Effect of Ferredoxin on the Diaphorase Activity of Cyanobacterial Ferredoxin-NADP Reductase.
The interaction of ferredoxin-NADP reductase (FNR) and ferredoxin (Fd) results in an enhanced rate of reaction and a shift of the pH optimum for the FNR-mediated diaphorase reaction. Low concentrations of NaCl (<100 millimolar), favorable for formation of the FNR:Fd complex, further magnify the alteration of the diaphorase reaction; the activity is enhanced 3-fold and pH optimum is shifted from 9.5 to 7.8. The Fd-stimulated diaphorase activity of FNR may result either from a conformational change of the enzyme and/or from a transition from a two electron to a one electron reaction.
Melamed-Harel
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The Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot, Israel.
Tel-Or
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Pietro
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