  A recently proposed model of non-autocatalytic reactions in dipeptide
reactions leading to spontaneous symmetry breaking and homochirality is
examined. The model is governed by activation, polymerization, epimerization
and depolymerization of amino acids. Symmetry breaking is primarily a
consequence of the fact that the rates of reactions involving homodimers and
heterodimers are different, i.e., stereoselective, and on the fact that
epimerization can only occur on the N-terminal residue and not on the Cterminal
residue. This corresponds to an auto-inductive cyclic process that works only
in one sense. It is argued that epimerization mimics both autocatalytic
behavior as well as mutual antagonism - both of which were known to be crucial
for producing full homochirality.
