Degradation of cytokinins by cytokinin oxidases in plants

The degradation metabolism of cytokinins is an important process that contr ols the levels of cytokinin active forms and their distribution in plant ti ssues. It appears to be due, in large part, to the activity of a specific e nzyme, cytokinin oxidase. This review attempts to collate the limited infor mation available about this enzyme and introduce new facts, obtained in our laboratory, concerning the mechanism of degradation of cytokinins bearing unsaturated isoprene side chains. However, complete clarification of the ef fects of cytokinin oxidase on cytokinin regulation and its molecular and bi ochemical properties will be dependent upon the purification of the protein with cytokinin oxidase activity to homogeneity and progress in the develop ment of requisite molecular probes.