COMPARATIVE CHARACTERIZATION OF HYDROLYSIS AND TRANSGLYCOSYLATION CATALYZED BY BETA-1,3-GLUCANASES FROM VARIOUS SOURCES

Hydrolytic and transglycosylating activities of endo-beta-1,3-glucanas e and exo-beta-1,3-glucanase isolated from marine and terrestrial inve rtebrates, marine bacteria, and higher plants were comparatively studi ed. The effects of structural features of substrates on hydrolysis and transglycosylation catalyzed by these enzymes were investigated. Endo -beta-1,3-glucanases had equal hydrolytic activities but differed in t ransglycosylation abilities. Endo-beta-1,3-glucanases from marine moll usks and marine bacteria displayed the highest transgly-cosylating act ivities, whereas plant endo-beta-1,3-glucanases had the lowest transgl ycosylating activities. The enzymes studied in this work had different rates of hydrolysis of 1,3;1,6-beta-D-glucans with various contents o f beta-1,6 linkages. Endo-beta-1,3-glucanase from chitons and exo-beta -1,3-glucanase LII from the terrestrial mollusk were the most structur e-sensitive in hydrolysis reactions, whereas endo-P-l,3-glucanases LII I and LIV from marine mollusks were the least sensitive. In contrast, the rates of transglycosylation reactions mediated by endo-beta-1,3-gl ucanases LO and LIV strongly depended on the substrate structure and s harply decreased with a decrease in their contents of beta-1,6-linked glucose residues. Laminaran from Laminaria cichorioides was found to h ave an optimal structure for all enzymes studied, both in hydrolysis a nd transglycosylation reactions.