Nitric Oxide Reaction Mechanism Of Zeatin

Nitric oxide (NO) is a bioactive molecule, and increasing evidence indicates that NO is one of the most widespread signaling molecules in living organisms.NO is involved in the regulation of growth and development, and in the response to abiotic and biotic stresses. Peroxynitrite is the product of the rapid, diffusion limited reaction between NO and superoxide ion in biological tissues .Peroxynitrite is a more powerful oxidizing and nitrating agent. It can cause cellular and tissue injury by multiple pathways.It has been reported previously that high cytokinins suppressed NO action.To . assess the molecular mechanism by which high level of cytokinins antagonizes the action of NO, we used a chemical approach to exam whether NO and cytokinins reacted directly in vitro. The determination results of HPLC and HPLC-MS indicated that zeatin reacted with peroxynitrite in vitro.The products of this reaction were identified with UV, MS and NMR after separated by Semi-prepared LC. The products are as follows: 8-nitro-zeatin ,N⁶-nitro-zeatin,N⁶-nitroso-zeatin. On the effects of pH and NaHCO₃ to the reaction of zeatin with peroxynitrite,as well as those reported previously in the literatures on the mechanisms for the nitrosation of other compound by peroxynitrite ,we propose here a free radical mechanism for intonation and nitration of zeatin by peroxynitrite .In conclusion, we have provided, biochemical evidence to show that NO interacts with cytokinins most likely through NO nitrating and nitrosating cytokinins. For the first time, we have shown a unique mechanism of NO-hormone interaction in plants by which two biomolecules combine to form new products via a chemical reaction.