Faculty of Science - National Centre for Biomolecular Research, Masaryk University, Kamenice 5, CZ-625 00, Brno, Czech Republic.
J Mol Model. 2012 Mar;18(3):871-9. doi: 10.1007/s00894-011-1116-2. Epub 2011 May 28.
Vectorial proton transfer among carbonyl oxygen atoms was studied in two models of tripeptide via quantum chemical calculations using the hybrid B3LYP functional and the 6-31++G basis set. Two principal proton transfer pathways were found: a first path involving isomerization of the proton around the double bond of the carbonyl group, and a second based on the large conformational flexibility of the tripeptide model where all carbonyl oxygen atoms cooperate. The latter pathway has a rate-determining step energy barrier that is only around half of that for the first pathway. As conformational flexibility plays a crucial role in second pathway, the effect of attaching methyl groups to the alpha carbon atoms was studied. The results obtained are presented for all four possible stereochemical configurations.
通过使用混合 B3LYP 函数和 6-31++G 基组的量子化学计算，研究了两种三肽模型中羰基氧原子之间的矢量质子转移。发现了两条主要的质子转移途径：第一条途径涉及质子在羰基双键周围的异构化，第二条途径基于三肽模型的大构象灵活性，其中所有羰基氧原子都协同作用。后一种途径的速率决定步骤能垒仅为第一种途径的一半左右。由于构象灵活性在第二条途径中起着至关重要的作用，因此研究了在α碳原子上附加甲基基团的影响。给出了所有四种可能的立体化学构型的结果。
