[Purification and characteristics of AMP-deaminase from trout white muscle]

AMP-deaminase was purified from trout white muscle and some of its properties were investigated. The enzyme preparation was electrophoretically homogeneous; the molecular mass of the polypeptides was equal to 71600 +/- 550 Da, the specific activity was 200-500 U./mg of protein. Activation of the enzyme caused by acidification of the medium in the physiological range of pH was the result of reduction of Km for the substrate. ADP and ATP activated the enzyme, while GTP inhibited it. The enzyme was also inhibited by IMP (this phenomenon had never been described before). A change in pH within the physiological range of pH (6.6-7.3) had no influence on ATP, GTP or IMP effects on AMP-deaminase. The enzyme activation by ADP was sensitive to pH. The possibilities of fish muscle AMP-deaminase regulation under conditions of intensified metabolism is discussed.