Reduction studies with naturally occurring quinones and their phosphate derivatives with reference to oxidative phosphorylation.

Plastoquinol dibenzyl-32P-phosphate was prepared by reduction of plastoquinone with dibenzyl-32P-phosphonate. Catalytic hydrogenation of the product resulted in the reduction of the polyisoprenoid side chain as well as debenzylation. Substantial reduction was also observed with the use of nuclear magnetic resonance for a number of naturally occurring quinones with conditions recommended for quinol phosphate synthesis. Previous studies with the use of reductive debenzylation with naturally occurring quinones did not consider this possibility. The double bond /3 ,y to the quinonoid ring was found to be more resistant to reduction, and the degree of saturation of the side chain could be partially controlled. The results of biological incorporation experiments carried out with quinol phosphates prepared by this route need to be interpreted in terms of these results. They are particularly relevant to the presumed participation of the isoprenoid double bond ,LI ,y to the quinonoid ring in oxidative phosphorylation.