Abstract
Apparently free-base cytokinins can interact with cupric ions in a specific manner. Oxidation of NADH by a horseradish peroxidase system was strongly promoted by such cytokinins provided cupric ions were present. Oxidation was promoted by 5 micromolar kinetin, zeatin, 6-benzylaminopurine (BA), or 6-(Δ2-isopentenylamino)purine (2iP) but not by adenine, 6-methylaminopurine or 6,6-dimethylaminopurine. The 6-methylaminopurine promoted oxidation at 500 micromolar but adenine and 6,6-dimethylaminopurine did not. Activity of the free-base purines correlated well with their activity in cell-division assays. However, addition of methoxymethyl-, cyclohexyl-, or tetrahydropyranyl- at N-9 of BA or of ribosyl- at N-9 of BA, 2iP, kinetin, or zeatin eliminated activity in the peroxidase system. In a nonenzymic system containing cupric ions, all of the bases, including adenine, inhibited the Cu2+ -stimulated oxidation of ascorbic acid. As in the peroxidase system, the N-9 derivatives were inactive. The cytokinin promotion of NADH oxidation by peroxidase may result from an interaction of the hormones with copper, with peroxidase conferring a specificity similar to the cytokinin specificity observed in growth and development.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- AKAZAWA T., CONN E. E. The oxidation of reduced pyridine nucleotides by peroxidase. J Biol Chem. 1958 May;232(1):403–415. [PubMed] [Google Scholar]
- Badwey J. A., Karnovsky M. L. Active oxygen species and the functions of phagocytic leukocytes. Annu Rev Biochem. 1980;49:695–726. doi: 10.1146/annurev.bi.49.070180.003403. [DOI] [PubMed] [Google Scholar]
- FRIEDEN E., ALLES J. Subtle interactions of cupric ion with nucleic acid and components. J Biol Chem. 1958 Feb;230(2):797–804. [PubMed] [Google Scholar]
- Miller C. O. Cytokinin inhibition of respiration in mitochondria from six plant species. Proc Natl Acad Sci U S A. 1980 Aug;77(8):4731–4735. doi: 10.1073/pnas.77.8.4731. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Miller C. O. Cytokinin modification of mitochondrial function. Plant Physiol. 1982 Jun;69(6):1274–1277. doi: 10.1104/pp.69.6.1274. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Moore T. S., Miller C. O. Effects of cytokinins on the respiration of soybean callus tissue. Plant Physiol. 1972 Nov;50(5):594–598. doi: 10.1104/pp.50.5.594. [DOI] [PMC free article] [PubMed] [Google Scholar]