Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.1 (chymotrypsin)
10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Treatment of raw soy flour with L-cysteine or N-acetyl-L-cysteine results in the introduction of new half-cystine residues into sulfur-poor legume proteins, with a corresponding improvement in nutritional quality as measured by the protein efficiency ratio (PER) in rats. The proteins are modified through formation of mixed disulfide bonds among added sulfhydryl compounds, proteolytic enzyme inhibitors, and structural legume proteins. This modification leads to loss of inhibitory activity and increased protein digestibility and nutritive value. Sodium sulfite is more effective than cysteine in facilitating inactivation of trypsin inhibitors in soy flour. The synergistic effect of sodium sulfite and heat may be due to ability to induce rearrangement of protein disulfide bonds to produce new structural entities without altering the amino acid composition and to the fact that the new structures lose their ability to complex with trypsin or chymotrypsin. The same treatment inactivated hemagglutinins (lectins) in lima bean flour. These considerations suggest a key role for sulfur amino acids in the nutritional quality and safety of legumes.
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PMID:Nutritional improvement of legume proteins through disulfide interchange. 379 84

Chymotrypsin/elastase isoinhibitors were radiolabeled when live, adult Ascaris suum were incubated in tissue culture medium (NCTC-135) supplemented with L-[35S]cysteine. This is the first demonstration that the synthesis of these proteins occurs in A. suum; the isoinhibitors are not host products utilized by the parasite against its host. Of five chymotrypsin/elastase isoinhibitors demonstrable in A. suum, only isoinhibitors 1, 4, and 5 were found in each worm. The amino acid sequences of these three isoinhibitors indicate that they are gene products and are not obtained by modification after translation. The two inhibitors that are not observed could arise by limited proteolysis. The same chymotrypsin/elastase isoinhibitor profile present in each nematode eliminates any speculation that the multiple forms arise from an adaptation between A. suum and its host. A new chymotrypsin/elastase isoinhibitor nomenclature is proposed, so that isoinhibitor 1 is now Isoinhibitor A, and isoinhibitors 4 and 5 are now Isoinhibitors B and C, respectively.
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PMID:Ascaris suum: biosynthesis and isoinhibitor profile of chymotrypsin/elastase isoinhibitors. 384 34

A protease inhibitor was purified from the African marama bean (Tylosema esculenturm). The inhibitor is present in large amounts, representing about 10.5% of the total protein. The molecular weight is slightly larger than soybean trypsin inhibitor and was estimated at 23,000 by SDS-gel electrophoresis or 24,500 by amino acid analysis. The amino acid composition was atypical of most other plant inhibitors with a cysteine content of only one or possibly two residues/mole and a blocked amino terminus. Inhibition studies indicated virtually no inhibition of chymotrypsin activity. Elastase, however, was inhibited to the same extent as trypsin, requiring about 2 moles of inhibitor for complete inhibition of the enzyme.
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PMID:Isolation and characterization of a proteinase inhibitor from marama beans. 385 Jun 10

The primary structure of rat liver microsomal glutathione transferase has been determined. The 14C-carboxymethylated protein was fragmented with CNBr and proteolytic enzymes. The basis of the analysis was information from sequenator degradations of the intact protein, the largest CNBr fragment, and a large COOH-terminal fragment derived from a digest with Glu-specific staphylococcal protease. Remaining, smaller fragments were analyzed with the manual dimethylaminoazobenzene isothiocyanate method. Pepsin and limited acid hydrolysis were used to obtain peptides to confirm and overlap hydrophobic structures in the COOH-terminal half of the protein where trypsin and chymotrypsin failed to give any cleavage. Combined, these data permit the deduction of a 154-residue amino acid sequence. No evidence for micro-heterogeneity was obtained. The NH2-terminal alanine residue has a free alpha-amino group and the cysteine residue involved in activation of the enzymatic activity by sulfhydryl reagents is at position 49. The protein chain contains three regions with predictions for long beta strand secondary structures (positions 11-26, 103-120, and 131-145). Predictions may be inaccurate in membrane-associated proteins, but two of these regions also affect the three most hydrophobic segments. Thus, residues 11-35 form a long, largely hydrophobic part interrupted by only one charged residue (Lys-25), and residues 81-97 and 114-126 constitute the most hydrophobic segments directly noticeable from the hydrophilicity curve of the protein chain. These special parts of the molecule are of interest in relation to membrane interactions.
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PMID:Microsomal glutathione transferase. Primary structure. 393 48

Two trypsin inhibitors, CPPTI-I and CPPTI-II of Mr 3 250 and 7 850, respectively, were isolated from resting white bush seeds. Both inhibitors are cysteine-rich proteins. In addition to trypsin, they inhibit a trypsin-like enzyme isolated from Streptomyces griseus proteinase but they do not act on chymotrypsin, kallikrein or subtilopeptidase A. The isolated inhibitors contain a lysine residue in position P1 of the reactive site.
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PMID:Isolation of two trypsin inhibitors from resting seeds of the white bush (Cucurbita pepo var. patissonina) and their properties. 393 88

Several types of carboxyl-modified amino acids and peptides were prepared in forms having N-terminal modifications (carrier fragments) suitable for one of several representative protease enzymes, and their inhibitory action toward those enzymes were evaluated. The carboxyl modifications (inhibitory units) included (b) CONH2, (c) CSNH2, (d) CN, (e) trans-CH = CHCO2Me, and (f) trans-CH = CHSO2Me. The carrier fragments included NH2(PhCH2)CHX (1), AcNH(PhCH2)CHX (2), H2NCH2CONH(PhCH2)CHX (3), and AcNH(PhCH2)CHCONHCH2X (4). Compounds 1b, 1d, 1e, and 1f were competitive inhibitors of both microsomal and cytosolic leucine aminopeptidase (Ki = 14.8, 67, 61, and 3.7 mM with the former and 14.1, 26.4, 27.3, and 8.8 mM with the latter, respectively). Neither compound 1c nor leucine thioamide had any detectable effect on either enzyme. Compounds 2b-f were also competitive inhibitors toward chymotrypsin (Ki = 13.9, 23.0, 5.3, 30.8, and 29.4 mM, respectively). While 4b, 4c, and 4d were competitive inhibitors of papain (Ki = 4.7, 0.095, and 0.0011 mM, respectively), 4e proved to be an irreversible affinity label (Ki = 0.026 mM and k2 = 0.0018 s-1). Inactivation of papain by 4e was retarded in the presence of 4d and could not be reversed by dialysis. Similarly 3b and 3d were competitive inhibitors of dipeptidyl aminopeptidase I (DPP-I, EC 3.4.14.1) (Ki = 6.2 and 0.0027 mM, respectively), while 3e and 3f were irreversible affinity labels (Ki = 0.22 and 0.18 mM, and k2 = 0.015 and 0.010 s-1, respectively). Inhibition of DPP-I by 3d provides only the second example of a cysteine protease which is strongly inhibited by a nitrile analogue of a specific substrate. Further studies are needed to determine the generality and potential utility of this finding. Compounds 3e, 3f, and 4e exemplify a new class of specific affinity labels for cysteine proteases whose activity probably derives from irreversible Michael addition of the catalytic cysteine to the activated double bond.
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PMID:Carboxyl-modified amino acids and peptides as protease inhibitors. 394 5

A method has been developed for the purification of cytosolic and mitochondrial isoenzymes of fumarase from total homogenates of pig liver. Separation of the isoenzymes from one another was achieved using chromatofocusing. The isoenzymes were pure as judged by production of single bands on electrophoresis in the presence of sodium dodecyl sulphate; they appeared to have identical or very similar subunit molecular weights. The isoenzymes differed in electrophoretic properties under nondenaturing conditions. One-dimensional peptide maps of fragments produced from the two isoenzymes by chemical cleavage at cysteine residues were identical; maps obtained after digestion with the V8 proteinase from Staphylococcus aureus showed small differences at short times of digestion which could have reflected variations in rates of hydrolysis rather than structural differences. However, two-dimensional peptide maps of digests obtained by treatment of the isoenzymes with trypsin followed by chymotrypsin had 58 peptides in common, but showed two peptides unique to the mitochondrial isoenzyme and five peptides unique to the cytosolic form. Using the dansylation procedure, the mitochondrial isoenzyme was shown to have N-terminal alanine and the cytosolic form to have N-terminal glutamic acid or glutamine. We conclude that the isoenzymes of fumarase are identical over nearly all of their amino acid sequences but differ at their N-termini; the extent of these differences is yet to be established. These results are consistent with the claim (Edwards, Y.H. and Hopkinson,D.A. (1979) Ann. Human Genet. Lond. 42, 303-313) that the isoenzymes are determined at the same genetic locus, but they raise interesting questions about the biosynthesis of the isoenzymes.
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PMID:Purification and structural comparisons of the cytosolic and mitochondrial isoenzymes of fumarase from pig liver. 396 32

The seeds of pea (Pisum sativum L.) contain several proteins in the albumin solubility fraction that are significant components of total cotyledonary protein (5-10%) and are accumulated in developing seeds concurrently with storage-protein synthesis. One of these proteins, of low Mr and designated 'Psa LA', has been purified, characterized and sequenced. Psa LA has an Mr of 11000 and contains polypeptides of Mr 6000, suggesting that the protein molecules are dimeric. The amino acid sequence contains 54 residues, with a high content (10/54) of asparagine/aspartate. It has no inhibitory action towards trypsin or chymotrypsin, and is distinct from the inhibitors of those enzymes found in pea seeds, nor does it inhibit hog pancreatic alpha-amylase. The protein contains no methionine, but significant amounts of cysteine (four residues per polypeptide), suggesting a possible role as a sulphur storage protein. However, its sequence is not homologous with low-Mr (2S) storage proteins from castor bean (Ricinus communis) or rape (Brassica napus). Psa LA therefore represents a new type of low-Mr seed protein.
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PMID:Purification, properties and amino acid sequence of a low-Mr abundant seed protein from pea (Pisum sativum L.). 397 26

The major protein constituent of human plasma high density lipoproteins has been isolated and its complete amino-acid sequence determined. The protein, designated apolipoprotein-glutamine-I by the presence of carboxyl-terminal glutamine, is a single polypeptide chain of 245 amino-acid residues, including three residues of methionine. The protein is devoid of cysteine, cystine, and isoleucine. Cleavage of apolipoprotein-glutamine-I with cyanogen bromide yields four fragments with 94, 90, 36, and 25 amino acids. The amino-acid sequence of each fragment was determined by conventional methods, with proteolytic digestion with trypsin, chymotrypsin, and thermolysin. The alignment of the cyanogen bromide fragments was determined by the isolation of the methionine-containing tryptic peptides from apolipoprotein-glutamine-I. Inspection of the sequence of apolipoprotein-glutamine-I suggests an interesting distribution of amino acids that may account for its helical structure and its ability to bind and transport lipid.
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PMID:The primary structure of high density apolipoprotein-glutamine-I. 437 30

Ficin that had been prepared from the latex of Ficus glabrata by salt fractionation and chromatography on carboxymethylcellulose was completely and irreversibly inhibited with 1,3-dibromo[2-(14)C]acetone and then treated with N-(4-dimethylamino-3,5-dinitrophenyl)maleimide in 6m-guanidinium chloride. After reduction and carboxymethylation of the labelled protein, it was digested with trypsin and alpha-chymotrypsin. Two radioactive peptides and two coloured peptides were isolated chromatographically and their sequences determined. The radioactive peptides revealed the amino acid sequences around the active-site cysteine and histidine residues and showed a high degree of homology with the omino acid sequence around the active-site cysteine and histidine residues in papain. The coloured peptides allowed the amino acid sequence around the buried cysteine residue in ficin to be determined.
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PMID:The amino acid sequence around the active-site cysteine and histidine residues, and the buried cysteine residue in ficin. 542 43


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