Holm N G, Ertem G, Ferris J P
Department of Geology and Geochemistry, Stockholm University, Sweden.
Orig Life Evol Biosph. 1993 Jun;23(3):195-215. doi: 10.1007/BF01581839.
The iron oxide hydroxide minerals goethite and akaganéite were likely constituents of the sediments present in, for instance, geothermal regions of the primitive earth. They may have adsorbed organics and catalyzed the condensation processes which led to the origins of life. The binding to and reactions of nucleotides and oligonucleotides with these minerals was investigated. The adsorption of adenosine, 5'-AMP, 3'-AMP, 5'-UMP, and 5'-CMP to these minerals was studied. Adenosine did not bind to goethite and akaganéite. The adsorption isotherms for the binding of the nucleotides revealed that they all had close to the same affinity for the mineral. Binding to goethite was about four times stronger than to akaganéite. There was little difference in the adsorption of each nucleotide suggesting the binding was between the negative charge on the phosphate group and the positive charges on the mineral surface. The absence of binding of adenosine is consistent with this explanation. Binding decreases as the pH increases due to the titration of the positive (acidic) centers on the minerals. Two times as many moles of polynucleotides were bound to these minerals as compared to the mononucleotides. Watson-Crick hydrogen bonding of adenosine and 5'-AMP to poly(U) complexes with goethite and akaganéite was observed. There was no interaction of uridine with the poly(U)-goethite complex as expected if Watson-Crick hydrogen bonding is taking place. Neither goethite nor akaganéite catalyzed the oligomerization of the phosphorimidazolide of adenosine (ImpA). The template directed synthesis of oligomers of 5'-GMP on the poly(C) bound to goethite was observed. Higher molecular weight oligomers were observed when the poly(C) was bound to goethite than was found in the absence of the mineral.
氢氧化铁氧化物矿物针铁矿和四方纤铁矿可能是早期地球地热区域等沉积物中的成分。它们可能吸附了有机物并催化了导致生命起源的缩合过程。研究了核苷酸和寡核苷酸与这些矿物的结合及反应。研究了腺苷、5'-AMP、3'-AMP、5'-UMP和5'-CMP对这些矿物的吸附。腺苷不与针铁矿和四方纤铁矿结合。核苷酸结合的吸附等温线表明，它们对矿物的亲和力都接近相同。与四方纤铁矿的结合力比对针铁矿的结合力强约四倍。每种核苷酸的吸附差异不大，这表明结合发生在磷酸基团上的负电荷与矿物表面的正电荷之间。腺苷不结合与这一解释一致。由于矿物上正（酸性）中心的滴定，随着pH值升高结合减少。与单核苷酸相比，结合到这些矿物上的多核苷酸摩尔数是其两倍。观察到腺苷和5'-AMP与针铁矿和四方纤铁矿的聚（U）复合物形成沃森-克里克氢键。如果发生沃森-克里克氢键，预期尿苷与聚（U）-针铁矿复合物没有相互作用。针铁矿和四方纤铁矿都没有催化腺苷磷酰咪唑（ImpA）的寡聚反应。观察到在与针铁矿结合的聚（C）上5'-GMP的模板导向寡聚物合成。当聚（C）与针铁矿结合时，观察到的寡聚物分子量比没有矿物时更高。
