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)

The L-asparagine analogue 5-diazo-4-oxo-L-[5-14C]norvaline binds irreversibly to the active site of Escherichia coli L-asparaginase. Conditions for optimal labeling in buffers containing 50% dimethylsulfoxide have been developed and kinetic parameters of the inactivation have been determined. After reduction, alkylation and subsequent degradation of the modified enzyme with alpha-chymotrypsin, the principal radioactive decapeptide of sequence Val-Gly-Ala-Met-Arg-Pro-Ser-Thr-Ser-Met was isolated. A second radioactive hexapeptide Arg-Pro-Ser-Thr-Ser-Met resulting from chymotryptic digestion of the decapeptide was also isolated. Evidence is presented for the attachment of the 5-diazo-4-oxo-L-norvaline residue to serine-9 in the decapeptide via an acid-labile linkage.
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PMID:Structure of peptide from active site region of Escherichia coli L-asparaginase. 32 49

This paper presents the experimental details which led to the elucidation of the complete primary structure of S16, a protein which belongs to the small subunit of E. coli ribosomes. Protein S16 was digested with trypsin, alpha-chymotrypsin, and the staphylococcal protease. The resulting peptides were purified on paper and their amino acid composition and sequence were determined. Automatic Edman degradation with a modified sequenator on the complete protein yielded information from the 56N-terminal residues. The combination of all these results led to the following complete amino acid sequence: Met-Val-Thr-Ile-Arg-Leu-Ala-Arg-His-Gly-Ala-Lys-Lys-Arg-Pro-Phe-Tyr-Gln-Val-Val-Val-Ala-Asp-Ser-Arg--Asn-Ala-Arg-Asn-Gly-Arg-Phe-Ile-Glu-Arg-Val-Gly-Phe-Phe-Asn-Pro-Ile-Ala-Ser-Glu-Lys-Glu-Glu-Gly-Thr-Arg-Leu-Asp-Leu-Asp-Arg-Ile-Ala-His-Trp-Val-Gly-Gln-Gly-Ala-Thr-Ile-Ser-Asp-Arg-Val-Ala-Ala-Leu-Ile-Lys-Glu-Val-Asn-Lys-Ala-Ala. The molecular weight derived from the sequence amounts to 9 162.
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PMID:The complete amino acid sequence of protein S16 from Escherichia coli. 33 10

The largest fragment produced by complete cyanogen bromide digestion of the alpha chain of human fibrinogen contains 236 residues and has a calculated molecular weight of 23,949. The complete amino acid sequence of the fragment was determined by the isolation of peptides generated by plasmin, trypsin (including digestion of citraconylated material), staphylococcal protease, and chymotrypsin. In addition, some key subfragmentation was achieved by selective chemical cleavage at tryptophan residues. The fragment has an unusual amino acid composition, more than half of its residues being glycine, serine, threonine, and proline. There are very few nonpolar residues, although 7 of the alpha-chain's 10 tryptophans occur in this fragment. The fragment contains 2 cysteine residues located 30 residues apart which are connected by an intrachain disulfide bond in the native molecule. The tryptophans occur with a definite periodicity that highlights a series of 13-residue homology repeats. The fragment also contains the two principal alpha-chain cross-linking sites.
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PMID:Amino acid sequence studies on the alpha chain of human fibrinogen. Complete sequence of the largest cyanogen bromide fragment. 51 44

Casein epsilon-aminolysyl residues were converted to the methyl (and dimethyl), isopropyl or cyclopentyl derivatives in high yield with formaldehyde, acetone or cyclopentanone, respectively, in the presence of sodium borohydride. When incorporated into diets at 10% as the sole protein source, the chemically modified caseins failed to support growth of young rats. Methyl casein did, however, support limited growth after about 5 days. Plasma threonine levels increased and lysine levels decreased markedly in rats fed the alkyl caseins. The respective alkyllsine derivatives were present in plasma and urine. In another experiment, nearly normal or normal growth was obtained by feeding lysine-supplemented methyl or isopropyl casein, respectively. A preparation of partially methylated casein, containing approximately equal amounts of monomethyl- and dimethyllysines, supported normal rat growth. These results demonstrate that lysine deficiency was produced by feeding highly alkylated caseins. Digestibility of the chemically modified caseins in vivo was not affected, although in vitro studies with trypsin and alpha-chymotrypsin showed lowered digestibility. Since no apparent toxicity was observed limited methylation of food proteins may be useful for protection of lysyl residues against deteriorative reactions during processing and storage.
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PMID:Effect of reductive alkylation of the epsilon-amino group of lysyl redsidues of casein on its nutritive value in rats. 56 44

The selective cleavage of peptide bonds by a serine protease from skeletal muscle (SK-protease) was examined using glucagon and neurotensin as substrates. Among the peptide bonds cleaved in these substrates, the most susceptible were Phe-Thr-Ser, Tyr-Leu, Trp-Leu, and Tyr-Ile. These results indicate that the SK-protease hydrolyzed the carboxyl side of aromatic amino acid residues under the experimental conditions. When the amino acid on the carboxyl side of aromatic amino acid residues was serine, threonine or glutamic acid, these peptide bonds, such as Phe-Thr, Tyr-Ser, and Tyr-Glu, were not susceptible to another serine protease from small intestine (SI-protease) under the same experimental conditions. The peptide bond between the arginines of Pro-Arg-Arg-Pro in neurotensin was hydrolyzed by the SI-protease, but not by the SK-protease. Thus the specificity of the SK-protease differs from that of the SI-protease. These results suggest that the specificity of the hydrolytic action of the SK-protease is more like that of bovine chymotrypsin A than like that of porcine chymotrypsin C and of the SI-protease.
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PMID:Selective cleavage of peptide bonds by a serine protease from rat skeletal muscle. 70 Dec 36

Peptides of glycophorin AMN were prepared by cyanogen bromide cleavage and by chymotryptic and tryptic digestion. Cyanogen bromide cleavage produces three fragments which account for the entire polypeptide chain. Trypsin and chymotrypsin cleave completely at several sites, but incompletely at sites within the glycosylated segment of the polypeptide chain. Some of the latter sites become accessible to proteolysis after desialation in addition to exposure of new sites for cleavage. The amino acid sequence of glycophorin AMN has been determined by manual Edman degradation, using both the direct Edman and the dansyl-Edman procedures simultaneously for determination of glycosylated amino acid residues. The automated procedure was used for sequence determination of a hydrophobic peptide. Glycophorin A is a polypeptide chain of 131 amino acid residues and contains 16 oligosaccharide units attached to the amino-terminal third of the molecule. Fifteen oligosaccharides are linked O-glycosidically to either threonine or serine residues and one complex oligosaccharide unit is attached N-glycosidically to an asparagine residue. Amino-terminal sequences are different for glycophorin AM and AN, the two forms of the glycophorin A molecule coded for by genes at the MN locus. The differences in sensitivity to proteases of various sites on glycophorin A seem to be due to heterogeneity in the carbohydrate components and not to differences in the primary structure of the polypeptide chains. This work contains a number of revisions and corrections of earlier preliminary reports [Segrest, J.P., Jackson, R. chem. Biophys. Res. Commun, 49, 964-969; Tomita, M., & Marchesi, V.T. (1975) Proc. Natl. Acad. Sci. U.S.A. 72, 2964-2968].
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PMID:Primary structure of human erythrocyte glycophorin A. Isolation and characterization of peptides and complete amino acid sequence. 72 84

Monomer proteoglycan was isolated from porcine ovarian follicular fluid by isopycnic CsCl centrifugation in the presence of 4 M guanidine HCl and protease inhibitors. The elution profile of the D1 preparation on Sepharose 2B was similar to that of monomer proteoglycan from bovine nasal cartilage, indicating a similar molecular size. Follicular fluid proteoglycans consist of about 20% protein, 50% dermatan sulfate, and 20% oligosaccharides rich in sialic acid, galactose, mannose, glucosamine, and galactosamine. The amino acid composition of this proteoglycan is significantly different from that of cartilage proteoglycans, with a higher proportion of aspartic acid, threonine, and lysine, and lower amounts of proline and glycine. Alkali-released dermatan sulfate chains are larger on Sepharose 6B (average Mr = 56,000) than chondroitin sulfate chains from cartilage proteoglycans (average Mr = 25,000), and iduronic acid accounts for 9% of total hexuronic acid. Disaccharide units released by chondroitinase ABC consists of 67% 4-sulfated, 22% 6-sulfated, 5% non-sulfated, and 5% disulfated disaccharides. After treatment with 0.05 M NaOH, 1 M NaBH4 at 45 degrees C for 24 h, two major sialic acid-containing oligosaccharides were observed on Sephadex G-25, corresponding to penta- and hexasaccharides. The pentasaccharide contained sialic acid, galactose, glucosamine, and galactosamine in the proportions 1:2:1:1. The galactosamine is O-glycosidically linked to the protein core. This oligosaccharide accounts for approximately 77% of all the sialic acid in the follicular fluid proteoglycans. The hexasaccharide fraction contained sialic acid, galactose, mannose, and glucosamine in the proportions 1:2:1:2. It also contained a small amount of fucose and galactosamine. The linkage of these oligosaccharides to the protein core remains to be determined. The follicular fluid proteoglycans, unlike those from cartilage, do not interact with hyaluronic acid. Digestion with trypsin, chymotrypsin, or plasmin released dermatan sulfate-peptides nearly as small as those released by papain or alkali; in contrast, cartilage proteoglycans were resistant to plasmin and released peptides containing an average of more than four chondroitin sulfate chains after trypsin or chymotrypsin digestion.
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PMID:Isolation and characterization of proteoglycans from porcine ovarian follicular fluid. 76

Hydrolysis by chymotrypsin of bovine immunoglobulins (IgG1, type) isolated from colostral whey yields glycopeptides, structural studies of which lead to the following results. 1. IgG1 colostral immunoglobulins possess two glycan moieties which are linked to the peptidic chain by an N-(beta-aspartyl)-N-acetylglucosaminylamine bound. 2. The peptidic sequence is Asn (Glycan)-Ser-Thr-Tyr. 3. Application of partial acidic hydrolysis, periodic oxidation, hydrazinolysis-nitrous deamination, methylation and use of specific glycosidases lead to the determination of the following structure of the glycan moieties: (see article). These structures are related to the general glycan structure so-called of "N-acetyllactosamine type" because they possess the pentasaccharidic core common to numerous glycoproteins Man alpha (1 leads to 3) [Man alpha (1 leads to 6)] Man beta (1 leads to 4) GlcNAc beta (1 leads to 4) GlcNAc beta (leads to) Asn on which are conjugated two N-acetyllactosamine residues. They present a microheterogeneity which is due to the varying number of additional N-acetylneuraminic acid and fucose residues.
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PMID:[Structure of the carbohydrate groups of IgG1 immunoglobulins of cow colostrum]. 82 50

Two protein proteinase inhibitors were isolated and purified from the leech Hirudo medicinalis by means of gel filtration and ion-exchange chromatography. They inhibit chymotrypsin, subtilisin and the granulocytic neutral proteases elastase and cathepsin G. They proved to be homogeneous in polyacrylamide and dodecylsulfate gel electrophoresis and by end group analysis; only threonine was found as N-terminal amino acid residue using the dansylation technique. These inhibitors, which we call eglins, are stable in neutral and weakly acid (pH 3) solutions and resist non-specific proteolysis. From the amino acid compositions, a molecular weight of 6 600 - 6 800 is calculated for both inhibitory proteins, which is in good agreement with a value of about 6000 estimated by dodecylsulfate electrophoresis. The eglins contain an unusually large amount of hydrophobic amino acid residues but no methionine, isoleucine or--a rarity--cysteine residues or disulfide bridges. To our knowledge, the eglins are the first examples of proteinase inhibitors of the protein type which are not stabilized by disulfide bridges.
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PMID:Isolation and characterisation of a low molecular weight inhibitor (of chymotrypsin and human granulocytic elastase and cathepsin G) from leeches. 92 84

Bovine immunoglobulins (IgG1 type) have been isolated from colostral whey. Hydrolysis by pronase, trypsin and (or) chymotrypsin yield several glycopeptides structural studies of which lead to the following results. 1. IgG1 colostral immunoglobulins possess two glycan moieties which are linked to the peptidic chain by an N-(beta-aspartyl)-N-acetylglucosaminylamine bound. 2. The peptidic sequence around the linkage region has been determined by classical methods and is as follows: Thr-Lys-Pro-Arg-Glu-Glu-Gln-Phe-Asn(Glycan)-Ser-Thr-Tyr-Arg. 3. The following procedures: partial acidic hydrolysis, periodic oxidation, hydrazinolysis-nitrous deamination, methylation and use of specific glycosidases allowed us to determine the structure of the glycan moieties which fit with the general following scheme: (see article) Thus they could be related to the general glycan structure so-called of "N-acetyllactosamine type" because they possess the pentasaccharidic core common to numerous glycoproteins Man alpha 1 leads to [Man alpha 1 leads to 6] Man beta 1 leads to 4 GlcNAc beta 1 leads to 4 GlcNAc beta 1 leads to Asn on which are conjugated 2 N-acetyllactosamine residues. Besides they present a microheterogeneity which is due to the varying number of additional N-acetylneuraminic acid and fucose residues. 4. These structures are compared to various immunoglobulin structures proposed by others: bovine serum IgG and human serum IgG, IgE and IgA.
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PMID:[Complete structure of glycopeptides isolated from IgG immunoglobulins of cow colostrum]. 99 Mar 35


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