Synthesis of Valine and Isoleucine in Primitive Earth Conditions

Abstract

SYNTHESIS of small amounts of valine, isoleucine and leucine from the polymerization of ammonium cyanide solutions has been reported^1,2 in addition to the substantial yields of glycine, alanine, aspartic acid and serine³. We have been unable to find any valine, isoleucine or leucine synthesized by the polymerization reaction of NH₄CN alone. On adding acetone or methyl ethyl ketone to the NH₄CN solutions, significant yields of valine, alloisoleucine and isoleucine are, however, obtained. The previous identifications were based on the elution pattern from a Beckman¹ automatic amino-acid column⁴. Because several non-protein amino-acids appear at the same elution positions as valine, isoleucine and leucine^5,6 (for example, isoasparagine elutes with isoleucine), an error of identification is possible, although the specific amino-acids in this case are not known. We have used a more elaborate separation scheme to avoid the problem of overlapping peaks.