Kinetic comparison of cytokinin nucleosidase activity isolated from normally ripening and mutant tomato varieties.

Kinetic parameters for cytokinin nucleosidase activity which catalyzes the deribosylation of N(6)(Delta(2)-isopentenyl)adenosine (I(6)Ado) to produce the more "active" free base N(5)(Delta(2)-isopenetyl)adenine (I(6)Ade) were compared for a normally ripening tomato (Lycopersicon esculentum L.) cultivar Rutgers, and two mutant tomato varieties (Nor and Rin). K(m) for nucleosidase activity in Rutgers was lower (K(m) = 0.1 millimolar) than that in either Nor (K(m) = 0.14 millimolar) or Rin (K(m) = 0.13 millimolar).