166 BREAKDOWN OF NITEOGENOUS MATERIAL 



oxidative deamination, the H-acceptor being another amino- 

 acid molecule rather than a coenzyme as in the deamination of 

 glutamic acid by Esch. coli. It is possible that a coenzyme is 

 involved as carrier in the " Stickland " reaction, but the 

 enzyme kinetics of the reaction have not yet been studied in 

 detail. The amino-acids so far tested fall into the following 

 groups : — 



H-acceptors H-donators 



Glycine Alanine Leucine 



Proline Valine Phenylalanine 



Hydroxyproline Cysteine Serine 



Ornithine Histidine Aspartic acid 



Arginine Glutamic acid 



Tryptophan 

 CI. sporogenes also possesses a very active hydrogenase 

 enzyme activating molecular hydrogen so that it can be 

 utilised by the H-acceptor group of amino-acids. The 

 products of reduction have been isolated and identified in 

 some cases. Proline undergoes reduction with opening of 

 the ring to give S-amino-valeric acid without animonia 

 formation 



HoC — CH, 



"l I -f2H ^CHaNH^.CHa.CHg.CHa.COOH 



HgC CH.COOH 



\x 



N ■■ 



H 

 Ornithine, on the other hand, is also reduced to S-amino-valeric 

 acid but with the liberation of one molecule of ammonia, 



CH2NH2 . CH2 . CH2 . CHNH2 . COOH -f 2H 



> CH2NH2.CH2.CH2.CH2.COOH -f NH3. 



Glycine is reductively deaminated to acetic acid, and the 

 Stickland reaction between glycine and alanine takes place 

 as follows, presumably with the intermediate formation of 

 pyruvic acid from alanine, 



