Interfacial tryptophan residues: a role for the cation-pi effect?

ABSTRACT: Integral membrane proteins are characterized by having a preference for aromatic residues, e.g., tryptophan (W), at the interface between the lipid bilayer core and the aqueous phase. The reason for this is not clear, but it seems that the preference is related to a complex interplay between steric and electrostatic forces. The flat rigid paddle-like structure of tryptophan, associated with a quadrupolar moment (aromaticity) arising from the pi-electron cloud of the indole, interacts primarily with moieties in the lipid headgroup region hardly penetrating into the bilayer core. We have studied the interaction between the nitrogen moiety of lipid molecule headgroups and the pi-electron distribution of gramicidin (gA) tryptophan residues (W9, W11, W13, and W15) using molecular dynamics (MD)

SUBMITTER: Petersen FN 

PROVIDER: S-EPMC1366964 | biostudies-literature | 2005 Dec

REPOSITORIES: biostudies-literature