SUMMARY: The fate of radiolabeled cyanide added to washed non-proliferating suspensions of the cyanogenic organism was studied. Within 6 h of addition, over 90% of the added cyanide had been metabolized to other compounds, except when -glutamate alone was included in the suspension medium; in this case only 50% of the added cyanide had been metabolized after 6h incubation. Less than 2% of radioactivity was incorporated into cell material; the rest remained in the suspension medium. The only identified compound into which radioactivity accumulated was β-cyanoalanine. Formation of β-cyanoalanine was stimulated by inclusion of -glutamate and either -acetyl--serine or -serine in the incubation medium. Under optimal conditions, approximately 50% of added radiolabel accumulated in β-cyanoalanine. Compounds capable of supplying carbon for growth of were able to substitute, to some extent, for -glutamate in stimulating β-cyanoalanine synthesis. Both -acetyl--serine and -serine inhibited β-cyanoalanine formation when included at concentrations in excess of 3 m. -Cysteine, -threonine and -alanine were unable to substitute for -acetyl--serine or -serine, and -cysteine inhibited β-cyanoalanine synthesis. -Methionine inhibited β-cyanoalanine formation by cells resuspended in cyanide, -glutamate and -acetyl--serine or -serine. The effect of growth conditions on the ability of resuspended cells to synthesize β-cyanoalanine was studied.


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