PORPHYRINS 



mate and carbon dioxide, the radioactivity of which is several 

 times greater than that produced from glycine-2-C^* (9). 



The condensation of glycine with either "active" succinate 

 or "active" acetate provides a pathway whereby glycine can be 

 oxidized to carbon dioxide and the intermediates produced in 

 the cycle drawn off for the synthesis of other compounds. This 

 is similar to the citric acid cycle, in which another two-carbon 

 compound is oxidized to carbon dioxide and intermediates are 

 produced which can be drawn off for synthesis. In the suc- 

 cinate-glycine cycle, succinate is the catalyst instead of oxalo- 

 acetate. 



References 



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