70 BACTERIAL FERMENTATIONS 



obtained. Munch-Petersen 43 has studied the conversion of 

 glutamate-4-C 14 to mesaconate and has shown that the C 14 

 is all present in the carbon atom adjacent to the methyl 

 group (see Fig. 3) . This means that the methyl carbon 

 must be derived from carbon 3 of glutamate and excludes 

 any mechanism of methyl group formation involving a 



iCOOH iCOOH 



2 CHNH 2 2 CH 



=FNH 3 s ±h 2 o 



3 CH 2 ^=±r 4 C— COOH ^^ 



4 CH 2 3 CH 3 



5 COOH 



Fig. 3. Role of Mesaconate and Citramalate in Glutamate Decomposition. 



transfer of the carboxyl carbon 5 of glutamate from carbon 

 4 to carbon 3, which would be similar to the interconver- 

 sion of methyl malonate and succinate reported by Flavin 

 et al. 44 The conversion of glutamate to mesaconate appar- 

 ently involves a transfer of carbon atoms 1 and 2 of gluta- 

 mate from carbon atom 3 to carbon atom 4. This would 

 leave carbon atom 3 in the position occupied by the methyl 

 group of mesaconate. 



The conversion of mesaconate to citramalate involves a 



