ABSTRACT
Cytokinin degradation is an important component process in the metabolic network that controls the levels of cytokinin metabolites and their distribution in plant systems. The existence in plant tissues of enzymatic machinery capable of degrading cytokinins to inactive products was demonstrated in the earliest studies of cytokinin metabolism. The Michaelis Constant values that have beer, reported for cytokinin oxidase vary by two orders of magnitude for the same substrate tested with enzyme preparations from different plant sources. The activity of cytokinin oxidase appears to be inhibited by cytokinin-active phenylurea derivatives. The physical characterization of cytokinin oxidase proteins has been limited, to date, primarily to information defined by the chromatographic properties of the enzymes. The regulation of cytokinin degradation in plant tissues is, undoubtedly, dependent in part on the other metabolic transformations to which the molecules are subject and on the substrate specificity of cytokinin oxidase.
