Abstract
The effect of pH on the pathways of carbon in photosynthesis was examined in chloroplast preparations from Acetabularia mediterranea. The flow of carbon into a number of photosynthetic intermediates, particularly sucrose, glycine, serine, glycolate, and the insoluble fraction, was strongly influenced by pH. At higher pH a much larger portion of the (14)C entered intermediates of the glycolate pathway. Although maximal apparent photosynthesis occurred at pH 7.6 to 7.7, cytoplasmic pH was found to be 8.0 to 8.4, using indicators. The pattern of distribution of (14)C in intermediates of whole cells was closest to that in chloroplasts at the higher pH range.