Detection of Heterogeneous Protein S-Acylation in Cells

The use of synthetically synthesized azide and alkyne fatty acid analogs coupled with bioorthogonal Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition reaction-based detection methods to study protein S-acylation reactions has replaced the traditional method of using in vivo metabolic radiolabeling with tritiated palmitic acid and has greatly facilitated our understanding of this essential cellular process. Here, we describe the chemical synthesis of myristic (C:14), palmitic (C16:0), and stearic (C18:0) acid-azide probes and detail how they may be utilized as chemical reporters for the analysis of S-acylation of exogenously expressed proteins in cells.

[Changes in the content of plasma lipoproteins in persons subjected to diets prepared with sunflower oil alone or mixed with palm olein]

We analyzed in 31 subjects, regular guests of the University food service of the Central University of Venezuela (UCVFS), in Caracas, the effects of replacing sunflower oil, commonly used in the preparation of meals, by a mix of sunflower oil and palm olein 70/30 (v/v) respectively. Plasma concentrations of total cholesterol, low and very low density lipoproteins were not changed after 40 days of the substitution. On the contrary, concentrations of high density lipoprotein and total triglycerides increased. The resistance to the oxidation of low-density lipoproteins increased considerably (p < 0.01). Today this resistance is considered as a protective factor of great importance in the prevention of the initiation of the atherogenic process. Taking into account the favorable modifications of HDL cholesterol and the clear increased resistance to the oxidation of LDL, we think that palm olein, mixed with other oils with a high ratio linoleic/palmitic (sunflower, corn, soya an the likes), can be used as a healthy alternative in human nutrition.

[Study on chemical constituents of volatile oil from rhizomes and leaves of Pileostegia viburnoides var. glabrescens by GC-MS]

OBJECTIVE

To analyze the chemical constituents of volatile oil from the rhizomes and leaves of Pileostegia viburnoides var. glabrescens by GC-MS.

METHODS

The volatile oil was extracted from the rhizomes and leaves of Pileostegia viburnoides var. glabrescens by steam distillation. The constituents of volatile oil were identified by GC-MS technology.

RESULTS

37 compounds were identified from the oil of rhizomes. 36 compounds were identified from the oil of leaves. The rhizomes and leaves volatile oil had 18 compounds in common.

CONCLUSION

This study is the first one to report the volatile components of Pileostegia viburnoides var. glabrescens. It can provide a scientific basis for rational use of the rhizomes and leaves of Pileostegia viburnoides var. glabrescens.

[Analysis of fatty acids from the flowers of Trollius chinensis]

OBJECTIVE

To analyze and identify fatty acids from the flowers of Trollius chinensis Bunge.

METHODS

To isolate and determine the constituents using GC/MS technique, quantitatively analyze their content by area normalization method.

RESULTS

31 fatty acids and 7 other constituents were isolated and determined.

CONCLUSION

The major fatty acids were hexadecanoic (19.85%), (Z,Z)-9,12-octadecadienoic (14.37%), tetradecanoic (13.93%), (Z)-9-octadecenoic (13.00%), dodecanoic (6.79%), 10-hydroxy-hexadecanoic (4.37%) and octadecanoic (3.34%) acids.

Methodology for the In Vivo Measurement of the Δ9-Desaturation of Myristic, Palmitic, and Stearic Acids in Lactating Dairy Cattle

There is limited methodology available to quantitatively assess the activity of the Delta9-desaturase enzyme in vivo without chemically inhibiting the enzyme or using radioactively labeled substrates. The objective of these experiments was to develop methodology to determine the incorporation and desaturation of 13C-labeled fatty acids into milk lipids. In a preliminary experiment, 3.7 g [1-13C]myristic acid ([1-13C]14:0), 19.5 g [1-13C]palmitic acid ([1-13C]16:0), 20.0 g [1-13C]stearic acid ([1-13C]18:0) were combined and infused into the duodenum of a cow over 24 h. In a following experiment, 5.0 g [1-13C]14:0, 40.0 g [1-13C]16:0, and 50.0 g [1-13C]18:0 were infused into the abomasums of separate cows as a bolus over 20 min or continuously over 24 h. Milk fat was extracted using chloroform:methanol. Fatty acids were methylated, and fatty acid methyl esters (FAME) were converted to dimethyl disulfide derivatives (DMDS). The FAME and DMDS were analyzed by gas chromatography mass spectrometry. In the preliminary experiment, 13C enrichment in 14:0 but not 16:0 or 18:0 was observed. When dosage amounts were increased in the following experiment, peak enrichments from the bolus infusion were observed at 8 h. Enrichments for continuous infusion peaked at 16 h for 14:0 and 18:0, and at 24 h for 16:0. The Delta9-desaturase products of these fatty acids were estimated to be 90% of cis-9 14:1, 50% of cis-9 16:1, and 59% of cis-9 18:1. This study demonstrates that 13C-labeled fatty acids may be utilized in vivo to measure the activity of the Delta9-desaturase enzyme.

Milk in the island of Chole [Tanzania] is high in lauric, myristic, arachidonic and docosahexaenoic acids, and low in linoleic acid reconstructed diet of infants born to our ancestors living in tropical coastal regions

BACKGROUND

We need information on the diet on which our genes evolved.

OBJECTIVE

We studied the milk fatty acid [FA] composition of mothers living in the island of Chole [Tanzania, Indian Ocean]. These mothers have high intakes of boiled marine fish and coconut, and consume plenty amount of fruits and vegetables.

DESIGN

The outcome was compared with three fish-eating tribes living along Tanzanian freshwater lakes [Kerewe, Nyakius, Nyiramba], four tribes living in the Tanzanian inland [Hadzabe, Maasai, Sonjo, Iraqw] and our milk FA database.

RESULTS

Milk from Chole contained high levels of 12:0 [20.17 g%], 14:0 [21.19], 12:0/14:0 ratio [0.92 g/g], arachidonic acid [AA, 0.50 g%] and docosahexaenoic acid [DHA, 0.73], but low levels of linoleic acid [LA, 4.23]. The combination of a high medium chain fatty acid [MCFA; <C16] content and 12:0/14:0 ratio derives notably from coconut consumption, as opposed to a carbohydrate rich diet, while non-existent use of vegetable oils explains low LA. Milk AA/DHA ratios of the four fish-eating groups were related to the AA/DHA ratios of the available fish. Chole MCFA and LA did not fulfill Western recommendations for formulae, while AA and DHA were well above minimum levels.

CONCLUSIONS

The Chole milk FA composition is likely to reflect the dietary FA composition of babies born to our ancient ancestors living in East-African coastal regions. The poor compliance with present recommendations raises doubts on the validity of recommendations that are based on milk from Western mothers consuming diets that confer high risk of diseases typical for affluent countries.

Identification of fatty acids and fatty acid amides in human meibomian gland secretions

PURPOSE

The complex superficial lipid layer of the tear film functions to prevent evaporation and maintain tear stability. Although classes of lipids found in the tear film have been reported, individual lipid species are currently being studied with more sophisticated.

METHODS

The purpose of this work was to show the identification of fatty acids and the fatty acid amides in human meibomian gland secretions by using electrospray mass spectrometry. methods. Human meibomian gland secretions (meibum) were analyzed by electrospray quadrupole time-of-flight mass spectrometry (positive- and negative-ion mode). Accurate mass determination and collision-induced dissociation of meibum, and lipid standards were used to identify lipid species.

RESULTS

Mass analysis of meibum in an acidic chloroform-methanol solution in positive-ion mode revealed a mass peak of m/z 282.3, which was identified as the protonated molecule of oleamide [C(18)H(35)NO+H](+). The high-resolution mass analysis of the m/z 282.2788 peak (oleamide) demonstrated a mass accuracy of 3.2 parts per million (ppm). Collision-induced dissociation of this species from meibum, compared with an oleamide standard, confirmed its identification. Myristic, palmitic, stearic, and oleic free fatty acids were identified in a similar manner, as were the other fatty acid amides (myristamide, palmitamide, stearamide, and erucamide).

CONCLUSIONS

The findings indicate that oleamide (cis-9-octadecenamide), an endogenous fatty acid primary amide, is a predominant component of meibum when examined by electrospray mass spectrometry. The novel finding of oleamide and other members of the fatty acid amide family in the tear film could lead to additional insights into the role of fatty acid amide activity in human biological systems and may indicate a new function for this lipid class of molecules in ocular surface signaling and/or in the maintenance of the complex tear film.

Decreased polyunsaturated and increased saturated fatty acid concentration in spermatozoa from asthenozoospermic males as compared with normozoospermic males

The lipid composition of the sperm membrane has been shown to exert a significant effect upon the functional quality of spermatozoa. We have studied fatty acid composition of the phospholipids in spermatozoa in asthenozoospermic and normozoospermic men and determined the ratio of polyunsaturated fatty acids (PUFAs) to saturated fatty acids of spermatozoa of these two groups. Fatty acid concentration of spermatozoa was determined in 15 asthenozoospermic and eight normozoospermic semen samples by thin layer chromatography and gas chromatography. The most abundant polyunsaturated and saturated fatty acids in normozoospermic samples were docosahexaenoic acid (DHA 22 : 6 omega3, 98.5 +/- 4.5 nmol per 10(8) spermatozoa, mean +/- SE) and palmitic acid (103 +/- 17 nmol per 10(8) spermatozoa) respectively. The mean +/- SE values of DHA and palmitic acid in asthenozoospermic samples were 53.9 +/- 11.6 and 145 +/- 14.7 nmol per 10(8) spermatozoa respectively. Compared with normozoospermic samples, asthenozoospermic samples showed lower levels of PUFA and higher amount of saturated fatty acids. The mean +/- SE ratios of sperm PUFA/saturated fatty acids in asthenozoospermic and normozoospermic samples were 0.66 +/- 0.06 and 1.45 +/- 0.16 (P < 0.001) respectively. This study demonstrates that spermatozoa of asthenozoospermic men have lower levels of PUFA compared with saturated fatty acids. This may be contributory to the poor motility noted in samples from these men.

[Study on chemical constituents of the essential oil from Myristica fragrans Houtt. by supercritical fluid extraction and steam distillation]

Essential oils were extracted from Myristica fragrans Houtt. by supercritical fluid extraction (SFE) and steam distillation (SD). Their components were analyzed by gas chromatography-mass spectrometry and compared. 48 compounds were identified for the essential oil extracted by supercritical carbon dioxide, and its main components have been found to be myristic acid, myristicin, terpinen-4-ol, alpha-pinene and safrole. 38 compounds were identified for the essential oil obtained by SD, and its main components have been found to be beta-pinene, terpinen-4-ol, alpha-pinene, gamma-terpinene and beta-phellandrene.

Fatty acid composition and productive traits of broiler fed diets containing conjugated linoleic acid

An experiment was carried out to evaluate the transfer of dietary CLA to broiler chicken tissues (breast, drumstick meat, skin, and abdominal fat) and its effect on productive traits and on carcass yields of birds. Cobb 500 females (n=360), divided into three groups, received from 22 d to slaughtering age (47 d) a grower diet supplemented with 2% conjugated linoleic acid (CLA) source containing 60% CLA methyl esters (CLA2) or 4% CLA source (CLA4). The control group had no supplementation. The addition of CLA source to chicken diet decreased the content of monounsaturated fatty acid (MUFA) (oleic and palmitoleic acids) in breast and drumstick meat. The deposition of CLA in muscles significantly increased as the dietary CLA increased, whereas only little amounts of CLA were detected in the control group. Arachidonic acid (ARA) content was significantly depressed and linearly related to the addition of CLA to the chicken diet. Other non-CLA polyunsaturated fatty acids (PUFA) were little affected by the dietary CLA supplementation. Saturated fatty acids (myristic and stearic acids) significantly increased about 30% in abdominal fat pad of both treated groups enhancing the firmness of abdominal fat. Productive performances--as well as carcass yields--were similar across dietary treatment of birds.

Thermal properties of partially hydrolyzed starch-glycerophosphatidylcholine complexes with various acyl chains

Complexes of starch and monoacyl-sn-glycerophosphatidylcholine (GPC) containing various acyl (myristoyl, palmitoyl, and stearoyl) chains were subjected to hydrolysis with glucoamylase (EC 3.2.1.3). The enzyme hydrolyzed approximately 40% of starch control and 20-28% of starch-GPC complexes. Among the GPCs examined, 1- and 2-monomyristoyl-sn-GPC showed the highest resistance to enzyme hydrolysis, and the hydrolysis rate of starch-GPCs was greater with longer chains. Enzymatic hydrolysis strongly affected the thermal properties of the starch. After enzymatic hydrolysis of starch-GPC complexes for 24 h, their thermograms had broader peaks with lower enthalpies than the corresponding starch without enzyme; however, the starch-GPC complexes showed little change. The surface of starch-GPC granules was less eroded. These results showed that the increasing amount of starch-GPC complexes could be more resistant to hydrolysis.

Comparison of the contents of the main biochemical compounds and the antioxidant activity of some Spanish olive oils as determined by four different radical scavenging tests

The aim of this study was to compare the contents of the main biochemical compounds and the antioxidant capacity of five Spanish olive oils by four different antioxidant tests and to find out the most valuable oil for disease preventing diets. Fatty acids, sterols and individual antioxidant compounds in Arbequina, Hojiblanca, Extra Virgin, Picual and Lampante Spanish olive oils were determined. Antioxidant activities were done as well using different radical scavenging activities: total radical-trapping antioxidative potential by ABAP (TRAP-ABAP), radical scavenging activity by DPPH (RSA-DPPH), antioxidant assay by beta-carotene-linoleate model system (AA-beta-carotene) and total antioxidant status by ABTS (TAA-ABTS). The highest content of all studied antioxidant compounds (353; 329; 4.6 and 2.7 mg/kg for tocopherols, tocotrienols, polyphenols and o-diphenols, respectively) was found in Extra Virgin oil. Also the highest antioxidant capacity was observed in Extra Virgin oil (668 nM/ml; 29.4%; 40.4% and 2.64 mM TE/kg for TRAP-ABAP, RSA-DPPH, AA- beta-carotene and TAA-ABTS, respectively). The correlation between total phenols and antioxidant capacities measured by four methods was very high, but the highest for the beta-carotene (R = 0.9958). In conclusion, the best method for determination of the antioxidant capacity of olive oils is the beta-carotene test. Extra Virgin olive oil has high organoleptic properties and the highest antioxidant activity. The above-mentioned makes this oil a preferable choice for diseases preventing diets.

[Characterization of lipopolysaccharides from Ralstonia solanacearum]

Lipopolysaccharides (LPSs) from four strains of Ralstonia solanacearum belonging to biovar I (ICMP 6524, 8115, 5712, and 8169) were isolated and investigated. The structural components of the LPS molecule, such as lipid A, the core oligosaccharide, and O-specific polysaccharide (O-PS), were obtained after mild acid hydrolysis of the LPS preparations. In lipid A from all the LPS samples studied, 3-hydroxyhexadecanoic, 2-hydroxyhexadecanoic, tetradecanoic, and hexadecanoic fatty acids prevailed. The dominant monosaccharides of the core oligosaccharides of all of the strains studied were rhamnose, glucose, glucosamine, 2-keto-3-deoxyoctulosonic acid, and heptose. However, individual strains varied in the content of galactose, ribose, xylose, and arabinose. Three types of the O-PS structure were established, which differed in their configuration (alpha or beta), as well as in the type of the bond between glucosamine and rhamnose residues (1-->2 or 1-->3).

Fatty acid composition of adipose tissue and serum lipids are valid biological markers of dairy fat intake in men

The fatty acid intake is in part reflected by the fatty acid composition of adipose tissue and serum lipids. We evaluated whether the proportions of myristic (14:0), pentadecanoic (15:0) and heptadecanoic (17:0) fatty acids in the adipose tissue triacylglycerols and serum cholesterol esters and phospholipids reflect long-term dairy fat consumption in free-living men. In 114 healthy men aged 40-76 y, we compared the relative content of 14:0, 15:0 and 17:0 in subcutaneous adipose tissue and in serum lipids with relative intake (g/100 g of total fat) assessed by two 1-wk weighed food records made 6 mo apart and assessed by fourteen 24-h dietary recall interviews equally distributed during 1 y. According to food records, the mean +/- SD dairy fat intake was 24.9 +/- 13.1 g/d (29.6 +/- 10.5 g/100 g total fat); intake of 14:0, 15:0 and 17:0 was 4.6, 0.23 and 0.16 g/100 g total fat, and the content in adipose tissue was 3.6, 0.36 and 0.25 g/100 g fatty acids, respectively. Pearson correlation coefficients between intake of dairy fat (based on 24-h recalls) and fatty acid composition of adipose tissue were 0.64 (P: < 0.001) for 14:0, 0.74 (P: < 0.001) for 15:0 and 0.60 (P: < 0.001) for 15:0 + 17:0. Corresponding correlations with serum cholesterol esters were 0.34 (P: < 0.001) (14:0), 0.45 (P: < 0.001) (15:0) and 0.56 (P: < 0.001) (15:0 + 17:0), and with serum phospholipids the values were 0.30 (P: < 0.01) (14:0), 0.50 (P: < 0.001) (15:0) and 0.50 (P: < 0.001) (15:0 plus 17:0). In our study population, the relative content of 15:0 or 14:0 in adipose tissue is a valid biomarker for long-term dairy fat intake in free-living individuals. When adipose tissue is not available, 15:0 content in serum cholesterol esters or phospholipids might be used. Intake data based on repeated 24-h recalls are equally informative and may be an equivalent choice in nutritional studies.

Characterization of a biosurfactant, mannosylerythritol lipid produced from Candida sp. SY16

One yeast strain, SY16, was selected as a potential producer of a biosurfactant, and identified as a Candida species. A biosurfactant produced from Candida sp. SY16 was purified and confirmed to be a glycolipid. This glycolipid-type biosurfactant lowered the surface tension of water to 29 dyne/cm at critical micelle concentration of 10 mg/l (1.5 x 10(-5) M), and the minimum interfacial tension was 0.1 dyne/cm against kerosene. Thin-layer and high-pressure liquid chromatography studies demonstrated that the glycolipid contained mannosylerythritol as a hydrophilic moiety. The hydrophilic sugar moiety of the biosurfactant was determined to be beta-D-mannopyranosyl-(1-->4)-O-meso-erythritol by nuclear magnetic resonance (NMR) and fast atom bombardment mass-spectroscopy analyses. The hydrophobic moiety, fatty acids, of the biosurfactant was determined to be hexanoic, dodecanoic, tetradecanoic, and tetradecenoic acid by gas chromatography-mass spectroscopy. The structure of the native biosurfactant was determined to be 6-O-acetyl-2,3-di-O-alkanoyl-beta-D-mannopyranosyl-(1-->4)-O-meso- erythritol by NMR analyses. We newly determined that an acetyl group was linked to the C-6 position of the D-mannose unit in the hydrophilic sugar moiety.

Structure of the anchor-domain of myristoylated and non-myristoylated HIV-1 Nef protein

Negative factor (Nef) is a regulatory myristoylated protein of human immunodeficiency virus (HIV) that has a two-domain structure consisting of an anchor domain and a core domain separated by a specific cleavage site of the HIV proteases. For structural analysis, the HIV-1 Nef anchor domain (residues 2-57) was synthesized with a myristoylated and non-myristoylated N terminus. The structures of the two peptides were studied by1H NMR spectroscopy and a structural model was obtained by restrained molecular dynamic simulations. The non-myristoylated peptide does not have a unique, compactly folded structure but occurs in a relatively extended conformation. The only rather well-defined canonical secondary structure element is a short two-turn alpha-helix (H2) between Arg35 and Gly41. A tendency for another helical secondary structure element (H1) can be observed for the arginine-rich region (Arg17 to Arg22). Myristoylation of the N-terminal glycine residue leads to stabilization of both helices, H1 and H2. The first helix in the arginine-rich region is stabilized by the myristoylation and now contains residues Pro14 to Arg22. The second helix appears to be better defined and to contain more residues (Ala33 to Gly41) than in the absence of myristoylation. In addition, the hydrophobic N-terminal myristic acid residue interacts closely with the side-chain of Trp5 and thereby forms a loop with Gly2, Gly3 and Lys4 in the kink region. This interaction could possibly be disturbed by phosphorylation of a nearby serine residue, and modifiy the characteristic membrane interactions of the HIV-1 Nef anchor domain.

Adipose tissue fatty acids in men from two populations with different cardiovascular risk: the LiVicordia study

The LiVicordia study was set up to investigate possible causes for coronary heart disease mortality in middle-aged Lithuanian men being four times higher than in Swedish men. In a previous part of this study we found lower total and low density lipoprotein (LDL) cholesterol in the Lithuanian men in spite of them having a higher fat intake than in the Swedish men. Their LDL was also more susceptible to oxidation in vitro than was that of the Swedish men. Fat quality can influence LDL oxidation. In order to obtain data on long-term fat quality intake we measured the fatty acid composition of abdominal wall adipose tissue by gas chromatography in men aged 50 years from Vilnius, Lithuania (n=50) and Linköping, Sweden (n=50). Men from Vilnius had a significantly higher percentage of adipose tissue long chain polyunsaturated fatty acids (PUFA) (20:4n6, 20:5n3, 22:5n5, 22:6n3) and lower percentage of saturated fatty acids, especially myristic acid (14:0), 3.4+/-0.7 versus 4.6+/-0.8, p<0.0001. The percentage content of adipose tissue linoleic acid (18:2n6) was 11.5+/-2.1 versus 11.0+/-1.4 (n.s.) and of linolenic acid (18:3n3) 0.7+/-0.3 versus 0.6+/-0.2 (n.s.) in men from Vilnius and Linköping, respectively. It is concluded that the adipose tissue content of essential fatty acids is similar in men from Vilnius and men from Linköping and therefore the intake is also likely to be similar. The higher contents of long chain highly unsaturated fatty acids in men from Vilnius may be of importance in the oxidation process of LDL.

Novel acylation of poxvirus A-type inclusion proteins

Myristylation is one of several post-translational modifications that occur on vaccinia virus (VV) proteins. Previously, time course labeling of VV-infected cells with myristic acid had indicated that five late proteins (17, 25, 36, 38 and 92 kDa) are myristylated. Four of these proteins were mapped to the E7R, L1R, AI6L and G9R open-reading frames, respectively, because of the predicted presence of the N-myristyltransferase recognition sequence (M-G-X-X-X-S/T/A) at their amino termini. In contrast, computer analyses of large (80-100 kDa) VV open reading frames did not reveal any predicted species with this N-terminal motif. By immunoprecipitation with monospecific sera and transient expression of cloned gene products, the myristylated 92-kDa protein has been demonstrated to be the A-type inclusion protein encoded by the Western Reserve (WR) strain of VV. Labeling of cowpox virus (CPV) infected cells with myristic acid indicated that the 160-kDa A-type inclusion protein appears to be myristylated as well. Both the VV 92-kDa and the CPV 160-kDa A-type inclusion proteins labeled with myristic acid were stable to hydroxylamine treatment, suggesting an amide linkage between the fatty acid and the acceptor protein. HPLC analysis confirmed that the 92-kDa protein was in fact myristylated. This data suggests that poxvirus ATI proteins may be subject to a novel type of internal myristylation modification, and the roles such modifications may play in the replication cycles of these viruses is discussed.

Protein S-myristoylation in Leishmania revealed with a heterologous reporter

Reversible esterification of myristic acid to cysteine residue(s) (S-myristoylation) was documented recently in the protozoan Trypanosoma brucei. Unlike N-myristoylation, S-myristoylation appears to be rare (or non-existent) in animal cells and has not been documented in any other trypanosome. Reasoning that a lack of knowledge of appropriate substrates may have contributed to this state of affairs, we devised an assay to test for protein S-myristoylation in the ancient eukaryote Leishmania. A cDNA encoding a glycosylphosphatidylinositol-phospholipase C (GPI-PLC) from T. brucei was transfected into Leishmania and the expressed protein analyzed for covalent lipid modifications. Leishmania modified the reporter with myristate in a thio-ester linkage. From these observations, we infer that (i) GPI-PLC may be used as a reporter of this lipid modification in eukaryotes, and (ii) protein S-myristoylation might have ancient origins.

Intense myristoylation of a single protein in the ocular lens

A single protein of the ocular lens was intensely myristoylated following short term incubation of cultured bovine lens epithelial cells and intact rat lenses with 3H-myristic acid. It was acidic (pI <5), about 19 kDa and present exclusively in the cytosol of both cultured epithelial cells and the epithelium of the young rat lens. Fiber cell proteins were not labeled. The myristoylated protein was not seen in the epithelium of the adult rat. Essentially no protein mass was evident in the 19-20 kDa range when samples of the labeled-soluble protein were fractionated by either HPLC coupled with SDS-PAGE or 2D-electrophoresis. These findings suggest that the myristoylated-soluble protein of 19 kDa in lens (p19L) is a rapidly-turning over minor protein likely associated with lens growth. The absence of any apparent membrane association for a myristoylated protein appears unusual. The trace nature of p19L has frustrated attempts at its identification by MALDI-MS.

Saccharomyces cerevisiae cell fatty acid composition and release during fermentation without aeration and in absence of exogenous lipids

Medium-chain fatty-acids (MCFA) are among the main aroma compounds of fermented beverages. High concentrations of MCFA have been found in sluggish and stuck fermentations. It has been suggested that they arrest cell growth, as they may be toxic, but the causes of sluggish and stuck fermentations are still unclear. The aim of this work was to see whether the production of MCFA is related to fatty acid synthesis in the absence of exogenous lipids and aeration, and whether their increase can be regarded as a consequence, instead of the cause, of sluggish and stuck fermentations. Two possibilities were considered: (i) MCFA are produced to replace unsaturated fatty acids (UFA) for cell membrane fluidity when the lack of oxygen makes desaturation of saturated fatty acids (SFA) impossible; or (ii) MCFA are produced following the release of medium-chain acyl-CoA from the fatty acid synthetase complex (FAS) due to the accumulation of SFA, and their hydrolysis to recycle CoA-SH. In the first hypothesis, MCFA should be active in cell metabolism and be found in cell structures; in the second, MCFA should be a discard and prevalently found outside the cell. We carried out a Saccharomyces cerevisiae fermentation experiment in a synthetic, lipid-free medium without aeration. We measured the fatty acid composition of yeast cells and the amounts of MCFA and their ethyl esters in the medium throughout the fermentation. Cell growth and the oxygen content of the medium were also monitored. We found that MCFA are not immobilized in cell structures, but mainly released into the medium. Cell growth is arrested because fatty acid biosynthesis is prevented by the lack of oxygen. The higher MCFA concentrations found in sluggish and stuck fermentations can be thus regarded as an effect, and not the cause, of this arrest. Some suggestions for the prevention of these events are proposed.

Profiles of the fatty acids in the plasma membrane of human brain tumors

Several studies demonstrated that certain fatty acids have specific effects on tumor cells. n-3 series fatty acids (alpha-linolenic acid, eicosapentaenoic acid and docosahexaenoic acid) may suppress the carcinogenesis, whereas n-6 series fatty acids (arachidonic acid, linoleic acid) may exert tumor promoting effects. In this study, 19 patients with various brain tumors and 12 control brain tissues were studied. n-3, n-6, n-9 unsaturated fatty acids and certain saturated fatty acids levels were measured in the plasma membrane of tumor or control brain tissues by capillary gas chromatography. We found that the level of docosahexaenoic acid from n-3 series fatty acids was significantly lower in gliomas and meningiomas than controls (p = 0.000). Total n-3 fatty acids level was also significantly lower in tumors than controls (p = 0.000). The levels of linoleic acid, arachidonic acid and dihomogamma linolenic acid from n-6 series were significantly higher in gliomas and meningiomas compared with controls (p = 0.000). Total n-6 fatty acids level was also significantly higher in tumors than controls (p = 0.000). Furthermore, in total n-9 fatty acids, total unsaturated fatty acids and total saturated fatty acids levels, there were no significant differences in gliomas and meningiomas compared with controls (p = 0.6840, p = 0.4388 and p = 0.4343, respectively). This findings suggest that n-6 fatty acids can act as a tumor-promoting agent in human brain tumors.

Divergent incorporation of dietary trans fatty acids in different serum lipid fractions

Trans fatty acids may be involved in atherosclerotic vascular diseases. We investigated the incorporation of dietary trans fatty acids and oleic acid into the serum triglycerides (TG), cholesterol esters (CE), and phospholipids (PL). Fourteen healthy female volunteers, aged 23.2+/-3.1 yr (mean+/-SD), body mass index 20.8+/-2.1 kg/m2 participated in this study. All subjects consumed both a trans fatty acid-enriched diet (TRANS diet) and an oleic acid-enriched diet (OLEIC diet) for 4 wk according to a randomized crossover design. Both experimental diet periods were preceded by consumption of a baseline diet for 2 wk which supplied 37% of total energy (E%) as fat: 18 E% from saturated fatty acids (SFA), 12 E% from monounsaturated fatty acids, and 6 E% from polyunsaturated fatty acids. Five E% of the SFA in the baseline diet was replaced by trans fatty acids (18:1t and 18:2c,t + 18:2t,t, where c is cis and t is trans) in the TRANS diet and by oleic acid (18:1n-9) in the OLEIC diet. After the TRANS diet, the proportions of 18:1t and 18:2t increased (P<0.001) in all serum lipid fractions analyzed. The increase of 18:1t in TG and PL (1.80+/-0.28 vs. 5.26+/-1.40; 1.07+/-0.34 vs. 3.39+/-0.76 mol% of total fatty acids, respectively) was markedly higher than that in CE (0.44+/-0.07 vs. 0.92+/-0.26), whereas that of 18:2t was nearly the same in all three fractions. The proportions of palmitic, stearic, arachidonic, and eicosapentaenoic acids in TG, CE, and PL and that of oleic acid in TG and CE were decreased when compared with the baseline value. In contrast, the proportion of palmitoleic acid in TG and PL and that of linoleic acid in PL increased on the TRANS diet. After consumption of the OLEIC diet, the proportion of oleic acid increased in all three lipid fractions analyzed, and the percentage increase was nearly the same in all fractions. In contrast, the proportions of 18:1t in TG and PL and 18:2t in TG and CE decreased when compared with the baseline value. In conclusion, a moderate increase in dietary trans fatty acids resulted in a marked incorporation into serum lipids and decreased the conversion of linoleic acid to its more unsaturated long-chain metabolites. Analysis of 18:1t from serum TG and PL seems to reflect reliably the dietary intake of this fatty acid.

The catalytic subunit of the cAMP-dependent protein kinase of ovine sperm flagella has a unique amino-terminal sequence

The basis for the unusual properties of the catalytic subunit (C) of ram sperm cAMP-dependent protein kinase was investigated. Ram sperm C was purified and found by mass spectrometry (MS) to be approximately 890 Da smaller than Calpha, the predominant somatic isoform. Partial internal amino acid sequence from ram sperm C was an exact match to that of bovine Calpha, but differed from the predicted sequences for the Cbeta and Cgamma isoforms. MS analysis of 2-nitro-5-thiocyanatobenzoic acid fragments showed that the mass difference originated in the amino-terminal region. A unique blocked amino-terminal fragment was isolated from sperm C and sequenced by a combination of tandem mass spectrometry and Edman degradation of a subfragment. The results revealed that the amino-terminal myristate and the first 14 amino acids of Calpha are replaced by an amino-terminal acetate and six different amino acids in sperm C. The predicted mass difference due to these changes is 899 Da. The region of homology between sperm C and Calpha begins at the exon 1/exon 2 boundary in Calpha, suggesting that sperm C results from use of an alternate exon 1 in the Calpha gene. The different amino terminus of sperm C may be related to a unique requirement for localization of the "free" C subunit within the sperm flagellum.

Effects of nitric oxide synthase inhibition on phospholipid fatty acid composition of brown adipose tissue

We investigated the effects of nitric oxide synthase inhibition on the phospholipid fatty acid composition of brown adipose tissue by administering chronic N omega-nitro-L-arginine methyl ester (L-NAME) (0.01%) to rats via drinking water. L-NAME caused a significant decrease in C14:0, C16:0, C16:1 and C18:1, with a concomitant increase in C18:0 and C18:2, L-NAME treatment elicited an increase in the unsaturation index. There were no significant changes in other fatty acids including the polyunsaturated fatty acids docosahexaenoate (DHA, C22:6) and arachidonate (C20:4). Polyunsaturated fatty acid linoleate (C18:2) was increased and the arachidonate index decreased in the L-NAME-treated group, suggesting a diminished conversion of C18:2 to C20:4.