The biochemistry of rumen protozoa. 6. The maltases of Dasytricha ruminantium, Epidinium ecaudatum (Crawley) and Entodinium caudatum

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Abstract
Extracts of cells of three species of rumen protozoa, Dasytricha ruminantium, Epidinium ecaudatum (Crawley) and Entodinium caudatum have been prepared, and the properties of some of their carbohydrases studied, with particular reference to maltase. The maltase of D. ruminantium has maximum activity at pH 5.5, that of Epidinium ecaudatum at pH 6.7, and that of Entodinium caudatum at pH 5.7-6.1. The maltases of Epidinium ecaudatum and Entodinium caudatum, but not that of D. ruminantium, are more active in buffer solutions containing citrate ions than in phosphate. The maltases of Epidinium ecaudatum and Entodinium caudatum are most active at 38[degree], and their activity is much reduced at temperatures above 40[degree]. The IX ruminantium maltase has maximum activity at 50[degree], and retains moderate activity at 60[degree]. The three enzymes are specific maltases, and do not hydrolyse methyl [alpha]-D-glucoside, [alpha][alpha]-trehalose, turanose, sucrose or maltitol. Only the D. ruminantium enzyme can hydrolyze maltotri-itol. Maltotriose is slowly hydrolyzed by all three enzymes. All three enzymes exhibit transferase properites when incubated with 1% (w/v) or higher concentrations of maltose. Epidinium ecaudatum and Entodinium caudatum transfer glucose to C-4 of maltose; D. ruminantium transfers to both C-4 and C-6 of maltose.