Paramagnetic isoprenoid carrier lipids. 1. Chemical synthesis and incorporation into model membranes.
The synthesis, purification, and characterization of two types of spin-labeled glycosyl carrier lipids and shorter chain isoprenols are described. As models for phosphorylated lipids intermediates, phosphodiesters of tempol and the prenols dolichol, ficaprenol, solanesol, phytol, and farnesol were prepared. For analogues of neutral species each prenol was esterified with a pyrrolidinecarboxylic acid based label. Tripropylbenzenesulfonyl chloride was used as the condensing agent in both cases. Phosphodiester yields ranged from 36% for the 55-carbon compound to greater than 66% for the 95-carbon prenol. Both types of probes were incorporated into phospholipid bilayers, where each became oriented with the artificial head group at, or very close to, the water--hydrocarbon interface. Electron spin resonance spectra of the phosphodiesters are matrix dependent, indicating rapid isotropic tumbling in chloroform but highly anisotropic reorientation in unsaturated phosphatidylcholine (PC) hosts. Rotation or large amplitude oscillation about either or both the tempo C4--O linkage and the P--O (chain) bond as well as whole molecule rotation within the bilayer could account for the observed x-axis anisotropy. Segmental motion within the polyprene chain does not appear to be a determinant.
D004288:Dolichol Phosphates / Q000138:chemical synthesis; D004286:Dolichols; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D008099:Liver; D009682:Magnetic Resonance Spectroscopy; D008567:Membranes, Artificial; D008968:Molecular Conformation; D011106:Polyisoprenyl Phosphates / Q000138:chemical synthesis; D013055:Spectrophotometry, Infrared; D013113:Spin Labels
D004288:Dolichol Phosphates; D004286:Dolichols; D008567:Membranes, Artificial; D011106:Polyisoprenyl Phosphates; D013113:Spin Labels