Formation of Amino Acids etc. 143 



Histidine 

 CHOCH2CH(NH2)COOH is formed as mentioned in tlie reaction (ii). 



CH2O + CHOCH2CH(NH2)COOH ^ OHCH2 • CO ■ CH2CH(NH2)COOH (34) 

 2CH2O + H2O ^ CH3OH + HCOOH (35) 



HCOOH + 2NH3 ^ NH2CH = NH + 2H2O (36) 



CH CH 



/ \ ^ \ 



NH NH2 N N (37) 



+ I II 



OHCH2COCH2CH(NH2)COOH ^ CH2— C— CH2CH(NH2)COOH 



CH CH 



/ \ /- \ 



NN N NH 



I II II (38) 



CH2 — C— CH2CH(NH2)COOH ^ CH = C— CH2CH(NH2)COOH 



(Histidine) 



Alanine 



The formation of aspartic acid has been described above. This can easily 

 convert to alanine by the decarboxylation of the carboxyl group away from the 

 amino group. 



COOHCH2CH(NH2)COOH ^ CH3CH(NH2)COOH + CO2 (39) 



(Alanine) 



Threonine 



Serine is formed as mentioned above. This undergoes following series of 



reactions to give rise to threonine. 



OHCH2CH(NH2)COOH + CH2O ^ OHCH2CH(OH)CH(NH2)COOH (40) 



OHCH2CH(OH)CH(NH2)COOH + CH2O ^ 

 CHOCH2CH(OH)CH(NH2)COOH + H2O (41) 



CHOCH2CH(OH)CH(NH2)COOH + O ^ COOHCH2CH(OH)CH(NH2)COOH (42) 



COOHCH2CH(OH)CH(NH2)COOH ^ CH3CH(OH)CH(NH2)COOH + CO2 (43) 



(Threonine) 



Leucine 

 Glutamic acid is formed as described before : 



COOHCH2CH2CH(NH2)COOH ^ CH3CH2CH(NH2)COOH + CO2 (44) 

 2CH3OH + CH3CH2CH(NH2)COOH ^ (CH3)2CHCH2CH(NH2)COOH + 2H2O (45) 



(Leucine) 



Norleucine 

 OHCH2CH2CH2CH(NH2)COOH is formed as described in reaction (14). 

 CH2O + OHCH2CH2CH2CH(NH2)COOH ^ CHO(CH2)3CH(NH2)COOH (46) 

 2H + CHO(CH2)3CH(NH2)COOH ^ CH2(OH)(CH2)3CH(NH2)COOH (47) 

 CH2O + CH2(OH)(CH2)3CH(NH2)COOH ^ CHO(CH2)4CH(NH2)COOH (48) 

 CHO(CH2)4CH(NH2)COOH + O ^ COOH(CH2)4CH(NH2)COOH (49) 



COOHCH2(CH2)3CH(NH2)COOH ^ CH3(CH2)3CH(NH2)COOH + CO2 (50) 



(Norleucine) 



