FUNCTION 



and W. Christian ^ showed that the coenz5mae, codehydrogenase II, 

 which is widely distributed in animal tissue, contained nicotinamide, 

 and Albus et al^ showed that it was a constituent of another co- 

 enzyme, codehydrogenase I or cozjmiase, which occurs in yeast and 

 acts as a catalyst in alcoholic fermentation. Both coenz3mies are com- 

 pounds of adenine, nicotinamide, ribose and phosphoric acid, and were 

 given the formulae : 



N=C.NH3 



N— C-N 



,— P— O— CH^— < 



OH O- 



CoenzyTiie I 



CONH2 



N=C • NHj 



C C-N. 



II II >CH 



N_C-N/ H H H 



/ 



H 



C-C-C-C-CH2-O-P-O-P-O-P-O- 

 I OH OH I OH OH 6- 



I o ' 



Coenz5nne II 



CH, 



H H H H 



-c-c-'c-c- 



i OH OH 

 I o — 



ONH2 



■N+ 



Coenzymes I and II are usually referred to as diphosphopyridine 

 nucleotide and triphosphopyridine nucleotide respectively. They are 

 essential links in a series of transformations the effect of which is to 

 transfer hydrogen from a substrate, which is thereby oxidised, to 

 molecular oxygen with the formation of water. 



A method for the isolation of coenzyme I from bakers' yeast was 

 described by S. Williamson and D. E. Green,^ who obtained 500 mg. 

 of material with a purity of 65 % from 3-2 kg. A method of purifying 

 the enzyme was described by F. Schlenk.* 



An improved method for the isolation of diphosphopyridine 

 nucleotide was published by G. A. Le Page,^ who obtained, from i lb. 

 of bakers' yeast, 50 to 70 mg. of a preparation with a purity of about 



63 %. 



The constitution of coenzyme I or codehydrogenase I was estab- 

 lished as follows. On hydrolysis it yielded adenine, nicotinamide and 

 2 moles of D-ribose-phosphoric acid. The phosphoric acid was 

 attached to the ribose in the 5-position, because periodic acid failed to 



275 



