Enzymatic properties of pyruvate kinase from the rumen ciliates genus Entodinium

1. Pyruvate kinase from the rumen ciliates genus Entodinium was partially purified and the enzymatic properties were investigated. 2. Three types of pyruvate kinase (type I, II and III) on DEAE-cellulose column were eluted with a linear gradient of KCl. The enzymatic properties differed among the types of enzyme, especially type I and type III displayed different kinetic properties to each other. The enzymatic property of type II enzyme was an intermediate between type I and III. 3. The principal enzyme, type I, required a divalent cation, Mg2+ and was activated with AMP and FDP. ATP was a potent inhibitor. The saturation curves for the substrates, PEP and ADP, were hyperbolic and Km values were 0.15 and 0.27 mM, respectively.