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)

Cyanogen bromide treatment of thymidylate synthetase of Lactobacillus casei, which had been converted to a ternary complex with [2-14c] FdUMP and 5,10-methylene-tetrahydrofolate followed by S-carboxymethylation, yielded at least four visible peptide bands, the largest with a molecular weight of about 13,000, on polyacrylamide gel electrophoresis in sodium dodecyl sulfate-urea. Identical results were obtained with enzyme that had all four of its cysteinyl residues S-carboxymethylated with iodo [I-14C] acetate in the absence of FdUMP and cofactor. In each case, only the second band from the top of the gel (CN2), with an approximate molecular weight of 10,000= was labeled. Analysis of CN2 that had been labeled with [2-14C] FdUMP and nonradioactive iodoacetate and of that labeled only with iodo[1-14C] acetate revealed that their amino-acid contents were almost identical except for the presence of two S-carboxymethyl (Cm)-cysteinyl residues in the latter peptide and only one in FdUMP-CN2. A nonapeptide was isolated from (Cm)2-CN2 after chymotrypsin digestion that contained the following sequence by dansyl-Edman analysis: Ala-Leu-Pro-Pro-[Cm-Cys]-His-Thr-Leu-Tyr. This peptide was found to be located on the NH2-terminal end of CN2. Automatic sequence analysis of the first 13 residues of (Cm)2-CN2 and of the FdUMP-containing CN2 yielded identical results except for the fifth, or cysteinyl, residue, which could not be identified in the latter peptide. These findings strongly suggest that FdUMP is linked to a cysteinyl residue in thymidylate synthetase that has been inactivated irreversibly by this nucleotide.
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PMID:Amino acid sequence at the FdUMP binding site of thymidylate synthetase. 106 57

The covalent structure of the rat liver 60 S ribosomal subunit protein L37 was determined. Twenty-four tryptic peptides were purified and the sequence of each was established; they accounted for all 111 residues of L37. The sequence of the first 30 residues of L37, obtained previously by automated Edman degradation of the intact protein, provided the alignment of the first 9 tryptic peptides. Three peptides (CN1, CN2, and CN3) were produced by cleavage of protein L37 with cyanogen bromide. The sequence of CN1 (65 residues) was established from the sequence of secondary peptides resulting from cleavage with trypsin and chymotrypsin. The sequence of CN1 in turn served to order tryptic peptides 1 through 14. The sequence of CN2 (15 residues) was determined entirely by a micromanual procedure and allowed the alignment of tryptic peptides 14 through 18. The sequence of the NH2-terminal 28 amino acids of CN3 (31 residues) was determined; in addition the complete sequences of the secondary tryptic and chymotryptic peptides were done. The sequence of CN3 provided the order of tryptic peptides 18 through 24. Thus the sequence of the three cyanogen bromide peptides also accounted for the 111 residues of protein L37. The carboxyl-terminal amino acids were identified after carboxypeptidase A treatment. There is a disulfide bridge between half-cystinyl residues at positions 40 and 69. Rat liver ribosomal protein L37 is homologous with yeast YP55 and with Escherichia coli L34. Moreover, there is a segment of 17 residues in rat L37 that occurs, albeit with modifications, in yeast YP55 and in E. coli S4, L20, and L34.
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PMID:The primary structure of rat liver ribosomal protein L37. Homology with yeast and bacterial ribosomal proteins. 635 Feb 92

The purification and properties of an estradiol-sensitive hydrolytic activity from mouse uterus which fits several criteria for being an induced protein are described. The activity in the uteri of immature animals can be stimulated 2--4-fold by estradiol to that approaching the adult level. Stimulation is blocked by puromycin. The enzyme which we have designated hydrolase II, was purified approx. 400-fold to apparent homogeneity by chromatography on Affigel Blue, DEAE-cellulose and octyl-Sepharose. Hydrolase II is a single chain polypeptide with an estimated mol. wt = 65,000 daltons and has an N-terminal serine residue. A variety of N-blocked L-amino acid nitrophenyl esters are cleaved by the enzyme. Km's at pH 7.2 were all approx. 40 microns. Of substrates tested, phenylalanine nitrophenyl ester had the highest Vmax. Cbz-beta-alanine nitrophenyl ester, which is not a normal protease substrate was cleaved with a Km of 145 microM. The enzyme had no detectable activity against peptide nitroanilide substrates for trypsin-, chymotrypsin- or elastase-like enzymes. It is inhibited by ZPCK and DIFP but not by TLCK and Ala-Ala-Pro-Ala chloromethyl ketone, a potent inhibitor of elastase-like enzymes. Mouse plasma protein protease inhibitors were without effect as was SBTI. Our results rule out hydrolase II being a carnosinase, non-serine esterase, plasminogen activator, collagenase or collagenase activator and suggest that it is a chymotrypsin-like protease.
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PMID:Properties of an estrogen-induced hydrolytic enzyme from mouse uterus. 635 Jul 23

The amino acid sequence of cyanogen bromide peptide CN2 from the heavy chain (HA1) of the haemagglutinin of the Hong Kong variant A/Memphis/102/72 has been obtained by direct, automated sequence analysis on the whole fragment and by manual dansyl-Edman degradation of tryptic, peptic and chymotryptic peptides. It was found to contain 92 amino acid residues, including a large, insoluble, tryptic core peptide (residues 62-87). It did not contain any half-cystine residues or carbohydrate. The determination of its structure was complicated by the presence of an Asn-Ile bond at positions 48-49 which was readily cleaved by both trypsin and chymotrypsin.
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PMID:Amino acid sequence of cyanogen bromide fragment CN2 from Hong Kong influenza haemagglutinin heavy chain. 743 63