Cytokinin oxidase strikes again

Research into the enzymes involved in several aspects of cytokinin metabolism (including storage and catabolic pathways) is undergoing an unprecedented period of success. We recently reported1 on new findings concerning the biochemical and molecular properties of cytokinin oxidase (CKO), a poorly characterized, but crucial enzyme, which irreversibly inactivates cytokinins. Although CKO has been classified as a copper-containing amine oxidase1, clear evidence is now emerging that argues against this classification [2], [3] and [4]. In particular, as previously described1, there is evidence that CKO from wheat is an FAD-containing flavoprotein (P. Galuszka et al., unpublished), and recent advances have further extended this finding [3] and [4]