Alexander P. Tulloch

A study of mobility and order in model membranes using 2H NMR relaxation rates and quadrupole splittings of specifically deuterated lipids

Abstract 2 H NMR spectra have been observed for several selectively deuterated phospholipid and fatty acid probes intercalated in the liquid crystalline phase of egg phosphatidylcholine in aqueous dispersion. For unsonicated lamellar dispersions and planar multibilayers, quadrupole splittings may be observed which lead directly to a value for the order parameter for the carbon-deuterium bond. Sonicated dispersions yield high-resolution spectra, from which spin-lattice relaxation rates and correlation times for rotational diffusion can be obtained. The presence of cholesterol in the dispersion has no effect on the quadrupole splittings and relaxation rates for 2 H in the choline methyl groups, in contrast to its profound effect on the spectra for 2 H in the hydrocarbon chains.

Beeswax: Structure of the esters and their component hydroxy acids and diols☆

Abstract Beeswax has been separated into hydrocarbons (14%), monoesters (35%), diesters (14%), triesters (3%), hydroxy monoesters (4%), hydroxypolyesters (8%), free acids (12%), acid monoesters (1%), acid polyesters (2%) and unidentified material (7%). The esters have been identified by thin layer chromatography, gas liquid chromatography and nuclear magnetic resonance spectroscopy and by comparison with synthetic mono-, di- and triesters, hydroxy mono- and diesters and acid esters. The compositions of the acids, hydroxy acids, alcohols and diols from each ester fraction have been determined by gas liquid chromatography. The major hydroxy acid (70%) obtained on hydrolysis was 15-hydroxyhexadecanoic acid, other hydroxy acids were 14-hydroxyhexadecanoic, 16-hydroxyoctadecanoic, 17-hydroxyoctadecanoic, 19-hydroxyeicosanoic, 21-hydroxydocosanoic and 23-hydroxytetracosanoic acids. The diols were 1,23-tetracosanediol, 1,25-hexacosanediol, 1,27-octacosanediol and 1,29-triacontanediol. Minor amounts of α, ω-C 24 -C 28 diols were also detected. The hydroxy acids and diols were mixtures of d - and l -isomers with the l -isomer predominating.

Composition of leaf surface waxes of Triticum species: Variation with age and tissue☆

Abstract The composition of cuticular wax from plants of spring wheat (varieties Selkirk and Manitou) and of durum wheat (variety Stewart 63) at various stages of growth, and of wax from different parts of the plants varies considerably. Wax was analysed, without preliminary separation, by GLC using Dexsil 300 as liquid phase. Alcohols are major components of wax from leaf blades and β-diketones are major components of wax from leaf sheaths, especially the flag leaf sheath. Glaucousness of the leaf sheath is due to the high β-diketone content. In the first 50 days after germination, before sheaths and flag leaf are completely developed, the major component is octacosanol (> 50%). At 66 days, when sheath development is complete, β-diketone content is greatest. Hydrocarbon composition differs for wax from leaf blade and leaf sheath and also for different leaf blades and between adaxial and abaxial sides of the flag leaf. From 66 to 100 days ester content of wax increases, especially in Selkirk wheat, apparently due to formation of wax containing high proportions of esters of trans-α,β-unsaturated C22 and C24 acids. The content of these acids in the free fatty acids and of diesters based on these acids also increases during this period.

Leaf wax of Triticum aestivum

Abstract Leaf waxes from spring wheat varieties Selkirk and Manitou contain hydrocarbons (6%, 10%), long chain esters (14%, 13%), free acids (5%, 8%), free alcohols (19%, 21%), β-diketone (16%, 20%), hydroxy β-diketones (8%, 10%), unidentified gum (29%, 16.5%) and minor amounts of diol diesters, glycerides and aldehydes. The major hydrocarbon is nonacosane and major esters are octacosyl esters of C 14 –C 32 acids but C 20 and C 22 alcohol esters of trans 2-docosenoic and tetracosenoic acids are also present (Selkirk 20%, Manitou 10% of total esters). Previously unknown trans 2-docosen-1-ol is present as an ester (Selkirk 5%, Manitou 2.5% of total esters). Free acids are C 14 –C 32 acids and trans 2-docosenoic and tetracosenoic acids (Selkirk 30%, Manitou 9% of free acids). Octacosanol is the principal free alcohol. Hentriacontane-14,16-dione is the β-diketone and the hydroxy β-diketones are a 1:1 mixture of 8- and 9- hydroxyhentriacontane-14,16-diones.

The properties of gel state lipid in membranes of acholeplasma laidlawii as observed by 2H NMR

Deuterium nuclear magnetic resonance (‘H NMR) has proven to be an informative, perturbation-free monitor of the molecular organization of lipids in model [ 1,2] and biological [3,4] membranes. However, in most cases studies have been limited to the liquid crystalline squid) state of the membrane lipids due to the difficulty of observing the broad spectrum of the gel phase. With the innovation of the quadrupole echo technique [S] , and attention to various aspects of spectrometer design, it is now possible to observe these broad ‘H powder spectra [4,6]. We describe here a detailed study of the palmitoyl chains in the lipids of A. 2aidlawiz’membranes over the temperature range 145°C. We have shown that the gel and liquid crystalline states of the lipid coexist in slow exchange over the range of the calorimetricallyobserved gel-liquid crystal transition. Only -25% of the palmitoyl chains are still in the liquid crystalline state at the low temperature end of the calorimetricallydetermined transition region. At this temperature, the orientations of those chains in the gel phase still undergo considerable motion. There is a distribution of o~entation~ order parameters, the average being -50% that of completely immobilized chains. This average value is that expected for chains in the alltrans conformation rotating about their long axes. As the temperature is lowered below the transition region, the number of immobilized acyl chainsincreases steadily down to 1°C where almost all the chains are

TORULOPSIS BOMBICOLA SP. N.

A new yeast species,Torulopsis bombicola, is described, that produces extracellular hydroxy fatty acid sophorosides. It utilizes relatively few carbon compounds. It forms a mannan having a proton magnetic resonance spectrum similar to the spectra of the galactomannans ofTorulopsis apis, Torulopsis nodaensis andT. magnoliae, but differing from those ofT. gropengiesseri galactomannan andT. apicola mannan.

Epicuticular waxes of Secale cereale and Triticale hexaploide leaves

Wax on leaves of rye and of hexaploid Triticale (60–70-day-old plants) contains hydrocarbons (6–8%), esters (10%), free alcohols (14-8%), free acids (3%), hentriacontane-14,16-dione (39–45%), 25 (S)-hydroxyhentriacontane-14,16-dione (13–11%) and unidentified (14–15%). Diesters (1–3%) are also present in rye wax. Compositions of hydrocarbons (C27-C33) and esters (C28,C58) are similar for both waxes. Free and combined alcohols of rye wax are mainly hexacosanol but alcohols of Triticale wax are mainly octacosanol. The composition of Triticale wax is close to that of its wheat parent Triticum durum (cv. Stewart 63). Esters of wax from ripe rye contain 58% of trans 2,3-unsaturated esters. *NRCC No. 14033.

Leaf Wax of Durum Wheat

Abstract : Leaf waxes from durum wheat varieties Pelissier and Stewart 63 contained hydrocarbons (9%), esters (9%), alcohols (17%), acids (3%), beta-diketone (36%), hydroxy beta-diketone (9%) and unidentified material (17%). The major hydrocarbon was nonacosane, the C36-C56 esters were esters of C20-C28 alcohols with C16-C30 saturated acids and trans 2-docosenoic and 2-tetracosenoic acids, and the principal alcohol was octacosanol. The beta-diketone was hentriacontane-14,16-dione and the hydroxy beta-diketone was 25(S)-hydroxyhentriacontane-14,16-dione. (Author)

Epicuticular waxes of abies balsamea and picea glauca: Occurrence of long-chain methyl esters

Abstract Epicuticular wax from Abies balsamea contains methyl esters (7%), hexyl and octyl esters (9%), nonacosan-10-ol (14%), free acids (20%), diterpene acids (3%) and free acids and diols (2%) and wax from Picea glauca has methyl esters (6%), hexyl and octyl esters (5%), aldehydes (3%), nonacosan-10-ol (30%), free acids (3%), diterpene acids (10%) and free alcohols and diols (2%). The major methyl ester is methyl triacontanoate; the long-chain esters are C 30 C 44 hexyl and octyl esters of C 24 C 34 acids; the major aldehyde is triacontanal. Major free acids and alcohols are C 16 C 32 and the principal diol is nonacosane-5,10-diol.

Synthesis of deuterium and carbon-13 labelled lipids☆

Abstract Methods of preparing deuterated fatty acids by exchange and reduction, reaction with small deuterated compounds and synthesis using deuterated intermediates and biological synthesis are discussed. About 100 deuterated fatty acids are listed. Synthesis of a number of deuterated glycerides and phospholipids are also described. Preparations of twenty [13C]fatty acids and a few [13C]phospholipids are considered.