ACTIVATION AND INHIBITION BY BIVALENT METAL IONS OF YEAST GLYCYLGLYCINE DIPEPTIDASE
1958 年 45 巻 12 号 p. 991-1004
詳細
1958 年 45 巻 12 号 p. 991-1004
1. Using glycylglycine dipeptidase isolated from baker's yeast, kinetic studies were performed with special reference to the effect of various bivalent ions acting as activators or inhibitors for the enzyme reaction.
2. Among the various metal ions studied, only Co++ was found to activate the enzyme reaction over a wide range of concentration.
3. The activity of the enzyme (in the presence of Co++ as the activator) is strongly inhibited by Cd++, Cu++, Mn++, and Zn++. The inhibitory action of these ions was found to be competitive with the activating effect of Co++. Under the experimental conditions studied, Ni++, Fe++, and Ba++ had no effect on the reaction rate.
4. A scheme of reaction of glycylglycine dipeptidase was proposed, which was shown to be in harmony with the experimental results obtained. It was concluded that a bridge formation by virtue of Co++ ion between enzyme and substrate is an essential step in the mechanism of the enzyme reaction.
5. The enzyme was found to be strongly inhibited by SH-inhibitor such as p-chlorornercuribenzoate and monoiodoacetate.
The author wishes to thank Prof. A. Takamiya and Prof. H. Tamia for their valuable suggestions and encouragement in this work.
