Wiesław Jankowski

Preparative separation of naturally occurring mixtures of polyprenols on hydroxyalkoxypropyl-Sephadex.

Abstract A procedure is described for the efficient preparation of individual polyprenols from naturally occurring mixtures of dolichols, ficaprenols, and betulaprenols.

Occurrence of Polyprenols and Dolichols in Plants

Summary Polyprenols of different chain length, composed of five to approximately fifty isoprene units are frequently encountered in the unsaponifiable lipid fraction from leaves of Spermatophyta . Extensive search for these lipids has confirmed common occurrence and frequent accumulation of di- or tri- trans -poly- cis fully unsaturated prenols. Accumulation of α-dihydropolyprenols in leaves seems to be very scarce. Available data obtained in our and other laboratories allow to draw an overview describing occurrence of these prenyllipids in some main taxons of Spermatophyta .

Formation of lipid-linked sugars in rat liver and brain microsomes

Abstract Fractionation of unsaponifiable pig liver lipids on DEAE-cellulose yielded two lipids which stimulate the incorporation of labeled glucose from UDPglucose into lipids of rat liver microsomes. The main one appeared to be dolichol monophosphate. Synthetic ficaprenol phosphate also stimulated the formation of polyisoprenol monophosphate sugar from UDPglucose. Phytol phosphate had no stimulatory effect. No formation of lipid-linked sugars from labeled UDPgalactose was observed in rat liver and brain microsomes.

The enzymic formation of dolichyl phosphate mannose from C-3 enantiomeric dolichyl phosphates

Abstract The racemic, optically inactive mixture of C-3 enantiomeric forms of C 95 -dolichyl phosphate can be prepared chemically from fully unsaturated, di trans -polycis-C 95 -prenol isolated from leaves of Sorbus suecica . Purified mannosyl transferase from yeast was capable of catalysing the mannosylation of over 75% of this 1:1 R / S mixture, demonstrating that both enantiomers could function as acceptors. However, the R -form appears to accept mannose more slowly than the S -form. Both R - and S -forms of C 75 -dolichyl phosphate and C 55 -dolichyl phosphate prepared from the respective plant tri trans -poly cis -prenol were also active as lipid acceptors of mannose from GDPmannose.

Formation of polyprenol monophosphate glucose in Shigella flexneri.

Abstract An enzyme synthesizing polyprenol monophosphate glucose from UDPglucose is present in the membrane fraction from Shigella flexneri 2a; UDPgalactose can also be used as the sugar donor. GDPmannose, UDPglucuronic acid and UDP-N-acetylglucosamine were ineffective. Triton X-100 or deoxycholate were required for enzymic activity. Ficaprenol (mainly C 55 ) phosphate was the most effective lipid acceptor of glucose. The phosphate esters of other polyprenols (phytol, betulaprenol, solanesol and dolichol) were much less effective. Lipid extracts from Sh. flexneri did not stimulate the formation of lipid-linked glucose. No polyprenol phosphate phosphatase was detected in membrane preparations from 2a and Y strains of Sh. flexneri .

Uptake and metabolism of polyprenols by animal cells cultured in vitro

Several mammalian, chicken, and mosquito cells grown in vitro take up tritiated dolichol supplied to the incubation medium. The extent of labelling varied markedly between different cell cultures. After 20 h incubation most of the dolichol taken up was unchanged and the major product of metabolism of dolichol was identified as its fatty acid esters. Green-monkey kidney cells were tested with 8 fully unsaturated and 6 alpha-saturated polyprenols ranging from C35 to C105. In general the uptake of alpha-saturated polyprenols (dolichol type, was higher. Considerable differences were found between the uptake of polyprenols of differing chain lengths. Less than 1% of the polyprenols taken up was converted into more polar product, mainly polyprenyl phosphates and polyprenyl phosphate sugars. The short-chain polyprenols, from C35 to C65, were metabolized more rapidly than the long-chain polyprenols, as judged from the amount of polar products and fatty acid esters of polyprenols.

Specificity of cellular processes and enzymes towards polyisoprenoids of different structure

Abstract Results of the study of the dependence of cellular processes and enzymic reactions on the structure of polyisoprenoids are reviewed. Efficiency and kinetics of the cellular uptake of dolichols are a characteristic feature of a particular cell line. Grown in vitro, cells preferentially take up dolichols or polyprenols built of 95 or 85 and 55 carbons. Essential divergence in the specificity of several enzymes, which catalyze interconversion of dolichols and their fatty acid esters, control intracellular concentration of dolichyl phosphate or utilize it in the reactions leading to glycosylation of proteins, has been noticed. It seems that affinity of the enymes degrading the acyl or phosphate esters of dolichols is not directed towards the dolichol moiety, the esterase which hydrolyze fatty acid esters of dolichols recognizes first of all the moiety of the acylating acid and the phosphatase apparently prefers short chain fully unsaturated polyprenols. Higher specificity toward utilized polyprenoid substrate, expressed as significant preference of dolichols over polyprenols is characteristic for the following enzymes: acyl transferase, dolichol kinase and the transferases of mannose or glucose residue forming the respective dolichylo-monophospho-sugar. Transferases of N-acetylglucosaminyl(phosphate) residue are the most specific of all the enzymes described here: they accept as the lipid substrate only the phosphates of dolichols and the chitobiose residue is transferred onto the peptide acceptor exclusively from the chitobiosyl-pyrophosphate of dolichol of S(−) configuration. Conclusions derived from the studies on the specificity of the enzymes utilizing polyisoprenoids are presented and discussed.

Unusual Fatty Acid Composition of Cuticular Lipids From Leaves of Oenothera

Composition of cuticular lipids washed out with hexane from the surface of fresh leaves of evening primrose ( Oenothera ) was examined. 25 different lipid classes were distinguished in the extract afterwards divided into the neutral (63 %) and acidic lipids (37 %). The main components of the neutral lipid fraction were hydrocarbons and fatty acid esters of sterols or fatty alcohols. Unsaponif iable lipids constituted about 77 % of neutral lipids, however, α-linolenic acid was the principal component (90 %) of the acidic lipid fraction. The occurrence on the leafs surface of high concentration of α-linolenic acid and only trace amounts of trienoic acids with conjugated double bonds, originated from it by oxidative rearrangement, is very unusual. The mechanism of protection of α-linolenic acid against oxidative degradation remains to be explained.

The occurrence and characteristics of long chain polyprenols from leaves of Sapindaceae

Summary A number of species of the Sapindaceae family, characteristic for tropical flora mainly of South East Asia were found to contain large amounts of C 50–75 -polyprenols in leaves. C 60- , C 65- and C 70- polyprenols accumulated in leaves of Nephelium litchii and Euphoria longean were isolated, purified and analyzed by mas spectrometry and nuclear magnetic resonance spectrometry. Their structure was found to be of the tri-traps-poly-cis type similar to that of C 55- and C 60- polyprenols occurring in most angiosperm plants. They differ from the polyprenols of the same chain length isolated from gymnosperm plant ( Picea abies ) which were confirmed to be di-traps-poly-cis-prenols. The presence of C 60- , 70- polyprenols in leaves is the characteristic chemotaxonomic marker for the majority of studied species of Sapindaceae family.