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1.
Reuben S.E. Young Andrew P. Bowman Kaylyn D. Tousignant Berwyck L.J. Poad Jennifer H. Gunter Lisa K. Philp Colleen C. Nelson Shane R. Ellis Ron M.A. Heeren Martin C. Sadowski Stephen J. Blanksby 《Journal of lipid research》2022,63(6):100223
The cellular energy and biomass demands of cancer drive a complex dynamic between uptake of extracellular FAs and their de novo synthesis. Given that oxidation of de novo synthesized FAs for energy would result in net-energy loss, there is an implication that FAs from these two sources must have distinct metabolic fates; however, hitherto, all FAs have been considered part of a common pool. To probe potential metabolic partitioning of cellular FAs, cancer cells were supplemented with stable isotope-labeled FAs. Structural analysis of the resulting glycerophospholipids revealed that labeled FAs from uptake were largely incorporated to canonical (sn-) positions on the glycerol backbone. Surprisingly, labeled FA uptake also disrupted canonical isomer patterns of the unlabeled lipidome and induced repartitioning of n-3 and n-6 PUFAs into glycerophospholipid classes. These structural changes support the existence of differences in the metabolic fates of FAs derived from uptake or de novo sources and demonstrate unique signaling and remodeling behaviors usually hidden from conventional lipidomics. 相似文献
2.
Immunogold labelling was used to study the distribution of acyl carrier protein (ACP) in Escherichia coli and a variety of plant tissues. In E. coli, ACP is distributed throughout the cytoplasm, confirming the observation of S. Jackowski et al. (1985, J. Bacteriol., 162, 5–8_. In the mesocarp of Avocado (Persea americana) and maturing seeds of oil-seed rape (Brassica napus cv. Jet Neuf), over 95% of the ACP is localised to plastids. The protein is almost exclusively located in the chloroplasts of leaf material from oil-seed rape. Approximately 80% of the gold particles associated with the ACP were further localized to the thylakoid membrane of the chloroplast. Since acetyl-CoA carboxylase has been reported to be localized to the thylakoid membrane (C.G. Kannangara and C.J. Jensen, 1975, Eur. J. Biochem., 54, 25–30), these results are consistent with the view that the two sequential enzymes in fatty-acid synthesis are in close spacial proximity.Abbreviations ACC
acetyl CoA carboxylase
- ACP
acyl carrier protein
- FAS
fatty-acid synthetase 相似文献
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Robert R. Rando 《Journal of bioenergetics and biomembranes》1991,23(1):133-146
The key step in the visual pigment regeneration process is an enzyme-catalyzedtrans tocis retinoid isomerization reaction. This reaction is of substantial general interest, because it requires the input of metabolic energy. The energy is needed because the 11-cis-retinoid reaction products are approximately 4kcal/mol higher in energy than their all-trans congeners. In the retinal pigment epithelium a novel enzymatic system has been discovered which is capable of converting all-trans-retinol into all-trans retinyl esters, by means of a lecithin retinol acyl transferase (LRAT), followed by the direct processing of the ester into 11-cis-retinol. In this process the free energy of hydrolysis of a retinyl ester, estimated to be approximately –5kcal/mol, is coupled to the endothermic (+4kcal/mol) isomerization reaction, resulting in an overall exothermic process. The overall process is analogous to ATP-dependent group transfer reactions, but here the energy is provided by the membrane phospholipids. This process illustrates a new role for membranes: they can serve as an energy source. 相似文献
5.
Potato cells (cv. Norchip) were cultured from tuber parenchymal tissue and subcultured to dissociate and habituate the despecialized cells. After several subculturings on a minimal nutrient media, this line of cells demonstrated repeatable physical growth profiles for dry weight (DW), fresh weight (FW) and protein. Two enzymes of plant lipid metabolism were investigated, lipolytic acyl hydrolase (LAH) and lipoxygenase (LOX), which respectively liberate and peroxidize fatty acids from lipid in cellular membranes. LAH, measured as p-nitrophenyl palmitate hydrolase, was present in this line of cells in easily detectable amounts (317 units g-1 DW) albeit much lower than that found in mother tuber (9878 units g-1 DW). The presence of LAH in this line is significant because LAH isozymes are often described as storage proteins, yet activity per gram fresh weight in these unorganized cells is reasonably constant until culture growth exits the linear phase. However, LOX, the most active free fatty acid metabolizing enzyme in potato tubers (89,800 units g-1 DW), was not detectable in this line of callus or suspension cultured cells. The absence of LOX activity in this line of cells was verified by a number of assay approaches and was confirmed by activity staining of extracted enzymes separated in polyacrylamide gels. The absence of LOX in these cultured cells is especially important in determining the functions of this lipid peroxidation system and how it may be genetically regulated.Mention of company or trade name does not imply endorsement by the United States Department of Agriculture over others not named.A laboratory cooperatively operated by the Midwest Area, Agricultural Research Service, U.S. Department of Agriculture, The Minnesota Agricultural Experiment Station, the North Dakota Agrcultural Experiment Station, and the Red River Valley Potato Grower's Association. 相似文献
6.
Clathrin-associated proteins contain bound nucleotide 总被引:2,自引:0,他引:2
An alcohol dehydrogenase isolated from Zymomonas mobilis was found to be activated by ferrous ions but not by zinc, after inactivation with metal-complexing agents. Cobaltous ions also re-activated to a lesser extent. It is suggested that in this species the alcohol dehydrogenase naturally contains iron. Kinetic studies on the iron-treated enzyme indicate an 'alcohol activation' phenomenon, which may have physiological relevance in overcoming product inhibition during fermentation. 相似文献
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The expression of an Arabidopsis acyl carrier protein (ACP) gene promoter has been examined in transgenic tobacco plants by linking it to the reporter gene -glucuronidase (GUS). Fluorometric analysis showed that the ACP gene promoter was most active in developing seeds. Expression was also high in roots, but significantly lower in young leaves and downregulated upon their maturation. Etiolated and light-grown seedlings showed the same level of GUS activity, indicating that this promoter is not tightly regulated by light. Histochemical studies revealed that expression was usually highest in apical/ meristematic zones of vegetative tissues. Young flowers (ca. 1 cm in length) showed GUS staining in nearly all cell types, however, cell-specific patterns emerged in more mature flowers. The ACP gene promoter was active in the stigma and transmitting tissue of the style, as well as in the tapetum of the anther, developing pollen, and ovules. The results provide evidence that this ACP gene is regulated in a complex manner and is responsive to the array of signals which accompany cell differentiation, and a demand for fatty acids and lipids, during organogenesis. 相似文献
10.
By the use of EPR spectroscopy, it has been shown that acyl nitroso compounds can act as spin traps for short-lived radicals with the formation of acyl aminoxyl radicals. The reaction was studied for the system benzohydroxamicacid[Ph-C (= O)N(H)] - dimethyl sulfoxide - hydrogen peroxide. The acyl aminoxyl radicals appeared almost immediately when the reaction mixture was irradiated in situ in the EPR cavity with UV light. The trapping reaction involved two photochemical reactions, i.e. the oxidation of the hydroxamic acid to the acyl nitroso compound Ph-C (= O)NO, and the formation of methyl radicals from dimethyl sulfoxide. The EPR spectra are superpositions of the spectra of two species of acyl aminoxyl radicals, i.e. the radicals Ph-C (= O)N(O·)H formed by oxidation of the parent benzohydrox-amic acid, and the radical Ph-C (= O)N(O·)CH3, formed by trapping of methyl radicals. 相似文献