Formation of Amino Acids etc. 141 



taking place in those days and are still taking place though the concentrations 

 of the different reactants have changed. Those amino acids formed the basic 

 material for the chemical origin of Hfe on Earth [5] which is the most relevant 

 theory on the formation of life [6]. Once the amino acids are formed, here are 

 possibihties that peptide hnkages are also formed in the mixture. Experiments 

 on these lines are being carried out in our laboratories. 



The mechanism of these reactions can be explained in a simple manner by 

 making use of only the fundamental reactions as hydration, dehydration, con- 

 densation, hydrogénation, etc. Such reactions have been observed in the bio- 

 genesis of different plant products and so can be considered to be taking place 

 in these mixtures also, under suitable conditions in the presence of hght [7]. 



A scheme on the formation of most of the amino acids from the preliminary 

 starting materials as formaldehyde — or carbon dioxide dissolved in water which 

 on exposure to Hght soon gets converted to formaldehyde [8-1 1] with fixed 

 nitrogen in the presence of a suitable catalyst has been given below. 



FORMATION OF MONO-AMINO MONO- 

 CARBOXYLIC ACIDS 



Glycine 



CH2O + 2H ^ CH3OH (I) 



CH2O + O ^ HCOOH (2) 



O + 2CH2O ^ HOCH2COOH (3) 



HO • CH2 • COOH ^ CHO • COOH + 2H (4) 



CHO • COOH + 2NH3 ^ NH : CH • COO • NH4 (5) 



NH : CH • COONH4 + 2H ^ NH2 • CH2 ■ COONH4 (6) 



NH2 • CH2 • COONH4 + H2O ^ NH2 • CH2 • COOH + NH3 (7) 



(Glycine) 



Serine 



Glycine is synthesized as described in reaction (7). Glycine on condensation 

 with formaldehyde gives serine. 



CH2(NH2)COOH + CH2O ^ OHCH2CH(NH2)COOH (8) 



(Serine) 



Homoserine 

 OHCH2CH(NH2)COOH + CH2O ^ CHOCH2CH(NH2)COOH + H2O (9) 



CHOCH2CH(NH2)COOH + 2H ^ OHCH2CH2CH(NH2)COOH (10) 



(Homoserine) 



Proline 



Serine is synthesized as mentioned in the reaction (8). It can give rise to 



proline through the following series of reactions. 



OHCH2CH(NH2)COOH + CH2O ^ CHOCH2CH(NH2)COOH + H2O (11) 



CHOCH2CH(NH2)COOH + 2H ^ OHCH2CH2CH(NH2)COOH + H2O (12) 

 CH2O + OHCH2CH2CH(NH2)COOH 



?^ CHOCH2CH2CH(NH2)COOH + H2O (13) 



CHOCH2CH2CH(NH2)COOH + 2H ^ OHCH2CH2CH2CH(NH2)COOH (14) 



