31P-NMR studies of oriented multilayers formed from isolated sarcoplasmic reticulum and reconstituted sarcoplasmic reticulum Evidence that ‘boundary-layer’ phospholipid is not immobilized

摘要: 31P-NMR spectra were obtained from oriented multilayer preparations of normal sarcoplasmic reticulum and reconstituted with lipid to protein ratios varying between 42 : 1 110 1. The dependence the on alignment membranes respect magnetic field was used draw two conclusions about motion phospholipid molecules that contribute observed spectra. First, phosphate group adjacent methylene groups are able rapidly rotate (i.e., τR⪡⪡10−5S) around plane membrane. Second, restricted internal glycerol CH2OP is very similar found in liposomes formed phospholipids. Calibration experiments showed all (100 ± 7%) membrane can be accounted for Thus, essentially have same polar headgroup region as model bilayer membranes. Since a large fraction (between one-quarter one-half, depending ratio) immediately surrounding calcium-pump protein, we conclude does not perturb these ‘boundary-layer’ lipids.