ESR determination of lipid translational diffusion coefficients at low spin-label concentrations in biological membranes, using exchange broadening, exchange narrowing, and dipole-dipole interactions

Selectivity of interaction of spin-labelled lipids with peripheral proteins bound to dimyristoylphosphatidylglycerol bilayers, as determined by ESR spectroscopy

“…Typical lipid translational diffusion rates in fluid dimyristoyl phosphatidylcholine bilayers are: v,~+= 4DT/( x 2 ) = (7-9). 107 s-t [15], and our unpublished values for DMPG are of a similar order of mag~nitude. Thus the fast exchange approximation may hold, at least for the spin-labelled lipids with smaller values of AAron.…”

“…Hen egg white lysozyme and poly(L-lysine). HBr (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) were from Serva (Heidelberg, F.R.G.). 5-DGSL was synthesized from 5-PCSL by a phospholipase C (Boehringer-Mannheim) catalyzed hydrolysis reaction [4].…”

Field Gradient ESR and Molecular Diffusion in Model Membranes

“…At 22°C, D ... ,micro = (1.0 ± 0.4) x 10-7 cm2 s -I. By comparison, linewidth studies by Sachse et al (60) yielded Dmicro = 1.2 x 10 -7 cm2 s -I (from the HE contribution) at 30°C for 16-PC in DMPC.…”

“…Nevertheless, these meth ods are extremely important for investigating the microscopic dynamic molecular structure of membranes. Several groups have used micro scopic ESR methods to measure translational diffusion over distances of molecular dimensions in model membranes (4,22,56,60). Although ESR techniques can potentially be used to study the diffusion of com ponents at a microscopic scale in mixed membranes, there have been no reports on this matter.…”

Regulation of KCNQ/Kv7 family voltage-gated K + channels by lipids

“…Spin-labeled lipids in protein-lipid systems show a transiently immobilized subpopulation corresponding to lipids associated with the membrane protein [32]. The lipid on-rate constant is assumed to be diffusion controlled, while the off-rate reflects the strength of the protein-lipid interaction [33]. The acyl chains of the annular lipids are conformationally restricted relative to bulk lipids as a consequence of packing against the protein transmembrane surface.…”