Molecular forms of pigeon skeletal muscle AMP deaminase

Abstract

Phosphocellulose chromatography of pigeon leg muscle extract revealed the existence of two well-separated forms of AMP deaminase. This was in contrast to the pigeon breast muscle extract, which yielded only one form. The two leg muscle enzyme isoforms manifested similar kinetic and regulatory properties. They were activated by very low concentration of potassium ions and demonstrated similar patterns of pH and effector dependence. At pH 6.5, as well as at other pH values tested. ADP and ATP slightly stimulated, whereas GTP and orthophosphate inhibited the two molecular forms of pigeons leg muscle enzyme. Surprisingly, the molecular form of AMP deaminase present in pigeon breast muscle was inhibited by ATP at all pH values tested. The kinetic and regulatory properties of the three molecular forms of pigeon skeletal muscle AMP deaminase examined do not resemble those which have been described for pigeon heart muscle enzyme.