PHOTOSYNTHESIS OF GLYCINE AND SERINE IN GREEN PLANTS1

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Abstract
1. The effects of “carbonyl” reagents on the photosynthetic in-corporation of 14CO2 into the assimilation products of tobacco and spinach leaves were studied. The presence of “carbonyl” reagents causes an increase in the ratio of 14CO2 incorporated in glycine and a decrease in serine. The incorporation of 14C from glycolate-1-14C and glycolaldehyde-2-14C into glycine and serine was also affected by “carbonyl” reagents, as in the case of 14CO2-experiment. 2. The feeding experiments of glycine-1-14C and serine-1-14C in the presence and in the absence of “carbonyl” reagents revealed that these reagents inhibit the conversion of glycine to serine. 3. The results obtained above, together with the effects of thiols on 14CO2 incorporation presented in this paper, support the assumption that glycine and serine are formed via glycolate and glyoxylate during photosynthesis in green plants. 4. Comparison of 14C incorporation in malate from 14CO2, glycolate-1-14C, glycine-1-14C and serine-1-14C in the presence and in the absence of “carbonyl” reagents suggested the occurrence of the pathway of the malate formation via glycolate and glyoxylate, not passing through glycine and serine, during photosynthesis.