IV. BIOCHEMICAL SYSTEMS 425 



Burns and IMcKihhiir'- used 19% "vitamin-test" casein in purified diets 

 for puppies, together with 68% carbohydrate, 7% cottonseed oil, 2% cod 

 liver oil, minerals, and vitamins (without choline). The animals grew slowly 

 and in many cases de\'eloped fatty livers. The li\'ers of dogs had low total 

 lipid contents in a similar experiment where supplementary choline was 

 fed. Two dogs on this regime were put Ijack on the basal diet and developed 

 signs of liver dysfunction, including high fat content of liver biopsy samples, 

 in 70 to 100 days. Injections of 0.4 mg. of vitamin Bi2 were then given on 

 alternate days, following which there was a reduction in plasma alkaline 

 phosphatase and in li\'er fat. The authors considered that the diet had 

 produced a deficiency which responded to either vitamin B^ or choline. 



D. VITAMIN Bio AND TYROSINE METABOLISM 



Distiu'bances in tyrosine metabolism have been noted in pernicious ane- 

 mia,^'' and, since pteroylglutamic acid (PGA) has been related to the oxida- 

 tion of tyrosine,'^'*' '^ speculation has arisen that these disturl)ances might 

 be caused by the PGA deficiency which is associated with pernicious ane- 

 mia.^^ Since vitamin B12, like PGA, causes hemopoietic remission in perni- 

 cious anemia, the urinary phenol fractions were studied in patients during 

 the i^rogress of remission under treatment with \dtamin Bi2.*^ Prompt 

 changes in these fractions were observed following this treatment. A de- 

 crease in the ratio of hydroxyphenyl acids to ether-soluble phenols not 

 soluble in NaHCOa was noted in three of four patients. It is not possible 

 to say whether these changes were caused by vitamui B12 per se or whether 

 Bi2 had an effect on the metabolism of folic acid which in turn affected 

 the breakdow^n of tyrosine. 



E. SINGLE-CARBON UNITS 



The participation of certain sources of a "single-carbon fragment" in- 

 cluding formate, formaldehyde, and methanol in a number of biochemical 

 reactions has been studied principally in rats and in tissue preparations 

 derived from them. The use of isotopically tagged compounds has made 

 possible the exploration and extension of this field. 



Formate, glycine, and serine are related in the following manner: 



CH,(XH,)C00n -* HCOOH + CH2(XH2)COOH ;=± CH,OHCIUNH,)COOH 



32 M. M. Burns and J. M. McKibbin, J. Nutrition 44, 487 (1951). 



" M. E. Swendseid, B. Wandruff, and F. H. Bethell, J. Lab. Clin. Med. 32, 1242 



(1947). 

 3" G. Rodney, M. E. Swendseid, and A. L. Swanson, J. Biol. ('hem. 168. 395 (1947). 

 " C. W. Woodruff and W. J. Darby, ./. Biol. Chem. 172, 851 (1948). 

 3«G. Rodney, M. E. Swendsied, and A. L. Swanson, J. Biol. Chem. 179, 19 (1949). 

 " L. D. Abbott, Jr. and G. W. James, III, ./. Lab. Clin. Med. 35, 35 (1950). 



