The creatine-creatinine equilibrium. The apparent dissociation constants of creatine and creatinine

Abstract

The dissociation constants of the 2 bases were determined at different temp. and treated as acid constants. For creatinine at 30[degree] C. k'' = 1.90 X 108 and Pk =4.72. For creatine the values were less satisfactory and a provisional value is given, k'' =2.40 XI0-3 and pk'' = 2.62 at 30[degree] C. The velocity constants of the system creatine[long dash]creatinine, determined at 30[degree] C. over Ph range 2-10, show well-defined pH optima at about PH 3, below which the system is irreversible and above which it is reversible. They are related to the dissociation constants and to certain empirical constants. The data give a general confirmation of Hahn and Meyer''s calculations relating urinary creatinine to the active mass of creatine in muscle, the temp. and the ph of the muscle.