Kinetics of Activation of Nicotinamide Adenine Dinucleotide Kinase by Phytochrome—Far Red-absorbing Form

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RESUMO

The effects of exogenous redox cofactors and purine analogues on the activation of the NAD kinase by Pfr were examined. Addition of phenazine methosulfate, flavin mononucleotide, or methylene blue increased the activation of NAD kinase by red light in a partially purified preparation of phytochrome. Phenazine methosulfate and flavin mononucleotide do not absorb light in the red or far red region, so they do not act as light receptors in this activation. Thus they probably intervene in electron transfer between phytochrome and NAD kinase. Addition of kinetin with these compounds increased photopotentiation further. In the presence of phenazine methosulfate and kinetin, the activation of NAD kinase by red light was counteracted by illumination with far red light immediately after red light.

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