Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Carboxypeptidase B (peptidyl-L-lysine (-L-arginine) hydrolase, EC 3.4.12.3) has been isolated and purified to apparent homogeneity from activated extracts of human pancreas tissue. The purified enzyme has been shown to be a single polypeptide of 34 000 daltons. In this respect the enzyme from pancreatic tissue, designated native human carboxypeptidase B, differs from the two forms present in human pancreatic juice (fractions I and II), both of which are composed of two polypeptides of approximately 24 000 and 9000 daltons. In addition, the three forms of human carboxypeptidase B differ in electrophoretic mobility in polyacrylamide gel electrophoresis and in chromatographic behavior on DEAE-cellulose. Two immunological methods, micro-complement fixation and radioimmunoassay, have shown a high degree of structural similarity between the three forms of human carboxypeptidase B. Micro-complement fixation experiments indicate that the amino acid sequences of the three enzymes differ by less than one percent. In vitro digestion studies have indicated that trypsin alone is sufficient to convert native carboxypeptidase B to carboxypeptidase B II. However, no combination of trypsin, chymotrypsin, and/or elastase was capable of converting native carboxypeptidase B to carboxypeptidase B I in vitro.
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PMID:Human carboxypeptidase B. II. Purification of the enzyme from pancreatic tissue and comparison with the enzymes present in pancreatic secretion. 100 23

Limited proteolysis of actin with trypsin removes its two or three C-terminal amino acid residues [Proc. Natl. Acad. Sci. USA 81 (1984) 3680-3684]. Carboxypeptidase B-treatment of G- and F-actin previously digested with trypsin revealed that in the first case preferential release of three and in the second two C-terminal amino acid residues takes place. Tryptic removal of three but not two C-terminal amino acid residues of actin causes weakening of its interaction with caldesmon and lowering of the caldesmon-induced inhibitory effect on actomyosin ATPase activity. Therefore, it is concluded that the third amino acid residue from the C terminus of actin, Lys-373, is important for the interaction with caldesmon.
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PMID:Lys-373 of actin is involved in binding to caldesmon. 138 67

This study identifies the in vitro differences (markers) between virulent and attenuated transmissible gastroenteritis (TGE) viruses. Exposure of virulent Miller strain and attenuated Purdue strain TGE viruses to a spectrum of acidities indicated that the Miller strain was more stable at pH 2. Acidities at or above pH 3 did not reduce viral infectivity of either strain. When virulent and attenuated viruses were exposed to gastric fluids of either fed or fasted swine, there was a similar degree of sensitivity. Carboxypeptidase B, alpha-amylase, and alkaline phosphatase present in porcine small intestinal fluids did not cause a significant difference in sensitivity between virulent and attenuated virus isolates. The digestive enzymes: trypsin, alpha-chymotrypsin, pancreatin, peptidase, and carboxypeptidase A did not (or only slightly) inactivate virulent Miller strain TGE virus, but greatly reduced infectivity of attenuated viruses (Purdue strain and TGE vaccine virus isolates). The attenuated strains were significantly more sensitive to small intestinal fluids from both fasted and fed adult swine. Differential sensitivities between virulent and attenuated TGE viruses to digestive fluids from stomach and small intestine further substantiate the notion of differential susceptibility to small intestinal proteases as a correlate of viral virulence.
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PMID:Enzymatic and acidic sensitivity profiles of selected virulent and attenuated transmissible gastroenteritis viruses of swine. 298 96

Previous studies have demonstrated the presence of two type III hexokinase isozymes in pig mature erythrocytes. The prevalence of a specific isozyme species is an age-dependent phenomenon. The mature erythrocyte of young adult pigs (less than 6 mo old) possess an isozyme that has an apparent Km for glucose that is lower than in adult pigs. The data in this report suggest several basic differences between the two isozymes. D-Mannoheptulose, a structural analogue of glucose, was observed to differentially inhibit the isozymes. The young adult isozyme tended to be heat sensitive when compared with adult isozymes. Carboxypeptidase B and trypsin inhibited the activity of both isozymes, but the young adult isozyme was most dramatically affected by carboxypeptidase B. When the two isozymes were incubated in the presence of two sulfhydryl group inhibitors, HgCl2 and 5,5'-dithiobis [2-nitrobenzoic acid] (DTNB), the young adult isozyme exhibited the greater inhibition in the presence of DTNB. The data suggest that the young adult isozyme exhibited pronounced differences in activity when incubated in the presence of DTNB and carboxypeptidase B. These two agents may be used as probes to further characterize the properties of the two isozymes.
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PMID:Properties of pig mature erythrocyte hexokinase. 407 95