FUNCTION 



Notatin 



The oxidation of glucose to gluconic acid by micro-organisms is 

 effected by another flavine enzyme.^*' ^^ A preparation of this 

 enzyme was isolated by Coulthard et al.^^ from the metabolism solution 

 of Penicillium notatum, and was given the name notatin. Other 

 workers ^'"^^ isolated it from similar sources and called it penatin. 

 Notatin proved to be inhibitory in extremely high dilution to many 

 bacteria in presence of glucose. On investigation it was shown to 

 effect the oxidation of glucose to gluconic acid with the production 

 of hydrogen peroxide ; the hydrogen peroxide was responsible for the 

 antibacterial activity. The reduced form of the enzyme was oxidised 

 by molecular oxygen. That the antibacterial action was in fact due 

 to the formation of hydrogen peroxide, was confirmed by the demon- 

 stration that other flavoproteins were equally effective. F. Lipmann 

 and C. R. Owen ^° and D. E. Green and R. Pauli ^^ showed that milk 

 xanthine oxidase had similar properties, but other flavoproteins were 

 more difficult to test, as it was impossible to free them from catalase 

 that destroyed the hydrogen peroxide as it was formed. 



Fumaric Hydrogenase 



Fumaric acid is reduced to succinic acid by an enzyme system 

 which contains riboflavine adenine dinucleotide.^^ This enzyme was 

 also shown to reduce maleic acid, crotyl alcohol, phenyl crotyl alcohol 

 and geraniol, but the rate of reduction of these compounds was only 

 a fraction of the rate at which fumaric acid was reduced. The identity 

 of fumaric hydrogenase with eight other flavoproteins was excluded 

 by subsequent work carried out by Fischer et al.,^^ but it may be 

 identical with the xanthine oxidase-like enzyme isolated by Green 

 et al.^^ 



Lactic and Pyruvic Acid Oxidases 



Two other enzymes containing fiavine-adenine-dinucleotide are 

 pyruvic acid oxidase,^* and an enzyme isolated from Mycobacterium 

 phlei that was specific for the oxidation of lactic acid to pyruvic acid 

 under anaerobic, and to acetic acid under aerobic, conditions. ^^ 



Luciferin 



F. H. Johnson and H. Eyring ^^ showed that the substrate, luci- 

 ferin, of the luminescent system of Cypridina consists of a pyridine 

 nucleotide and a flavoprotein. 



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