Synthesis Of Prebiotic Amino Acids Under The Condition Of Mimicking The Environment Of Submarine Hydrothermal Systems

The issue of the origin of life is one of the three problems in natural science on the earth.Historically, people have never stopped the study of the origin of life. There have beenseveral hypotheses such as creationism theory, spontaneous generation theory, biogenesistheory, and cosmogony theory. The hypothesis of chemical evolution is widely accepted bymajority of scholars. This assumption means that life is gradually transformed fromnon-living matter. On early earth, non-living materials (nuclear, elements and molecules, etc.)have been transformed into complex organic compounds through a series of complexchemical processes, and organic matter can be developed into biological macromolecules andmulti-cellular system until the primitive life forms.Submarine hydrothermal systems were discovered in1977. The vent systems have beensuggested as the most likely sites for the origin and evolution of life. There are primordialenvironments with reactive gases, dissolved elements, and thermal and chemical gradients.Owing to their physical and chemical environment, they lay the foundation of material andenergy for the origin of life, as well as provide a basis for the synthesis research of prebioticorganic molecules in prebiotic simulation experiments.By simulating the environment of deep-sea hot spring, my thesis has designed abioticamino acids synthesis involving reactions between acetic acid and ammonia underhydrothermal conditions by different catalysts. On part one, we effect the catalytic effect ofseveral typical transition metal oxide (Co3O4、Cr2O3、Mn3O4) and sulfide (Na2S) on theformation of Glycine. Cobaltosic oxide has been acted as a catalyst in the direct reaction ofacetic acid and ammonia. However, Cr2O3, Mn3O4and Na2S do not affect the catalytic actionin the same reaction. It is proposed that cobaltosic oxide might have played a special role inthe synthesis of glycine under mimicked experimental environment. Among the parametersinvestigated, we find that high temperature and long reaction time are beneficial to theaccumulation of glycine with the catalyst of cobaltosic oxide. On part two, we investigate thecatalytic effect of various salts which are present in significant concentrations in hot spring on the formation of amino acids. It turned out that the catalytic effect was specificallydifferent. ZnCl2, MgCl2·6H2O, MnCl2, NaCl and KCl did not lead to emerge of amino acids.On the contrary, a certain amount of amino acids were formed under the action of the saltsrespectively including BaCl2·2H2O, FeCl3, CaCl2·2H2O and CuCl2·2H2O, and reached thehighest yield in the presence of copper chloride. This section had also investigated thesynthesis of amino acids in the presence of copper chloride under various reaction conditions.Studies have shown that in certain reaction time and temperature range, with the increase ofthe reaction temperature and reaction time, the yield of amino acids show a trend to increasegradually.In this study, using acetic acid and ammonia as raw materials, we explored the catalyticeffect of several typical substances on the synthesis of amino acids. They played a differentrole in the formation of amino acids. The results suggested that Co3O4, BaCl2·2H2O, FeCl3,CaCl2·2H2O and CuCl2·2H2O catalyzed effectively the synthesis of prebiotic amino acidswith mimicking the hydrothermal vent systems. It indicated that in the deep-sea hot springsystems, not only the transition metal oxides of iron, which were abundant in primitiveoceans, could catalyze the synthesis of abiotic amino acids, but also cobaltosic oxide anddifferent salts seemed to affect significantly the generation of amino acids. At the same time,the results of this paper broaden the road for the synthesis and accumulation of amino acidsand other organic molecules.