Multiple Components of Endo-polyguluronide Lyase of Pseudomonas sp.

Abstract

A lyophilized alginate lyase preparation obtained from dialyzed extract of sonicated Pseudomonas sp. cells was fractionated by gel filtration on a Sephadex G-150 column, and three alginate lyase [EC 4.2.2.3] fractions, peaks I, II, and III, were obtained. They were remarkably thermolabile. The lyase fractions degraded two kinds of alginate fragments, a polyguluronide (SG), and a polyuronide consisting of both mannuronic and guluronic acid residues (SMG), as well as commercial alginate, but were virtually inactive toward polymannuronide fragment (SM). The modes of degradation of these substrates by the lyase fractions were endowise with different degrees of randomness. Attack by the peak I fraction was more random than those by peaks II and III. The main lysis products formed from SG and SMG by these layses were identified as mixtures of unsaturated tri- and monouronides. The unsaturated triuronide from SG was δUGG and SMG yielded a mixture of δUGG and a poorly characterized unsaturated trimer, possibly δUMG. However, the patterns of monomer and trimer production by these lyase fractions changed in different ways during incubation.