Two forms of AMP deaminase in bovine heart.

Two forms of bovine heart AMP deaminase were separated by phosphocellulose column chromatography. Form A with lesser affinity to phosphocellulose exhibited a hyperbolic type of substrate curve and was relatively insensitive to ATP. Form B was strongly activated by 1 mM ATP and its substrate saturation kinetics (without ATP) indicated a cooperative effect. The alteration of adenylate energy charge affected forms A and B differently but within the physiological range, the activity of both forms decreased with the increase in energy charge. The Mr of the two forms was identical as estimated by gel filtration. These activities are compared to those of AMP deaminases from the hearts of other species.