Comparison of Various Types of Hydrogen Bonds Involving Aromatic Amino Acids

• DOI: 10.1021/ja027200q
• Publication Date: 2002-10-30T06:16:59Z
• Authors: Steve Scheiner; Tapas Kar; Jayasree Pattanayak
• Keywords: Imidazole; Residue (chemistry)

Ab initio calculations are used to compare the abilities of aromatic groups Phe, Tyr, Trp, and His amino acids (modeled respectively by benzene, phenol, indole, imidazole) form H-bonds three different types. Strongest all conventional (e.g., OH··O OH··N). forms strongest such H-bond, followed then Trp. Whereas OH··φ bonds formed approach a proton donor π electron cloud above system somewhat weaker, they nonetheless represent an important class stabilizing interactions. The strengths in this category follow trend Trp > Tyr ∼ Phe. CH··O interactions weaker still, only those involving strong enough make significant contributions protein structure. A protonated residue as HisH+ makes for very powerful donor, that even its stronger than neutral groups.