Acevedo O L, Orgel L E
The Salk Institute for Biological Studies, San Diego, California 92138, USA.
Nature. 1986 Jun 19;321:790-2. doi: 10.1038/321790a0.
Bernal, and subsequently other authors, have suggested that the prebiotic synthesis of the precursors of biopolymers could have occurred on a solid surface such as that provided by clay or some other mineral. The separation of products from the other components of the reaction mixture in such a system is reminiscent of modern solid-phase synthesis of polypeptides and polynucleotides. One such scheme envisages that growing polymers were localized by adsorption to a mineral surface where an activating agent or activated monomers were supplied continuously or cyclically. We have been trying to test this scheme using reactions which we believe may be related to those that occurred during prebiotic evolution. We have already reported that oligonucleotides adsorbed onto hydroxylapatite provide suitable templates for the oligomerization of (guanosine 5'-phosphor)-2-methylimidazolide (2-MeImpG). However, this is not a suitable test reaction, as 2-MeImpG oligomerization proceeds almost to completion in a single step. Here we report that a sequence of reactions in which initially formed oligo(G)s are reactivated by conversion to phosphorimidazolides in the presence of poly(C) and then allowed to ligate is ideal, in that repeated cycles can be carried out on the surface of hydroxylapatite, whereas in the liquid phase the cycle could be achieved only with considerable difficulty.
伯纳尔及随后的其他作者提出，生物聚合物前体的益生元合成可能发生在固体表面，如黏土或其他矿物所提供的表面。在这样一个系统中，产物与反应混合物的其他组分的分离让人联想到现代多肽和多核苷酸的固相合成。一种这样的设想是，不断生长的聚合物通过吸附到矿物表面而被固定下来，在该表面上，活化剂或活化单体被持续或循环供应。我们一直在尝试用一些反应来检验这一设想，我们认为这些反应可能与益生元进化过程中发生的反应有关。我们已经报道，吸附在羟基磷灰石上的寡核苷酸为（鸟苷5'-磷酸）-2-甲基咪唑酯（2-MeImpG）的寡聚反应提供了合适的模板。然而，这并不是一个合适的测试反应，因为2-MeImpG的寡聚反应几乎一步就可完成。在此我们报道，一系列反应是理想的，其中最初形成的寡聚鸟苷（oligo(G)s）在聚胞苷酸（poly(C)）存在下通过转化为磷酰咪唑酯而被重新活化，然后进行连接，因为在羟基磷灰石表面可以进行重复循环，而在液相中，只有克服相当大的困难才能实现这个循环。
