Isozymes of rat AMP deaminase

Three AMP deaminase isozymes (EC 3.5.4.6 AMP aminohydrolase) were purified from rat heart, kidney and muscle. These enzyme preparations contained only the required isozyme. Antisera to individual isozymes were prepared and immunological relationships were tested. There was no cross-reactivity as tested by precipitation experiments. The antisera precipitated only the corresponding isozyme and there was no effect on other isozymes. These isozymes were also different in Km values for AMP and in substrate specificity. From the present studies, combined with previous results, it seems clear that the heart, kidney and muscle enzymes are different basic types. It is proposed that the muscle enzyme be designated as AMP deaminase A; the enzyme in kidney and liver, AMP deaminase B; the enzyme in heart, AMP deaminase C. Brain extracts contained five isozymes; two parent isozymes (B and C) and presumably their three hybrids.