Modelling of the prebiotic synthesis of oligopeptides: silicate catalysts help to overcome the critical stage |
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Authors: | Zamaraev Kirill I. Romannikov Vyacheslav N. Salganik Rudolph I. Wlassoff Wjatschesslaw A. Khramtsov Valeriy V. |
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Affiliation: | (1) Boreskov Institute of Catalysis, Russian Academy of Sciences, Lavrentyev Avenue 5, 630090 Novosibirsk, Russia;(2) Institute of Cytology and Genetics, Russian Academy of Sciences, Lavrentyev Avenue 10, 630090 Novosibirsk, Russia;(3) Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Institutskaya Str. 3, 630090 Novosibirsk, Russia |
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Abstract: | On the basis of experimental studies of the initial stages of glycine oligomerization in aqueous suspension of zeolite and kaolinite catalysts, a model is suggested for the prebiotic synthesis of oligopeptides from -amino acids. The formation of linear dipeptides by hydrolysis of one amide bond in the cyclic piperazinedione intermediate (formed from glycine spontaneously) is found to be the critical stage of the reaction. This stage is base catalyzed and its rate increases when pH of the medium goes up. The linear glycyl-glycine yield rises under effect of hydroxyl anions generated from different sources including insoluble silicates and soluble sodium bicarbonate. During prebiotic evolution silicates capable of cation-exchange can serve as local sources of the hydroxyl anions which dramatically accelerate formation of linear dipeptides from cyclic ones. Oligopeptides of higher molecular weight are then easily formed from the linear dipeptides at neutral pH, even in the absence of catalysts or sources of energy (e.g. such as light). The described catalytic synthesis could occur in the proximity of submarine hydrothermal vents. |
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