title: Hypodermin B, a trypsin-related enzyme from the insect Hypoderma lineatum. Comparison with hypodermin A and Hypoderma collagenase, two serine proteinases from the same source.
abstract: Hypodermin B, a serine proteinase with a molecular weight of 23000, was purified to homogeneity from the larvae Hypoderma lineatum. It is stoichiometrically inhibited by diisopropylfluorophosphate and fully inactivated by N-tosyllysine chloromethyl ketone and soya bean and bovine pancreatic trypsin inhibitors. N-Tosylphenylalanine chloromethyl ketone and ovomucoid are without effect on its activity. Hypodermin B hydrolyses both amide and ester substrates of trypsin but does not display any chymotryptic activity on synthetic substrates. Its specificity on the B chain of insulin is slightly broader than that of bovine trypsin. Its amino acid composition and N-terminal sequence suggest structural homology with serine proteinases of the trypsin family and with two other serine proteinases, hypodermin A and Hypoderma collagenase, previously isolated from the same larvae. Hypodermins A and B are very similar with respect to their inhibition and specificity, they differ however strongly from Hypoderma collagenase.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D004175:Diptera / Q000201:enzymology*; D010450:Endopeptidases / Q000378:metabolism*; D007814:Larva / Q000201:enzymology; D003012:Microbial Collagenase / Q000378:metabolism*; D008970:Molecular Weight; D012697:Serine Endopeptidases; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds / Q000032:analysis
chemical_list: D000596:Amino Acids; D013438:Sulfhydryl Compounds; D010450:Endopeptidases; D012697:Serine Endopeptidases; C030092:hypodermin; D003012:Microbial Collagenase