Purification and Properties of a Pectate Lyase inErwinia aroideae

Abstract

A strain of Erwinia aroideae produced an extracellular pectolytic enzyme under growth conditions with pectin or pectic acid as the inducer. This strain also produced a pectin lyase when nalidixic acid is added to a culture medium. The pectolytic enzyme produced under the growth conditions was purified approximately 40-fold from the culture fluid by carboxy- methyl cellulose and Sephadex G-75 gel column chromatographies. The purified enzyme was almost homogeneous on sodium dodecyl sulfate polyacrylamide gel electrophoresis, having a molecular weight of about 36,000 to 38,000. This enzyme, with optimal activity at pH 9.0 to 9.2, produced reaction products which had a strong absorption at 230 nm indicating a lyase type of the reaction. The enzyme activity was markedly stimulated by calcium ion and completely inhibited by cobalt and mercuric ions and by ethylenediaminetetraacetate. Pectic acid or pectin with lower methoxyl content was a good substrate for this enzyme, while no significant activity was observed when pectin with higher methoxyl content was used as a substrate. It was concluded that the enzyme produced under the normal growth conditions is an endo-pectate lyase and differs from the pectin lyase induced by nalidixic acid.