IV. moniKMICAL SYSTEMS 



5. Summary 



585 



Biittiii appears to pailici])atc in xarious ciizyinatic reactions such as in 

 the (lecarl)o\ylat ion ot oxalacelate and snecinate, in the (h'aininat ion of 

 aspartic acid, serine, and tlireonino, in the tlehy(h-ofi;enation of succinic 

 acid, and in(hrectly in the synthesis of citniUine and oleic acid. 



Tlie theoretical attempt has been made to ex])hiin practicallx' all these 

 enzymatic reactions by one single mechanism, namely by intra- or inter- 

 molecular hydrogen transport.-^ Tlie following schemes were devised for 

 the various specific enzyme reactions: 



a. ^[spartic Acid Deaminase 



COOH 



H-C-(g) 



±XH, 



h-c-n; 



I 



COOH 



H 



COOH 



1 

 H-C 



II 

 H-C 



I 



COOH 



h. Serine and Threonine Deaminase (FUustraled for Serine) 



COOH 



H 



H-C-OH 

 H 



-H,0 



COOH 



I 

 C-NH, 



II 

 CHo 



COOH 



I 

 C=KH 



I 

 CH, 



+ II;0 



COOH 

 I 

 C-0 



I 

 CH3 



c. Oxalacetate Decarboxylase 



COO® 



H-C-H 



I 



c=o 



I 



COOH 



d. Succinate Decarboxylase 



COO® 



H-C-H 

 I 



H-C-H 

 I 

 COOH 



±C02 



CH3 



C=0 

 I 

 COOH 



-CO2 



CH3 



I 

 CH2 



I 

 COOH 



The role of biotin in this hydrogen tran.sport may be summarized by 



