The determination of the specific radioactivities of the chlorophylls and carotenoids of algae after photosynthesis with C/sup 14/O/sub 2/ is a formidable task, due to the extreme lability of these compounds. The whole success of the method depends on adequate chromatographic separations of the pigments from the colorless contaminants which are closely associated with them, and yet the time involved for such separations is sufficient for marked decomposition of the pigments to occur. It is suggested that the techniques of column chromatography, followed by centrifugallyaccelerated paper chromatography of the spectroscopically pure pigments, may resolve this problem. In an investigation of the action of cyanide on photosynthesis, green algae have been treated with radioactive cyanide. A multitude of products have been found to be formed in very short exposure times. One of these was identified with a material formed when algae are given radioactive CO/sub 2/ and nonradioactive KCN. This material has been identified as the cyanide addition product of ribulose-1,5- diphosphate. Upon hydrolysis it gives a branched-chain sugar acid (or mixture of isomers) closely related to hamamelonic acid. Perhaps the most important aspect of this work is the demonstration of the chemlcal role of cyanide. (auth)

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