title: Determination of arrangement of isoprene units in pig liver dolichol by 13C-n.m.r. spectroscopy.
abstract: The arrangement of isoprene units in pig liver dolichol-18, -19 and -20 was determined by 1H- and 13C-n.m.r. spectroscopies. The alignment of trans and cis isoprene units was found to be in the order: dimethylallyl unit, two trans units, a sequence of 14-16 cis units, and a saturated isoprene unit terminated with a hydroxyl group, which verified the presumed chemical structure of dolichol. The absence of geometric isomers was confirmed. A slight amount of impurity was detected in each reversed-phase h.p.l.c. fraction of dolichol obtained by a conventional method. Detailed assignments of the 13C-n.m.r. spectrum were given for these dolichols by using model compounds and INEPT (insensitive nuclei enhanced by polarization transfer) measurement. The chemical structure of synthetic dolichol-19, which was prepared by the addition of a saturated isoprene unit to the polyprenol-18 isolated from Ginkgo biloba, was confirmed to be identical with that of pig liver dolichol-19.
mesh_terms: D000818:Animals; D002070:Butadienes / Q000032:analysis*; D004224:Diterpenes; D004286:Dolichols; D045782:Hemiterpenes; D008099:Liver / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D010420:Pentanes; D013552:Swine
chemical_list: D002070:Butadienes; D004224:Diterpenes; D004286:Dolichols; D045782:Hemiterpenes; D010420:Pentanes; C005059:isoprene