Frequent side chain methyl carbon-oxygen hydrogen bonding in proteins revealed by computational and stereochemical analysis of neutron structures (Proteins: Structure, Function, and Bioinformatics)

The propensity of backbone C? atoms to engage in carbon-oxygen (CH?O) hydrogen bonding is well-appreciated in protein structure, but side chain CH?O hydrogen bonding remains largely uncharacterized. The extent to which side chain methyl groups in proteins participate in CH?O hydrogen bonding is examined through a survey of neutron crystal structures, quantum chemistry calculations, and molecular dynamics simulations. Using these approaches, methyl groups were observed to form stabilizing CH?O hydrogen bonds within protein structure that are maintained through protein dynamics and participate in correlated motion. Collectively, these findings illustrate that side chain methyl CH?O hydrogen bonding contributes to the energetics of protein structure and folding. This article is protected by copyright. All rights reserved.