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)

Two murine monoclonal antibodies (H5 and B6) generated against bovine heart type II regulatory subunit of cAMP-dependent protein kinase were shown to cross-react equally well with the homologous subunit from porcine heart. The antibodies demonstrated specificity for only the type II regulatory subunit and showed negligible cross-reactivity with the type I regulatory subunit, the catalytic subunit, and cGMP-dependent protein kinase. Following limited proteolysis of type II regulatory subunit with chymotrypsin, the H5 monoclonal antibody was shown to cross-react with the Mr = 37,000 cAMP-binding domain corresponding to the COOH-terminal region of the polypeptide chain. To more specifically localize the antigenic sites, the porcine type II regulatory subunit was carboxymethylated and cleaved with cyanogen bromide. Both monoclonal antibodies cross-reacted with the NH2-terminal CNBr peptide, and this peptide demonstrated affinities similar to native bovine type II regulatory subunit in competitive displacement radioimmunoassays. Tryptic cleavage of this CNBr fragment destroyed all antigenicity for both monoclonal antibodies, whereas antigenicity was retained following chymotryptic digestion. A single major immunoreactive chymotryptic fragment that cross-reacted with H5 was isolated by gel filtration and reverse phase high performance liquid chromatography. this peptide retained the complete antigenic site and had the following sequence: Asn-Pro-Asp-Glu-Glu-Glu-Glu-Asp-Thr-Asp-Pro-Arg-Val-Ile-His-Pro-Lys-Thr-Asp-Gl n. This antigenic site was localized just beyond the major site of autophosphorylation, approximately a third of the distance from the NH2-terminal end of the polypeptide chain.
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PMID:Monoclonal antibodies as structural probes of surface residues in the regulatory subunit of cAMP-dependent protein kinase II from porcine heart. 618 75

cGMP-dependent protein kinase from bovine lung is labile to specific proteolysis. Limited digestion with chymotrypsin produces a 65,000-dalton monomer and a 16,000-dalton dimer from a 150,000-dalton dimeric enzyme. The larger proteolytic fragment represents the COOH-terminal portion of the enzyme and contains the catalytic site along with the cGMP binding site. The smaller fragment representing the NH2-terminal portion of the enzyme contains the autophosphorylation site and the interchain disulfide bond(s). A model defining the functional domains of cGMP-dependent protein kinase is presented and comparisons with cAMP-dependent protein kinase regulatory subunit are discussed.
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PMID:Structural analysis of cGMP-dependent protein kinase using limited proteolysis. 624 42