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At least 307 records · Page 17Linked to original sources
PubMed2002

Proteomics analysis of cellular response to oxidative stress. Evidence for in vivo overoxidation of peroxiredoxins at their active site.

The proteomics analysis reported here shows that a major cellular response to oxidative stress is the modification of several peroxiredoxins. An acidic form of the peroxiredoxins appeared to be systematically increased under oxidative stress conditions. Peroxiredoxins are enzymes catalyzing the destruction of peroxides. In doing so, a reactive cysteine in the peroxiredoxin active site is weakly oxidized (disulfide or sulfenic acid) by the destroyed peroxides. Cellular thiols (e.g. thioredoxin) are used to regenerate the peroxiredoxins to their active state. Tandem mass spectrometry was carried out to characterize the modified form of the protein produced in vivo by oxidative stress. The cysteine present in the active site was shown to be oxidized into cysteic acid, leading to an inactivated form of peroxiredoxin. This strongly suggested that peroxiredoxins behave as a dam upon oxidative stress, being both important peroxide-destroying enzymes and peroxide targets. Results obtained in a primary culture of Leydig cells challenged with tumor necrosis factor alpha suggested that this oxidized/native balance of peroxiredoxin 2 may play an active role in resistance or susceptibility to tumor necrosis factor alpha-induced apoptosis.

Animals↗
PubMed1977

Sulphur metabolism in Paracoccus denitrificans. Purification, properties and regulation of cysteinyl-and methionyl-tRNA synthetase.

Cysteinyl- and methionyl-tRNA synthetases (EC 6.11.-) were purified 1200- and 1000-fold, respectively, from sonic extracts of Paracoccus denitrificans strain 8944, and kinetics, substrate specificity and regulatory properties were determined using the ATP-PPi exchange reaction. Both enzymes had pH optima of approx. 8 and were inhibited by sulphydryl-group reagents. Cysteinyl-tRNA synthetase catalysed L-selenocysteine- and alpha-aminobutyric acid-dependent ATP-PPi exchange and methionyl-tRNA synthetase catalysed L-homocysteine-, L-selenomethionine- and norleucine-dependent ATP-PPi exchange. Both enzymes were inhibited by O-acetylserine. Cysteinyl-tRNA synthetase activity was stimulated by methionine and methionyl-tRNA synthetase activity was stimulated by sulphide, cysteine, and cysteic acid.

Adenosine Triphosphate↗
PubMed1998

The primary structure of soluble cytochrome c-551 from the phototrophic green sulfur bacterium Chlorobium limicola, strain Tassajara, reveals a novel c-type cytochrome.

Chlorobium limicola, strain Tassajara, cytochrome c-551 is a soluble dimeric protein containing identical subunits of about 30 kDa. The amino acid sequence was determined by a combination of automated Edman degradation and mass analysis. There are 258 residues with a single heme binding site located at cysteine positions 172 and 175. In addition, there is a disulfide bridge between Cys78 and Cys109, and a free cysteine at position 219 which was found to occur as cysteic acid. The only homologue of soluble cytochrome c-551 is the soxA protein which is part of the thiosulfate utilization operon of Paracoccus denitrificans. They are 32% identical with three small gaps. This is consistent with the observation that cytochrome c-551 is the electron acceptor for a thiosulfate-oxidizing enzyme. On the basis of the redox potential of 135 mV, the sixth heme ligand should be a methionine. Among the seven methionine residues that are present in c-551, only one is conserved, two residues ahead of the heme-binding site. The far-UV circular dichroism spectrum indicates 40% alpha helix and 25% beta secondary structure. No other known cytochrome c has such a mixed structure; they are either all helical or all beta. Thus, Chlorobium soluble cytochrome c-551 and soxA are likely to be representative of a new class of c-type cytochromes.

Amino Acid Sequence↗
PubMed1979

Similarities between cysteinesulphinate transaminase and aspartate aminotransferase.

A method for the purification of two cysteinesulphinate transaminases, A and B (EC 2.6.1), is described. These enzymes catalyse the conversion of cysteinesulphinic acid to beta-sulphinyl pyruvate. The final preparations are homogeneous by polyacrylamide gel electrophoresis, sodium dodecyl sulphate-polyacrylamide gel electrophoresis and isoelectrofocusing. The molecular weight of the subunits is 41 000 for cysteinesulphinate transaminase A and 43 400 for B. Both enzymes are unspecific, as L-asparate, L-glutamate and L-cysteic acid serve as substrates in addition to L-cysteinesulphinic acid. Cysteinesulphinate transaminase A has a Km of 9.8 mM for cysteinesulphinic acid and 0.25 mM for aspartic acid, whereas the B enzyme has a Km of 6.5 mM for cysteinesulphinic acid and 1.4 mM for aspartic acid. The Vmax values of the A and B enzymes are respectively 7.1 and 6.2 mmol h-1 mg-1 protein for aspartic acid and 45 and 9.3 mmol h-1 mg-1 protein for cysteinesulphinic acid. Both enzymes exhibit maximum activity at pH 8.6. A high specific activity is found in optimal conditions for these two transaminases, the pI values being 9.06 and 5.70 for cysteinesulphinate transaminase A and B respectively. These results have been compared with those already obtained for purified aspartate aminotransferase. Similarities in the pathways of taurine and gamma-aminobutyric acid (GABA) metabolism are discussed.

Aging↗
PubMed1973

Galactosylserine in extensin.

Cell walls obtained from tomato suspension cultures were treated at pH1 for 1h at 100 degrees C to remove arabinose oligosaccharide substituents from the hydroxyproline residues of extensin. Tryptic attack of these acid-stripped walls yielded glycopeptides containing galactose. When one of these glycopeptides (designated S(2)A(6); sequence NH(2)-Ser-Hyp-Hyp-Hyp-Hyp-Ser-Hyp-Lys-CO(2)H) was treated with (a) NaOH-NaBH(4) or (b) NaOH-Na(2)SO(3) some of the serine was converted into (a) alanine or (b) cysteic acid, and the peptide lost galactose. Maleylation or 3-carboxypropionylation of N-terminal serine was necessary for conversion of this residue and for complete loss of galactose. These results indicate that a single galactose residue is attached O-glycosidically to each of the two serine residues. Hydrazinolysis of peptide S(2)A(6) or of isolated cell walls also led to destruction of serine. In control experiments non-glycosylated serine was not destroyed during hydrazinolysis. Thus the galactosylserine linkage is sensitive to N(2)H(4).

Amino Acid Sequence↗
PubMed1995

Toxicity of sulphur-containing compounds to neuronal cell lines.

Cysteine and its metabolites cysteine sulphinic acid (CSA) and taurine (TA) were shown to be toxic to human and rat neuronal cell lines. However, the mechanisms of action of CSA and TA appeared to be different. As MND/ALS patients have high plasma and CSF cysteine levels, they may have increased levels of neurotoxins in vivo, since cysteine was more toxic than CSA in the assay system used. Cysteic acid, homocysteic acid, BMAA and BOAA were also toxic to the cell lines used.

Animals↗
PubMed1997

C-terminal sequence determination of modified peptides by MALDI MS.

Peptides, cleaved by a mixture of carboxypeptidases CPP and CPY, can be detected by MALDI MS and the amino acid sequence thereby determined by calculation of the differences between consecutive peaks. In the present study we have used derivatizations of Lys and Cys to facilitate identification of these residues. Since the mass values do not readily distinguish Lys from Gln, we have converted Lys to homoarginine by guanidination, allowing simple detection of Lys. To identify the Cys positions in peptides that contain cystine, cysteic acid, or carboxymethylcysteine is not possible using CPY and CPP because of the lack of proteolytic cleavage. Instead we find that identification of Cys residues within the sequence can be achieved after conversion to a basic derivative, 4-thialaminine (Thi), by trimethylaminoethylation.

Amino Acid Sequence↗
PubMed1975

Effect of sulfur-containing dietary supplements on gizzard lining erosions.

Three experiments were conducted with crystalline amino acid basal diets containing 5% isolated soy protein to ascertain the supplementary effect of sulfur-containing compounds on blood constituents and gizzard lining erosion. At the 0.40% methionine dietary level, the plasma albumin protein values were improved by supplements of sulfate and fishery products, whereas, the globulin values were variable. At the methionine content of 0.55%, the hematocrit value was also increased. Taurine, cysteic acid or fish meal ash did not improve the growth of chicks fed 0.45% methionine. Gizzard lining erosions were quite prevalent and severe when chicks were fed inadequate methionine and were improved considerably but not totally prevented by the 0.70 to 1.25% levels of sulfur amino acids.

Animal Feed↗
PubMed2004

Potential role of methionine sulfoxide in the inactivation of the chaperone GroEL by hypochlorous acid (HOCl) and peroxynitrite (ONOO-).

GroEL is an Escherichia coli molecular chaperone that functions in vivo to fold newly synthesized polypeptides as well as to bind and refold denatured proteins during stress. This protein is a suitable model for its eukaryotic homolog, heat shock protein 60 (Hsp60), due to the high number of conserved amino acid sequences and similar function. Here, we will provide evidence that GroEL is rather insensitive to oxidants produced endogenously during metabolism, such as nitric oxide (.NO) or hydrogen peroxide (H(2)O(2)), but is modified and inactivated by efficiently reactive species generated by phagocytes, such as peroxynitrite (ONOO(-)) and hypochlorous acid (HOCl). For the exposure of 17.5 microm GroEL to 100-250 microm HOCl, the major pathway of inactivation was through the oxidation of methionine to methionine sulfoxide, established through mass spectrometric detection of methionine sulfoxide and the reactivation of a significant fraction of inactivated GroEL by the enzyme methionine sulfoxide reductase B/A (MsrB/A). In addition to the oxidation of methionine, HOCl caused the conversion of cysteine to cysteic acid and this product may account for the remainder of inactivated GroEL not recoverable through MsrB/A. In contrast, HOCl produced only negligible yields of 3-chlorotyrosine. A remarkable finding was the conversion of Met(111) and Met(114) to Met sulfone, which suggests a rather low reduction potential of these 2 residues in GroEL. The high sensitivity of GroEL toward HOCl and ONOO(-) suggests that this protein may be a target for bacterial killing by phagocytes.

Amino Acid Sequence↗
PubMed1975

The amino-acid sequence of isoinhibitor K form snails (Helix pomatia). A sequence determination by automated Edman degradation and mass-spectral identification of the phenylthiohydantoins.

Performic-acid-oxidized isoinhibitor K of snails (Helix pomatia) was subjected to arginine-directed tryptic proteolysis. Six peptide fragments including one overlap peptide from limited cleavage of the Arg-3-Pro-4 bond were purified to homogeneity. Four arginine peptides and the C-terminal peptide were sequenced by automatic Edman degradation using a special peptide program. The phenylthiohydantoins were all identified by chemical ionization mass spectrometry, except four cysteic acid residues that were identified on an amino acid analyzer after acid hydrolysis. Quantitative evaluation of the phenylthiohydantoins by chemical ionization mass spectrometry using total molecular-ion beam integration greatly facilitated sequencing. The mass spectrum of the dipeptide less than Glu-Gly revealed that the N-terminus was blocked by pyroglutamic acid. The complete amino acid sequence of isoinhibitor K was determined. An almost 50% homology between the sequences of the snail inhibitor and the bovine trypsin-kallikrein inhibitor (Kunitz) became obvious. A comparison of all homologous sequences of this particular class of proteins known to date is presented.

Amino Acid Sequence↗
PubMed1984

Amino acid sequence around a cysteine residue in the active center of jack bean urease.

Cysteine residues in the active center of jack bean urease [EC 3.5.1.5] were modified with 14C-labeled diazonium-1H-tetrazole (DHT). The labeled enzyme was carboxymethylated with iodoacetic acid, and then hydrolyzed with trypsin. The tryptic digest was subjected to gel filtration on Sephadex G-50, yielding two radioactive fractions. The [14C]DHT-labeled peptide having a lower molecular weight, which was determined to be approximately 1,000 by the method of gel filtration, was further purified to homogeneity by ion-exchange chromatography on DEAE-Sephadex A-25. [14C]DHT-labeled cysteine was identified as cysteic acid after performic acid oxidation, and the amino acid sequence of the low-molecular-weight [14C]DHT-labeled peptide was determined to be Phe-Glu-Pro-Gly-Asp-Cys-Asn-Ser-Thr-Phe-Lys.

Amino Acid Sequence↗
PubMed1983

Effect of amino acids, peptides and related compounds on the autooxidation of ascorbic acid.

The autooxidation rate of ascorbic acid (AA) at 10(-5) M under aerobic conditions at pH 7.4 was found to be 1.16 mumol/min/l. A number of compounds at low concentrations were found to inhibit this oxidation rate. These were in order of effectiveness: EDTA (10(-6) M) greater than Mercaptoethanol greater than aminoethyl cysteine, oxidized glutathione greater than glycylglycylhistidine greater than glycylhistidyllysine greater than 3-methyl histidine approximately histidine greater than histamine greater than hypertensin greater than cysteic acid greater than imidazole greater than glutamine greater than hydroxyproline, and lysine. All other amino acids and peptides examined had little or no effect on the autooxidation rate of ascorbic acid. Ascorbate solutions, treated with Chelex-100 (divalent chelating resin) or containing low concentrations of EDTA (10(-7) M) did not show a significant reduction of the rate of autooxidation. Of particular interest was the finding that 3-methyl histidine had a significant inhibitory effect on ascorbic acid oxidation whereas 1-methyl histidine had no effect. These data suggest that ascorbic acid forms complexes with certain compounds and that this interaction stabilizes ascorbic acid against auto-oxidation.

Amino Acids↗
PubMed1987

Neurochemical characterization of cysteine sulfinic acid, an excitatory amino acid, in hippocampus.

In this communication, I have summarized our studies on the possible roles of cysteine sulfinic acid (CSA) in the central nervous system (CNS), from these observations, CSA was suggested to be a neurotransmitter. We reported the presence of CSA in the CNS and subsequently characterized Na+-dependent high affinity uptake and depolarization-induced release of CSA. Depolarization-induced release of [14C]CSA from the preloaded hippocampal slices was specifically attenuated by benzodiazepines and GABA agonists. Synaptic membranes have a Na+-dependent specific binding site for cysteic acid, an analogue of CSA, which may be a possible binding site for CSA. This binding site seemed to be distinct from that for glutamate. To assess CSA as a physiologically active candidate which is distinct from glutamate, two neurochemical experiments were performed: one experiment determined the enhancement by excitatory amino acids of depolarization-induced release of [3H]GABA from the preloaded slices, and the other one monitored the cyclic AMP formation by excitatory amino acids in hippocampal slices. In both studies, differences in the responses to the various antagonists indicate that CSA receptors are distinct from glutamate receptors. Furthermore, we proposed that excitatory amino acid receptors which are subsequently linked to adenylate cyclase are functionally related to the Cl- channel.

Amino Acids↗
PubMed1993

Isolation and characterization of microsomal acyl-CoA thioesterase. A member of the rat liver microsomal carboxylesterase multi-gene family.

We have isolated and characterized an acyl-CoA thioesterase from rat liver microsomes. The enzyme consists mainly of a monomer of 59 kDa. However, the final preparation was found to contain minor amounts of a trimeric form of the protein. The enzyme was purified more than 85-fold from isolated microsomes and used for NH2-terminal sequence analysis and for analysis of peptides isolated after proteolytic digestion. The NH2-terminal sequence was unique but highly conserved compared to those of other carboxylesterases. Internal sequence data, covering almost 20% of the protein, showed high similarity to the deduced amino acid sequences from a cDNA encoding a carboxylesterase synthesized in the liver and subsequently secreted to the blood [Alexson, S. E. H., Finlay, T. H., Hellman, U., Diczfalusy, U. & Eggertsen, G., unpublished results] and nonspecific rat liver microsomal carboxylesterase with isoelectric point of 6.1 [Robbi, M., Beaufay, H. & Octave, J.-N. (1990) Biochem. J. 269, 451-458], thus confirming earlier suggestions that this enzyme is a member of the microsomal carboxylesterase multigene family. The peptide sequences contained two of the four conserved cysteic acid residues found in other carboxylesterases. Amino acid analysis indicated that the protein contains five cysteine residues in contrast to most other described carboxylesterases which contain four highly conserved cysteins. The purified protein was used for immunization and the antiserum was used to detect the protein as well as its trimeric form, which is a minor component, in isolated rat liver microsomes. The antiserum recognized proteins of similar sizes in microsomes and 100,000 x g supernatant prepared from hamster brown adipose tissue, a tissue known to contain very high activity of carboxylesterase, and to recognize carboxylesterases isolated from porcine and rabbit liver.

Amino Acid Sequence↗
PubMed2000

Capillary electrophoresis of peptides and proteins in isoelectric buffers: an update.

Capillary electrophoresis in acidic, isoelectric buffers is a novel methodology allowing fast protein and peptide analysis in uncoated capillaries. Due to the low pH adopted and to the use of dynamic coating with cellulose derivatives, silanol ionization is essentially suppressed and little interaction of macromolecules with the untreated wall occurs. In addition, due to the low conductivity of quasi-stationary, isoelectric buffers, high-voltage gradients can be applied (up to 800 V/cm) permitting fast peptide analysis with a high resolving power due to minimal diffusional peak spreading. Four such buffers are here described: cysteic acid (Cys-A, pI 1.85), iminodiacetic acid (IDA, pI 2.23), aspartic acid (Asp, pI 2.77) and glutamic acid (Glu, pI 3.22). A number of applications are reported, ranging from food analysis to the study of folding/unfolding transitions of proteins.

Animals↗
PubMed2001

Induction of 2-amino-D2-thiazoline-4-carboxylic acid hydrolase and N-carbamoyl-l-cysteine amidohydrolase by S-compounds in Pseudomonas putida AJ3865.

The induction of 2-amino-Delta(2)-thiazoline-4-carboxylic acid hydrolase (ATCase) and N-carbamoylcysteine amidohydrolase (NCCase), both of which are involved in the conversion step of 2-amino-Delta(2)-thiazoline carboxylic acid (ATC) to cysteine, was studied with Pseudomonas putida AJ3865. We found that L-ATC induced L-ATCase and L-NCCase, but that D-ATC induced only L-NCCase, whereas L- or D-NCC and thiazoline derivatives did not induce both enzymes. The bacterium showed neither D-ATCase nor D-NCCase activities, indicating that the role of L-ATC and D-ATC was different in the enzyme induction. We also found new inducers, d- and l-methionine, S-methyl-L-cysteine, cysteic acid, and 2-aminoethane sulfonic acid. However, the induction level of both enzymes by new inducers was much lower than those by L-ATC and D-ATC. Furthermore, the induction rate of both enzymes was synergistically increased only under a combination of D,L-ATC and new inducers. S-Compounds, however, such as new inducers except S-methyl-L-cysteine, inhibited both enzyme activities. This is the first report on the new inducers, synergistic induction, and the new inhibitors of L-ATCase and L-NCCase.

Journal Article↗
PubMed1972

Glutamate dehydrogenase: amino-acid sequence of the bovine enzyme and comparison with that from chicken liver.

Further investigation of the amino-acid sequence of bovine glutamate dehydrogenase (EC 1.4.1.3) has led to the correction of an earlier tentative sequence. The presently known sequence contains 500 residues in the subunit single peptide chain. The sequence of the homologous enzyme from chicken liver indicates that it contains 503 residues. Of the presently established 485 residues in the chicken dehydrogenase, only 26 residues differ from those in the bovine enzyme. The chicken dehydrogenase also differs in having an additional three residues at the amino terminus. The amino-terminal residue of the chicken enzyme was found to be cysteic acid.

Amino Acid Sequence↗
PubMed1995

Characterization of the proton/glutamate symport protein of Bacillus subtilis and its functional expression in Escherichia coli.

Transport of acidic amino acids in Bacillus subtilis is an electrogenic process in which L-glutamate or L-aspartate is symported with at least two protons. This is shown by studies of transport in membrane vesicles in which a proton motive force is generated by oxidation of ascorbate-phenazine methosulfate or by artificial ion gradients. An inwards-directed sodium gradient had no (stimulatory) effect on proton motive force-driven L-glutamate uptake. The transporter is specific for L-glutamate and L-aspartate. L-Glutamate transport is inhibited by beta-hydroxyaspartate and cysteic acid but not by alpha-methyl-glutamate. The gene encoding the L-glutamate transport protein of B. subtilis (gltPBsu) was cloned by complementation of Escherichia coli JC5412 for growth on glutamate as the sole source of carbon, energy, and nitrogen, and its nucleotide sequence was determined. Putative promoter, terminator, and ribosome binding site sequences were found in the flanking regions. UUG is most likely the start codon. gltPBsu encodes a polypeptide of 414 amino acid residues and is homologous to several proteins that transport glutamate and/or structurally related compounds such as aspartate, fumarate, malate, and succinate. Both sodium- and proton-coupled transporters belong to this family of dicarboxylate transporters. Hydropathy profiling and multiple alignment of the family of carboxylate transporters suggest that each of the proteins spans the cytoplasmic membrane 12 times with both the amino and carboxy termini on the inside.

Amino Acid Sequence↗