抄録
Two different types of lysozyme, types I and II, that lysed the lyophilized cells of Micrococcus lysodeikticus were purified from the skin mucus of ayu Plecoglossus altivelis by sequential column chromatographies on SP-Toyopearl 650M, Heparin Sepharose CL-6B, Mono S HR 5/5, and Superose 12HR 10/30.
The types I and II enzymes had an isoelectric point of approximately 9.4 and 9.8, re-spectively, and were separated by Mono S ion exchange column chromatography using an FPLC system. The molecular weight of both enzymes was estimated to be about 18, 000 by SDS-PAGE. Amino acid compositions of both lysozymes were similar to each other, but the concentrations of basic amino acids (Lys and His) in type II were higher than those in type I. For lysozyme activity of both enzymes, optimum pH was 6.3-6.9, optimum temperature was about 35°C, and optimum molarity of phosphate buffer was 0.01. Lysozyme activity of type I was inhibited by 100units/ml of heparin, but that of type II was not inhibited even by 200units/ml of heparin. Both enzymes were inactivated by 10mM histamine. Lysozyme activities by the enzymes were found against formalin-killed bacterial cells of Pasteurella piscicida and Aero-monas hydrophila, but not against those of Vibrio anguillarum.
