Degradation of myofibrils and formation of premer omyosin by a neutral protease produced by Pseudomonas fragi

Abstract

Rabbit muscle myofibrils were treated with a neutral protease (200: 1-protein: enzyme) isolated from Pseudomonas fragi (P. fragi) at 0° C in 100 m m KCl, 5·0 m m CaCl 2, 0·2 m m DTT (dithiothreitol) and 20 m m TRIS. HCl (pH 7·50) for 0–60 min. SDS-polyacrylamide disc gel electrophoresis showed extensive fragmentation of the myofibrillar proteins. Three of the major products correspond in molecular weight to heavy meromyosin (HMM), light meromyosin (LMM) and the recently discovered premeromyosin (PMM). Results demonstrated that the neutral protease produced by P. fragi is capable of hydrolysing myosin and probably plays an important role in microbial breakdown of the muscle proteins during meat spoilage.