专题：Science报道
据2月19日的《科学》杂志报道说，新的研究证明了硅酸盐离子是如何曾经在一个原始的地球上使得复杂糖分子的增长变得容易。研究人员说，这一发现扩大了生命起源的可能的环境范围。
Joseph Lambert及其同僚开展了一系列的在室温中用简单的糖分子进行的化学反应。他们发现，硅酸盐离子是稳定那些基本反应物从而形成更复杂的糖的关键。在硅酸钠存在的情况下，简单的2碳和3碳糖分子会自动地形成较大的4碳和6碳化合物。这一观察为一种经典的甲醛聚糖反应（即从甲醛可制造出复杂的糖分子）可为这个星球上的生命提供所需的必要建材提供了证据。从理论上说，简单的甲醛分子可形成像核糖这样的复杂糖分子，而这些糖分子最终会形成RNA。然而，这些反应究竟是如何在数十亿年之前在地球上完成的一直是存在着许多争议的话题。由于硅酸盐离子在地球早期的表层水中相对比较丰富，这一发现提示，甲醛聚糖类的反应是合成复杂糖分子的一种可行的途径，可能也是地球上生命开始的途径。
推荐原始出处：
Science 19 February 2010:DOI: 10.1126/science.1182669
The Silicate-Mediated Formose Reaction: Bottom-Up Synthesis of Sugar Silicates
Joseph B. Lambert,* Senthil A. Gurusamy-Thangavelu, Kuangbiao Ma
Understanding the mechanism of sugar formation and stabilization is important for constraining theories on the abiotic origin of complex biomolecules. Although previous studies have produced sugars from small molecules through the formose and related reactions, the product mixtures are complex and unstable. We have demonstrated that simple two- and three-carbon molecules (glycolaldehyde and glyceraldehyde), in the presence of aqueous sodium silicate, spontaneously form silicate complexes of four- and six-carbon sugars, respectively. Silicate selects for sugars with a specific stereochemistry and sequesters them from rapid decomposition. Given the abundance of silicate minerals, these observations suggest that formose-like reactions may provide a feasible pathway for the abiotic formation of biologically important sugars, such as ribose.
Department of Chemistry, Northwestern University, Evanston, IL 60208, USA.
