Asymmetric autocatalysis and its implications for the origin of homochirality

Abstract

An autocatalytic reaction in which the reaction product serves as a catalyst to produce more of itself and to suppress production of its enantiomer serves as a mechanistic model for the evolution of homochirality. The Soai reaction provided experimental confirmation of this concept, nearly 50 years after it was first proposed. This Perspective offers a rationalization of the Soai autocatalytic reaction; accounting for enantiomeric excess and rate observations, that is both simple as well as gratifying in its implications for the chemical origin of life.

The origin of biological homochirality

“…The ultimate product ee that may be achieved in such an autocatalytic reaction is limited only by the size of the substrate pool. This model demonstrates that effective amplification of ee in autocatalysis depends less on sophisticated stereoselection and more on higher relative activity for the homochiral dimers, repeated over many autocatalytic cycles [15].…”

Amplification of chirality as a pathway to biological homochirality

“…The enantioselectivity observed in this autocatalytic reaction should be high enough to expect a remarkable phenomenon, i.e., asymmetric autocatalysis with amplification of ee [45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61], which prompted the examination of the reaction using an autocatalyst with a low ee. As a result, we found for the first time that the initial small 2% ee was significantly amplified to a high enantioenrichment (88% ee) [44] (Fig.…”

“Wenn Schweine fliegen könnten”: Zum Prinzip der mikroskopischen Reversibilität

“…[5] Die Frage, wie sich ein streng auf l-Aminosäuren und d-Zuckern basierendes Leben aus der mutmaßlich racemischen Ursuppe entwickeln konnte, birgt reichlich Substanz für wissen-schaftliche Diskussionen. Nachdem das Feld in den 1950er Jahren mit theoretischen Konzepten von Frank [6] und Calvin [7] eröffnet wurde, ist es in den letzten zwei Jahrzehnten dank verblüffender experimenteller Befunde sowohl zum physikalischen Phasenverhalten [8][9][10][11] als auch zu diversen chemischen Reaktionen [12,13] enorm expandiert. Tatsächlich ist kürzlich angemerkt worden, dass wir nun die "Qual der Wahl" an Möglich-keiten haben, wie unsere gegenwärtige biologische Realität entstanden sei.…”