Carbohydrases of the rumen ciliate Epidinium ecaudatum (Crawley). 2. α-Galactosidase and isomaltase

Abstract

Extracts prepared from Epidinium ecaudatum by two disintegration procedures contain [alpha]-galactosidase and isomaltase activities. Nearly all of the [alpha]-galactosidase is extracted by water. The [alpha]-galactosidase hydrolyses galactosylgalactosylglycerol faster than it does melibiose and hydrolyses other compounds containing [alpha]-(l[forward arrow]6)-linked galactose more slowly than melibiose. 4-[alpha]-Galactosylgalactose is also hydrolysed but melibiitol is scarcely attacked and methyl [beta]-L-arabinopyranoside not at all. Galactose is liberated from intact clover galactosyl-lipids, although no lipase activity could be demonstrated in the extracts. [beta]-Galactosylglycerol is not hydrolysed by the epidinial extracts. The [alpha] -galactosidase has optimum activity over the pH range 5.0-5.5 and temperature range 38-55[degree], and acts as a transferase in the presence of 2% of melibiose, galactose or galactosylgalactosylglycerol. The isomaltase, which appears to be a separate enzyme, has optimum activity at pH 6.0.