[Acid gamma-amylase of rabbit and human brain]

Preparations of acidic gamma-amylase, which cleaved glycogen and maltose, were isolated from human and rabbit brain tissues. The specific activity of the gamma-amylase preparations from human brain was approximately twice higher than the activity of the enzyme from rabbit brain. In degradation of glycogen gamma-amylases from human and rabbit brain had the pH optima at pH 4.9 and 4.6 and with maltose as a substrate- at pH 4.3 and 4.1, respectively. gamma-Amylases from both sources possessed the high stability in presence of monovalent cations. K+ distinctly increased the cleavage of glycogen by gamma-amylase from human and rabbit brain. alpha, alpha-Trehalose and alpha-menthyl glucoside proved to be inhibitors of the glucoamylase activity of the enzymes from both sources. Km values of the gamma-amylases for glycogen were equal to 19.3 mM 19.8 and for maltose -5.54 mM and 5.78 mM, respectively. The data obtained suggest that acidic gamma-amylases from human and rabbit brain are similar to acidic gamma-amylases from other sources.