Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark.
ACS Nano. 2011 Aug 23;5(8):6651-60. doi: 10.1021/nn202157m. Epub 2011 Jul 19.
Xanthine molecule is an intermediate in nucleic acid degradation from the deamination of guanine and is also a compound present in the ancient solar system that is found in high concentrations in extraterrestrial meteorites. The self-assembly of xanthine molecules on inorganic surfaces is therefore of interest for the study of biochemical processes, and it may also be relevant to the fundamental understanding of prebiotic biosynthesis. Using a combination of high-resolution scanning tunneling microscopy (STM) and density functional theory (DFT) calculations, two new homochiral xanthine structures have been found on Au(111) under ultrahigh vacuum conditions. Xanthine molecules are found to be self-assembled into two extended homochiral networks tiled by two types of di-pentamer units and stabilized by intermolecular double hydrogen bonding. Our findings indicate that the deamination of guanine into xanthine leads to a very different base pairing potential and the chemical properties of the base which may be of relevance to the function of the cell and potential development of human diseases. Moreover, the adsorption of xanthine molecules on inorganic surfaces leading to homochiral assemblies may be of interest for the fundamental understanding of the emerged chirality at early stages of life.
黄嘌呤分子是核酸降解过程中鸟嘌呤脱氨的中间产物，也是在古老的太阳系中存在的一种化合物，在天外陨石中浓度很高。因此，黄嘌呤分子在无机表面上的自组装对于研究生化过程很有意义，也可能与前生物合成的基本理解有关。使用高分辨率扫描隧道显微镜（STM）和密度泛函理论（DFT）计算的组合，在超高真空条件下，在 Au(111)上发现了两种新的同手性黄嘌呤结构。发现黄嘌呤分子自组装成两个由两种类型的二戊五聚体单元平铺的扩展同手性网络，并通过分子间的双重氢键稳定。我们的研究结果表明，鸟嘌呤脱氨成黄嘌呤会导致非常不同的碱基配对潜力和碱基的化学性质，这可能与细胞的功能和人类疾病的潜在发展有关。此外，黄嘌呤分子在无机表面上的吸附导致同手性组装可能对生命早期出现的手性的基本理解感兴趣。
