Digestive carbohydrases from the hepatopancreas of two Antarctic euphausiid species (Euphausia superba and E. crystallorophias)

Abstract

The hepatopancreatic extracts of Euphausia superba Dana and E. crystallorophias Holt and Tattersall collected from the Antarctic. Ocean during January 1985, are most effective in hydrolysing substrates containing (1→3)-β-glucosidic linkages. Three enzymes appear to be involved in the depolymerization of (1→3)-β-D-glucans in the euphausiid diet: (1) an exo-(1→3)-β-D-glucanase, (2) an endo-(1→3)-β-D-glucanase and (3) a β-D-glucosidase. The glucanases have a pH optimum of 5.4, a temperature optimum of 50°C and are optimally extracted in bistripropane buffer, pH 7.2. Levels of (1→3)β-D-glucanase in laboratory-cultured E. superba are inversely affected by food availability, and activities double ..