Spectrophotometric methods for determining the activity of cytokinin oxidase/cytokinin dehydrogenase (EC 1.5.99.12) were developed and optimized. A sensitive end-point method based on a combination of the electron acceptor 2,6-dichlorophenolindophenol and Schiff base formation of the reaction product with 4-aminophenol under acidic conditions can be applied to crude cell and tissue extracts. The assay was also adapted for other substrates than N6-(2-isopentenyl)adenine, such as zeatin and the aromatic cytokinins, although an enzyme which degrades the latter compounds has not yet been identified. The second novel method is an initial rate method based on the coupled redox reaction of phenazine methosulfate and 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide resulting in the formation of a formazan dye. This method can be used for kinetic studies with purified enzyme and is entirely substrate independent.

Department of Biochemistry Faculty of Science Palacký University Slechtitelů 11 Olomouc Czech Republic

References provided by Crossref.org

Cytokinin functions as an asymmetric and anti-gravitropic signal in lateral roots

Manipulation of cytokinin level in the ergot fungus Claviceps purpurea emphasizes its contribution to virulence

Modification of Barley Plant Productivity Through Regulation of Cytokinin Content by Reverse-Genetics Approaches

New Urea Derivatives Are Effective Anti-senescence Compounds Acting Most Likely via a Cytokinin-Independent Mechanism

Production and Role of Hormones During Interaction of Fusarium Species With Maize (Zea mays L.) Seedlings

Novel thidiazuron-derived inhibitors of cytokinin oxidase/dehydrogenase

Biochemical Characterization of Putative Adenylate Dimethylallyltransferase and Cytokinin Dehydrogenase from Nostoc sp. PCC 7120

Proteasomal control of cytokinin synthesis protects Mycobacterium tuberculosis against nitric oxide

Overexpression of cytokinin dehydrogenase genes in barley (Hordeum vulgare cv. Golden Promise) fundamentally affects morphology and fertility

Characterization of new maize genes putatively involved in cytokinin metabolism and their expression during osmotic stress in relation to cytokinin levels

Kinetic and chemical analyses of the cytokinin dehydrogenase-catalysed reaction: correlations with the crystal structure

Catalytic reaction of cytokinin dehydrogenase: preference for quinones as electron acceptors