THE FLAVOPROTEINS 



135 



HOCH 

 HOtH 



pO-PO,H; 



'jng 



H3C 



HX- 



:-i^^VV%o 



2H 



H 



HOCH 

 HOCH 

 ^ H 



^fS^y^^r^^ 



ALLOXAZINE 

 MONONUCLEOTIDE 



1^ 6 



DIHYDROALLOXAZINE 

 MONONUCLEOTIDE 



FIGURE 1 



Jauregg (7) made the observation that when riboflavin and also 

 alloxazine are reduced in acid solution red-colored intermediates 

 with absorption bands having maxima at 490 m[jL were formed. 

 Haas (8) was able to demonstrate this intermediate formation with 

 the old yellow enzyme and it has also been found in the case of 



H H 

 H2^0-§-0-P-0-CH2 



HOCH HO9H 

 HOCH 



ho6h 



H3C 



CH2 



NH 



HOCH 

 HOCH 

 CH2 



HC 



jT 



c^Vh 



"%y^^^^^ 



\ 



^N' 



-C>. ^NH 

 X' 



H, 



ALLOXAZINE ADENINE 

 DINUCLEOTIDE 



FIGURE 2 



