title: Ubiquinones: stereochemistry and biological implications.
abstract: Proton NMR and 13C-NMR studies on the configuration of CoQn homologues show that the polyisoprenoid side-chain is in the all-trans configuration and confers a higher degree of rigidity to the quinones with respect to the acyl-chains of the phospholipids within the membrane bilayer. The quinonoid ring appears to be specifically involved in the redox function of the coenzyme while the side-chain length only affects the lipophilicity of the molecule. LIS data show that the ring strongly interacts with metals as a consequence of the high pi-electron density on the carbonyls that is somewhat larger on the carbonyl oxygen to alpha to the isoprenoid chain.
mesh_terms: D002247:Carbon Isotopes; D055598:Chemical Phenomena; D002621:Chemistry; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D008674:Metals, Rare Earth; D008968:Molecular Conformation; D011522:Protons; D014451:Ubiquinone / Q000494:pharmacology
chemical_list: D002247:Carbon Isotopes; D008674:Metals, Rare Earth; D011522:Protons; D014451:Ubiquinone; C025203:Ubiquinone Q1