IV. BIOCHEMICAL SYSTEMS 



335 



CH3— 



CH3— 



o 



Riboflavin-5-phosphate 



Its structure has not been proved by synthesis. According to Warburg and 

 Christian, 1^ it is composed of one adenine, one flavin, two pentose, and two 

 phosphoric acid molecules and may be visualized as a combination of ribo- 

 flavin phosphate and adenylic acid with the elimination of one molecule 

 of water. 



H2C- 

 HO— C- 



HO— C- 



I 

 HO— C- 



-O- 

 -H 

 -H 

 -H 



H 



O 



-P- 

 O 



H 

 O 

 -0— P— O— CH2 



o I 



— CH 



O 



CH3 



CH3 



CH2 



I 



N N 



N 



C 



II 



o 



/ 



HOCH 



) I 

 HOCH 



I 

 CH 



I 

 N— C 



/ 

 HC 



N 



\ 



C— H 



\ 



N— C 



^ 



N 



Flavin adeiiino diiiucleotide 



The enzymatic phosphorylation of riboflavin by an enzyme in yeast 

 named flavokinase has recently been reported by Kearney and Englard.^'' 



" O. Warburg and W. Christian, Biochem. Z. 298, loU (l'j:3S). 

 » E. B. Kearney and S. Englard, ./. Biol. Chem. 193, 821 (1951). 



