| Abstract: | Activation of purified adenylate deaminase from the duck myocardium by K+ ions is accompanied by a change in the substrate specificity of the enzyme and appearance of ability to deaminate adenosine and adenine. Adenosine deaminase activity appears with K+ in a concentration exhibiting maximal stimulating effect (0.15 M) and it increases with an increase in the K+ concentration, parallel with a decrease in Hill's coefficient. It can be concluded from the pH dependence, the character of inhibition by phosphate, and the effect of cations of the alkali metals that deamination of adenosine takes place at natural combining sites of adenylate deaminase, the conformation of which is modified by the activator.Laboratory of Biochemistry of Amines and Other Nitrogenous Bases, Institute of Biological and Medical Chemistry, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. N. Orekhovich.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 11, pp. 535–537, November, 1978. |
