ANTIBODIES SPECIFIC FOR RIBONUCLEOSIDES AND RIBONUCLEOTIDES AND THEIR REACTION WITH DNA

c or reduced phenazine methosulfate coupled with the reduction of ubiquinone. We wish to report now that chromatophores from aerobically grown R. spheroides, strain Ga, sensitize these reactions efficiently (with quantum requirements of a few quanta per electron transfer), whereas chromatophores from the nonphotosynthetic mutant strain PM-8 are entirely unable to drive these photochemical processes. The failure of strain PM-8 to catalyze the photooxidation of reduced phenazine methosulfate is the more remarkable because this reaction is sensitized by purified bacteriochlorophyll in vitro. These findings show that the major component of bacteriochlorophyll is inert with respect to the foregoing light-induced activities, and that a special kind of reaction center is needed for the photochemistry that leads to photosynthesis. The results of experiments with exogenous reagents will be published in detail elsewhere.