Glycine Polymerization on Oxide Minerals
Glycine Polymerization on Oxide Minerals
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DOI：
10.1007/s11084-016-9516-z
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发表时间：
2017-06-01
影响因子：
2
通讯作者：
Nakashima, Satoru
中科院分区：
文献类型：
--
作者：
Kitadai, Norio;Oonishi, Hiroyuki;Nakashima, Satoru
长期以来，人们一直认为矿物表面在原始地球上的肽键形成中发挥了重要作用。然而，目前还不清楚哪些矿物物种是生命前过程的关键。这是因为，由于实验条件的不同，所报道的矿物对氨基酸聚合的催化效率之间存在很大的差异。本研究探讨聚合甘氨酸（Gly）上九个氧化物矿物（无定形二氧化硅，石英，α-氧化铝和γ-氧化铝，金红石，赤铁矿，磁铁矿，镁橄榄石）使用相同的制备，加热和分析程序。结果表明，金红石表面是最有效的网站为甘氨酸聚合的量和长度的合成的甘氨酸聚合物。催化效率的大小顺序为金红石>金红石> γ-氧化铝>镁橄榄石> α-氧化铝>磁铁矿>赤铁矿>石英>无定形二氧化硅。基于报道的分子水平上的信息，吸附的甘氨酸对这些矿物，聚合活化被推断为已经出现从吸附的甘氨酸的NH3（+）基团的亲核性NH 2基团的去质子化，并从撤回的电子密度从羧基碳的表面金属离子。Gly在矿物表面的吸附取向也是影响Gly反应活性的一个因素。在相同的实验条件下考察了甘氨酸与矿物的相互作用，从而可以直接比较各种矿物的催化效率，并讨论了聚合机理及其相对影响。（预计将取得成果）结合未来的微观表面分析，将阐明矿物质在非生物肽键形成过程中的作用。
It has long been suggested that mineral surfaces played an important role in peptide bond formation on the primitive Earth. However, it remains unclear which mineral species was key to the prebiotic processes. This is because great discrepancies exist among the reported catalytic efficiencies of minerals for amino acid polymerizations, owing to mutually different experimental conditions. This study examined polymerization of glycine (Gly) on nine oxide minerals (amorphous silica, quartz, alpha-alumina and gamma-alumina, anatase, rutile, hematite, magnetite, and forsterite) using identical preparation, heating, and analytical procedures. Results showed that a rutile surface is the most effective site for Gly polymerization in terms of both amounts and lengths of Gly polymers synthesized. The catalytic efficiency decreased as rutile > anatase > gamma-alumina > forsterite > alpha- alumina > magnetite > hematite > quartz > amorphous silica. Based on reported molecular-level information for adsorption of Gly on these minerals, polymerization activation was inferred to have arisen from deprotonation of the NH3 (+) group of adsorbed Gly to the nucleophilic NH2 group, and from withdrawal of electron density from the carboxyl carbon to the surface metal ions. The orientation of adsorbed Gly on minerals is also a factor influencing the Gly reactivity. The examination of Gly-mineral interactions under identical experimental conditions has enabled the direct comparison of various minerals' catalytic efficiencies and has made discussion of polymerization mechanisms and their relative influences possible Further systematic investigations using the approach reported herein (which are expected to be fruitful) combined with future microscopic surface analyses will elucidate the role of minerals in the process of abiotic peptide bond formation.