232 Harland G. Wood 



(The values in this and subsequent diagrams are in counts/min./mg. C.) 



With methyl labelled acetate the tracer occurred equally 

 in the 1, 2, 5, 6 while with the acetone the tracer was 

 higher in the 1, 6 than the 2, 5 positions and in addition the 

 3, 4 positions contained a high concentration of ^*C. It 

 therefore appeared that the major pathway of acetone 

 metabolism was not via acetoacetate and "acetate." In 

 evaluating these and the subsequent results it should be borne 

 in mind that the 1, 6 and 2, 5 labelling is indicative of the 

 relative isotope concentration of the methyl and carbonyl 

 carbon of the precursor "pyruvate" that took part in the 

 synthesis of glycogen. On the other hand, the 3, 4 position 

 is indicative of the labelling of the carboxyl carbon of the 

 "pyruvate." Apparently, therefore, the composite "pyru- 

 vate" as formed from the acetone was labelled highest in the 

 methyl and carboxyl groups. Disregarding for the moment 

 the high labelling of the 3, 4 positions and considering only 

 the 1, 2, 5, 6 positions, it is seen that the distribution found 

 with acetone was comparable to that obtained with methyl 

 labelled lactate or with labelled formate as illustrated below: — 



C -C -C -C -C -C 

 i^CHgCHOHCOOH 826 679 204 204 679 826 



(Lorber et al., 1950fl) 



Hi^COOH 512 321 212 212 321 512 



(Sakami, 1948) 



The idea that "formate" might arise from acetone by a C2 

 and Cj split was therefore considered a possibility: — 



C*H3 • CO • C*H3-^"C*H3COOH" + "HC*00ir' 



/ \ 



Q*_Q*_QO_QO_Q*_Q* Q*_QO_QO_QO_QO_Q* 



and 

 H0C*H2 • CH(NH2) • COOH 



