Abstract
This study is a continuation of our research on understanding the possible chemical routes to the evolution of life on earth based on the “Selective Energy Transfer” (SET) theory. This theory identifies the specific vibrational mode of the catalyst that is in energy-resonance with a suitable vibrational mode of the reactant. In this way, energy is transferred from catalyst to reactant up to the energy of activation, making possible a particular chemical outcome. Then, we extend this model to the mostly unknown and highly complex environment of the hydrothermal vents, to speculate how prebiotic chemicals, necessary for the evolution of life, could have formed. It is to the credit of the SET theory that it can reflect the slight difference in the catalytic system that gives dramatically very different chemical outcome. It is shown, here, how in model laboratory experiments, methanol gives dimethyl ether (DME) in a 100% yield with Cu exchanged montmorillonite as the catalyst, or a very different product methyl formate (MF) in lower yields, with another Cu2+ ion-exchanged clay mineral (laponite) as the catalyst system. We also show, based on standard laboratory experiments, how COS (carbonyl sulfide) with a strong absorption band at 2079 cm−1 by itself and/or catalyzed by montmorillonite with strong Si-O-Si asymmetric vibration of 1040 cm−1 can react with alpha-amino acids to form alpha-amino acid thiocarbamate (AATC), which we feel could represent the most primitive analogue to coenzyme A (CoASH), a highly versatile bio-enzyme that is vital both for the metabolism and the synthesis of biochemicals in the living system. AATC itself may have undergone evolutionary developments through billions of years to transform itself into coenzyme A (CoASH) and its acetyl ester analogue acetyl coenzyme A (ACoA).
Highlights
Introduction published maps and institutional affilIt is widely recognized that the undersea hydrothermal vents were the putative locations where life in its most primitive form evolved
For example, Christian de Duve speculated on a primitive “thioester world” [4,5] necessary for the evolution of life. We show in this and related publications [6,7] how Selective Energy Transfer” (SET) theory, developed by one of us (R.L.) [8,9,10], can be a useful guide for understanding the prebiotic chemical evolution leading to the origin of life
This observation calls for an explanation of the reaction mechanism, different from that described for the montmorillonite catalysis
Summary
After this exposition of the powerful ability of montmorillonite to trigger the same reactions that the COS molecule mastered, is it possible to find some physical property that is common to both systems?. Since the ν3 of COS (2079 cm−1 ) has the ability to activate the ρw(NH2 ) out-ofplane bending of an amino acid [9], we started to search for possible analogues in the montmorillonite system. Twice this value, i.e., 2 × 1040 = 2080 cm−1 , is very near to that of ν3 of COS (2079 cm−1 ) This might mean that two quanta of the montmorillonite vibration would be able to perform the same actions that one quantum of COS could do. Whereas the COS catalyst comes streaming from the hot atmosphere of a volcano outlet, and is highly activated from the start, the reactions catalyzed by montmorillonite occur at modest temperatures and each separate vibration is probably not activated to more than one or possibly two quantum numbers.
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