title: Purification and characterization of an elastinolytic proteinase secreted by cercariae of Schistosoma mansoni.
abstract: An elastinolytic proteinase secreted by tissue-invasive larvae of Schistosoma mansoni has been purified to homogeneity. Size-exclusion chromatography and chromatofocusing were used to purify the enzyme 18-fold from crude larval secretions. The native enzyme has a molecular weight of 30,000, a pI of 8, a pH optimum of 9, and a calcium dependence of 2 mM. A second Mr 17,000 form of the enzyme was present in crude secretions and appears to be an autoproteolysis product. The enzyme is a serine proteinase that preferentially binds tetrapeptide inhibitors or substrates with an aromatic or hydrophobic residue at the P-1 site. In addition to being active against elastin, the enzyme degrades Azocoll, gelatin, laminin, fibronectin, keratin, and type IV collagen.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002850:Chromatography, Gel; D003902:Detergents / Q000494:pharmacology; D004549:Elastin / Q000378:metabolism*; D010450:Endopeptidases / Q000302:isolation & purification*; D007525:Isoelectric Focusing; D008970:Molecular Weight; D012550:Schistosoma mansoni / Q000201:enzymology*; D013696:Temperature
chemical_list: D003902:Detergents; D004549:Elastin; D010450:Endopeptidases