Intracellular localization of dinucleosideoligophosphate phosphorylase from Euglena gracilis.

1. Formation of labeled ADP in the ADP-(32)P -exchange reaction, the inherent property of the dinucleosideoligophosphate (DNOP) phosphorylase demonstrated recently in Euglena gracilis can be used to detect specifically the enzyme activity in crude extracts among interfering enzymes like phosphodiesterase I, adenylate kinase or non-specific phosphatases. 2. The initial velocity was measured in an incubation mixture lacking Mg(2+) but containing EDTA and/or Ap(5)A an inhibitor of the adenylate kinase. 3. Using different sucrose-density gradients and controlling activities of the marker enzymes it has been proved that the DNOP phosphorylase is a cytosolic enzyme in E. gracilis.