The Original Formation of Amino Adds 101 



In a solution of formaldehyde and ammonium nitrate treated in the same way, 

 the following were identified: serine, glycine, glutamic acid, alanine and valine 

 (Fig. 2). Lowering of the temperature of the experiment to 1-2 °C, while 

 keeping all the other conditions unchanged and using ammonium nitrate, led 

 to the formation of isoleucine, phenylalanine and basic amino acids as well as 

 those just listed (Fig. 2). 



If the experiments were carried out in the presence of chalk (i.e., at pH 5-6-2) 

 the basic amino acids predominated while glutamic acid, alanine, valine and 

 phenylalanine were only formed in negUgible amounts under these conditions 

 (Fig. 2). The aminc-acid content was lO"^ M. In control experiments, in which 

 the mixtures were not irradiated, amino acid spots were not found. 



The idea that bacterial contamination might have been a factor in the forma- 

 tion of amino acids is, to our minds, precluded by the conditions under which 

 the experiments were conducted, involving the intensive exposure to ultra- 

 violet irradiation for 20 hours of a solution containing 2-5% of formaldehyde at 

 a pH of 1-5 and a temperature of 45 °C. Furthermore, the results of the control 

 experiments (without irradiation) were negative. We checked this by special 

 microbiological experiments in which the experimental solution was cultured on 

 nutrient media : meat-peptone-agar and wort-agar. The absence of grov^h of 

 colonies after 72 hours demonstrated the complete sterility of the experimental 

 solution. 



THE ACTION OF ELECTRIC DISCHARGES 



In the gaseous mixtures (of methane, ammonia, hydrogen and water vapour) 

 studied by Miller, the formation of amino acids was hindered by a deficiency of 

 oxygen and a great excess of hydrogen such as he believed to have been present 

 in the primaeval reducing atmosphere of the Earth. For every molecule of amino 

 acid formed, two atoms of oxygen were needed and these could only be obtained 

 from two molecules of water. At least one atom of nitrogen was also needed and 

 this required a molecule of ammonia. At least two atoms of carbon were also 

 needed and they could only be obtained from two molecules of methane. But 

 even in the mixture 2H2O + NH3 + 2CH4 there are 15 atoms of hydrogen of 

 which no more than half are required for the formation of the simplest amino acids 

 (glycine and alanine), while Miller's mixtures contained, in addition, free, and 

 obviously superfluous, hydrogen. When molecules of more complicated amino 

 acids are formed the proportions, as one can easily see, remain unfavourable. 

 For this reason the composition of the gaseous medium used by Miller is 

 unsuited to the formation of amino acids. We arrive at the same conclusion 

 by a thermodynamical calculation in respect of the overall reaction by which 

 alanine, for example, is formed. When they take place under standard con- 

 ditions there is a great increase in free energy (A Zq) : 



2H2O + 3CH4 + NH3-> CH3-CH(NH2)COOH + 6H2 

 A Zo = + 62,040 cal/mole 



Naturally, in an electrical discharge the energy of the discharge will cover 

 this increase in AZo, but even when reactions are proceeding in an electrical 



