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 G-200 flow-through fraction of the extract of sea urchin eggs contained a complex form of glutathione reductase (GR) [EC 1.6.4.2]. The complex was unstable and gradually dissociated with ain increase in GR activity. The activation was facilitated by high concentrations of EDTA, KCI or (NH4)2SO4. The rate of activation by salts was apparently dependent on the ionic strength. The complex form was also activated rather quickly by treatment with proteinases such as trypsin [EC 3.4.21.4], alpha-chymotrypsin [EC 3.4.21.1] or subtilisin [EC 3.4.21.14]. Trypsin caused the complex to release the free form of GR. Even after trypsin treatment, little change was observed in the dependence of the GR activity on GSSG or NADPH concentration. The GR activity of the complex form was not inhibited at all by 0.2 mM N-ethylmaleimide (NEM) in the presence of GSSG, but was reduced to 3% in the presence of NADPH. When excess NEM was sequestered with GSH, the NEM-treated complex form was strikingly activated by trypsin, while no activation was detected with the free form of enzyme pretreated with NEM. These results suggest that the active site of GR in the complex form is largely masked by a polypeptide moiety of theinhbitiory component.
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PMID:Glutathione reductase in the sea urchin egg. III. Activation of the complex form by proteinases. 1 74

A reinvestigation of the modification reactions of alpha-chymotrypsin with phenacyl bromide was carried out. Results conclusively demonstrate that the chemically and physically different modified enzymes prepared at pH 4 and at pH 7 both contain the phenacyl group at methionine-192 in the sulphonium salt form. Evidence to suppoort this conclusion derives from 13C nuclear-magnetic-resonance spectroscopic observations on [methylene-13C]phenacyl-enriched enzymes. More conclusively, the methionine-192-containing C-chain, derived by performic acid oxidative cleavage of radioactively-labelled enzyme prepared at pH 7, was shown to contain the phenacyl moiety and to undergo dealkylation by 2-mercaptoethanol with loss of this moiety. In addition, thermolytic cleavage of the high-pH enzyme results in fragmentation of the polypeptide chain in a fashion analogous to model reactions of phenacylmethionyl dipeptides and other methionine-192 sulphonium salts. A rationalization of the unusual nature of the high-pH phenacyl-modified enzyme based on the irreversible formation of stable conformation in which the phenacyl moiety is rigidly located in interior regions of the enzyme is presented and discussed.
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PMID:Evidence for a pH-dependent irreversible formation of a stable conformation of phenacyl-alpha-chymotrypsin. 2 56

A 60,000-dalton polypeptide (p60) has been identified in the feline leukemia virus (FeLV) pseudotype of Moloney sarcoma virus [MSV(FeLV)]. This polypeptide is present in the purified virus complex in concentrations greater than either the murine p30 or the feline p27. Purified p60 crossreacts immunologically with murine p30 group antiserum and contains several interspecies determinants, whereas the group specific determinant of FeLV p27 is not detected. Comparison of peptide fingerprints of p60 and murine p30 show many peptides in common. Limited digestion of p60 with either trypsin or chymotrypsin produced p30-35 and p20 peptides which retain the MuLV p30 group and interspecies antigenic activities. The p30 produced by both enzymes comigrates in polyacrylamide gels with the murine p30 of MSV(FeLV), thus suggesting that p60 may be an uncleaved precursor to p30.
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PMID:A p60 polypeptide in the feline leukemia virus pseudotype of Moloney sarcoma virus with murine leukemia virus p30 antigenic determinants. 4 60

Human properdin (P) was found to be sensitive to the action of trypsin, chymotrypsin, pepsin, and Streptomycetes caesipitosus protease. Incubation of P with these enzymes resulted in loss of its functional activity and the production of antigenically deficient components compared to untreated P. Upon incubation with trypin, P was initially cleaved into a minor fragment and a major fragment. Further degradation ot the fragments occurred with prolongation of inculation time. The minor fragment was highly susceptible to further proteolysis compared to the major fragment which contained the carbohydrate moiety of the molecule. SDS-polyacrylamide gel electrophoretic analysis of trypsin-digested P suggested that the subunit polypeptide chains were initially cleaved at similar points to produce the major and minor fragments. The sedimentation velocity of the major fragment was higher than that of the intact molecule. The implications of these observations of the configuration of P are discussed.
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PMID:Effect of proteolytic digestion on the structure and function of human properdin. 5 3

Analysis of platelet membrane proteins and glycoproteins by SDS polyacrylamide gel electrophoresis was carried out before and after treatment with thrombin. Extended incubation with thrombin (in the presence of EDTA or adenosine, which inhibit aggregation) produced extensive changes in the bands observed. With incubation times of a few minutes however, the changes were restricted to a glycopeptide, GP IV (approx. 90,000 Daltons) and one or two polypeptides of low molecular weight, in particular polypeptide 16 (approx. 23,000 Daltons). At 0--3 degrees C only polypeptide 16 was still hydrolyzed. Chymotrypsin, which does not activate platelets, attacked glycopeptides I, II, III but no changes were apparent in GP IV and polypeptide 16. When chymotrypsin-treated platelets were further incubated with thrombin, only GP IV and one to two low molecular weight polypeptides, especially polypeptide 16, were affected. As polypeptide 16 appears to be an integral membrane component it is possible that it, either by itself or in combination with GP IV, represents the primary thrombin substrate involved in platelet activation. Aggregated IgG, which also activates platelets, does not modify the membrane glycoproteins but does change the low molecular weight region in particular band 16.
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PMID:Effects of thrombin, chymotrypsin and aggregated gamma-globulins on the proteins of the human platelet membrane. 7 80

Purified avian myeloblastosis virus reverse transcriptase contains two subunits that are structurally related. The large subunit, beta (molecular weight, 95,000), was converted in vitro by chymotrypsin into a polypeptide of molecular weight 63,000. This polypeptide was indistinguishable from the small subunit, alpha (molecular weight, 65,000), in its chromatographic behavior on the phosphocellulose column and its tryptic peptide composition. During this proteolytic conversion, a polypeptide of molecular weight 32,000 (fragment B) was obtained. It was composed of tryptic peptides unique to beta and appeared to be derived from the portion of the beta subunit that was cleaved off during the conversion of beta into alpha. Upon continued proteolysis, a smaller polypeptide of molecular weight 24,000 (fragment A) was generated. This polypeptide manifested only RNase H activity and shared common amino acid sequences with beta and alpha subunits. Fragment A did not share any amino acid sequence homology with fragment B.
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PMID:Reverse transcriptase of RNA tumor viruses. V. In vitro proteolysis of reverse transcriptase from avian myeloblastosis virus and isolation of a polypeptide manifesting only RNase H activity. 7 71

Treatment of hepatitis B surface antigen (HBsAg) with either chloroform-methanol (2:1, v/v) or 50% 1,1',3,3'-tetramethylurea did not affect the morphological integrity of the particles (about 20 nm in diameter), although the major portion of lipids was released as indicated by their increased buoyant density in CsCl (1.27 g/cm3 as compared with 1.20 g/cm3 for intact HBsAg). The antigenicity and polypeptide composition of HBsAg was not altered by delipidation. The carbohydrate chains of HBsAg contain penultimate beta-D-galactosyl residues. HBsAg was cleaved by chymotrypsin into fragments which were smaller than intact HBsAg by two orders of magnitude and which contained both the a and d determinants.
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PMID:Properties of delipidated hepatitis B surface antigen (HBsAg) and preparation of its proteolytic cleavage fragments carrying HBsAg-specific antigenic determinants. 7 67

Large and small plaque variants of A12 foot-and-mouth disease virus were shown to have specific antigenic determinants. Large plaque virus antigenic specificity was destroyed by trypsin treatment, but the small plaque antigen was resistant despite cleavage of the trypsin-sensitive polypeptide. The cleavage of polypeptide VP3 by trypsin resulted in the formation of a new antigen not present on untreated virus. The effects of chymotrypsin and trypsin on the polypeptides of the plaque variants have been examined and related to changes in antigenicity, infectivity, and exposure of the polypeptides at the surface of the capsid. The results are discussed in relation to the orientation of the trypsin-sensitive polypeptide in the virus capsid.
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PMID:Effect of trypsin and chymotrypsin on the polypeptides of large and small plaque variants of foot-and-mouth disease virus: relationship to specific antigenicity and infectivity. 8 54

A cationic polypeptide growth factor, isolated from human serum and purified to homogeneity, has stimulated the replication of density-inhibited BALB/c 3T3 cells. It has a molecular weight of 1.3 x 10(4) daltons and an isoelectric point of 9.7. Trypsin or chymotrypsin digestion reduces the growth-stimulatory activity by 75%, whereas 2-mercaptoehanol completely abolishes it. The growth factor is heat-stable (100 degrees C X 10 min) and free of insulin-like activity. The highly purified serum growth factor has been labeled with 125I, and an antiserum to the growth factor was produced in the rabbit. A specific, highly sensitive radioimmunoassay has been developed. Factors with growth-stimulating activity have also been detected in human platelets and human pituitary gland extracts. Platelets and pituitary glands have antigenic determinants that are recognized by antibodies to the serum growth factor. The platelet and pituitary gland growth factors are also cationic and heat stable, and are destroyed by 2-mercaptoethanol. Thus the human serum, platelet, and pituitary gland growth factors have similar properties.
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PMID:Growth factors derived from human serum, platelets, and pituitary: properties and immunologic cross-reactivity. 8 59

Crossed immunoelectrophoresis of rat serum demonstrated considerably increased serum concentrations of at least ten different proteins during turpentine-induced inflammation. One protein, which moved during electrophoresis like an alpha 1 globulin, showed a particularly large increase. This protein was purified to homogeneity by ammonium sulfate fractionation followed by chromatography on DEAE-cellulose. Sephadex G-100, and concanavalin A-Sepharose, and finally disc electrophoresis in polyacrylamide gel. It has a molecular weight of 56,000 determined by equilibrium ultracentrifugation. An apparent molecular weight of 68,000 was estimated for the reduced protein by electrophoresis in polyacrylamide gel plus sodium dodecyl sulfate, suggesting that the native protein is composed of a single polypeptide chain. It has an E2801%, 1 cm of 5.2, an isoelectric pH of 4.7, and contains 19% carbohydrate. The protein does not inhibit bovine trypsin or chymotrypsin. Its physical properties and amino acid composition distinguish this protein from all other rat serum proteins hitherto characterized. During acute inflammation, induced 25 h previously, rats incorporated 20 times more [14C]leucine into this particular protein than did normal rats. However, incorporation into total serum protein during acute inflammation increased only slightly. Regardless of whether inflammation was induced by surgical injury or by a subcutaneous turpentine injection, within 48 h the serum concentration of this major acute-phase protein rose from the normal value of 0.46 g/liter to a maximum value of 7.2 g/liter, which constituted 10% of the total serum protein.
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PMID:A rat serum glycoprotein whose synthesis rate increases greatly during inflammation. 9 5


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