The missing enzymatic link in syntrophic methane formation from fatty acids

2021 ◽  
Vol 118 (40) ◽  
pp. e2111682118
Author(s):  
Michael Agne ◽  
Sebastian Estelmann ◽  
Carola S. Seelmann ◽  
Johannes Kung ◽  
Dennis Wilkens ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Saturated Fatty Acids ◽  
Methanogenic Archaea ◽  
Acid Oxidation ◽  
Methane Formation ◽  
Fermentation Products ◽  
Membrane Bound ◽  
Acyl Coenzyme A ◽  
Key Steps ◽  
Syntrophus Aciditrophicus

The microbial production of methane from organic matter is an essential process in the global carbon cycle and an important source of renewable energy. It involves the syntrophic interaction between methanogenic archaea and bacteria that convert primary fermentation products such as fatty acids to the methanogenic substrates acetate, H2, CO2, or formate. While the concept of syntrophic methane formation was developed half a century ago, the highly endergonic reduction of CO2 to methane by electrons derived from β-oxidation of saturated fatty acids has remained hypothetical. Here, we studied a previously noncharacterized membrane-bound oxidoreductase (EMO) from Syntrophus aciditrophicus containing two heme b cofactors and 8-methylmenaquinone as key redox components of the redox loop–driven reduction of CO2 by acyl–coenzyme A (CoA). Using solubilized EMO and proteoliposomes, we reconstituted the entire electron transfer chain from acyl-CoA to CO2 and identified the transfer from a high- to a low-potential heme b with perfectly adjusted midpoint potentials as key steps in syntrophic fatty acid oxidation. The results close our gap of knowledge in the conversion of biomass into methane and identify EMOs as key players of β-oxidation in (methyl)menaquinone-containing organisms.

scholarly journals Nrf2 affects the efficiency of mitochondrial fatty acid oxidation

2014 ◽  
Vol 457 (3) ◽  
pp. 415-424 ◽  
Author(s):  
Marthe H. R. Ludtmann ◽  
Plamena R. Angelova ◽  
Ying Zhang ◽  
Andrey Y. Abramov ◽  
Albena T. Dinkova-Kostova
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Saturated Fatty Acids ◽  
Acid Oxidation ◽  
Mitochondrial Fatty Acid Oxidation ◽  
Atp Production ◽  
Mitochondrial Fatty Acid ◽  
Mitochondrial Oxidation ◽  
Long Chain

Transcription factor Nrf2 affects fatty acid oxidation; the mitochondrial oxidation of long-chain (palmitic) and short-chain (hexanoic) saturated fatty acids is depressed in the absence of Nrf2 and accelerated when Nrf2 is constitutively activated, affecting ATP production and FADH2 utilization.

scholarly journals Biochemical effects of the hypoglycaemic compound pent-4-enoic acid and related non-hypoglycaemic fatty acids. Fatty acid oxidation

1968 ◽  
Vol 110 (3) ◽  
pp. 511-519 ◽  
Author(s):  
A. E. Senior ◽  
B. Robson ◽  
H. S. A. Sherratt
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Saturated Fatty Acids ◽  
Chain Fatty Acid ◽  
Enoic Acid ◽  
Acid Oxidation ◽  
Long Chain Fatty Acid ◽  
Cyclopropanecarboxylic Acid ◽  
Long Chain

1. The effects of the hypoglycaemic compound, pent-4-enoic acid, and of four structurally related non-hypoglycaemic compounds (pentanoic acid, pent-2-enoic acid, cyclopropanecarboxylic acid and cyclobutanecarboxylic acid), on the oxidation of saturated fatty acids by rat liver mitochondria were determined. 2. The formation of 14CO2 from [1−14C]palmitate was strongly inhibited by 0·01mm-pent-4-enoic acid. 3. The inhibition of oxygen uptake was less than that of 14CO2 formation, presumably because fumarate was used as a sparker. 4. The oxidation of [1−14C]-butyrate, -octanoate or -laurate was not strongly inhibited by 0·01mm-pent-4-enoic acid. 5. The other four non-hypoglycaemic compounds did not inhibit the oxidation of any saturated fatty acid when tested at 0·01mm concentration, though they all inhibited strongly at 10mm. 6. The oxidation of [1−14C]-myristate and -stearate, but not of [1−14C]decanoate, was strongly inhibited by 0·01mm-pent-4-enoic acid. 7. The oxidation of [1−14C]palmitate was about 50% carnitine-dependent under the experimental conditions used. 8. The percentage inhibition of [1−14C]palmitate oxidation by pent-4-enoic acid was the same whether carnitine was present or not. 9. Acetoacetate formation from saturated fatty acids was inhibited by 0·1mm-cyclopropanecarboxylic acid to a greater extent than their oxidation. 10. The other compounds tested inhibited acetoacetate formation from saturated fatty acids proportionately to the inhibition of oxidation. 11. Possible mechanisms for the inhibition of long-chain fatty acid oxidation by pent-4-enoic acid are discussed. 12. There was a correlation between the ability to inhibit long-chain fatty acid oxidation and hypoglycaemic activity in this series of compounds.

scholarly journals Vitamin B12 Induces Hepatic Fatty Infiltration through Altered Fatty Acid Metabolism

2021 ◽  
Vol 55 (3) ◽  
pp. 241-255
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Vitamin B12 ◽  
Fatty Acid Oxidation ◽  
Lipid Droplets ◽  
De Novo ◽  
Quantitative Polymerase Chain Reaction ◽  
Saturated Fatty Acids ◽  
Fatty Infiltration ◽  
Acid Oxidation

Background/Aims: Rise in global incidence of obesity impacts metabolic health. Evidence from human and animal models show association of vitamin B12 (B12) deficiency with elevated BMI and lipids. Human adipocytes demonstrated dysregulation of lipogenesis by low B12 via hypomethylation and altered microRNAs. It is known de novo hepatic lipogenesis plays a key role towards dyslipidaemia, however, whether low B12 affects hepatic metabolism of lipids is not explored. Methods: HepG2 was cultured in B12-deficient EMEM medium and seeded in different B12 media: 500nM(control), 1000pM(1nM), 100pM and 25pM(low) B12. Lipid droplets were examined by Oil Red O (ORO) staining using microscopy and then quantified by elution assay. Gene expression were assessed with real-time quantitative polymerase chain reaction (qRT-PCR) and intracellular triglycerides were quantified using commercial kit (Abcam, UK) and radiochemical assay. Fatty acid composition was measured by gas chromatography and mitochondrial function by seahorse XF24 flux assay. Results: HepG2 cells in low B12 had more lipid droplets that were intensely stained with ORO compared with control. The total intracellular triglyceride and incorporation of radio-labelled-fatty acid in triglyceride synthesis were increased. Expression of genes regulating fatty acid, triglyceride and cholesterol biosynthesis were upregulated. Absolute concentrations of total fatty acids, saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), trans-fatty acids and individual even-chain and odd-chain fatty acids were significantly increased. Also, low B12 impaired fatty acid oxidation and mitochondrial functional integrity in HepG2 compared with control. Conclusion: Our data provide novel evidence that low B12 increases fatty acid synthesis and levels of individual fatty acids, and decreases fatty acid oxidation and mitochondrial respiration, thus resulting in dysregulation of lipid metabolism in HepG2. This highlights the potential significance of de novo lipogenesis and warrants possible epigenetic mechanisms of low B12.

scholarly journals The Quality Characteristic and Fatty Acid Profile of Cold-Pressed Hazelnut Oils during Nine Months of Storage

Agronomy ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2045
Author(s):  
Katarzyna Król ◽  
Magdalena Gantner ◽  
Anna Piotrowska
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Saturated Fatty Acids ◽  
Fatty Acid Content ◽  
Storage Period ◽  
Storage Conditions ◽  
Quality Characteristic ◽  
Hazelnut Oil ◽  
Acid Oxidation ◽  
Cold Pressed

Poland is one of the largest producers of hazelnuts in Europe; however, information regarding the storage of cold-pressed hazelnut oil is limited. Thus, the aim of this study was to determine the oxidative indices and fatty acid composition of oils from six hazelnut cultivars during 9 months of storage. At the beginning of storage, the hazelnut oils showed zero or very low oxidation values, which indicated the absence of initial triglyceride hydrolysis and fatty acid oxidation. Acid values increased with storage time, which was statistically significant, ranging from 0.17 to 0.34 mg KOH/g oil. The peroxide value in the first 5 months of storage was undetectable, whereas after 9 months the oils showed a slight increase in oils obtained from the ‘Olbrzym z Halle’ cultivar, followed by the ‘Barcelonski’ cultivar, at 3.39 and 2.15 meq O2/kg, respectively. The lipid content of the kernels was very stable under storage conditions. Total monounsaturated fatty acid content exhibited the highest proportion, while saturated fatty acids (SFAs) had the lowest content over the entire storage period. The percentage of polyunsaturated fatty acids showed a small decrease during storage, but was not statistically significant; therefore, polyunsaturated fatty acid remained stable. The percentage of monounsaturated fatty acids decreased by approx. 1.6%, thus the percentage of SFA increased by approx. 13.7% during 9 months of storage. The oil yield ranged from 69% for nuts from the ‘Nottinghsamski’ cultivar to 75% from the ‘Webba Cenny’ and ‘Barcelonski’ cultivars.

Regulation of leptin secretion from white adipocytes by free fatty acids

2003 ◽  
Vol 285 (3) ◽  
pp. E521-E526 ◽  
Author(s):  
Philippe G. Cammisotto ◽  
Yves Gélinas ◽  
Yves Deshaies ◽  
Ludwik J. Bukowiecki
Keyword(s):  
Fatty Acids ◽  
Chain Length ◽  
Unsaturated Fatty Acids ◽  
Saturated Fatty Acids ◽  
Acid Oxidation ◽  
Mitochondrial Fatty Acid Oxidation ◽  
White Adipocytes ◽  
Mitochondrial Fatty Acid ◽  
A Chain ◽  
Long Chain

Norepinephrine stimulates lipolysis and concurrently inhibits insulin-stimulated leptin secretion from white adipocytes. To assess whether there is a cause-effect relationship between these two metabolic events, the effects of fatty acids were investigated in isolated rat adipocytes incubated in buffer containing low (0.1%) and high (4%) albumin concentrations. Palmitic acid (1 mM) mimicked the inhibitory effects of norepinephrine (1 μM) on insulin (10 nM)-stimulated leptin secretion, but only at low albumin concentrations. Studies investigating the effects of the chain length of saturated fatty acids [from butyric (C4) to stearic (C18) acids] revealed that only fatty acids with a chain length superior or equal to eight carbons effectively inhibited insulin-stimulated leptin secretion. Long-chain mono- and polyunsaturated fatty acids constitutively present in adipocyte triglyceride stores (oleic, linoleic, γ-linolenic, palmitoleic, eicosapentanoic, and docosahexanoic acids) also completely suppressed leptin secretion. Saturated and unsaturated fatty acids inhibited insulin-stimulated leptin secretion with the same potency and without any significant effect on basal secretion. On the other hand, inhibitors of mitochondrial fatty acid oxidation (palmoxirate, 2-bromopalmitate, 2-bromocaproate) attenuated the stimulatory effects of insulin on leptin release without reversing the effects of fatty acids or norepinephrine, suggesting that fatty acids do not need to be oxidized by the mitochondria to inhibit leptin release. These results demonstrate that long-chain fatty acids mimic the effects of norepinephrine on leptin secretion and suggest that they may play a regulatory role as messengers between stimulation of lipolysis by norepinephrine and inhibition of leptin secretion.

scholarly journals Variation Patterns of the Volatiles during Germination of the Foxtail Millet (Setaria Italic): The Relationship between the Volatiles and Fatty Acids in Model Experiments

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1238 ◽  
Author(s):  
PengLiang Li ◽  
Yin Zhu ◽  
ShaoHui Li ◽  
AiXia Zhang ◽  
Wei Zhao ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Unsaturated Fatty Acids ◽  
Material Selection ◽  
Saturated Fatty Acids ◽  
Foxtail Millet ◽  
Raw Material ◽  
Acid Oxidation ◽  
Model Experiments ◽  
Flight Mass Spectrometry

Functional and nutritional compounds are increased during foxtail millet germination while bad smell is produced due to the fatty acid oxidation. To eliminate the unpleasant aroma, the origins of the volatiles must be known. A comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry showed forty-nine volatiles containing 8 ketones, 10 aldehydes, 20 alkanes, 4 alcohols, 5 alkenes, and 2 furans were tentatively identified, and they increased during the germination of the foxtail millet. To identify the origin of some volatiles, model experiments by adding 6 fatty acids to the crude enzymes of the foxtail millet was designed, and 17 volatiles could be detected. The saturated fatty acids (palmitic acid and stearic acid) had no contributions to the formation of the volatiles, whereas the unsaturated fatty acid played important roles in the formation of volatiles. Among the unsaturated fatty acids, palmitoleic acid and linoleic acid produced most aldehydes, alcohols, and ketones, while linolenic acid produced the most alkanes and alkenes. This study will be helpful for controlling the smell of germinated seeds from the raw material selection.

scholarly journals Decreased Triacylglycerol Content and Elevated Contents of Cell Membrane Lipids in Colorectal Cancer Tissue: A Lipidomic Study

2020 ◽  
Vol 9 (4) ◽  
pp. 1095
Author(s):  
Adriana Mika ◽  
Alicja Pakiet ◽  
Aleksandra Czumaj ◽  
Zbigniew Kaczynski ◽  
Ivan Liakh ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Fatty Acids ◽  
Cell Membrane ◽  
Lipid Composition ◽  
Membrane Lipids ◽  
Saturated Fatty Acids ◽  
Gas Chromatography Mass Spectrometry ◽  
Acid Oxidation ◽  
Cancer Tissue ◽  
Cancer Tissues

Recent evidence suggests that lipid composition in cancer tissues may undergo multiple alterations. However, no comprehensive analysis of various lipid groups in colorectal cancer (CRC) tissue has been conducted thus far. To address the problem in question, we determined the contents of triacylglycerols (TG), an energetic substrate, various lipids necessary for cell membrane formation, among them phospholipids (phosphatidylcholine, phosphatidylethanolamine), sphingolipids (sphingomyelin) and cholesterol (free, esterified and total), and fatty acids included in complex lipids. 1H-nuclear magnetic resonance (1H-NMR) and gas chromatography-mass spectrometry (GC-MS) were used to analyze the lipid composition of colon cancer tissue and normal large intestinal mucosa from 25 patients. Compared with normal tissue, cancer tissues had significantly lower TG content, along with elevated levels of phospholipids, sphingomyelin, and cholesterol. Moreover, the content of oleic acid, the main component of TG, was decreased in cancer tissues, whereas the levels of saturated fatty acids and polyunsaturated fatty acids (PUFAs), which are principal components of polar lipids, were elevated. These lipidome rearrangements were associated with the overexpression of genes associated with fatty acid oxidation, and the synthesis of phospholipids and cholesterol. These findings suggest that reprogramming of lipid metabolism might occur in CRC tissue, with a shift towards increased utilization of TG for energy production and enhanced synthesis of membrane lipids, necessary for the rapid proliferation of cancer cells.

scholarly journals Peroxisomal fatty acid oxidation and inhibitors of the mitochondrial carnitine palmitoyltransferase I in isolated rat hepatocytes

1992 ◽  
Vol 281 (2) ◽  
pp. 561-567 ◽  
Author(s):  
C Skorin ◽  
C Necochea ◽  
V Johow ◽  
U Soto ◽  
A M Grau ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Saturated Fatty Acids ◽  
Rat Hepatocytes ◽  
Acid Oxidation ◽  
Peroxisomal Fatty Acid Oxidation ◽  
Carnitine Palmitoyltransferase I ◽  
Cpt I ◽  
Peroxisomal Fatty Acid

Fatty acid oxidation was studied in the presence of inhibitors of carnitine palmitoyltransferase I (CPT I), in normal and in peroxisome-proliferated rat hepatocytes. The oxidation decreased in mitochondria, as expected, but in peroxisomes it increased. These two effects were seen, in variable proportions, with (+)-decanoylcarnitine, 2-tetradecylglycidic acid (TDGA) and etomoxir. The decrease in mitochondrial oxidation (ketogenesis) affected saturated fatty acids with 12 or more carbon atoms, whereas the increase in peroxisomal oxidation (H2O2 production) affected saturated fatty acids with 8 or more carbon atoms. The peroxisomal increase was sensitive to chlorpromazine, a peroxisomal inhibitor. To study possible mechanisms, palmitoyl-, octanoyl- and acetyl-carnitine acyltransferase activities were measured, in homogenates and in subcellular fractions from control and TDGA-treated cells. The palmitoylcarnitine acyltransferase was inhibited, as expected, but the octanoyltransferase activity also decreased. The CoA derivative of TDGA was synthesized and tentatively identified as being responsible for inhibition of the octanoylcarnitine acyltransferase. These results show that inhibitors of the mitochondrial CPT I may also inhibit the peroxisomal octanoyl transferase; they also support the hypothesis that the octanoyltransferase has the capacity to control or regulate peroxisomal fatty acid oxidation.

Dietary Changes in Fasting Levels of Factor VII Coagulant Activity (FVII: C) Are Accompanied by Changes in Factor VII Protein and other Vitamin K-dependent Proteins

1995 ◽  
Vol 73 (02) ◽  
pp. 239-242 ◽  
Author(s):  
E M Bladbjerg ◽  
T Tholstrup ◽  
P Marckmann ◽  
B Sandström ◽  
J Jespersen
Keyword(s):  
Fatty Acids ◽  
Vitamin K ◽  
Protein C ◽  
Saturated Fatty Acids ◽  
Factor Vii ◽  
Dietary Regimen ◽  
Blood Samples ◽  
Dietary Changes ◽  
Coagulant Activity ◽  
Before And After

SummaryThe mechanisms behind dietary effects on fasting coagulant activity of factor VII (FVII: C) are not clarified. In the present study of 15 young volunteers, two experimental diets differing in composition of saturated fatty acids (C18:0 [diet S] or C12:0 + C14:0 [diet ML]) were served for 3 weeks each. Fasting blood samples were collected before and after the dietary regimen and analysed for triglycerides, FVII:C, and protein concentrations of FVII, FII, FX, protein C, CRP, albumin, fibrinogen, and F1+2. FVII:C was significantly reduced on diet S compared with diet ML. This was accompanied by a decrease in FVII protein, F1+2 and the vitamin K-dependent proteins FII, FX, and protein C. In contrast, no changes were observed in triglycerides, FVII:C/FVII: Ag, albumin and CRP. Fibrinogen was increased on diet S compared with diet ML. Our findings suggest that the change in fasting FVII:C was part of a general change in concentrations of vitamin K-dependent proteins.

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