Fluorescence studies on the active sites of porcine pepsin and Rhizopus-pepsin.

摘要: Fluorescence studies on the interaction, with porcine pepsin, of oligopeptides bearing a mansyl (Mns, 6-(N-methylanilino)-2-naphthalenesulfonyl) or dansyl (Dns, 5-dimethylaminonaphthalene-1-sulfonyl) group at NH2 COOH terminus have provided further evidence showing that probe is drawn into extended active site largely as consequence specific binding peptide portion substrate. The does not appear to appreciable intrinsic affinity for group, and principal contribution peptide-protein interaction by sensitive L-phenylalanyl-L-phenylalanyl (Phe-Phe) unit substrates tested. pepsin inhibitor pepstatin can displace such Mns-(Gly)n-Phe-Phe-OR Gly-Gly-Phe-Phe-NHNH-Mns from pepsin; in these circumstances bound weakly separate, nonspecific locus, distinct site, which accept Mns-Gly-Gly-OR mansylamide. In Dns-(Gly)n-Phe-Phe-OR, above conclusions also apply Rhizopus-pepsin. With Gly-Gly-Phe-Phe-NHNH-Mns, however, Rhizopus-pepsin shows less fluorescent than suggesting structural differences between two acid proteinases region their sites bind COOH-terminal small oligopeptide substrates.