Studies on mammalian glucoamylases with special reference to monkey intestinal glucoamylase.

1. Highly purified preparations of glucoamylase were obtained from liver, spleen and intestine of the monkey. The enrichment factor was lower for intestine (60-fold) compared with that of liver (1200-fold) and of spleen (2000-fold) but the final specific activities were of a similar magnitude. 2. The liver and spleen enzymes had maximum activity at pH4.8 whereas the intestinal enzyme showed an optimum at pH5.8. The K(m) values for both starch and maltose with spleen and liver enzymes were higher than for the intestinal enzyme. With the intestinal enzyme, the V(max.) values were higher for both starch and maltose than those of the spleen and liver enzymes. 3. Gel filtration on Sephadex G-200 under identical conditions revealed that liver and spleen enzymes emerge from the columns much later than the intestinal enzyme. 4. Evidence is presented that the glucoamylase activity of the intestinal mucosa is exhibited by the maltase II fraction. 5. Tris, pentaerythritol and turanose inhibited glucoamylase from all the three tissues, but turanose inhibited the spleen and liver enzymes to a higher degree than the intestinal enzyme.