286 Harland G. Wood 



be very interesting to have data for heart glycogen similar 

 to those presented here for liver. Practically all the experi- 

 ments on the conversion of labelled fatty acids to glycogen 

 in which isotope distribution patterns have been determined 

 have dealt with liver glycogen. However, it is more than 

 likely in experiments of short duration, even though done 

 with whole animals, that the liver glycogen may in a large 

 part reflect only liver metabolism. 



The significance of acetone metabolism as a source of 

 metabolites such as "formate" is likewise an interesting 

 problem. 



Propanediol or Propanediol Phosphate as a Possible 

 Intermediate of Acetone Metabolism 



Propanediol phosphate was found by Lindberg (1943) to 

 occur in sea urchin eggs, and he later isolated the ester from 

 mammalian liver, kidney and brain (Lindberg, 1946). The 

 highest concentration was in brain, in which the ester made 

 up about 5 per cent of the acid soluble phosphate. The 

 metabolic significance of this compound is relatively unknown. 

 Lindberg (1946) has made ^^p-labelled propanediol phosphate 

 and has found that it is fairly rapidly metabolized and that 

 the phosphate group is transformed into an easily hydro- 

 lysable ester. The unphosphorylated compound is well 

 metabolized and is glycogenic (Hanzlik, Newman, Van 

 Winkle, Lehman and Kennedy, 1939). 



The possibility that propanediol is an intermediate of 

 acetone metabolism is an attractive hypothesis and is being 

 investigated in our laboratories by Rudney (1950). The 

 following reaction is suggested: — 



OH H 



II O HOH O 



CH3CCH3^CH3C:CH2+ or -^CU^C- 



H3PO, 



CH2OH -> "acetate" 

 + "formate" 



H 



This reaction is analogous to the conversion of phosphoenol 

 pyruvate to phosphogly eerie acid: — 



