SOME CHARACTERISTICS OF AN ENDO‐PECTATE LYASE PRODUCED BY A THERMOPHILIC BACILLUS ISOLATED FROM OLIVES

Abstract

ABSTRACTAn endo pectate lyase (PAL), or endo‐pectic acid transeliminase secreted by a thermophilic Bacillus sp., responsible for softening in pickled olives, was purified 30‐fold by ammonium sulfate precipitation and successive chromatography on Bio‐gel P‐100, DEAE‐cellulose, and CM‐cellulose columns. It degraded both pectic acid and pectin N.F. in a random manner, but did not attack fully esterified Link pectin. The end products of its action on polygalacturonic acid were largely unsaturated di‐ and tri‐galacturonic acids, with smaller amounts of saturated di‐ and tri‐galacturonic acids. Both saturated and unsaturated pentra‐ and tetra‐galacturonic acids were cleaved by the enzyme. Addition of either the culture or the isolated enzyme to the pickled olives caused softening of the tissue within a week at 37°C when a Chatillon spring punch (0.064 in.) was applied. The activation energy of this heat‐stable pectate lyase enzyme on 0.5% pectic acid was 17.1 kcal/mole, and the Q10 value was 2.35 between 60 and 70°C. The enzyme had a Vmax at 0.56 μmoles reducing groups/min and Km at 0.34% polygalacturonic acid.