242 Harland G. Wood 



an adjacent hydroxy! and amino group yield formaldehyde 

 or "formate." A reversal of these reactions would constitute 

 a synthesis with formaldehyde. 



It is rather a strange coincidence that formaldehj^de was 

 postulated as the major intermediate of photosynthesis for 

 many years but then lost favour. It is now almost certain 

 that it will once more receive serious consideration in photo- 

 synthesis, though probably not in terms of the old proposal 

 of a carbon-bj^-carbon build up of sugars by aldol condensa- 

 tion of formaldehyde. 



Formaldehvde is also formed in the oxidation of N-methvl 

 groups, as first observed by Handler, Bernheim and Klein 

 (1941) and recently confirmed by Mackenzie (1950). One 

 looks with new interest on the experiments with Fusarium 

 (Goepfert, 1941), in which formaldehyde was obtained during 

 the oxidation of acetone, isopropyl alcohol and propanediol 

 when dimedon was used as a fixative. 



Summary* 



Glycogen and serine have proved to be very useful indicators 

 of the mechanism of metabohsm of acetone by animals. 

 Evidence is reviewed which apparently shows that there is a 

 Cg and Ci cleavage of acetone, and in addition a conversion 

 of the intact 3-carbon chain to a carbohydrate precursor. 

 No evidence has been obtained by the glycogen and serine 

 indicator method that a major pathway of metabolism of 

 acetone occurs via its carboxylation to acetoacetic acid, nor 

 was there evidence that acetoacetic acid was metabolized to 

 any significant extent via acetone. These results are con- 



*The bibliography is by no means complete because the discussion is mostly 

 intended to illustrate how glycogen and serine may be used as indicators of 

 metabolism. It should be noted that Sonne, Buchanan and Delluva (1948) 

 demonstrated that formate was converted to the 2 and 8 positions of uric 

 acid, and thus drew attention to the fact that formate might play a role in 

 metabolism by animals. Greenberg's group in California and Neuberger's 

 in England have been very active in studies of serine synthesis, and Ehrensvard 

 and co-workers in Sweden found in 1947 that glycine was converted to serine 

 by Torula. Hastings' group at Harvard has long been active in glycogen 

 studies and has done excellent work in determining the isotope distribution 

 pattern of glycogen. 



