Biophysics Laboratories, School of Biology, University of Portsmouth, Portsmouth, PO1 2DT, UK.
Department of Biology, Johns Hopkins University, Baltimore, MD, 21218, USA.
Eur Biophys J. 2022 Sep;51(6):515-517. doi: 10.1007/s00249-022-01611-2. Epub 2022 Aug 12.
The thermodynamic forces driving the formation of H-bonds in macromolecules have long been the subject of speculation, theory and experiment. Comparison of the energetic parameters of AT and GC base pairs in DNA duplexes has recently led to the realisation that formation of a 'naked' hydrogen bond, i.e. without other accompanying Van der Waals close contacts, is a non-enthalpic process driven by the entropy increase resulting from release of tightly bound water molecules from the component polar groups. This unexpected conclusion finds a parallel in the formation of ionic bonds, for example between the amino groups of DNA binding proteins and the oxygens of DNA phosphate groups that are also non-enthalpic and entropy driven. The thermodynamic correspondence between these two types of polar non-covalent bonding implies that the non-enthalpic nature of base pairing in DNA is not particular to that specific structural circumstance.
长期以来，驱动大分子中氢键形成的热力学力一直是推测、理论和实验的主题。最近，对 DNA 双螺旋中 AT 和 GC 碱基对的能量参数的比较，使人们认识到形成“裸露”氢键，即没有其他伴随的范德华近距离接触，是一个非焓过程，由从组成的极性基团中释放紧密结合的水分子导致的熵增加所驱动。这一出乎意料的结论在离子键的形成中找到了类似之处，例如在 DNA 结合蛋白的氨基基团和 DNA 磷酸基团的氧之间形成的离子键，它们也是非焓和熵驱动的。这两种类型的极性非共价键之间的热力学对应关系表明，DNA 中碱基对的非焓性质并非特定于该特定结构环境。
