Experimental Measurement of the Strength of a Cα-H…O Bond in a Lipid Bilayer

摘要

The energy of interaction between two dipoles is strongly dependent on the distance between the dipoles and the polarity of the solvent. As such, interactions that would normally be regarded as weak and insignificant in an aqueous environment may be substantial in the hydrophobic lipid bilayer milieu. One such interaction is the hydrogen bond between the nonpolar C hydrogen and a carbonyl oxygen, thought to take place as a stabilization driving force in numerous transmembrane -helical bundles.1 As an example, the GxxxG motif, which forms the protein-protein interface in the transmembrane helical dimer of glycophorin A (GPA),2 is thought to drive dimerization due (in part) to a Gly Cα-H…O bond1. Thus, the close apposition of the helices, enabled by the small side chain of the Gly residues, facilitates the formation of a Cα-H…O bond.