Evidences for Cooperative Resonance-Assisted Hydrogen Bonds in Protein Secondary Structure Analogs.

ABSTRACT: Cooperative behaviors of the hydrogen bonding networks in proteins have been discovered for a long time. The structural origin of this cooperativity, however, is still under debate. Here we report a new investigation combining excess infrared spectroscopy and density functional theory calculation on peptide analogs, represented by N-methylformamide (NMF) and N-methylacetamide (NMA). Interestingly, addition of the strong hydrogen bond acceptor, dimethyl sulfoxide, to the pure analogs caused opposite effects, namely red- and blue-shift of the N-H stretching infrared absorption in NMF and NMA, respectively. The contradiction can be reconciled by the marked lowering of the energy levels of the self-associates between NMA molecules due to a cooperative effect of the hydrogen bonds. On the contr

SUBMITTER: Zhou Y 

PROVIDER: S-EPMC5111121 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature