238 Harland G. Wood 



labelled products would contribute activity to the 1, 2, 5, 6 

 positions. On the other hand with CH3 • CHOH • I'^CHaOH the 

 situation would differ in that the "pyruvate" from the direct 

 conversion would only be labelled in the carboxyl group and 

 the "acetate" from the Cg and C^ split would be unlabelled. 

 These products would not label the 1, 2, 5, 6 positions. Thus, 

 contrary to the situation wdth labelled acetone, the only 

 source of tracer for the 1, 2, 5, 6 positions from propanediol 

 is the "formate" of the Cg and C^ cleavage. Thus a lower 

 activity would be expected than was observed with the 

 acetone. 



The results are sufficiently encouraging to warrant further 

 study of the relation of acetone metabolism to propanediol 

 phosphate. Rudney has now developed methods for the 

 isolation of propanediol phosphate in pure form from tissues, 

 and will shortly feed labelled acetone and isolate the propane- 

 diol phosphate to see if there is an indication of a direct 

 conversion of the acetone to propanediol phosphate. 



The Role of Formaldehyde in the Propionic Acid 



Fermentation 



It is interesting that the propionic acid fermentation, which 

 played such an important part in the discovery of the role of 

 CO 2 in metabolism, has now assumed a somewhat similar 

 part in the demonstration of the importance of the C\- 

 compound, formaldehyde, in metabolism. Leaver (1950) has 

 shown in our laboratories that [^*C] formaldehyde is utilized 

 by the propionic acid bacteria during the fermentation of a 

 number of substrates, and that the tracer is fixed in every 

 position of the resulting propionic acid. Typical results are 

 as follows: — 



H14CH0 

 Hi^CHO 

 Hi^CHG 



The formaldehyde was fixed in approximately equal amount 

 in the a and ^ positions of propionate and in still greater 



