UK PubMed Central (United Kingdom)

We have synthesized a novel stable precursor, saligenin phosphorotrichloridate, which, on reaction with N-monobiotinyldiamines, generates a series of biotinylated covalent inhibitors of serine esterases....Full Text Available

UK PubMed Central (United Kingdom)

PknB is a member of the newly discovered eukaryotic-like protein serine/threonine kinase (PSTK) family of proteins. The pknB gene was cloned and expressed in Escherichia coli....Full Text Available

UK PubMed Central (United Kingdom)

Skeletal muscle uses calcium as a second messenger to respond and adapt to environmental stimuli. Elevations in intracellular calcium levels activate calcineurin, a serine/threonine phosphatase, resulting...Full Text Available

British Library Electronic Table of Contents (United Kingdom)

We describe a method for the analysis of multi-site phosphorylation in serine/threonine (Ser/Thr)-rich protein sequences. Site-specific mutagenesis was used to introduce tryptic cleavage sites in the serine glutamine/threonine glutamine cluster domain (SCD) of the human checkpoint protein kinase (Chk2). The mutant proteins were shown to autophosphorylate on residues that are inducibly phosphorylated when mammalian cells are exposed to ionizing radiation (serine 33/35, serine 516, threonine 68 and threonine 432). Five Ser/Thr clusters within the SCD were flanked by arginine or lysine residues to produce tryptic peptides for nanospray liquid chromatography (nanoLC)/linear quadrupole ion trap Fourier transform ion cyclotron resonance mass spectrometry. Phosphorylation sites were assigned usin...

Science.gov (United States)

An approach to generate mimics of phosphorylated serine proteins chemically through site-specific sulfonation of cysteine is presented. This chemical modification is reversible in the presence of reducing agent and therefore is analogous to the kinase/phosphatase system used in nature. PMID:21717004

UK PubMed Central (United Kingdom)

Sustained nigrostriatal dopamine depletion increases the serine/threonine phosphorylation of multiple striatal proteins that play a role in corticostriatal synaptic plasticity, including Thr²⁸⁶...Full Text Available

UK PubMed Central (United Kingdom)

SummaryActivating transcription factor 2 (ATF2) is regulated by JNK/p38 in response to stress. Here, we demonstrate that the protein kinase ATM phosphorylates ATF2 on serines...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

We report the results of ab initio calculations of cross sections and molecular-frame photoelectron angular distributions for C 1s ionization of CO2, and propose a mechanism for the recently observed asymmetry of those angular distributions with respect to the CO^+and O^+ions produced by subsequent Auger decay. The fixed-nuclei, photoionization amplitudes were constructed using variationally obtained electron-molecular ion scattering wave functions. We have also carried out electronic structure calculations which identify a dissociative state of the CO2^++ dication that is likely populated following Auger decay and which leads to O^+ + CO^+ fragment ions. We show that a proper accounting of vibrational motion in the computation of the photoelectron angular distributions, along with reasonable assumptions about the nuclear dissociation dynamics, gives results in good agreement with recent experimental observations. We also ...

UK PubMed Central (United Kingdom)

Hepatitis C virus NS3-4A is a membrane-bound enzyme complex that exhibits serine protease, RNA helicase, and RNA-stimulated ATPase activities. This enzyme complex is essential for viral genome replication...Full Text Available

International Nuclear Information System (INIS)

Phospholipid vesicles were found to be lysed by exposure to free radicals derived from irradiated glycine and galactose. The decomposition yield increased with vesicle concentration, and attained values of 0.0006 vesicles destroyed per radical added. Ionic charge at the phospholipid end groups was found to be more important than degree of unsaturation in determining this yield. Radicals derived from irradiated serine and alanine had no detectable lytic action at the vesicle concentrations tested.

UK PubMed Central (United Kingdom)

The NSP5 protein is required for viroplasm formation during rotavirus infection and is hyperphosphorylated into 32- to 35-kDa isoforms. Earlier studies reported that NSP5 is not hyperphosphorylated...Full Text Available

CERN Document Server

We study the processes gamma gamma -> K^0_S K+/- pi-/+ and gamma gamma -> K+ K- pi+ pi- pi0 using a data sample of 519.2 fb-1 recorded by the BaBar detector at the PEP-II asymmetric-energy e+e- collider at center-of-mass energies near the Upsilon(nS) (n = 2,3,4) resonances. We observe the eta_c(1S), chi_c0(1P), chi_c2(1P), and eta_c(2S) resonances produced in two-photon interactions and decaying to K+ K- pi+ pi- pi0, with significances of 18.1, 5.7, 5.2, and 5.3 standard deviations (including systematic errors), respectively. We measure the eta_c(2S) mass and width in K^0_S K+/- pi-/+ decays, m(eta_c(2S))=3638.5 +/- 1.5 +/- 0.8 MeV/c^2 and Gamma(eta_c(2S)) = 13.4 +/- 4.6 +/- 3.2 MeV, where the first uncertainty is statistical and the second is systematic. We search for the Z(3930) resonance and find no significant signal. We also provide the two-photon width times branching fraction values for the observed resonances.

Science.gov (United States)

The effects of pH on the calcium phosphate phase, of Tris and of amino acids, such as aspartic acid, glutamic acid, and serine on hydroxyapatite formation and morphology, were studied in double diffusion experiments. In this system, hydroxyapatite was only formed when the pH was around 7.4 or higher for the duration of the reaction. A decrease in pH resulted in the transformation of hydroxyapatite to octacalcium phosphate. Amino acids and Tris or the buffering capacity of Tris have an effect on the morphology of the synthetic hydroxyapatite. The presence of the additive results in spheres consisting of needles, blades or plates depending on the reaction system. PMID:12175941

Energy Technology Data Exchange (ETDEWEB)

X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) have been conducted on a new fuel cell electrocatalytic material based on a highly porous carbonized polyacrylonitrile (PAN) microcellular foam with very low platinum loading ({approximately}13 to 23 {micro}g/cm{sup 2}). TEM images of this material clearly show the existence of nanometer size platinum particles which are homogeneously distributed in the highly porous carbonized PAN matrix. An XPS study of Pt-loaded PAN indicates that C 1s, O 1s, and N 1s peaks shift to lower binding energies, compared to virgin PAN. It was concluded that special metal-support interaction exists, through the formation of a charge-transfer complex between platinum and pyridine-type nitrogen atoms of PAN support. This interaction leads to the enhancement of the catalytic activity, and the improvement of the long-time stability of this electrocatalyst.

British Library Electronic Table of Contents (United Kingdom)

Cyclooxygenase-2 (COX-2) content is increased in many types of tumor cells. We have investigated the mechanism by which resveratrol, a stilbene that is pro-apoptotic in many tumor cell lines, causes apoptosis in human head and neck squamous cell carcinoma UMSCC-22B cells by a mechanism involving cellular COX-2. UMSCC-22B cells treated with resveratrol for 24 h, with or without selected inhibitors, were examined: (1) for the presence of nuclear activated ERK1/2, p53 and COX-2, (2) for evidence of apoptosis, and (3) by chromatin immunoprecipitation to demonstrate p53 binding to the p21 promoter. Stilbene-induced apoptosis was concentration-dependent, and associated with ERK1/2 activation, serine-15 p53 phosphorylation and nuclear accumulation of these proteins. These effects were blocked by ...

British Library Electronic Table of Contents (United Kingdom)

Abstract The heterotetrameric K++-channel KCNQ1/KCNE1 is expressed in heart, skeletal muscle, liver and several epithelia including the renal proximal tubule. In the heart, it contributes to the repolarization of cardiomyocytes. The repolarization is impaired in ischemia. Ischemia stimulates the AMP-activated protein kinase (AMPK), a serine/threonine kinase, sensing energy depletion and stimulating several cellular mechanisms to enhance energy production and to limit energy utilization. AMPK has previously been shown to downregulate the epithelial Na++ channel ENaC, an effect mediated by the ubiquitin ligase Nedd4-2. The present study explored whether AMPK regulates KCNQ1/KCNE1. To this end, cRNA encoding KCNQ1/KCNE1 was injected into Xenopus oocytes with and without additional injection o...

Science.gov (United States)

Hydrogen cyanide (HCN) production by Pseudomonas aeruginosa in a synthetic medium is stimulated by the presence of glycine. Methionine enhances this stimulation but will not substitute for glycine as a stimulator of cyanogenesis. Threonine and phenylalanine are effective substitutes for glycine in the stimulation of HCN production. Glycine, threonine, and serine are good radioisotope precursors of HCN, but methionine and phenylalanine are not. Cell extracts of P. aeruginosa convert (/sup 14/C)threonine to (/sup 14/C)glycine. H14CN is produced with low dilution of label from either (1-/sup 14/C)glycine or (2-/sup 14/C)glycine, indicating a randomization of label either in the primary or secondary metabolism of glycine. When whole cells were fed (1,2-/sup 14/C)glycine, cyanide and bicarbonate were the only radioactive extracellular products observed.

Science.gov (United States)

The iron hormone hepcidin is inhibited by matriptase-2, a liver serine-protease encoded by TMPRSS6 gene. Cleaving the BMP-coreceptor hemojuvelin, matriptase-2 impairs the BMP/SMAD signaling pathway, downregulates hepcidin and facilitates iron absorption. TMPRSS6 inactivation causes iron-deficiency-anemia refractory to iron administration both in humans and mice. Genome wide association studies have shown that the SNP rs855791, which causes the matriptase-2 V736A amino acid substitution, is associated with variations of serum iron, transferrin saturation, hemoglobin and erythrocyte traits. Here we show that in vitro matriptase-2 736(A) inhibits hepcidin more efficiently than 736(V). Moreover, in a genotyped population, after exclusion of samples with iron deficiency and inflammation, hepcidin, hepcidin/transferrin saturation and hepcidin/ferritin ratios were significantly lower and iron parameters were consistently higher in homozygotes 736(A) than in 736(V). Our ...

Energy Technology Data Exchange (ETDEWEB)

Cell extracts of the thermophile Clostridium thermohydrosulfuricum catalyzed the phosphorylation by (..gamma..-/sup 32/P)ATP of several endogenous proteins with M/sub r/s between 13,000 and 100,000. Serine and tyrosine were the main acceptors. Distinct substrate proteins were found in the soluble (e.g., proteins p66, p63, and p53 of M/sub r/s 66,000, 63,000, and 53,000, respectively) and particulate (p76 and p30) fractions, both of which contained protein kinase and phosphatase activity. The soluble fraction suppressed the phosphorylation of particulate proteins and contained a protein kinase inhibitor. Phosphorylation of p53 was promoted by 10..mu..M fructose 1,6-bisphosphate or glucose 1,6-bisphosphate and suppressed by hexose monophosphates, whereas p30 and p13 were suppressed by 5 ..mu..M brain (but not spinach) calmodulin. Polyamines, including the odd polyamines characteristic of thermophiles, modulated the labeling of most of the phosphoproteins. Apart from ...

Energy Technology Data Exchange (ETDEWEB)

The /sup 31/P NMR method was first applied to characterize in vivo phosphorylation of H1 and H5 in calf thymus and chicken erythrocytes as well as in vitro phosphorylation of H1 and H5 by cAMP-dependent protein kinase. The amino acid residues phosphorylated in vivo in the histones were exclusively serine residues, and the mole fraction of phosphoserine was estimated to be 0.34 and 0.27 per molecule of calf thymus H1 and chicken erythrocyte H5, respectively. Interestingly, chicken erythrocyte H1 was not phosphorylated in vivo. Three H1 subtypes from calf thymus H1 varied in the /sup 31/P NMR spectra, and the bisected fragments of calf thymus H1 and chicken erythrocyte H5 exhibited characteristic spectral patterns, indicating that there are considerable diversities of the degree of phosphorylation and phosphorylation sites in very-lysine-rich histones. Furthermore, it was found that the microenvironment of phosphoserine residues phosphorylated in vivo in calf thymus ...

CERN Document Server

A complete macromolecule modeling package must be able to solve the simplest structure prediction problems. Despite recent successes in high resolution structure modeling and design, the Rosetta software suite fares poorly on deceptively small protein and RNA puzzles, some as small as four residues. To illustrate these problems, this manuscript presents extensive Rosetta results for four well-defined test cases: the 20-residue mini-protein Trp cage, an even smaller disulfide-stabilized conotoxin, the reactive loop of a serine protease inhibitor, and a UUCG RNA tetraloop. In contrast to previous Rosetta studies, several lines of evidence indicate that conformational sampling is not the major bottleneck in modeling these small systems. Instead, approximations and omissions in the Rosetta all-atom energy function currently preclude discriminating experimentally observed conformations from de novo models at atomic resolution. These molecular "puzzles" should serve as ...

International Nuclear Information System (INIS)

Aim: There has been a great demand for developments of the radioligands to visualize the N-methyl-D-aspartate (NMDA) receptors by PET/SPECT. We have recently synthesized two C-11 labeled antagonists for the glycine-binding site on NMDA receptors. The aim of this work is to examine for their in vitro and in vivo binding characteristics, and to evaluate their potentials as PET radioligands for the NMDA receptors. Materials and methods: Two C-11 labeled 4-hydroxy-2-quinolones (1 and 2) were synthesized by conventional methylation of the corresponding phenols with ["1"1C]methyl iodide. In vitro and ex vivo quantitative autoradiographs with imaging plate, as well as animal PET, were employed in order to evaluate their in vitro and in vivo binding to the NMDA receptors. Results: The compound 1 showed the specific binding to rat brain slices with higher localization in the hippocampus and cerebral cortex than in the cerebellum. Both glycine antagonists and agonists (glycine and ...

Energy Technology Data Exchange (ETDEWEB)

The authors have shown previously that the domain recognizing receptors on activated human platelets is located on the human fibrinogen {gamma} chain between residues 400 and 411. To study the correlation between the structure of this segment of the {gamma} chain and its reactivity toward receptors on ADP-activated human platelets, they designed a series of analogues containing replacements at 9 out of 12 positions. A double substitution of the normal His{sup 400}-His{sup 401} sequence by Ala-Ala reduced the inhibitory potency of the dodecapeptide 3-fold. When Lys{sup 406} was replaced by Arg, the inhibitory potency of the dodecapeptide decreased 15 times. On the other hand, substitution of Ala{sup 408} with Arg increased the inhibitory potency of the dodecapeptide 6-fold. A drastic decrease in the reactivity of the dodecapeptide toward platelet receptors was observed when Val{sup 411} was replaced by leucine or cysteine or tyrosine. A 3-fold decrease in reactivity was noted when ...

International Nuclear Information System (INIS)

Nucleotide sequence analysis of a genomic clone from an Ashkenazic Jewish patient with type 1 Gaucher disease revealed a single-base mutation (adenosine to guanosine transition) in exon 9 of the glucocerebrosidase gene. This change results in the amino acid substitution of serine for asparagine. Transient expression studies following oligonucleotide-directed mutagenesis of the normal cDNA confirmed that the mutation results in loss of glucocerebrosidase activity. Allele-specific hybridization with oligonucleotide probes demonstrated that this mutation was found exclusively in type 1 phenotype. None of the 6 type 2 patients, 11 type 3 patients, or 12 normal controls had this allele. In contrast, 15 of 24 type 1 patients had one allele with this mutation, and 3 others were homozygous for the mutation. Furthermore, some of the Ashkenazic Jewish type 1 patients had only one allele with this mutation, suggesting that even in this population there is allelic ...