Dutta Juhi, Sahu Akshay Kumar, Bhadauria Abhijeet S, Biswal Himansu S
School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhimpur-Padanpur, Via-Jatni, Khurda, Bhubaneswar 752050, India.
Training School Complex, Homi Bhabha National Institute, Anushakti Nagar, Mumbai 400094, India.
J Chem Inf Model. 2022 Apr 25;62(8):1998-2008. doi: 10.1021/acs.jcim.2c00015. Epub 2022 Mar 16.
Hydrogen bonding (H-bonding) without lone pair(s) of electrons and π-electrons is a concept developed 2-3 years ago. H-bonds involving less electronegative tetrahedral carbon are beyond the classical concept of H-bonds. Herein, we present the first report on H-bonds with tetravalent carbons in proteins. A special bonding arrangement is needed to increase the negative charge density around the sp-hybridized carbon atom. Therefore, less electronegative elements such as As and Mg, when bonded to sp-C, enable the C-atoms as H-bond acceptors. Careful protein structure analysis aided by several quantum chemical calculations suggests that these H-bonds are weak to moderate in strength. We developed an empirical equation to estimate the C-H···C H-bond energy in proteins from the distances between the C- and H-atoms. In proteins, the binding energies range from -5.4 to -14.0 kJ/mol. The C-H···C H-bonds assist the substrate binding in proteins. We also explored the potential role of these carbon-centered H-bonds in C-H bond activation through σ-bond metathesis. To our surprise, contribution from these H-bonds is almost of similar magnitude as that from C-H···π H-bonds for C-H bond activation.
不含孤对电子和π电子的氢键（H键）是2 - 3年前提出的概念。涉及电负性较小的四面体碳的H键超出了经典H键的概念。在此，我们首次报道了蛋白质中与四价碳形成的H键。需要一种特殊的键合排列来增加sp杂化碳原子周围的负电荷密度。因此，当与sp - C键合时，砷和镁等电负性较小的元素能使碳原子作为H键受体。借助多种量子化学计算进行的仔细蛋白质结构分析表明，这些H键的强度较弱到中等。我们开发了一个经验方程，根据C原子和H原子之间的距离来估算蛋白质中C - H···C H键的能量。在蛋白质中，结合能范围为 - 5.4至 - 14.0 kJ/mol。C - H···C H键有助于蛋白质中的底物结合。我们还通过σ键复分解探索了这些以碳为中心的H键在C - H键活化中的潜在作用。令我们惊讶的是，对于C - H键活化，这些H键的贡献几乎与C - H···π H键的贡献大小相似。
