Indications towards a stereoselectivity of the salt-induced peptide formation reaction

Abstract

Different reaction yields for l- and d-alanine in the salt-induced peptide formation (SIPF) reaction, differences in the circular dichroism spectra and the complex formation constants of the involved chlorocuprate complexes point at a stereoselective differentiation between the two stereoisomers in the SIPF reaction and give a possible explanation towards the origin of homochirality in the process of the origin of life. An explanation of the observed effects can for the time being only be based on assumptions but could possibly be related to the inherent chirality of the CuII ion as a central atom of the [CuCl(gly)(glyH2)(H2O)2]+ complex due to parity violation in weak interactions and to amplification of chirality related to the structural properties of the complex.

The question of the origin of homochirality is an essential part of the research concerned with the origin of life. In this paper we report about interesting differences in the complex formation constants and the CD spectra of copper(II)-amino acid complexes with l- and d-alanine due to parity violation and about different yields of peptides in a prebiotically highly relevant reaction based on these complexes.