14:30 〜 14:45
[MIS17-04] マグネシウムイオンによる水和構造変化に起因する粘土上へのヌクレオチド吸着
キーワード：粘土、水和、生命起源
Polymerization of nucleotide is an early stage of origin of life on the Earth. It is a dehydration reaction, so there are very few investigations which have succeeded to reproduce the polymerization in liquid environment. However, formation of long-chain oligomers in an aqueous solution in the presence of cations (transition metals, magnesium ion) and clay minerals have been reported [Ferris and Ertem (1992) Science 257, 1387-1389]. We have investigated the effects of impurities on the crystal growth in solution and the hydration structure by frequency modulation atomic force microscopy (FM-AFM). FM-AFM enables us to observe the atomic-scale phenomena and the three-dimensional water distribution at the solid surface in situ. So far, we have found that magnesium ions have the effect of disturbing the hydration structure at the calcite surface. This finding provided us an idea that hydrophilic ions such as magnesium instantly and locally induce dehydration of the molecular surface even in the polymerization reaction of nucleotide on the clay surface.
In this study, we carried out in situ observation of adsorption of nucleotide oligomers on mica by FM-AFM. All solution were prepared by using RNase free water. A solution of 30 oligomer (1 μg/mL) designed to have a characteristic ring shape as shown in the figure 1 was dropped onto a mica substrate and observed in RNase free water. No adsorbents were found on the mica surface (Fig.2a). Then, a magnesium chloride solution was added so as to be 100 mM. The adsorbate gradually increased on the mica (Fig.2b), and after 1 hour, the surface was almost covered with the adsorbates (Fig.2c). Such changes were not observed with the addition of KCl. These results indicate remarkable effect of magnesium ions on adsorption of oligomers. In the presentation, we will discuss the relation of hydration structure and the oligomer adsorption rate showing the results of changes the adsorption rate by the other cations and the change in hydration structure of mica.
In this study, we carried out in situ observation of adsorption of nucleotide oligomers on mica by FM-AFM. All solution were prepared by using RNase free water. A solution of 30 oligomer (1 μg/mL) designed to have a characteristic ring shape as shown in the figure 1 was dropped onto a mica substrate and observed in RNase free water. No adsorbents were found on the mica surface (Fig.2a). Then, a magnesium chloride solution was added so as to be 100 mM. The adsorbate gradually increased on the mica (Fig.2b), and after 1 hour, the surface was almost covered with the adsorbates (Fig.2c). Such changes were not observed with the addition of KCl. These results indicate remarkable effect of magnesium ions on adsorption of oligomers. In the presentation, we will discuss the relation of hydration structure and the oligomer adsorption rate showing the results of changes the adsorption rate by the other cations and the change in hydration structure of mica.