The Chloroplast as a Complete Photosynthetic Unit

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Abstract
Isolated whole chloroplasts fixed CO2 with a simultaneous evolution of oxygen in a reaction which was entirely light dependent and with a photosynthetic quotient of 1. Starch and the soluble comps. (a) phosphate esters of fructose, glucose, ribulose, dihydroxyacetone, (b) glycolic, malic, and aspartic acids (c) alanine, glycine, and free dihydroxyacetone were identified as products. Chloroplasts appear to have all the enzymes needed for complete photosynthesis. Experimental separation of the three phases of photosynthesis, namely, phytolysis, phosphorylation, and CO2 fixation to form carbohydrate is readily accomplished with the isolation of chloroplasts. It is proposed that the hydrogen from phytolysis proceeds toward recombination with O in successive steps, each step transforming a portion of the electron energy into phosphate bond energy. The adenosine triphosphate formed gives up its energy especially for the reduction of carboxyl to carbonyl groups in carbohydrate formation. Flavin mononucleotide, vitamin K and ascorbates have been identified so far as probable electron carriers in the electron ladder of phosphorylation.