Channel and nonchannel forms of spin-labeled gramicidin in membranes and their equilibria.

ABSTRACT: Channel and nonchannel forms of gramicidin A (GA) were studied by ESR in various lipid environments using new mono- and double-spin-labeled compounds. For GA channels, we demonstrate here how pulse dipolar ESR can be used to determine the orientation of the membrane-traversing molecule relative to the membrane normal and to study subtle effects of lipid environment on the interspin distance in the spin-labeled gramicidin channel. To study nonchannel forms of gramicidin, pulse dipolar ESR was used first to determine interspin distances corresponding to monomers and double-helical dimers of spin-labeled GA molecules in the organic solvents trifluoroethanol and octanol. The same distances were then observed in membranes. Since detection of nonchannel forms in the membrane is complicated by ag

SUBMITTER: Dzikovski BG 

PROVIDER: S-EPMC3076037 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature