of circulating BCAA and lower levels of glycine compared to LF-fed ZLR. Feeding ZFR with the LF-RES diet lowered circulating BCAA to levels found in LF-fed ZLR. Activity of the rate limiting enzyme in the BCAA catabolic pathway, branched chain keto acid dehydrogenase (BCKDH), was lower in liver but higher in skeletal muscle of ZFR compared to ZLR and was not responsive to diet in either tissue. BCAA restriction had very little impact on metabolites studied in liver of ZFR where BCAA content was low, and BCKDH activity was suppressed. However, in skeletal muscle of LF-fed ZFR compared to LF-fed ZLR, where BCAA content and BCKDH activity were increased, accumulation of fatty acyl CoAs was completely normalized by dietary BCAA restriction. BCAA restriction also normalized skeletal muscle glycine content and increased urinary acetyl glycine excretion in ZFR. These effects were accompanied by lower RER and improved skeletal muscle insulin sensitivity in LF-RES fed ZFR as measured by hyperinsulinemic-isoglycemic clamp. Our data are consistent with a model wherein elevated circulating BCAA contribute to development of

Branched-chain amino acid restriction in Zucker-fatty rats improves muscle insulin sensitivity by enhancing efficiency of fatty acid oxidation and acyl-glycine export

Directory of Open Access Journals (Sweden)

Phillip J. White

2016-07-01

Full Text Available Objective: A branched-chain amino acid (BCAA-related metabolic signature is strongly associated with insulin resistance and predictive of incident diabetes and intervention outcomes. To better understand the role that this metabolite cluster plays in obesity-related metabolic dysfunction, we studied the impact of BCAA restriction in a rodent model of obesity in which BCAA metabolism is perturbed in ways that mirror the human condition. Methods: Zucker-lean rats (ZLR and Zucker-fatty rats (ZFR were fed either a custom control, low fat (LF diet, or an isonitrogenous, isocaloric LF diet in which all three BCAA (Leu, Ile, Val were reduced by 45% (LF-RES. We performed comprehensive metabolic and physiologic profiling to characterize the effects of BCAA restriction on energy balance, insulin sensitivity, and glucose, lipid and amino acid metabolism. Results: LF-fed ZFR had higher levels of circulating BCAA and lower levels of glycine compared to LF-fed ZLR. Feeding ZFR with the LF-RES diet lowered circulating BCAA to levels found in LF-fed ZLR. Activity of the rate limiting enzyme in the BCAA catabolic pathway, branched chain keto acid dehydrogenase (BCKDH, was lower in liver but higher in skeletal muscle of ZFR compared to ZLR and was not responsive to diet in either tissue. BCAA restriction had very little impact on metabolites studied in liver of ZFR where BCAA content was low, and BCKDH activity was suppressed. However, in skeletal muscle of LF-fed ZFR compared to LF-fed ZLR, where BCAA content and BCKDH activity were increased, accumulation of fatty acyl CoAs was completely normalized by dietary BCAA restriction. BCAA restriction also normalized skeletal muscle glycine content and increased urinary acetyl glycine excretion in ZFR. These effects were accompanied by lower RER and improved skeletal muscle insulin sensitivity in LF-RES fed ZFR as measured by hyperinsulinemic-isoglycemic clamp. Conclusions: Our data are consistent with a model wherein

Acylation Reactions over Zeolites and Mesoporous Catalysts

Czech Academy of Sciences Publication Activity Database

Voláková, Martina; Vitvarová, Dana; Čejka, Jiří

2009-01-01

Roč. 2, č. 6 (2009), s. 486-499 ISSN 1864-5631 R&D Projects: GA ČR GA104/07/0383; GA ČR GD203/08/H032; GA MPO FT-TA5/005 Institutional research plan: CEZ:AV0Z40400503 Keywords : acylation * ketones * mesoporous materials * shape-selectivity * zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.767, year: 2009

Iodine-Catalyzed Direct Olefination of 2-Oxindoles and Alkenes via Cross-Dehydrogenative Coupling (CDC) in Air.

Science.gov (United States)

Huang, Hong-Yan; Wu, Hong-Ru; Wei, Feng; Wang, Dong; Liu, Li

2015-08-07

A direct intermolecular olefination of sp(3) C-H bond between 2-oxindoles and simple alkenes via a Cross-Dehydrogenative Coupling (CDC) strategy has been developed. In the absence of additional base, moderate to excellent yields have been obtained by using a catalytic amount of iodine with atmospheric oxygen as the reoxidant. Based on the observation of a radical capture experiment, the transformation is proposed to proceed via a radical process.

Defluoridation potential of jute fibers grafted with fatty acyl chain

Energy Technology Data Exchange (ETDEWEB)

Manna, Suvendu; Saha, Prosenjit [Materials Science Centre, IIT Kharagpur, WB 721302 (India); Roy, Debasis, E-mail: debasis@civil.iitkgp.ernet.in [Department of Civil Engineering, IIT Kharagpur, WB 721302 (India); Sen, Ramkrishna [Department of Biotechnology, IIT Kharagpur, WB 721302 (India); Adhikari, Basudam [Materials Science Centre, IIT Kharagpur, WB 721302 (India)

2015-11-30

Graphical abstract: - Highlights: • Acyl chain grafted jute has been shown to accumulate fluoride ions. • Covalent and hydrogen bonding and protonation were the contributing factors. • The process is relatively inexpensive and maintenance-free. • Acyl chain grafted jute showed higher fluoride ions accumulation than alternatives. - Abstract: Waterborne fluoride is usually removed from water by coagulation, adsorption, ion exchange, electro dialysis or reverse osmosis. These processes are often effective over narrow pH ranges, release ions considered hazardous to human health or produce large volumes of toxic sludge that are difficult to handle and dispose. Although plant matters have been shown to remove waterborne fluoride, they suffer from poor removal efficiency. Following from the insight that interaction between microbial carbohydrate biopolymers and anionic surfaces is often facilitated by lipids, an attempt has been made to enhance fluoride adsorption efficiency of jute by grafting the lignocellulosic fiber with fatty acyl chains found in vegetable oils. Fluoride removal efficiency of grafted jute was found to be comparable or higher than those of alternative defluoridation processes. Infrared and X-ray photoelectron spectroscopic evidence indicated that hydrogen bonding, protonation and C−F bonding were responsible for fluoride accumulation on grafted jute. Adsorption based on grafted jute fibers appears to be an economical, sustainable and eco-friendly alternative technique for removing waterborne fluoride.

Acyl coenzyme A thioesterase 7 regulates neuronal fatty acid metabolism to prevent neurotoxicity.

Science.gov (United States)

Ellis, Jessica M; Wong, G William; Wolfgang, Michael J

2013-05-01

Numerous neurological diseases are associated with dysregulated lipid metabolism; however, the basic metabolic control of fatty acid metabolism in neurons remains enigmatic. Here we have shown that neurons have abundant expression and activity of the long-chain cytoplasmic acyl coenzyme A (acyl-CoA) thioesterase 7 (ACOT7) to regulate lipid retention and metabolism. Unbiased and targeted metabolomic analysis of fasted mice with a conditional knockout of ACOT7 in the nervous system, Acot7(N-/-), revealed increased fatty acid flux into multiple long-chain acyl-CoA-dependent pathways. The alterations in brain fatty acid metabolism were concomitant with a loss of lean mass, hypermetabolism, hepatic steatosis, dyslipidemia, and behavioral hyperexcitability in Acot7(N-/-) mice. These failures in adaptive energy metabolism are common in neurodegenerative diseases. In agreement, Acot7(N-/-) mice exhibit neurological dysfunction and neurodegeneration. These data show that ACOT7 counterregulates fatty acid metabolism in neurons and protects against neurotoxicity.

Endotoxin Structures in the Psychrophiles Psychromonas marina and Psychrobacter cryohalolentis Contain Distinctive Acyl Features

Directory of Open Access Journals (Sweden)

Charles R. Sweet

2014-07-01

Full Text Available Lipid A is the essential component of endotoxin (Gram-negative lipopolysaccharide, a potent immunostimulatory compound. As the outer surface of the outer membrane, the details of lipid A structure are crucial not only to bacterial pathogenesis but also to membrane integrity. This work characterizes the structure of lipid A in two psychrophiles, Psychromonas marina and Psychrobacter cryohalolentis, and also two mesophiles to which they are related using MALDI-TOF MS and fatty acid methyl ester (FAME GC-MS. P. marina lipid A is strikingly similar to that of Escherichia coli in organization and total acyl size, but incorporates an unusual doubly unsaturated tetradecadienoyl acyl residue. P. cryohalolentis also shows structural organization similar to a closely related mesophile, Acinetobacter baumannii, however it has generally shorter acyl constituents and shows many acyl variants differing by single methylene (-CH2- units, a characteristic it shares with the one previously reported psychrotolerant lipid A structure. This work is the first detailed structural characterization of lipid A from an obligate psychrophile and the second from a psychrotolerant species. It reveals distinctive structural features of psychrophilic lipid A in comparison to that of related mesophiles which suggest constitutive adaptations to maintain outer membrane fluidity in cold environments.

Long Chain N-acyl Homoserine Lactone Production by Enterobacter sp. Isolated from Human Tongue Surfaces

Science.gov (United States)

Yin, Wai-Fong; Purmal, Kathiravan; Chin, Shenyang; Chan, Xin-Yue; Chan, Kok-Gan

2012-01-01

We report the isolation of N-acyl homoserine lactone-producing Enterobacter sp. isolate T1-1 from the posterior dorsal surfaces of the tongue of a healthy individual. Spent supernatants extract from Enterobacter sp. isolate T1-1 activated the biosensor Agrobacterium tumefaciens NTL4(pZLR4), suggesting production of long chain AHLs by these isolates. High resolution mass spectrometry analysis of these extracts confirmed that Enterobacter sp. isolate T1-1 produced a long chain N-acyl homoserine lactone, namely N-dodecanoyl-homoserine lactone (C12-HSL). To the best of our knowledge, this is the first isolation of Enterobacter sp., strain T1-1 from the posterior dorsal surface of the human tongue and N-acyl homoserine lactones production by this bacterium. PMID:23202161

Disruption of the Acyl-CoA binding protein gene delays hepatic adaptation to metabolic changes at weaning

DEFF Research Database (Denmark)

Neess, Ditte; Marcher, Ann-Britt; Bloksgaard, Maria

The acyl-CoA binding protein/diazepam binding inhibitor (ACBP/DBI) is an evolutionary conserved intracellular protein that binds C14-C22 acyl-CoA esters with very high affinity. ACBP is thought to act as an acyl-CoA transporter, and in vitro analyses have indicated that ACBP can transport acyl......-CoA esters between different enzymatic systems. However, little is known about the in vivo function in mammalian cells. We have generated mice with targeted disruption of ACBP (ACBP-/-). These mice are viable and fertile and develop normally. However, around weaning the ACBP-/- mice show decreased growth......) family, around the weaning period. As a result, the hepatic de novo cholesterogenesis is significantly decreased at weaning. The delayed induction of SREBP target genes around weaning is caused by a compromised processing and decreased expression of SREBP precursors leading to reduced binding of SREBP...

Relationships between acylated ghrelin with growth hormone, insulin resistance, lipid profile, and cardio respiratory function in lean and obese men

Directory of Open Access Journals (Sweden)

Hasan Matin Homaee

2011-01-01

Conclusions: Obese and lean inactive young men had different levels of acylated ghrelin, GH, insulin, insulin resistance index, cardiorespiratory function and body fat percent. Body fat percent, insulin, and GH levels appear to be best determinant factors of acylated ghrelin levels. Also, in both obese and lean young men, higher levels of cardiovascular function were associated with higher levels of acylated ghrelin.

Plasma fatty acyl-carnitines during 8 Weeks of overfeeding: relation to diet energy expenditure and body composition: the PROOF study.

Science.gov (United States)

Bray, George A; Redman, Leanne M; de Jonge, Lilian; Rood, Jennifer; Sutton, Elizabeth F; Smith, Steven R

2018-01-24

Overfeeding is a strategy for evaluating the effects of excess energy intake. In this secondary analysis we tested the possibility that different levels of dietary protein might differentially modify the response of fatty acyl-carnitines to overfeeding. Twenty-three healthy adult men and women were overfed by 40% for 8 weeks while in-patients with diets containing 5% (LPD), 15% (NPD) or 25% (HPD) protein. Plasma fatty acyl-carnitines were measured by gas chromatography/mass spectrometry (GC/MS) at baseline and after 8 weeks of overfeeding. Measurements included: body composition by DXA, energy expenditure by ventilated hood and doubly-labeled water, fat cell size from subcutaneous fat biopsies, and fat distribution by CT scan. Analysis was done on 5 groups of fatty acyl-carnitines identified by principal components analysis and 6 individual short-chain fatty acyl carnitines. Higher protein intake was associated with significantly lower 8 week levels of medium chain fatty acids and C2, C4-OH and C 6:1, but higher values of C3 and C5:1 acyl-carnitines derived from essential amino acids. In contrast energy and fat intake were only weakly related to changes in fatty acyl-carnitines. A decease or smaller rise in 8 week medium chain acyl-carnitines was associated with an increase in sleeping energy expenditure (P = 0.0004), and fat free mass (P < 0.0001) and a decrease in free fatty acid concentrations (FFA) (P = 0.0067). In contrast changes in short-chain fatty acyl-carnitines were related to changes in resting energy expenditure (P = 0.0026), and fat free mass (P = 0.0007), and C4-OH was positively related to FFA (P = 0006). Protein intake was the major factor influencing changes in fatty acyl carnitines during overfeeding with higher values of most acyl-fatty acids on the low protein diet. The association of dietary protein and fat intake may explain the changes in energy expenditure and metabolic variables resulting in the observed

Effect of room temperature ionic liquid structure on the enzymatic acylation of flavonoids

DEFF Research Database (Denmark)

Lue, Bena-Marie; Guo, Zheng; Xu, Xuebing

2010-01-01

Enzymatic acylation reactions of flavonoids (rutin, esculin) with long chain fatty acids (palmitic, oleic acids) were carried out in 14 different ionic liquid media containing a range of cation and anion structures. Classification of RTILs according to flavonoid solubility (using COSMO...... must be struck that maximized flavonoid solubility with minimum negative impact on lipase activity. The process also benefitted from an increased reaction temperature which may have helped to reduced mass transfer limitations. Keywords: Room temperature ionic liquids (RTILs); Biosynthesis; Acylation......; Flavonoids; Lipase; Long chain fatty acids...

A kinetic rate expression for the time-dependent coke formation rate during propane dehydrogenation over a platinum alumina monolithic catalyst

NARCIS (Netherlands)

Sint Annaland, van M.; Kuipers, J.A.M.; van Swaaij, W.P.M.

2001-01-01

Coke formation rates under propane dehydrogenation reaction conditions on a used monolithic Pt/¿-Al2O3 catalyst have been experimentally determined in a thermogravimetric analyser (TGA) as a function of time on stream covering wide temperature and concentration ranges. For relatively short times on

A kinetic rate expression for the time-dependent coke formation rate during propane dehydrogenation over a platinum alumina monolithic catalyst.

NARCIS (Netherlands)

van Sint Annaland, M.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria

2001-01-01

Coke formation rates under propane dehydrogenation reaction conditions on a used monolithic Pt/y-Al2O3 catalyst have been experimentally determined in a thermogravimetric analyser (TGA) as a function of time on stream covering wide temperature and concentration ranges. For relatively short times on

Microwave-assisted intramolecular dehydrogenative Diels-Alder reactions for the synthesis of functionalized naphthalenes/solvatochromic dyes.

Science.gov (United States)

Kocsis, Laura S; Benedetti, Erica; Brummond, Kay M

2013-04-01

Functionalized naphthalenes have applications in a variety of research fields ranging from the synthesis of natural or biologically active molecules to the preparation of new organic dyes. Although numerous strategies have been reported to access naphthalene scaffolds, many procedures still present limitations in terms of incorporating functionality, which in turn narrows the range of available substrates. The development of versatile methods for direct access to substituted naphthalenes is therefore highly desirable. The Diels-Alder (DA) cycloaddition reaction is a powerful and attractive method for the formation of saturated and unsaturated ring systems from readily available starting materials. A new microwave-assisted intramolecular dehydrogenative DA reaction of styrenyl derivatives described herein generates a variety of functionalized cyclopenta[b]naphthalenes that could not be prepared using existing synthetic methods. When compared to conventional heating, microwave irradiation accelerates reaction rates, enhances yields, and limits the formation of undesired byproducts. The utility of this protocol is further demonstrated by the conversion of a DA cycloadduct into a novel solvatochromic fluorescent dye via a Buchwald-Hartwig palladium-catalyzed cross-coupling reaction. Fluorescence spectroscopy, as an informative and sensitive analytical technique, plays a key role in research fields including environmental science, medicine, pharmacology, and cellular biology. Access to a variety of new organic fluorophores provided by the microwave-assisted dehydrogenative DA reaction allows for further advancement in these fields.

An insight on acyl migration in solvent-free ethanolysis of model triglycerides using Novozym 435.

Science.gov (United States)

Sánchez, Daniel Alberto; Tonetto, Gabriela Marta; Ferreira, María Luján

2016-02-20

In this work, the ethanolysis of triglycerides catalyzed by immobilized lipase was studied, focusing on the secondary reaction of acyl migration. The catalytic tests were performed in a solvent-free reaction medium using Novozym 435 as biocatalyst. The selected experimental variables were biocatalyst loading (5-20mg), reaction time (30-90min), and chain length of the fatty acids in triglycerides with and without unsaturation (short (triacetin), medium (tricaprylin) and long (tripalmitin/triolein)). The formation of 2-monoglyceride by ethanolysis of triglycerides was favored by long reaction times and large biocatalyst loading with saturated short- to medium-chain triglycerides. In the case of long-chain triglycerides, the formation of this monoglyceride was widely limited by acyl migration. In turn, acyl migration increased the yield of ethyl esters and minimized the content of monoglycerides and diglycerides. Thus, the enzymatic synthesis of biodiesel was favored by long-chain triglycerides (which favor the acyl migration), long reaction times and large biocatalyst loading. The conversion of acylglycerides made from long-chain fatty acids with unsaturation was relatively low due to limitations in their access to the active site of the lipase. Copyright © 2016 Elsevier B.V. All rights reserved.

Genetic basis for correction of very-long-chain acyl-coenzyme A dehydrogenase deficiency by bezafibrate in patient fibroblasts

DEFF Research Database (Denmark)

Gobin-Limballe, S; Djouadi, F; Aubey, F

2007-01-01

there is no established treatment. Recent data suggest that bezafibrate could improve the FAO capacities in beta-oxidation-deficient cells, by enhancing the residual level of mutant enzyme activity via gene-expression stimulation. Since VLCAD-deficient patients frequently harbor missense mutations with unpredictable...... values, for 21 genotypes that mainly corresponded to patients with the myopathic phenotype. In contrast, bezafibrate induced no changes in FAO for 11 genotypes corresponding to severe neonatal or infantile phenotypes. This pattern of response was not due to differential inductions of VLCAD messenger RNA......, as shown by quantitative real-time polymerase chain reaction, but reflected variable increases in measured VLCAD residual enzyme activity in response to bezafibrate. Genotype cross-analysis allowed the identification of alleles carrying missense mutations, which could account for these different...

Molecular Pathways: Fumarate Hydratase-Deficient Kidney Cancer: Targeting the Warburg Effect in Cancer

Science.gov (United States)

Linehan, W. Marston; Rouault, Tracey A.

2015-01-01

Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is a hereditary cancer syndrome in which affected individuals are at risk for development of cutaneous and uterine leiomyomas and an aggressive form of type II papillary kidney cancer. HLRCC is characterized by germline mutation of the tricarboxylic acid cycle (TCA) enzyme, fumarate hydratase (FH). FH-deficient kidney cancer is characterized by impaired oxidative phosphorylation and a metabolic shift to aerobic glycolysis, a form of metabolic reprogramming referred to as the Warburg effect. Increased glycolysis generates ATP needed for increased cell proliferation. In FH-deficient kidney cancer levels of AMPK, a cellular energy sensor, are decreased; resulting in diminished p53 levels, decreased expression of the iron importer, DMT1, leading to low cellular iron levels, and to enhanced fatty acid synthesis by diminishing phosphorylation of acetyl CoA carboxylase, a rate limiting step for fatty acid synthesis. Increased fumarate and decreased iron levels in FH-deficient kidney cancer cells inactivate prolyl hydroxylases, leading to stabilization of HIF1α, and increased expression of genes such as vascular endothelial growth factor (VEGF) and GLUT1 to provide fuel needed for rapid growth demands. Several therapeutic approaches for targeting the metabolic basis of FH-deficient kidney cancer are under development or are being evaluated in clinical trials, including the use of agents such as metformin, which would reverse the inactivation of AMPK, approaches to inhibit glucose transport, LDH-A, the anti-oxidant response pathway, the heme oxygenase pathway and approaches to target the tumor vasculature and glucose transport with agents such as bevacizumab and erlotinib. These same types of metabolic shifts, to aerobic glycolysis with decreased oxidative phosphorylation, have been found in a wide variety of other cancer types. Targeting the metabolic basis of a rare cancer such as fumarate hydratase-deficient

Murine FATP alleviates growth and biochemical deficiencies of yeast fat1Delta strains

DEFF Research Database (Denmark)

Dirusso, C C; Connell, E J; Færgeman, Nils J.

2000-01-01

following incubation of the cells with exogenous oleate. Expression of either Fat1p or murine FATP from a plasmid in a fat1Delta strain restored these phenotypic and biochemical deficiencies. Fat1p and FATP restored growth of fat1Delta cells in the presence of cerulenin and under hypoxic conditions....... Furthermore, fatty-acid transport was restored and was found to be chain length specific: octanoate, a medium-chain fatty acid was transported in a Fat1p- and FATP-independent manner while the long-chain fatty acids myristate, palmitate, and oleate required either Fat1p or FATP for maximal levels of transport....... Lignoceryl CoA synthetase activities were restored to wild-type levels in fat1Delta strains expressing either Fat1p or FATP. Fat1p or FATP also restored wild-type levels of beta-oxidation of exogenous long-chain fatty acids. These data show that Fat1p and FATP are functionally equivalent when expressed...

Synthesis of Versatile Chemicals through Oxidative Dehydrogenation on Solid Catalysts of Non-Petroleum Resource

OpenAIRE

Sugiyama, Shigeru; Nagai, Yuya; Sakamoto, Naotaka; Ohtake, Naotaka; Katoh, Masahiro

2016-01-01

To prepare 1,3-butadiene, one of versatile chemicals, from 1-butene, one of the main components in liquefied petroleum gas (LPG), the oxidative dehydrogenation of 1-butene on α-Bi2Mo3O12 doped with cerium was examined. Regardless to the doped amount of cerium, the conversion of 1-butene was constant while the selectivity to 1,3-butadiene decreased with the doped amount of cerium, while the selectivities to 2-butenes, CO and CO2 increased. It is concluded that the introduction of cerium into α...

Copper-based nanocatalysts for 2-butanol dehydrogenation: Screening and optimization of preparation parameters by response surface methodology

Energy Technology Data Exchange (ETDEWEB)

Geravand, Elham; Shariatinia, Geravand; Yaripour, Fereydoon [Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Sahebdelfar, Saeed [National Iranian Petrochemical Company, P. O. Box 1493, Tehran (Iran, Islamic Republic of)

2015-12-15

Two types of copper-based dehydrogenation nanocatalysts (Cu/ZnO/Al{sub 2}O{sub 3} and Cu/SiO{sub 2}) were prepared from various precursors by impregnation (IM), sol-gel (SG) and co precipitation (COPRE) methods. The structures of samples were characterized by N{sub 2} adsorption-desorption, XRD, XRF, TPR, N{sub 2}O-Titration, FT-IR, FE-SEM and TEM techniques. The catalytic performance tests in vapor-phase dehydrogenation of 2-butanol to methyl ethyl ketone (MEK) were carried out in a fixed-bed reactor at a temperature of 260 .deg. C under atmospheric pressure and LHSV of 4mL/(h·g cat). The experimental results indicated that (i) the copper oxide over the COPRE nanocatalyst was reduced at a lower temperature (222 .deg. C) in comparison with the CuO reduced on the SG and IM samples (243 and 327 .deg. C, respectively). Also, the percentage of reduction of CuO species on COPRE catalyst was the highest (98.8%) in comparison with the two other samples, (ii) the COPRE nanocatalyst exhibited the highest activity for the dehydrogenation of 2-butanol to MEK, and (iii) co-precipitation method was selected as an optimum method for preparation of nanocatalyst. The central composite experimental design method was applied for investigation of the effects of four critical preparation factors on the MEK selectivity of Cu/ZnO/Al{sub 2}O{sub 3} nanocatalyst. The results showed that Cu/Zn molar ratio and precipitation pH are the most effective factors on the response and the optimum conditions for synthesis of Cu/ZnO/Al{sub 2}O{sub 3} nanocatalyst with maximum selectivity of MEK were T(pre)=67.5 .deg. C, T(aging)=68.8 .deg. C, pH(pre)=7.27 and Cu/Zn molar ratio=1.38. The performance of the prepared nanocatalyst at the optimum conditions was comparable to the commercially available nanocatalyst.

AMP-acetyl CoA synthetase from Leishmania donovani: identification and functional analysis of 'PX4GK' motif.

Science.gov (United States)

Soumya, Neelagiri; Kumar, I Sravan; Shivaprasad, S; Gorakh, Landage Nitin; Dinesh, Neeradi; Swamy, Kayala Kambagiri; Singh, Sushma

2015-04-01

An adenosine monophosphate forming acetyl CoA synthetase (AceCS) which is the key enzyme involved in the conversion of acetate to acetyl CoA has been identified from Leishmania donovani for the first time. Sequence analysis of L. donovani AceCS (LdAceCS) revealed the presence of a 'PX4GK' motif which is highly conserved throughout organisms with higher sequence identity (96%) to lower sequence identity (38%). A ∼ 77 kDa heterologous protein with C-terminal 6X His-tag was expressed in Escherichia coli. Expression of LdAceCS in promastigotes was confirmed by western blot and RT-PCR analysis. Immunolocalization studies revealed that it is a cytosolic protein. We also report the kinetic characterization of recombinant LdAceCS with acetate, adenosine 5'-triphosphate, coenzyme A and propionate as substrates. Site directed mutagenesis of residues in conserved PX4GK motif of LdAceCS was performed to gain insight into its potential role in substrate binding, catalysis and its role in maintaining structural integrity of the protein. P646A, G651A and K652R exhibited more than 90% loss in activity signifying its indispensible role in the enzyme activity. Substitution of other residues in this motif resulted in altered substrate specificity and catalysis. However, none of them had any role in modulation of the secondary structure of the protein except G651A mutant. Copyright © 2015 Elsevier B.V. All rights reserved.

Mechanistic Bases of Neurotoxicity Provoked by Fatty Acids Accumulating in MCAD and LCHAD Deficiencies

Directory of Open Access Journals (Sweden)

Alexandre U. Amaral PhD

2017-03-01

Full Text Available Fatty acid oxidation defects (FAODs are inherited metabolic disorders caused by deficiency of specific enzyme activities or transport proteins involved in the mitochondrial catabolism of fatty acids. Medium-chain fatty acyl-CoA dehydrogenase (MCAD and long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD deficiencies are relatively common FAOD biochemically characterized by tissue accumulation of medium-chain fatty acids and long-chain 3-hydroxy fatty acids and their carnitine derivatives, respectively. Patients with MCAD deficiency usually have episodic encephalopathic crises and liver biochemical alterations especially during crises of metabolic decompensation, whereas patients with LCHAD deficiency present severe hepatopathy, cardiomyopathy, and acute and/or progressive encephalopathy. Although neurological symptoms are common features, the underlying mechanisms responsible for the brain damage in these disorders are still under debate. In this context, energy deficiency due to defective fatty acid catabolism and hypoglycemia/hypoketonemia has been postulated to contribute to the pathophysiology of MCAD and LCHAD deficiencies. However, since energetic substrate supplementation is not able to reverse or prevent symptomatology in some patients, it is presumed that other pathogenetic mechanisms are implicated. Since worsening of clinical symptoms during crises is accompanied by significant increases in the concentrations of the accumulating fatty acids, it is conceivable that these compounds may be potentially neurotoxic. We will briefly summarize the current knowledge obtained from patients with these disorders, as well as from animal studies demonstrating deleterious effects of the major fatty acids accumulating in MCAD and LCHAD deficiencies, indicating that disruption of mitochondrial energy, redox, and calcium homeostasis is involved in the pathophysiology of the cerebral damage in these diseases. It is presumed that these findings based on the

Kinetics with deactivation of methylcyclohexane dehydrogenation for hydrogen energy storage

Energy Technology Data Exchange (ETDEWEB)

Maria, G; Marin, A; Wyss, C; Mueller, S; Newson, E [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1997-06-01

The methylcyclohexane dehydrogenation step to recycle toluene and release hydrogen is being studied as part of a hydrogen energy storage project. The reaction is performed catalytically in a fixed bed reactor, and the efficiency of this step significantly determines overall system economics. The fresh catalyst kinetics and the deactivation of the catalyst by coke play an important role in the process analysis. The main reaction kinetics were determined from isothermal experiments using a parameter sensitivity analysis for model discrimination. An activation energy for the main reaction of 220{+-}11 kJ/mol was obtained from a two-parameter model. From non-isothermal deactivation in PC-controlled integral reactors, an activation energy for deactivation of 160 kJ/mol was estimated. A model for catalyst coke content of 3-17 weight% was compared with experimental data. (author) 3 figs., 6 refs.

RNAi inhibition of feruloyl CoA 6'-hydroxylase reduces scopoletin biosynthesis and post-harvest physiological deterioration in cassava (Manihot esculenta Crantz) storage roots.

Science.gov (United States)

Liu, Shi; Zainuddin, Ima M; Vanderschuren, Herve; Doughty, James; Beeching, John R

2017-05-01

Cassava (Manihot esculenta Crantz) is a major world crop, whose storage roots provide food for over 800 million throughout the humid tropics. Despite many advantages as a crop, the development of cassava is seriously constrained by the rapid post-harvest physiological deterioration (PPD) of its roots that occurs within 24-72 h of harvest, rendering the roots unpalatable and unmarketable. PPD limits cassava's marketing possibilities in countries that are undergoing increased development and urbanisation due to growing distances between farms and consumers. The inevitable wounding of the roots caused by harvesting triggers an oxidative burst that spreads throughout the cassava root, together with the accumulation of secondary metabolites including phenolic compounds, of which the coumarin scopoletin (7-hydroxy-6-methoxy-2H-1-benzopyran-2-one) is the most abundant. Scopoletin oxidation yields a blue-black colour, which suggests its involvement in the discoloration observed during PPD. Feruloyl CoA 6'-hydroxylase is a controlling enzyme in the biosynthesis of scopoletin. The cassava genome contains a seven membered family of feruloyl CoA 6'-hydroxylase genes, four of which are expressed in the storage root and, of these, three were capable of functionally complementing Arabidopsis T-DNA insertion mutants in this gene. A RNA interference construct, designed to a highly conserved region of these genes, was used to transform cassava, where it significantly reduced feruloyl CoA 6'-hydroxylase gene expression, scopoletin accumulation and PPD symptom development. Collectively, our results provide evidence that scopoletin plays a major functional role in the development of PPD symptoms, rather than merely paralleling symptom development in the cassava storage root.

Gas-phase acylation of aminopropyl-silica gel in the synthesis of some chemically bonded silica materials for analytical applications

International Nuclear Information System (INIS)

Basiuk, Vladimir; Khil'chevskaya, E.G.

1991-01-01

Gas-phase acylation of aminopropyl-silica gel with aliphatic dicarboxylic (succinic, adipic and sebacic) and 4-aminobenzoic acids is proposed as a rapid and efficient one-step method for the synthesis of carboxyalkyl- and 4-aminophenylamidopropyl-silica gels, usually used as zwitterion exchangers for liquid chromatography and matrices for multi-step syntheses of silica-bound aromatic azo reagents for the sorption and chromatographic separation of metal ions. Acylation degrees of 59-90% are achieved after 0.5 h. IR spectra of the acylation products and near-UV-visible spectra for bonded aromatic azo compounds, based on 4-aminobenzamidopropyl-silica gel, are presented. Some positive and negative aspects of the gas-phase acylation are discussed. (author). 34 refs.; 2 figs.; 2 tabs

Acylated 2-(N-arylaminomethylene)benzo[b]thiophene-3(2H)-Ones: Molecular Switches with Varying Migrants and Substituents

International Nuclear Information System (INIS)

Dubonosov, A.D.; Rybalkin, V.P.; Tsukanov, A.V.; Minkin, V.I.; Popova, L.L.; Revinsky, Y.V.; Bren, V.A.; Minkin, V.I.

2009-01-01

Synthesis and properties of photo chromic acylated 2-(N-arylaminomethylene)benzo[b]thiophene-3(2H)-ones are described. Their structure largely depends on the nature of acyl migrant and in a less degree on N-aryl substituent.

N-Cinnamoylation of Antimalarial Classics: Effects of Using Acyl Groups Other than Cinnamoyl toward Dual-Stage Antimalarials.

Science.gov (United States)

Gomes, Ana; Machado, Marta; Lobo, Lis; Nogueira, Fátima; Prudêncio, Miguel; Teixeira, Cátia; Gomes, Paula

2015-08-01

In a follow-up study to our reports of N-cinnamoylated chloroquine and quinacrine analogues as promising dual-stage antimalarial leads with high in vitro potency against both blood-stage Plasmodium falciparum and liver-stage Plasmodium berghei, we decided to investigate the effect of replacing the cinnamoyl moiety with other acyl groups. Thus, a series of N-acylated analogues were synthesized, and their activities against blood- and liver-stage Plasmodium spp. were assessed along with their in vitro cytotoxicities. Although the new N-acylated analogues were found to be somewhat less active and more cytotoxic than their N-cinnamoylated counterparts, they equally displayed nanomolar activities in vitro against blood-stage drug-sensitive and drug-resistant P. falciparum, and significant in vitro liver-stage activity against P. berghei. Therefore, it is demonstrated that simple N-acylated surrogates of classical antimalarial drugs are promising dual-stage antimalarial leads. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Crystallization of the C-terminal domain of the mouse brain cytosolic long-chain acyl-CoA thioesterase

International Nuclear Information System (INIS)

Serek, Robert; Forwood, Jade K.; Hume, David A.; Martin, Jennifer L.; Kobe, Bostjan

2006-01-01

The C-terminal domain of the mouse long-chain acyl-CoA thioesterase has been expressed in bacteria and crystallized by vapour diffusion. The crystals diffract to 2.4 Å resolution. The mammalian long-chain acyl-CoA thioesterase, the enzyme that catalyses the hydrolysis of acyl-CoAs to free fatty acids, contains two fused 4HBT (4-hydroxybenzoyl-CoA thioesterase) motifs. The C-terminal domain of the mouse long-chain acyl-CoA thioesterase (Acot7) has been expressed in bacteria and crystallized. The crystals were obtained by vapour diffusion using PEG 2000 MME as precipitant at pH 7.0 and 290 K. The crystals have the symmetry of space group R32 (unit-cell parameters a = b = 136.83, c = 99.82 Å, γ = 120°). Two molecules are expected in the asymmetric unit. The crystals diffract to 2.4 Å resolution using the laboratory X-ray source and are suitable for crystal structure determination

The Acyl-CoA synthetases encoded within FAA1 and FAA4 in Saccharomyces cerevisiae function as components of the fatty acid transport system linking import, activation, and intracellular Utilization

DEFF Research Database (Denmark)

Færgeman, Nils J.; Black, P N; Zhao, X D

2001-01-01

CoA levels were defined following incubation of wild type and mutant cells with limiting concentrations of exogenous oleate. These studies demonstrated oleoyl CoA levels were reduced to less than 10% wild-type levels in faa1 Delta and faa1 Delta faa4 Delta strains. Defects in metabolic utilization...