Catalytic properties and mode of action of endo-(1→3)-β-d-glucanase and β-d-glucosidase from the marine mollusk Littorina kurila Original Research Article

A complex of the enzymes from the liver of the marine mollusk Littorina kurila that hydrolyzes laminaran was investigated. Two (1→3)-β-d-glucanases (G-I and G-II) were isolated. The molecular mass of G-I as estimated by gel-permeation chromatography and SDS–PAGE analysis was 32 and 40 kDa, respectively. The G-II molecular mass according to SDS–PAGE analysis was about 200 kDa. The pH optimum for both G-I and G-II was pH 5.4. The G-I had narrow substrate specificity and hydrolyzed only the (1→3)-β-d-glucosidic bonds in the mixed (1→3),(1→6)- and (1→3),(1→4)-β-d-glucans down to glucose and glucooligosaccharides. This enzyme acted with retention of the anomeric configuration and catalyzed a transglycosylation reaction. G-I was classified as the glucan endo-(1→3)-β-d-glucosidase (EC 3.2.1.39).