RIBOFLAVINE 

 CH2 . (CHOH)3 . CH2O . PO(OH)2 j 



^"•\X\/N/NcO Protein 



I II I J. 



ch./^^n/^o/''" 



since flavines substituted in the 3-position did not form enzyme 

 systems ^^ and were devoid of vitamin activity. 



According to L. Laszt and F. Verzar/^ the formation of riboflavine- 

 phosphoric ester was promoted by the hormones of the adrenal cortex 

 and was inhibited by iodoacetic acid. They suggested that this 

 accounted for the toxicity of iodoacetic acid, and claimed that the 

 symptoms could be cured by administration of riboflavine-phosphoric 

 ester. H. Rudy/* however, found that riboflavine was just as effective 

 as riboflavine-phosphoric ester in restoring the growth of rats poisoned 

 with iodoacetic acid, whilst J. W. Ferrebee ^^ found that riboflavine was 

 phosphorylated as efficiently in adrenalectomised rats as in normal rats. 



The second coenzjone, riboflavine-adenine-dinucleotide, is present 

 in the enzymes known collectively as diaphorases. These are widely 

 distributed in animal tissues and micro-organisms and also occur in 

 plants. The dinucleotide has been isolated from liver, kidney, heart, 

 muscle tissue, Jensen rat sarcoma and yeast. ^^ To accomplish this 

 the apoenzyme was denaturated by heat, the mixture was extracted 

 with phenol and the dinucleotide was recovered from the phenol 

 extract by addition of water and ether, and then precipitated from 

 the aqueous solution as the silver salt. This was converted to the 

 barium salt which was recrystallised from water. The dinucleotide 

 was split by hydrolysis with enzyme ^^ or acid ^^ into riboflavine-5'- 

 phosphoric acid and adenosine-5'-monophosphoric acid (adenylic acid), 

 but how the two moieties are linked together has not been definitely 

 established, nor is it known how they are linked to the apoenzyme. 



A possible structure for the nucleotide is the following : 



-NCH 



■^\ H H H H OH OH H H H 



\:— C— €— C— CH2O— P— O— P— OCH2— C— C — C— CH, 

 H 



o- 



OHOH ^ ^ OH OH OH 



CH,, ,^ ,N. ^N. 



,92 ch3^X/\n/\:o/ 



CO 

 NH 



