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Amorphous Silica-Promoted Lysine Dimerization: a Thermodynamic Prediction.
Origins of Life and Evolution of Biospheres ( IF 2 ) Pub Date : 2017-08-16 , DOI: 10.1007/s11084-017-9548-z
Norio Kitadai 1 , Kumiko Nishiuchi 1 , Akari Nishii 2 , Keisuke Fukushi 3
Affiliation  

It has long been suggested that mineral surfaces played a crucial role in the abiotic polymerization of amino acids that preceded the origin of life. Nevertheless, it remains unclear where the prebiotic process took place on the primitive Earth, because the amino acid-mineral interaction and its dependence on environmental conditions have yet to be understood adequately. Here we examined experimentally the adsorption of L-lysine (Lys) and its dimer (LysLys) on amorphous silica over a wide range of pH, ionic strength, adsorbate concentration, and the solid/water ratio, and determined the reaction stoichiometries and the equilibrium constants based on the extended triple-layer model (ETLM). The retrieved ETLM parameters were then used, in combination with the equilibrium constant for the peptide bond formation in bulk water, to calculate the Lys-LysLys equilibrium in the presence of amorphous silica under various aqueous conditions. Results showed that the silica surface favors Lys dimerization, and the influence varies greatly with changing environmental parameters. At slightly alkaline pH (pH 9) in the presence of a dilute NaCl (1 mM), the thermodynamically attainable LysLys from 0.1 mM Lys reached a concentration around 50 times larger than that calculated without silica. Because of the versatility of the ETLM, which has been applied to describe a wide variety of biomolecule-mineral interactions, future experiments with the reported methodology are expected to provide a significant constraint on the plausible geological settings for the condensation of monomers to polymers, and the subsequent chemical evolution of life.

中文翻译:

非晶硅促进的赖氨酸二聚化:热力学预测。

长期以来,人们一直认为矿物质表面在生命起源之前的氨基酸非生物聚合中起着至关重要的作用。然而,尚不清楚益生元过程在原始地球上的哪个位置发生,因为尚未充分了解氨基酸与矿物质的相互作用及其对环境条件的依赖性。在这里,我们通过实验研究了L-赖氨酸(Lys)及其二聚体(LysLys)在无定形二氧化硅上的广泛pH,离子强度,吸附物浓度和固/水比的吸附,并确定了反应化学计量和平衡基于扩展三层模型(ETLM)的常量。然后将检索到的ETLM参数与散装水中形成肽键的平衡常数结合使用,计算在各种含水条件下无定形二氧化硅存在下的Lys-LysLys平衡。结果表明,二氧化硅表面有利于Lys二聚化,并且影响随环境参数的变化而变化很大。在稀的NaCl(1 mM)存在下,在弱碱性pH(pH 9)下,热力学上可得的LysLys从0.1 mM Lys达到的浓度约为没有二氧化硅时计算得出的浓度的50倍。由于ETLM的多功能性已被用于描述各种各样的生物分子与矿物之间的相互作用,因此使用该报道的方法学进行的未来实验预计将对单体缩合为聚合物的合理地质条件提供重大限制,并且生命的后续化学进化。
更新日期:2019-11-01
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