Formation of Radioactive Citrulline During PhotosyntheticC14O2-Fixation by Blue-Green Algae

摘要

Citrilline has been isolated and identified from extracts of Nostoc muscorum. All members of the Cyanophyceae hitherto investigated show a relatively large amount of the CO fixed during photosynthesis in citrulline (ranging as high as 20% in Nostoc) when compared to the trace amounts found in the Chlorophyceae. Nostoc also has the ability to fix C{sup 14} in citrulline during dark fixation, but at a rate slower than in light. As no free urea or arginine was found in Nostoc, it is likely that citrulline is functioning in reactions other than those leading to arginine and urea synthesis. Other possible functions for citrulline are briefly discussed.