C18 Unsaturated Fatty Acid Research Articles

A telomere-to-telomere gap-free reference genome assembly of avocado provides useful resources for identifying genes related to fatty acid biosynthesis and disease resistance.

Avocado (Persea americana Mill.) is an economically valuable plant because of the high fatty acid content and unique flavor of its fruits. Its fatty acid content, especially the relatively high unsaturated fatty acid content, provides significant health benefits. We herein present a telomere-to-telomere gapless genome assembly (841.6Mb) of West Indian avocado. The genome contains 40 629 predicted protein-coding genes. Repeat sequences account for 57.9% of the genome. Notably, all telomeres, centromeres, and a nucleolar organizing region are included in this genome. Fragments from these three regions were observed via fluorescence in situ hybridization. We identified 376 potential disease resistance-related nucleotide-binding leucine-rich repeat genes. These genes, which are typically clustered on chromosomes, may be derived from gene duplication events. Five NLR genes (Pa11g0262, Pa02g4855, Pa07g3139, Pa07g0383, and Pa02g3196) were highly expressed in leaves, stems, and fruits, indicating they may be involved in avocado disease responses in multiple tissues. We also identified 128 genes associated with fatty acid biosynthesis and analyzed their expression patterns in leaves, stems, and fruits. Pa02g0113, which encodes one of 11 stearoyl-acyl carrier protein desaturases mediating C18 unsaturated fatty acid synthesis, was more highly expressed in the leaves than in the stems and fruits. These findings provide valuable insights that enhance our understanding of fatty acid biosynthesis in avocado.

English

An experiment was conducted to determine fatty acid (FA) pro?les in Chinese Maiwa yak milk across the lactation cycle. Sixty-one healthy, similar weight, 4-7 years old, 3-6 parity Maiwa yaks with unrelated background were selected randomly from Hongyuan County, Sichuan province, in southwest of China (with the altitude over 3500 m). The yaks graze on natural pasture all year around without irrigation, fertilizer, or other changes to the pasture. The samples for each animal were collected separately at 1, 2, 3, 4, 5, 6, 7, 15, 30, 60, 120 and 180 days postpartum for fatty acid composition analysis. The most abundant FA species in yak milk were C16:0, C18:1c9, C18:0 and C14:0, all of which varied significantly with the lactation periods. C10:0, C12:0, C14:0 and C16:0 was positively correlated with each other, and negatively correlated with C18:0. C18:2t9c11 was negatively correlated with saturated FA (SFA). C18:1t11, iso-C15:0, C22:0 and C16:1c7 were located in the central positions of the correlation network. C18:1t11 showed close correlation with C18 unsaturated fatty acid (UFA) (C18:1t13 and C18:3n3), C16:0, C19:0, and anteiso-C17:0. Besides with each other, iso-C15:0 and C22:0 were associated with C15:0, anteiso-C15:0, C19:0, C20:0, and C20:0, anteiso-C15:0, iso-C14:0, 9,10-hexyl-C17:0, respectively. C16:1c7 was closely associated with C13:0, C17 FA (C17:0 and 9, 10-hexyl-C17:0), C16:1c9, C20:5n3 and C20:4n6. In conclusion, these data will be informative for the study on the regulatory mechanism of milk FA formation in yaks.   Key words: Correlations, fatty acid profile, lactation periods, Qinghai-Tibetan plateau, yak.  

Effect of Genotype × Environment Interaction for Seed Traits in Winter Oilseed Rape (Brassica napus L.)

Brassica napus (L.), winter oilseed rape (WOSR) or canola, is one of the most important oilseed crop species of the moderate climate zone. Improving the seed quality and yield makes the main target in breeding programs worldwide. In this study, we examined the genotype-by-environment (G×E) interaction with respect to six seed traits among 25 WOSR genotypes. The plant material included the registered canola cultivars, our newly developed mutant breeding lines and the Ogura F1 hybrids and their parental components, in addition to our domestic breeding lines including two semi-resynthesized (semi-RS) lines. The 25 genotypes were examined in field trials at two locations, in three growing seasons. Seed oil and protein content, total glucosinolates (GLS) content in seed meal and C18 unsaturated fatty acid (oleic, linoleic and linolenic) composition in seed oil were examined. The additive main effects and multiplicative interaction (AMMI) analyses revealed significant effects of both, genotype (G) and environment (E) as well as the G×E interaction regarding the analyzed seed traits. In our study, two Ogura F1 hybrids, a CMS line and a new high oleic mutant breeding line revealed high stability and good average values for most of the analyzed seed traits, thus making a valuable source of starting materials for further improvement.

Elaidate, a trans fatty acid, suppresses insulin signaling for glucose uptake in a manner distinct from that of stearate

The dietary intake of elaidate (elaidic acid), a trans-fatty acid, is associated with the development of various diseases. Since elaidate is a C18 unsaturated fatty acid with a steric structure similar to that of a C18 saturated fatty acid (stearate), we previously revealed that insulin-dependent glucose uptake was impaired in adipocytes exposed to elaidate prior to and during differentiation similar to stearate. However, it is still unknown whether the mechanism of impairment of insulin-dependent glucose uptake due to elaidate is similar to that of stearate. Here, we indicate that persistent exposure to elaidate has particular effects on insulin signaling and GLUT4 dynamics. Insulin-induced accumulation of Akt at the plasma membrane (PM) and elevations of phosphorylated Akt and AS160 levels in whole cells were suppressed in adipocytes persistently exposed to 50 μM elaidate. Interestingly, persistent exposure to the same concentration of stearate has no effect on the phosphorylated Akt and AS160 levels. When cells were exposed to these fatty acids, elaidate suppressed insulin-induced fusion, but not translocation, of GLUT4 storage vesicles in the PM, whereas stearate did not suppress the fusion and translocation of GLUT4 storage, indicating that elaidate has suppressive effects on the accumulation of Akt and fusion of GLUT4 storage vesicles and that both elaidate and stearate vary in the mechanisms by which they impair insulin-dependent glucose uptake.

SMRT sequencing of a full-length transcriptome reveals transcript variants involved in C18 unsaturated fatty acid biosynthesis and metabolism pathways at chilling temperature in Pennisetum giganteum

BackgroundPennisetum giganteum, an abundant, fast-growing perennial C4 grass that belongs to the genus Pennisetum, family Poaceae, has been developed as a source of biomass for mushroom cultivation and production, as a source of forage for cattle and sheep, and as a tool to remedy soil erosion. However, having a chilling-sensitive nature, P. giganteum seedlings need to be protected while overwintering in most temperate climate regions.ResultsTo elucidate the cold stress responses of P. giganteum, we carried out comprehensive full-length transcriptomes from leaf and root tissues under room temperature (RT) and chilling temperature (CT) using PacBio Iso-Seq long reads. We identified 196,124 and 140,766 full-length consensus transcripts in the RT and CT samples, respectively. We then systematically performed functional annotation, transcription factor identification, long non-coding RNAs (lncRNAs) prediction, and simple sequence repeat (SSR) analysis of those full-length transcriptomes. Isoform analysis revealed that alternative splicing events may be induced by cold stress in P. giganteum, and transcript variants may be involved in C18 unsaturated fatty acid biosynthesis and metabolism pathways at chilling temperature in P. giganteum. Furthermore, the fatty acid composition determination and gene expression level analysis supported that C18 unsaturated fatty acid biosynthesis and metabolism pathways may play roles during cold stress in P. giganteum.ConclusionsWe provide the first comprehensive full-length transcriptomic resource for the abundant and fast-growing perennial grass Pennisetum giganteum. Our results provide a useful transcriptomic resource for exploring the biological pathways involved in the cold stress responses of P. giganteum.

The hydrophobic region of the Leishmania peroxin 14: requirements for association with a glycosome mimetic membrane.

Protein import into the Leishmania glycosome requires docking of the cargo-loaded peroxin 5 (PEX5) receptor to the peroxin 14 (PEX14) bound to the glycosome surface. To examine the LdPEX14-membrane interaction, we purified L. donovani promastigote glycosomes and determined the phospholipid and fatty acid composition. These membranes contained predominately phosphatidylethanolamine, phosphatidylcholine, and phosphatidylglycerol (PG) modified primarily with C18 and C22 unsaturated fatty acid. Using large unilamellar vesicles (LUVs) with a lipid composition mimicking the glycosomal membrane in combination with sucrose density centrifugation and fluorescence-activated cell sorting technique, we established that the LdPEX14 membrane-binding activity was dependent on a predicted transmembrane helix found within residues 149-179. Monolayer experiments showed that the incorporation of PG and phospholipids with unsaturated fatty acids, which increase membrane fluidity and favor a liquid expanded phase, facilitated the penetration of LdPEX14 into biological membranes. Moreover, we demonstrated that the binding of LdPEX5 receptor or LdPEX5-PTS1 receptor-cargo complex was contingent on the presence of LdPEX14 at the surface of LUVs.

Differential tissue accumulation of 2,3,7,8-Tetrachlorinated dibenzo-p-dioxin in Arabidopsis thaliana affects plant chronology, lipid metabolism and seed yield.

BackgroundDioxins are one of the most toxic groups of persistent organic pollutants. Their biotransmission through the food chain constitutes a potential risk for human health. Plants as principal actors in the food chain can play a determinant role in removing dioxins from the environment. Due to the lack of data on dioxin/plant research, this study sets out to determine few responsive reactions adopted by Arabidopsis plant towards 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most toxic congener of dioxins.ResultsUsing a high resolution gas chromatography/mass spectrometry, we demonstrated that Arabidopsis plant uptakes TCDD by the roots and accumulates it in the vegetative parts in a tissue-specific manner. TCDD mainly accumulated in rosette leaves and mature seeds and less in stem, flowers and immature siliques. Moreover, we observed that plants exposed to high doses of TCDD exhibited a delay in flowering and yielded fewer seeds of a reduced oil content with a low vitality. A particular focus on the plant fatty acid metabolism showed that TCDD caused a significant reduction in C18-unsaturated fatty acid level in plant tissues. Simultaneously, TCDD induced the expression of 9-LOX and 13-LOX genes and the formation of their corresponding hydroperoxides, 9- and 13-HPOD as well as 9- or 13-HPOT, derived from linoleic and linolenic acids, respectively.ConclusionsThe current work highlights a side of toxicological effects resulting in the administration of 2,3,7,8-TCDD on the Arabidopsis plant. Similarly to animals, it seems that plants may accumulate TCDD in their lipids by involving few of the FA-metabolizing enzymes for sculpting a specific oxylipins “signature” typified to plant TCDD-tolerance. Together, our results uncover novel responses of Arabidopsis to dioxin, possibly emerging to overcome its toxicity.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0583-5) contains supplementary material, which is available to authorized users.

Diffusion coefficients of C18 unsaturated fatty acid methyl esters in supercritical carbon dioxide containing 10% mole fraction ethanol as modifier

To determine the molecular diffusion coefficients of C18 unsaturated fatty acid methyl esters in supercritical carbon dioxide (scCO2) containing 10mol% ethanol as a modifier, four methyl esters of C18 fatty acids, i.e., methyl oleate, methyl ricinoleate, methyl linoleate and methyl linolenate were selected as the typical solutes. The diffusion coefficients were measured at temperatures from 313.15 to 333.15K and pressures from 15 to 27MPa using the Taylor–Aris chromatographic peak broadening (CPB) technique. The influences of temperature, pressure, density and viscosity of the solvent mixture on the diffusion coefficients were examined. The results show that methyl oleate always diffuses faster than methyl ricinoleate at the same operating condition. Moreover, the D12 values in ethanol-modified scCO2 decrease with the increase of the number of C-C double bonds in C18-methyl ester, which is consistent with the trend reported in pure scCO2. The diffusivity data are compared with the estimation of eleven predictive models. The modified Wilke–Chang equation is the best purely predictive model and the free volume model of Dymond with two adjustable parameter gives the least errors with average absolute deviations lower than 2.5%.

Induction of Chlorosis, ROS Generation and Cell Death by a Toxin Isolated fromPyricularia oryzae

The ethyl acetate extract of the conidia germination fluid from an Avena isolate (Br58) of Pyricularia oryzae had chlorosis-inducing activity on oat leaf segments. The same activity was also present in the acetone extract of an oatmeal agar culture of Br58. Fungal cultures were used for a large-scale preparation. A series of acetone and ethyl acetate extraction monitored by chromatography was used to isolate an active fraction. The active principle was purified by HPLC. We show by NMR and LC/MS that the toxin was an oxidized C18 unsaturated fatty acid named Mag-toxin. Mag-toxin induced chlorosis on oat leaf segments incubated in the light but not in the dark. Reactive oxygen species (ROS) and cell death were induced by Mag-toxin in oat cells. The sub-cellular localization of ROS generation induced by the toxin treatment was correlated with the location of mitochondria. Interestingly, the induction of ROS generation and cell death by Mag-toxin was light-independent.

Major lipids and fatty acids in the liver and rumen fluid of the goat (Capra hircus) infected with the trematodeParamphistomum cervi

The present study records the occurrence of major lipid fractions and their fatty acids in a digenetic trematode parasite Paramphistomum cervi, and the rumen fluid and liver of the goat (Capra hircus). The amount of neutral lipids (NL), glycolipids (GL) and phospholipids (PL) of goat liver, rumen fluid and of the parasite shows that the rumen fluid is rich in NL, which is also in maximum quantity in the parasite, while the liver is rich in PL followed by NL. The number of fatty acids of total lipids (TL), NL and PL is greater in the parasite than those of the liver and rumen fluid. The number of fatty acids of GL is higher in the liver than in the parasite and the rumen fluid. Comparison of unsaturated fatty acid (UFA), C18 total and C18 UFA of TL, NL, GL and PL of the liver, rumen fluid and the parasite shows that the amount of C18 UFA is higher in P. cervi in all the lipid fractions, except for GL, than in the rumen fluid and the liver. The results reveal that P. cervi absorbs a greater number of fatty acids than its host.

C18 Unsaturated Fatty Acid Selectivity of Lipases During the Acidolysis Reaction Between Tripalmitin and Oleic, Linoleic, and Linolenic Acids

AbstractThe C18 unsaturated fatty acid (UFA) selectivity of three immobilized lipases, namely, Lipozyme TL IM from Thermomyces lanuginosa, Lipozyme RM IM from Rhizomucor miehei, and Novozym 435 from Candida antarctica, was determined in acidolysis conducted in hexane. Tripalmitin with a mixture of equimolar quantities of C18 UFAs was used as the substrate. Significantly different incorporation rates were observed for C18 UFAs used (p < 0.05). The highest incorporation was obtained for all three C18 UFAs with Novozym 435 followed by Lipozyme RM IM and Lipozyme TL IM catalyzed acidolysis under default conditions (substrate mole ratio 1:1; temperature 50 °C; reaction time 6 h; enzyme dosage 10%). Incorporation of the equimolar quantities of C18 UFAs was in the order C18:3 > C18:2 > C18:1 which also reflects C18 UFAs preferences of the lipases. The effects of operating variables on incorporation or UFA selectivity of lipases were also investigated. Among the experimental parameters including the mole ratio of fatty acid to triolein, temperature, enzyme dosage, and time on incorporation, the effect of the substrate mole ratio on UFA selectivity was greater than those of the others.

The Influence of Life-cycle on Phospholipid and Triacylglycerol Fatty Acid Profiles of Aelia rostrata Boheman (Heteroptera: Pentatomidae)

Abstract The fatty acid compositions of phospholipid and triacylglycerol fractions of total lipids prepared from eggs, nymphs, new-generation, aestivating, and diapausing adults of the wheat stink bug Aelia rostrata Boheman (Heteroptera: Pentatomidae) were analyzed by gas chromatography-mass spectrometry. The major components were C16 and C18 saturated and unsaturated fatty acid ubiquitous to most animal species. In addition to these components, several odd-chain (C13:0, C15:0, and C17:0) and prostaglandin-precursor fatty acids were found. The fatty acid profiles of phospholipids and triacyglycerols were substantially different. Generally, the phospholipids were higher than triacyglycerols in polyunsaturated fatty acids. The unsaturation/saturation ratio for phospholipid was higher than calculated for triacylglycerol. There were substantial differences in fatty acid compositions from different development stages. In phospholipid fractions, the fatty acid profiles from eggs and nymph were not the same, wit...

Novel Cationic Amphiphilic Derivatives from Vernonia Oil: Synthesis and Self-Aggregation into Bilayer Vesicles, Nanoparticles, and DNA Complexants

Self-assembling nanostructures were prepared from novel cationic amphiphilic compounds synthesized from vernonia oil, a natural epoxydized triglyceride. The presence of a 12,13-epoxy group on the C18 unsaturated fatty acid, vernolic acid, which is the main constituent of vernonia oil, permitted the synthesis of novel amphiphilic derivatives with a hydrogen-bonding hydroxyl and a cationic headgroup moiety on adjacent carbon atoms. The amphiphiles were prepared in a two-stage synthesis that comprised opening of the epoxy groups with a haloacetic acid, followed by quaternization of the halo group with a tertiary amine containing a C12 aliphatic chain. Intact vernonia oil as the starting material gave a triple-headed cationic amphiphile, containing three vernolic acid derived moieties connected through a glycerol backbone. A single-headed amphiphile with two alkyl chains and a single quaternary ammonium headgroup was synthesized from the methyl ester of vernolic acid as the starting material. The triple-headed derivative could form nonencapsulating structures. Cholesterol was required in the formulation (1:1) to make spherical vesicles that could encapsulate a water-soluble marker. The single-headed derivative, however, formed spherical encapsulating vesicles without cholesterol. TEM, NMR, and FT-IR were used to characterize the vesicles, and molecular structure vs morphology relationships were postulated on the basis of these data. The triple-headed amphiphile also formed a DNA complex that was highly resistant to hydrolysis by DNase. This amphiphile-DNA complex was used as vector for gene transfer in cell culture demonstrating efficient DNA transfection.

지방원으로 전지대두와 아마종실의 첨가가 반추위내 건물과 C18계-불포화지방산의 조성과 소실율에 미치는 영향

ABSTRACT This study was conducted to investigate the effects of dietary full-fat soybeans and linseed as fat sources on in vitro ruminal disappearances of dry matter and unsaturated fatty acids and fatty acids profile. The full-fat soybeans and linseed were high in linoleic acid (C18:2 n -6) and
i-linolenic acid (C18:3 n -3), respectively. The incubation times were 0, 3, 6, 12, 24, 48 and 72 h. After each time of incubation, medium digesta was lyophilized for analyzing its DM and fatty acids contents. DM disappearance was significantly higher in linseed treatment compared to full-fat soybeans treatment on 6 h (p<0.01), 12 h (p<0.05) and 24 h (p<0.01), but cumulative gas production was not significantly different between both treatments. Stearic acid (C18:0) content in medium digesta was increased in both soybeans and linseed as a result of complete biohydrogenation with increased incubation time and C18:0 and C18:1 contents of full-fat soybeans were significantly higher than those of linseed (p<0.05). The content of C18:2 and C18:3 in digesta of each treatment were decreased by biohydrogenation as incubation time was increased. The content of C18:2 in full-fat soybeans was significantly higher than that of linseed (p<0.05) while the content of C18:3 in linseed was significantly higher than that of full-fat soybeans (p<0.001). Net C18:0 production was significantly higher in full-fat soybeans (332.24%) than linseed (133.16%) on 72 h. Disappearance of C18:1 was significantly lower in full-fat soybeans than linseed (p<0.05), especially full-fat soybeans showed negative (
) values on 3, 6, 12 and 24 h. The disappearance of C18:3 was significantly higher in linseed than full-fat soybeans (p<0.05). The disappearance of C18-unsaturated fatty acid was significantly higher in linseed than full-fat soybeans. In conclusion, polyunsaturated fatty acid (PUFA) in both full-fat soybeans and linseed were extensively biohydrogenated. In addition, biohydrogenation of PUFA was more completed to C18:0 in full-fat soybeans than linseed, reflecting dietary PUFA composition. (

Characterization of Arabidopsis mutants that are associated with altered C18 unsaturated fatty acid metabolism

Polyunsaturated fatty acids are a major component of glycerolipids in plant cellular membranes. We have isolated four novel fatty acid mutants of Arabidopsis thaliana named regulator of fatty acid composition ( rfc) 1 through 4. The rfc1, rfc2 and rfc3 mutants had an increased oleic acid (18:1) level at the expense of α-linolenic acid (18:3) level among total fatty acids especially in root tissues. In these mutants, the transcripts of FAD2 and FAD3 gene for ER Δ12 and ω-3 fatty acid desaturases that are involved in the desaturation of 18:1 and linoleic acid (18:2), respectively, were accumulated to the wild-type levels. In the rfc4 mutant, over-accumulated 18:3 with a corresponding increase in the FAD3 mRNA over wild-type levels was observed. These results suggest that C18 unsaturated fatty acid metabolism in extra-plastid membranes is controlled by multiple loci in addition to the structural genes for fatty acid desaturases.

The effects of different amounts and types of fat on the extent of C18 unsaturated fatty acid hydrogenation in the rumen of sheep

The effects of different amounts and types of fat on the extent of C18 unsaturated fatty acid hydrogenation in the rumen of sheep

Enhanced Enteral Bioavailability of Vancomycin Using Water‐in‐Oil‐in‐Water Multiple Emulsion Incorporating Highly Purified Unsaturated Fatty Acid

The aim of this study was to evaluate the potential of an emulsion incorporating unsaturated fatty acids to improve the mucosal absorption of poorly absorbed drugs from rat intestinal loops in situ, using a water‐in‐oil‐in‐water (W/O/W) multiple emulsion. Vancomycin hydrochloride (VCM) was used as a model drug with low oral bioavailability. The entrapment efficiency of VCM in the emulsion was ∼60% and remained constant over storage for 1 month at 4°C. The emulsion incorporating C18 unsaturated fatty acids or docosahexaenoic acid (DHA) markedly enhanced VCM absorption after colonic and rectal dosing. The effectiveness of DHA on VCM colonic absorption improvement was the same as that of oleic acid, and less than that of linoleic and linolenic acids. For rectal dosing, bioavailability was similar among various emulsions, in the range 40–50%. The effect of the emulsion incorporating oleic acid or DHA on improving VCM enteral bioavailability was not increased proportional to the incorporated amount. The electrical resistance of membranes was not changed by the incorporation of various fatty acids in emulsions. Our results indicated that W/O/W emulsions incorporating C18 unsaturated fatty acid or DHA were useful carriers for improving the absorption of poorly absorbable drugs via the intestinal tract without gross changes to tight junction function. © 2000 Wiley‐Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 89:1243–1252, 2000.

Purification and characterization of a novel bioconverting lipase from Pseudomonas aeruginosa MB 5001

The purification and characterization of a lipase produced by Pseudomonas aeruginosa strain MB 5001 that was selected for its unique bioconversion properties is described herein. The purified lipase bioconverts dimethyl 5-(3-(2-(7-chloroquinolin-2-yl)-ethyl)phenyl)4, 6-dithianonanedioate (diester) to its (S)-ester acid, an intermediate in the synthesis of Verlukast, a leukotriene receptor antagonist. In its native form, the enzyme exists as high-molecular-weight aggregates that are dissociated with Triton X-100. The purified enzyme has a molecular weight of 29,000 daltons, a pH optimum of 8.0, a temperature optimum of 55°C, and is stable for 1 h at 40°C. This lipase is strongly inhibited by 1 m m ZnSo 4 (94% inhibition) but is stimulated by the addition of 10 m m CaCl 2 (1.24-fold) and 200 m m taurocholic acid (1.6-fold). It is more active on short-chain versus long-chain triglycerides, and hydrolyzes C18-unsaturated fatty acid esters more efficiently than it hydrolyzes C18-saturated fatty acid esters. In light of its catalytic and physicochemical properties, this enzyme is regarded as a novel lipase .

Enhancement of polyether biodegradation in activated sludge following exposure to conditioning agents

Abstract Activated sludge exposed to C18 unsaturated fatty acid diesters of polyethylene glycol (PEG) acquires the ability to degrade PEG of average molecular weight (Afn) 1,000, 1,450, 3,350 but not 8,000. Likewise, a polypropylene glycol (PPG) diester of oleic acid enhances the degradation of PPG Afn 1,025. An analogous enhancement in PEG degradative activity is effected by pre‐exposure to polyoxyethylene oleyl monoether. Enhancement of degradation is restricted to polyethers which are the same kind as used in the pretreatment; for example, samples pre‐exposed to PEG unsaturated diester are unable to degrade PPG. Thin layer chromatographic analysis of PEG incubations indicates disappearance of PEGs from the supernatant without a noticeable change in the molecular weight of remaining PEGs. Removal of these compounds from the supernatants occurs well before catabolic CO2 evolution is completed. Since there were negligible increases in the biomass and acetylesterase activity resulting from the catabolism o...

Effects of bis homoallylic and homoallylic hydroxyl substitution on the olefinic 13C resonance shifts in fatty acid methyl esters.

Substitution of a hydroxyl group at the bis homoallylic position (OH group located three carbons away from the olefinic carbon) in C18 unsaturated fatty acid esters (FAE) induces a 0.73 +/- 0.05 ppm upfield and a 0.73 +/- 0.06 ppm downfield shift on the delta and epsilon olefinic 13C resonances relative to the unsubstituted FAE, respectively. If the hydroxyl group is located on the carboxyl side of the double bond of the bis homoallylic hydroxy fatty acid esters (BHAHFA), the olefinic resonances are uniformly shifted apart by [formula: see text] where delta delta dbu represents the absolute value of the double bond resonance separation in the unsubstituted FAE and 1.46 ppm is the sum of the absolute values of the delta and epsilon shift parameters. With hydroxyl substitution on the terminal methyl side of the double bond, the olefinic shift separation is equal to [formula: see text] In homoallylic (OH group located two carbons away from the olefinic carbon) substituted FAE the gamma and delta induced hydroxyl shifts for the cis double bond resonances are +3.08 and -4.63 ppm, respectively while the trans double bond parameters are +4.06 and -4.18 ppm, respectively. The double bond resonance separation in homoallylic hydroxy fatty acid esters (HAHFA) can be calculated from the formula [formula: see text] for cis and [formula: see text] for the trans case when the OH substitution is on the carboxyl side of the double bond. Conversely, when the OH resides on the terminal methyl side, the double bond shift separations for cis and trans isomers are [formula: see text] and [formula: see text] respectively.(ABSTRACT TRUNCATED AT 250 WORDS)