Factors controlling ATP levels during photophosphorylation catalyzed by Rhodospirillum rubrum chromatophores

Summary Photophosphorylation of ADP catalyzed by chromatophores represents a possible method for regenerating ATP from ADP for use in large-scale enzymatic synthesis of complicated molecules. We found that the extent of conversion of ADP to ATP in the presence of ascorbate and magnesium chloride was influenced by the presence of bubbling gas in contact with the reaction mixture, and by the presence of fumarate: with no fumarate or gas contact, low conversions (usually about 50%) were obtained; however, under the same conditions, but in the presence of fumarate or bubbling gas, 100% conversions were obtained. We discuss mechanistic implications of our findings.