M. Schwartz
Feb 7, 1966
Citations
0
Influential Citations
42
Citations
Journal
Biochimica et biophysica acta
Abstract
Abstract N -Tetramethyl- p -phenylenediamine due to its autoxidizability under aerobic conditions acts as a Hill reagent for photophosphorylation in spinach chloroplasts. At saturating light intensities it mediates rates of phosphorylation and concomitant O 2 consumption equal to rates of phosphorylation and concomitant O 2 evolution observed with TPN + or ferricyanide as oxidants. TMPD, contrary to earlier reports, acts as a cofactor for reversing the inhibition by DCMU of phosphorylation in the presence of ascorbate. In this system under aerobic conditions the addition of TPN + and ferredoxin suppresses phosphorylation. Under anaerobic conditions the inhibition of phosphorylation is reversed by the addition of TPN + and ferredoxin, yielding rates of phosphorylation and concomitant TPN + reduction equivalent to the aerobic rates in DCMU-poisoned chloroplasts. The substitution of 2,6-dichlorophenolindophenol for TMPD in this system yields comparable rates of phosphorylation which, however, are not influenced by the presence or absence of O 2 or the addition of TPN + and ferredoxin.