No description available.

It has been suggested that membrane characteristics associated with carcinomas could be related to an altered molecular structure of lipids inplasma membrane. The microsomal and soluble fractions of the cell are major sites of de novo synthesis and elongation/desaturation of fatty acids. It was the purpose of this study to compare the fatty acid composition of microsomal and soluble fractions isolated from mammary adenocarcinomas with that of normal mammary tissue and to determine if deviations found in the plasma membrane isolated from tumors could be observed at these subcellular levels.Microsomal and soluble fractions were isolated by differential centrifugation from mammary adenocarcinomas and from normal mammary tissue of Strain A female mice. Activities of nicotinamide adenine dinucleotide, reduced (NADH) dependent cytochrome c reductase andnicotinamide adenine dinucleotide phosphate, reduced (NADPH) dependent cytochrome c reductase in these fractions were determined. The fatty acids were extracted, methylated, and methyl esters identified and quantified using gas liquid chromatography. Polar and non-polar GLC columns, silver nitrate thin layer chromatography, hydrogenation, and spiking was used to confirm the identity of some fatty acids.Fatty acid composition of the microsomal and soluble fractions was similar in tumor and normal tissue. There was a greater percentage of C24:1 in tumors. A reversal of the oleic to stearic acid ratio, an increase in the level of palmitic acid, and a tendency toward long chain polyenoic fatty acids, as reported in studies on the plasma membrane isolated from tumors, was not evident in either the microsomal or soluble fractions. There was evidence of greater utilization of NADPH in the reduction of cytochrome c reductase in tumors. This may result in a decreased availability of NADPH for fatty acid synthetase and lipogenesis.Results of this study do not demonstrate support for a shift in the biosynthetic pathway for the synthesis of fatty acids in carcinomas. It is possible that changes in the lipid composition in the plasma membrane of tumor cells occur after initial incorporation or a shift in biosynthesis could occur in the mitochondria, another site of de novo synthesis and elongation/desaturation of fatty acids.

Thesis (M. Sc. (Biochemistry)) -- University of Limpopo, 1999

No description available.

Call number: LD2668 .T4 1985 A28 / Master of Science

No description available.

Fourier transform infrared (FTIR) spectroscopy was employed to monitor the oxidation of edible oils in the absence and presence of antioxidants. Three synthetic antioxidants (butylated hydroxyanisole, propyl gallate and tert-butylhydroxyquinone) were added to menhaden oil at three different concentrations (1%, 0.1%, and 0.01%), and the FTIR spectra of the oils under conditions of oxidative stress were recorded as a function of time. The efficacy of each antioxidant was assessed by monitoring bands at 3444 cm$ sp{-1}$, characteristic of hydroperoxide formation, 971 cm$ sp{-1}$ for trans double bond formation, and 3008 cm$ sp{-1}$ for cis depletion. An FTIR spectroscopic method was also developed for the determination of the peroxide value of edible oils undergoing oxidation, based on the measurement of the 3444-cm$ sp{-1}$ band. The results of the FTIR method were compared to those from both the iodometric chemical method and the enzymatic hemoglobin-methylene blue assay for the determination of hydroperoxide content. The FTIR predictions were within $ pm$3% of the values obtained by both the chemical and the enzymatic method. Finally, the determination of the hydroxyl value of emulsifiers by FTIR spectroscopy was investigated. Both attenuated total reflectance (ATR) and transmission flow cell techniques were used to record the spectra of commercial monoglycerides. Calibration models for the prediction of hydroxyl value from the FTIR spectra were developed using partial-least-squares (PLS) regression for both the ATR and transmission spectra. Cross-validation of the calibration models yielded an overall average error in the predicted hydroxyl values of $ sim$3% for both the ATR and transmission flow cell methodologies. Linear regression of the FTIR-predicted versus the hydroxyl values determined by the reference chemical method yielded r = 0.998 for the ATR and r = 0.997 for the transmission flow cell method.

The purpose of this research was to determine the fatty acid composition of lipids as compared to those of normal tissue. The altered molecular structure of these lipids could cause changes in the plasma membrane fluidity and membrane integrity producing the membrane characteristics associated with carcinomas.Plasma membranes-were isolated by differential centrifugation from both tumor and normal tissue from Strong A female mice. The lipids were extracted, separated by thin-layer chromatography, saponified and the fatty acid methyl esters identified and quantified by gas chromatography. The lipids were separated into four classes, cholesterol esters, triglycerides, free fatty acids and phospholipids. The carcinoma samples exhibited a reduction in the fatty acids of 10 to 14, carbons in chain length by as much as 32 percent. The level of palmitic acid increased in the tumor fractions as much as double the normal amount. The level of palmitoleic acid also increased in the tumor fractions nearly proportional to the palmitic acid. The stearic acid content in the tumor fractions increased as did the oleic acid in three of the four lipid classes, again nearly proportional to the stearic acid. Levels as high as 29 percent of henicosanoic acid in some normal tissue samples were found, but the carcinoma samples exhibited no higher than 10 percent. The increased production of heptadecadienoic acid in the carcinoma fractions along with the appearance of eicosatrienoic acid when only low scattered amounts were found in the normal fractions indicated that a shift in fatty acid biosynthesis has occurred, it would appear that in the carcinoma, the biosynthetic pathway for synthesis of fatty acids in the plasma membranes shifted from a de novo to a chain elongation pathway as the principal route.

Microalgae have been so far identified as the major producers of organic matter through their photosynthetic activities. In the present work, Nannochloris sp. and Amphora sp., two marine microalgae, have been investigated for proteins and lipids production. Protein fraction was quantified using Bicinchoninic acid (BCA) assay. Protein content in Nannochloris sp. was 16.69 ±4.07 % of dry mass and in Amphora sp. it was 39.89 ±2.09 % of dry mass. Enzyme assays were conducted spectrophotometrically. Nannochloris sp. had malate dehydrogenase, peroxidase and catalase activities. Amphora sp. exhibited malate dehydrogenase, catalase and cytochrome C oxidase activities. These enzymes have several valuable applications in some metabolic pathways and as antioxidant nutrition additives. Besides, lipid extraction was conducted using methanol/ chloroform solvent extraction. Crude lipid extract was analyzed using gas chromatography-mass spectrometry. Lipid contents were 8.14 ±3.67 % in Nannochloris sp. and 10.48 ±1.26% on dry basis in Amphora sp., respectively. Nannochloris sp. fatty acids were composed of C16:0 and C18:0 that are valuable for biodiesel production, and É-3 C18:3, É-6 C18:2, É-6 C16:2 having great nutritional values. In Amphora sp., the fatty acids consisted of C14:0, C16:0 and C16:1 shown to be valuable for biodiesel production and É-3 C22:6 having high nutritional values. Furthermore, a single step conversion of microalgal oil to fatty acid methyl esters was carried out starting directly from lyophilized microalgae. This promising process, in situ transesterification, led to better yields of methyl esters as compared to conventional lipid extraction followed by separate transesterification. / Master of Science

No description available.