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)

Limited proteolysis of myosin by such proteolytic enzymes as trypsin, chymotrypsin or papain produces typical fragmentation of its heavy chain. Presently evidence is given that trypsin treatment cleaves the alkali light chain A-1 (20,700 dalton) to a shorter (ca 20,000 dalton) chain. The two "essential" thiols (SH-1 and 2) of moysin were alkylated with 17-C-N-ethylmaleimide and a non-negligible amount of radioactivity was also found in the two alkali light chains. Using the specific radioactivity of alkali light chain A-1 it was possible to identify it among heavy chain fragmentation products. The molecular weight of the newly formed A-1 indicates that limited tryptic cleavage of this A-1 confers on it a closer similarity with alkali light chain A-2.
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PMID:[Fragmentation of myosin A-1 light chain of fast muscle by trypsin]. 11 21

Bovine and porcine pancreatic residue, remaining after the extraction of insulin, has been used to prepare a proteinase powder. This powder was used as a source of trypsin and chymotrypsin. The individual enzymes were isolated and purified by chromatography on sulfopropyl (SP) - Sephadex C-25 and affinity chromatography on soybean trypsin inhibitor (STI) - Sepharose. The bovine proteinase powder contained alpha-chymotrypsin, trypsin and chymotrypsin B in the ratio 5 : 2 : 1. The porcine powder contained cationic trypsin, anionic trypsin and cationic chymotrypsin in the ratio 5 : 1.4 : 3. The isolated enzymes were characterized and found to be identical with enzymes isolated from fresh tissue with the exception of porcine chymotrypsin. Porcine cationic chymotrypsin was isolated as two distinct forms, A-1 and A-2, which appear to be different activation products of porcine chymotrypsinogen A. Both forms resemble bovine alpha-chymotrypsin, a three chain structure, rather than porcine chymotrypsin Api, a two chain structure. Futhermore, the B-chain appears to be cleaved, possibly at residues Phe89-Lys90.
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PMID:The preparation of trypsins and chymotrypsins from bovine and porcine residues after insulin extraction. 56 86

Binding of a denaturated polypeptide chain derived from chick skin collagen, the alpha 1(I) chain, by isolated membranes of human platelets has been demonstrated. The process is reversible, and time- and protein concentration-dependent. The binding is specific, with an association constant of 1.88 X 10(-6) M. Prior treatment of the isolated membranes with trypsin, chymotrypsin, and pronase, resulted in significant inhibition of the 14C-labeled alpha 1 chain binding, but neuraminidase or collagenase treatment had no effect. Dissociation of the bound radioactivity and subsequent chromatographic analyses on carboxymethylcellulose and agarose A-1.5m revealed that the alpha 1 chain was unaltered. Scatchard plot analysis suggested that there are approximately 20,000 binding sites per platelet. The binding of the alpha 1 chain was inhibited by a glycopeptide derived from alpha 1, alpha 1-CB5 and by purified glucosylgalactosyl hydroxylysine, but was not affected by other cyanogen bromide peptides of alpha 1, namely alpha 1-CB3, -CB4, -CB7, and -CB8. Kinetic studies demonstrated that inhibition by the hydroxylysine glycoside is competitive. Dose-response curves of platelet aggregation induced by alpha 1 and the binding of alpha 1 by platelet membranes correlate closely. These results indicate that there are specific binding sites for collagen alpha 1 chain on platelet membranes, and that the carbohydrate moiety of the alpha 1 chain plays a role in the binding. The findings also support the hypothesis that the chick skin alpha 1 chain mediates platelet aggregation and the release reaction by acting on platelet membranes.
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PMID:Binding of chick skin collagen alpha 1 chain by isolated membranes from human platelets. 97 74

Three alternatively spliced forms of the amyloid precursor protein (APP), APP-695, APP-751, and APP-770, were expressed in the baculovirus expression vector system. The recombinant proteins were secreted into the culture medium by infected insect cells, and APP molecules were detected in insect cells and medium 2 days after infection with the recombinant APP-baculoviruses. A partial sequence of the NH2 terminus of the secreted protein revealed identity with the native secreted protein and showed that the signal peptide was recognized and properly cleaved in insect cells. Purified secreted recombinant APP-751 comigrated with protease nexin 2 purified from platelets and fibroblasts. A 15-kDa COOH-terminal fragment of APP was also detected in cells infected with recombinant baculoviruses, suggesting that recombinant APP proteins were cleaved at the COOH-terminal end like native APP protein. Recombinant APP-751 and APP-770 formed complexes with epidermal growth factor-binding protein, whereas APP-695 did not. In addition, recombinant APP-751 and APP-770 inhibited trypsin and chymotrypsin activity, whereas APP-695 did not. Growth of a human fibroblast cell line, A-1, that required APP for complete growth, was restored upon addition of secreted recombinant APP-695 or APP-751. Thus, the appropriately sized, secreted recombinant APP proteins produced in this expression system are biologically active.
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PMID:Expression of active secreted forms of human amyloid beta-protein precursor by recombinant baculovirus-infected insect cells. 194 49

The carboxymethylated L-asparaginase from Escherichia coli A-1--3 was fragmented with cyanogen bromide and the resulting peptides were isolated by using gel filtration on Sephadex G-50 and column chromatography on DE-52. The amino acid sequences of the 7 cyanogen bromide peptides thus obtained were established completely or partially by further fragmentation with trypsin, chymotrypsin and pepsin, and the Dansyl Edman method. Based on the above results and the complete sequences of the tryptic peptides from the carboxymethylated L-asparaginase reported in the previous paper, the whole sequence of the enzyme was established. The reported sequence consists of 321 amino acid residues and its calculated molecular weight is 34 080.
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PMID:The primary structure of L-asparaginase from Escherichia coli. 676 94

During proteolytic digestion of myosin to prepare HMM or HMM-S-1 subfragments, myosin light chains are affected variously according to experimental conditions. In the presence of Ca2+ at low ionic strength trypsin rapidly degrades the DTNB light chain to a 18 K peptide. This new DTNB light chain is compared to a DTNB (17K) light chain obtained by chymotryptic digestion under similar conditions as shown here and in parallel studies. (Weeds and Pope (1977), J. Mol. Biol, 111, 129--157). Whereas the chymotryptic DTNB (17K) has lost its phosphorylation site (Ser-15), tryptic DTNB (18K) has lost only a strongly basic N-terminal peptide. A transitory (ca 14K) fragment is formed when digestion occurs in the presence of EDTA. A-1 light chain (20.7K) is cut to form a 20K species when myosin (of (CT)-HMM obtained ina high ionic strength medium) is digested with trypsin whether Me2+ is present or not. The new formed species has also lost its strongly basic N-terminal peptide and assumes a primary structure closer to that of A-2. Chymotrypsin was shown to have no effect on the A-1 light chain under the present conditions, whereas A-2 is not affected by chymotrypsin or trypsin under any of the conditions described in the present study.
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PMID:Fate of the light chains in the course of proteolytic digestion of rabbit fast skeletal myosin. 676 1