Further purification and characterization of the acid α-glucosidase

Abstract

1. Centrifugation of rat liver acid glucosidase, which had been purified by adsorption on dextran gel, on a density gradient of sucrose showed the enzyme to be impure. 2. Preliminary purification of the enzyme before the gel filtration improved the final degree of purity of this preparation. Disc gel electrophoresis of this preparation showed a single band of protein. 3. The sedimentation co-efficient and the molecular weight determined on a sucrose gradient were 4·9–5·1s and 76000–83000 respectively for the rat liver enzyme, and 5·6s and 97000 for the acid α-glucosidase purified by means of the same procedure from the human kidney. 4. The Michaelis constants of rat liver and human kidney enzyme were 4·7×10−3m and 13·6×10−3m respectively with maltose as substrate. 5. The enzyme from both tissues was inhibited by tris and by erythritol. The inhibition of the rat liver acid glucosidase by erythritol was competitive.