Synergistic interaction of an endo-beta-1,4-glucanase and a beta-gIucohydrolase leads to more efficient hydrolysis of cellulose-like polymers in the gecarcinid land crab, Gecarcoidea natalis

摘要

This study investigated synergism between endo-beta-1,4-glucanase and beta-glucohydrolase enzymes from Gecarcoidea natalis. Together, these enzymes efficiently hydrolyse the cellulose-like polymer, carboxymethyl cellulosc, to glucose. Endo-beta-l,4-glucanase and beta-glucohydrolase, isolated previously from G. natalis, were incubated in vitro using a ratio of the measured activities that matches that found in their digestive juice (5.4:1). Their combined activity, measured as the release of glucose from carboxymethyl cellulose, was greater than the sum of their separate activities. Hence they synergistically released glucose from carboxymethyl cellulose (degree of synergy: 1.27). This may be due to the complementary nature of the products of endo-beta-1,4-glucanase activity and the preferred substrates of the beta-glucohydrolase. beta-glucohydrolase may also enhance cellulose hydrolysis by removing cellobiose, a potential competitive inhibitor of endo-beta-1,4-glucanase. The synergistic interaction of these two enzymes further supports the previous suggestion that this species possesses a novel two-enzyme cellulase system that differs from the traditional three-enzyme fungal model.