Date of Award


Degree Type


Degree Name

Doctor of Philosophy


The seeds of monocotyledonous plants contain both dolichol, an homologous series of {dollar}\alpha{dollar}-saturated polyisoprenoid alcohols, and polyprenol, and homologous series of {dollar}\alpha{dollar}-unsaturated polyisoprenoid alcohols. Dolichyl phosphate (Dol-P) participates in the N-glycosylation of proteins. The function of polyprenol is unknown. Several possible roles for polyprenol were investigated in rye (Secale cereale L.). Methods for the extraction, separation, analysis, and quantification of polyisoprenoids were developed. Rye embryos contained twice as much polyprenol as dolichol; the ratio of polyprenyl phosphate to dolichyl phosphate was estimated at three to one.;Experiments on the metabolic labelling of polyisoprenoids with ({dollar}\sp3{dollar}H) H{dollar}\sb2{dollar}O, H{dollar}\sb3\lbrack\sp{lcub}32{rcub}{dollar}P) PO{dollar}\sb4{dollar}, or ({dollar}\sp{lcub}14{rcub}{dollar}C) mevalonolactone revealed that, during germination, the polyisoprenyl phosphates were formed by the phosphorylation of existing polyisoprenols and not be de novo synthesis. Polyprenol was not a precursor for dolichol, as the label that appeared in polyprenol could not be chased into dolichol, even after 48 h.;Dolichol kinase in microsomes from etiolated rye shoots was characterized. It had a low affinity for dolichol (K{dollar}\sb{lcub}\rm m{rcub}{dollar} in excess of 210 {dollar}\mu{dollar}M), a pH optimum of 8, and no need for divalent cations or exogenous nucleoside triphosphates. Cold polyprenol prevented the formation of ({dollar}\sp{lcub}14{rcub}{dollar}C) Dol-P nearly as well as comparable amounts of cold dolichol. ({dollar}\sp3{dollar}H) Polyprenol was synthesized in order to test the phosphorylation of polyprenol directly. Microsomes from rat liver phosphorylated ({dollar}\sp3{dollar}H) polyprenol poorly compared to ({dollar}\sp{lcub}14{rcub}{dollar}C) dolichol, while rye and soybean microsomes phosphorylated ({dollar}\sp3{dollar}H) polyprenol about 30% as well as ({dollar}\sp{lcub}14{rcub}{dollar}C) dolichol.;Several enzymes which act on dolichol were assayed in cultured peanut cells grown under lead stress or normal conditions. Lead stress increased dolichol kinase activity by 2-fold, and reduced GlcNAc transferase activity by about 80% and mannosyltransferase activity by about 50%.;In rye embryo microsomes, GlcNAc transferase activity was barely detectable, and mannosyltransferase was 36% of that in rye shoot microsomes. The replacement of Dol-P with Pol-P in the mannosyltransferase assay gave 8% activity. The formation of Dol-P-Glc was not observed under the assay conditions used; ({dollar}\sp3{dollar}H) Glc was incorporated into compounds with the properties of glucosylsitosterol or cerebrosides.



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