Polyprenols chain length

Although it could be established that saturation of the a-isoprene unit of polyprenol phosphate is important for these compounds to act as effective acceptors of glycosyl moieties in eukaryotic cells, little chain-length specificity was observed in such studies.39-41 This observation found support in the result that the same set of prenylogs occurs in total-yeast dolichol and in dolichol diphosphate-linked 2-acetamido-2-deoxy-D-glucose synthesized in vitro with yeast-cell homogenates.42 As already noted by Chojnacki and coworkers,40 dur-... 

Ibata K., Kageyu A., Takigawa T., Okada M, Nishida T., Mizuno M., Tanaka Y. (1984) Polyprenols from conifers multiplicity in chain length distribution. Phytochem. 23, 2517-21. 

The chemical shifts of the characteristic carbon signals in acyclic terpenes, polyprenols, and cis-trans isomerized poly-isoprenes are plotted in Fig. 3. Here, the chemical shifts are correlated using the w C-5 methyl carbon signal at 17.66 ppm as an internal standard (except for isomerized polyisoprenes) in order to compensate for the effect of solution concentration. It is clear that these chemical shifts are independent of the chain length of the compounds and can be used for the determination of the arrangement of isoprene units as well as the terminal units in various isoprenoid compounds (8). 

The dolichol moiety of lipid-intermediates is not homogeneous but a mixture of 14-20 isoprene units [71-73]. For the yeast OST it was shown that the enzyme hardly discriminates specific isoprene chain lengths [74]. Whether unsaturated poly-prenols, preferred in eubacterial cell wall synthesis, will be accepted is not known. However, the formation of the DolPP-GlcNAc, i.e. the first step in lipid-linked precursor formation shows an absolute dependency for saturation of the a-isoprenoid unit, i.e for dolichol-type polyprenols [74], what seems to be generally true for other eukaryotic glycosyltransferases involved in lipid-linked sugar formation [75, 76]. 

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