Abdulnur S F
Ciba Found Symp. 1978(67):195-209. doi: 10.1002/9780470720493.ch13.
Ab initio quantum mechanical calculations are used to study the interactions of the aldehydic group of methylglyoxal with the NH2 groups of protein side-chains, using methylamine as a representative molecule. The hydrogen-bonding interaction, C = O...H - N, results in an electronic charge transfer from methylglyoxal to methylamine in both the ground and first excited triplet states. In this latter state a slight possibility is found for the H atom in the hydrogen bond to tunnel from methylglyoxal to methylamine, leading to the possible formation of two free radical fragments. The approach of methylamine to methylglyoxal in the stacked conformation C...N to form a hemiacetal, associated with electron charge transfer from methylamine to methylglyoxal, is energetically unfavourable in vacuum. The concomitant tunnelling of a proton from a proton-donating solvent molecule to the aldehydic oxygen of methylglyoxal is shown to make this approach favourable. The relative stability of the keto and enol forms of methylglyoxal is also investigated, the keto form being found the more stable in vacuum.
采用从头算量子力学计算方法，以甲胺作为代表性分子，研究甲基乙二醛的醛基与蛋白质侧链氨基之间的相互作用。氢键相互作用C=O…H-N导致在基态和第一激发三重态下均有电子从甲基乙二醛转移至甲胺。在后一种状态下，发现氢键中的氢原子有轻微的可能性从甲基乙二醛隧穿至甲胺，从而可能形成两个自由基片段。在真空中，甲胺以堆积构象C…N接近甲基乙二醛以形成半缩醛，并伴有电子从甲胺转移至甲基乙二醛，这在能量上是不利的。结果表明，质子从供质子溶剂分子隧穿至甲基乙二醛的醛基氧会使这种接近变得有利。还研究了甲基乙二醛酮式和烯醇式的相对稳定性，发现酮式在真空中更稳定。
