Benner Steven A, Hutter Daniel
Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville 32611-7200, USA.
Bioorg Chem. 2002 Feb;30(1):62-80. doi: 10.1006/bioo.2001.1232.
Phosphate groups are found and used widely in biological chemistry. We have asked whether phosphate groups are likely to be important to the functioning of genetic molecules, including DNA and RNA. From observations made on synthetic analogs of DNA and RNA where the phosphates are replaced by nonanionic linking groups, we infer a set of rules that highlight the importance of the phosphodiester backbone for the proper functioning of DNA as a genetic molecule. The polyanionic backbone appears to give DNA the capability of replication following simple rules, and evolving. The polyanionic nature of the backbone appears to be critical to prevent the single strands from folding, permitting them to act as templates, guiding the interaction between two strands to form a duplex in a way that permits simple rules to guide the molecular recognition event, and buffering the sensitivity of its physicochemical properties to changes in sequence. We argue that the feature of a polyelectrolyte (polyanion or polycation) may be required for a "self-sustaining chemical system capable of Darwinian evolution." The polyelectrolyte structure therefore may be a universal signature of life, regardless of its genesis, and unique to living forms as well.
磷酸基团在生物化学中广泛存在并被广泛应用。我们曾探讨过磷酸基团对于包括DNA和RNA在内的遗传分子的功能是否可能至关重要。通过对DNA和RNA的合成类似物的观察（其中磷酸基团被非阴离子连接基团取代），我们推断出一组规则，这些规则突出了磷酸二酯主链对于DNA作为遗传分子正常发挥功能的重要性。聚阴离子主链似乎赋予了DNA按照简单规则进行复制并进化的能力。主链的聚阴离子性质对于防止单链折叠似乎至关重要，使其能够充当模板，引导两条链之间的相互作用以一种允许简单规则指导分子识别事件的方式形成双链体，并缓冲其物理化学性质对序列变化的敏感性。我们认为，对于一个“能够进行达尔文式进化的自我维持化学系统”而言，可能需要聚电解质（聚阴离子或聚阳离子）的特性。因此，聚电解质结构可能是生命的普遍特征，无论其起源如何，并且也是生命形式所独有的。
