Polyisoprenoid alcohol phosphate

Stage 2. This stage comprises the assembly of the two nucleotide precursors into disaccharide pentapeptide units. -1,4-GlNAc-MurNAc-pentapeptide, and their transport via an intermediate carrier to a final acceptor, i.e. the growing wall peptidoglycan (Fig. S) Several particulate enzymes and a C55 polyisoprenoid alcohol phosphate, most probably located on the cytoplasmic membrane, are involved in a complex cyclic reaction that may be visualized as a sequence of three transfer reactions. First, the MurNAc (pentapeptide)-monophosphate residue... 

Isoprenoid Lipids.—Lipids which contain a mono- or pyro-phosphate link between a polyisoprenoid alcohol and a carbohydrate residue are important intermediates in the biosynthesis of bacterial cell walls. The monophosphate derivatives are probably involved in the addition of single carbohydrate residues to existing polysaccharide chains while the pyrophosphates are probably intermediates in the biosynthesis of the main chain. Ficaprenyl (13 = 10), famesyl (13 = 2), dolichyl (14 n = 18), and citro-nellyl (14 n = 1) a-D-mannopyranosyl phosphates have now been... 

Dolichols. Group of polyisoprenoid alcohols (polyiso-prenes) with an a-saturated isoprene unit and a terminal primary alcohol group. The number of isoprene units varies in higher eukaryotes between 14 and 20. A D. with 20 isoprene units (C100H164O, Mr 1382.40, viscous, colorless oil, mp. -10°C, CAS [2067-66-5]) was first isolated from kidney tissue. D. occur in animal and plant organisms as free D. or esterified with long-chain fatty acids or, respectively, phosphoric acid (dolichyl phosphates). ... 

Dolichols (98), a family of polyisoprenoid alcohols, have isolated from all eukaryotic cells or archaebacteria." They play a role in the co-translational modification of proteins and are known in iV-glycosylation in the form of dolichol phosphate. The synthesis of the photochemical probes 118 and 119 bearing a photoreactive group [3-(trifiuoromethyl)-3-aryldiazirine], analogues of dolichol and dolichol phosphate, is described in Scheme 5.19. The synthetic strategy involves the sequential alkylation of a monoterpenoid hydroxysulfonyl dianion with allyl chlorides, and MBH adduct 102 as a starting material. 

Long-chain polyisoprenoid. molecules with a terminal alcohol moiety are called, polyprenols. The dolichols, one class of polyprenols (Figure 8.18), consist of 16 to 22 isoprene units and, in the form of dolichyl phosphates, function to carry carbohydrate units in the biosynthesis of glycoproteins in animals. Polyprenyl groups serve to anchor certain proteins to biological membranes (discussed in Chapter 9). 

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