Cooperative influence of water binding to peptides by N-H?OH _2 and C=O?HOH hydrogen bonds: Study by Ab Initio calculations

摘要

In this article, the geometry structures of hydrogen bond chains of formamide and N-methylacetamide and their hydrogen-bonded complexes with water were optimized at the MP2/6-31G* level. Then, we performed M?ller-Plesset perturbation method with 6-311++g**, aug-cc-pvtz basis sets to study the cooperative influence to the total hydrogen bond energy by the N-H?OH _2 and C=O?HOH hydrogen bonds. On the basis of our results, we found that the cooperativity of the hydrogen-bonded complexes become weaker as N-H?OH _2 and C=O?HOH hydrogen bonds replacing N-H?O=C hydrogen bonds in protein and peptide. It means that the N-H and C=O bonds in peptide prefer to form N-H?O=C hydrogen bond rather than to form C=O?HOH and N-H?OH _2. It is significant for understanding the structures and properties of the helical or sheet structures of protein and peptide in biological systems.