scholarly journals Solubilization of the alternative oxidase of cuckoo-pint (Arum maculatum) mitochondria. Stimulation by high concentrations of ions and effects of specific inhibitors

1985 ◽  
Vol 228 (2) ◽  
pp. 309-318 ◽  
Author(s):  
C J Kay ◽  
J M Palmer
Keyword(s):  
Fatty Acids ◽  
Oxidase Activity ◽  
Alternative Oxidase ◽  
Alternative Pathway ◽  
Reduced Form ◽  
Quinol Oxidase ◽  
Low Concentrations ◽  
Competitive Inhibitors ◽  
High Concentrations ◽  
Arum Maculatum

Selective solubilization of cyanide- and antimycin-insensitive duroquinol oxidase activity from cuckoo-pint (Arum maculatum) mitochondria was achieved using taurocholate. Inhibitor-sensitivities and water-forming DQH2 (tetramethyl-p-hydroquinone, reduced form): O2 stoichiometry were the same for the alternative oxidase of intact Arum mitochondria. Cyanide-insensitive oxidation of DQH2 by intact and solubilized mitochondria was stimulated by up to four-fold by high concentrations of anions high in the Hofmeister series, such as phosphate, sulphate or citrate. Optimal (0.7 M) sodium citrate increased Vmax. for DQH2 oxidation by the solubilized preparation from 450 to 2400 nmol of O2 X min-1 X mg of protein-1 and decreased the apparent Km for DQH2 from 0.53 to 0.38 mM. Inhibition of solubilized DQH2 oxidase activity by CLAM (m-chlorobenzhydroxamic acid) and SHAM (salicylhydroxamic acid) was mixed competitive/non-competitive, with apparent inhibition constants for CLAM of 25 microM (Ki) and 81 microM (KI) and for SHAM of 53 microM (Ki) and 490 microM (KI). Propyl gallate and UHDBT were non-competitive inhibitors with respect to DQH2 (apparent Ki = 0.3 microM and 12 nM respectively). Low concentrations of C18 fatty acids selectively inhibited cyanide-insensitive oxidation by intact and solubilized mitochondria, and inhibition was reversed by 1% (w/v) bovine serum albumin. Inhibition was competitive with DQH2, suggesting that fatty acids interfere reversably with the binding of DQH2 to the oxidase. These results tend to support the view that quinol oxidation by the alternative pathway of Arum maculatum mitochondria is catalysed by a quinol oxidase protein, rather than by a non-enzymic mechanism involving fatty acid peroxidative reaction. [Rustin, Dupont & Lance (1983) Trends Biochem. Sci. 8, 155-157; (1983) Arch. Biochem. Biophys. 225, 630-639].

scholarly journals Kinetic analysis of the mitochondrial quinol-oxidizing enzymes during development of thermogenesis in Arum maculatum L

1996 ◽  
Vol 317 (1) ◽  
pp. 313-319 ◽  
Author(s):  
Graeme R. LEACH ◽  
Klaas KRAB ◽  
David G. WHITEHOUSE ◽  
Anthony L. MOORE
Keyword(s):  
Respiratory Rate ◽  
Succinate Dehydrogenase ◽  
Oxidase Activity ◽  
Alternative Oxidase ◽  
Alternative Pathway ◽  
Respiratory Control ◽  
Stage Of Development ◽  
Activation Level ◽  
Cytochrome Pathway ◽  
Arum Maculatum

The dependence of the rate of oxygen uptake upon the ubiquinone (Q)-pool reduction level in mitochondria isolated during the development of thermogenesis of Arum maculatum spadices has been investigated. At the α-stage of development, the respiratory rate was linearly dependent upon the reduction level of the Q-pool (Qr) both under state-3 and -4 conditions. Progression through the β/γ to the Δ-stage resulted in a non-linear dependence of the state-4 rate on Qr. In the Δ-stage of development, both state-3 and -4 respiratory rates were linearly dependent upon Qr due to a shift in the engagement of the alternative oxidase to lower levels of Qr. Western blot analysis revealed that increased alternative oxidase activity could be correlated with expression of a 35 kDa protein. Respiratory control was only observed with mitochondria in the α-stage of development. At the β/γ-stage of development, the addition of ADP resulted in a significant oxidation of the Q-pool which was accompanied by a decrease in the respiratory rate. This was due either to decreased contribution of the alternative pathway to the overall respiratory rate under state 3 or by deactivation of succinate dehydrogenase activity by ADP. Cold-storage of the spadices at the β-stage of development led to increased activity of both the cytochrome pathway and succinate dehydrogenase, without any change in alternative oxidase activity. Results are discussed in terms of how changes in the activation level of the alternative oxidase and succinate dehydrogenase influence the activity and engagement of the quinol-oxidizing pathways during the development of thermogenesis in A. maculatum.

The effect of fatty acids on the metabolism of lactic acid streptococci: II. Resistance of a variant of Streptococcus cremoris strain C 13

1964 ◽  
Vol 31 (1) ◽  
pp. 91-94 ◽  
Author(s):  
R. F. Anders ◽  
G. R. Jago
Keyword(s):  
Fatty Acids ◽  
Lactic Acid ◽  
Oleic Acid ◽  
Growth Medium ◽  
Streptococcus Cremoris ◽  
Low Concentrations ◽  
High Concentrations

SummaryIt was previously found that low concentrations of oleic acid in the growth medium inhibited the growth of Streptococcus cremoris strain C 13. However, a variant of this strain has now been isolated which is capable of growth in relatively high concentrations of oleic acid. This was achieved by the extended incubation of inocula of strain C 13 in milk containing various concentrations of oleic acid.

scholarly journals Stimulation of hepatic biogenesis of sterols on administration of adenosine compounds

1976 ◽  
Vol 154 (3) ◽  
pp. 639-645 ◽  
Author(s):  
G. S Rao ◽  
R George ◽  
T. Ramasarma
Keyword(s):  
Fatty Acids ◽  
Food Intake ◽  
Regulatory Role ◽  
Liver Slices ◽  
Low Concentrations ◽  
High Concentrations ◽  
Partial Deficiency ◽  
Coa Reductase ◽  
Stimulation Of

1. Re-feeding starved rats increased the biogenesis of sterols in livers, with highest activity at 6h after the start of food intake. 2. Complete deficiency of protein or fat and partial deficiency of carbohydrate in the diet had no effect on sterol biogenesis. 3. Glucose, citrate or pyruvate, when administered intraperitoneally to starved rats, stimulated the biogenesis of sterols only at high concentrations. 4. ATP given intraperitoneally at low concentrations (10mg/rat) stimulated biogenesis of sterols, but not of fatty acids, from [1-14C]acetate. This effect was also obtained with other adenosine compounds, but not with adenine or guanosine. 5. Administration of adenosine compounds to starved rats also increased the incorporation of [1-14C]acetate into sterols in liver slices and also the activity of microsomal 3-hydroxy-3-methylglutaryl-CoA reductase. The results suggest a regulatory role for adenosine compounds in the hepatic biogenesis of isoprenoid compounds.

A comparison of the acylation of 1-acyl-sn-glycero-3-phosphoinositol and 1-acyl-sn-glycero-3-phosphocholine in neuronal nuclei in vitro using radioactive arachidonate and oleate

1986 ◽  
Vol 64 (1) ◽  
pp. 1-7 ◽  
Author(s):  
R. Roy Baker ◽  
Huu-Yi Chang
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Nuclear Fraction ◽  
Maximal Rate ◽  
Low Concentration ◽  
Neuronal Nuclei ◽  
Low Concentrations ◽  
High Concentrations

A neuronal nuclear fraction (N1) was isolated from cerebral cortices of 15-day-old rabbits. Samples of N1 were incubated with a radioactive fatty acid ([3H]arachidonate or [14C]oleate), acylation cofactors, and 1-acyl-sn-glycero-3-phosphoinositol (1-acyl-GPI) or 1-acyl-sn-glycero-3-phosphocholine (1-acyl-GPC). In competition studies, both radioactive fatty acids were incubated with one lysophospholipid or the two lysophospholipids were incubated with one radioactive fatty acid. Using [3H]arachidonate and one lysophosphoglyceride, a maximal rate of incorporation into phosphatidylinositol (PI) was found at a relatively low concentration of 1-acyl-GPI (10 μM), while increasing rates of incorporation into phosphatidylcholine (PC) were seen with increasing concentrations of 1-acyl-GPC (to 65 μM). At low concentrations of lysophosphoglyceride (≤ 25 μM) the rate of arachidonate incorporation into PI greatly exceeded rates of arachidonate incorporation into PC. This higher rate of arachidonate incorporation into PI was also seen in incubations where both lysophospholipids were present. For oleate, greater rates of incorporation into PC were found in comparison with rates of labelling of PI in assays using relatively high concentrations of one or both lysophospholipids. When comparing arachidonate and oleate, in assays with one or both fatty acids, the polyunsaturate showed at least threefold higher rates of incorporation into PI. For PC labelling higher rates of arachidonate incorporation were evident at the higher concentrations of 1-acyl-GPC and the superiority over oleate was not as marked as that seen in PI labelling.

Elongases Synthesizing Very Long Chain Monounsaturated Fatty Acids in Developing Oilseeds and Their Solubilization

1989 ◽  
Vol 44 (7-8) ◽  
pp. 629-634 ◽  
Author(s):  
Denis J. Murphy ◽  
Kumar D. Mukherjee
Keyword(s):  
Fatty Acids ◽  
Monounsaturated Fatty Acids ◽  
Sinapis Alba ◽  
Pyridine Nucleotides ◽  
Low Concentrations ◽  
Malonyl Coa ◽  
Tropaeolum Majus ◽  
High Concentrations ◽  
Triton X ◽  
Long Chain

Particulate (15,000 x g ) fractions from developing seeds of mustard (Sinapis alba), honesty (Lunaria annua), and nasturtium (Tropaeolum majus) synthesize radioactive very long chain (n9)-(Z)-monounsaturated fatty acids, e.g. gadoleic (20:1). erucic (22:1). and nervonic (24:1) acids from [1-14C ]oleoyl-CoA with malonyl-CoA or from [2-14C]m alonyl-CoA with oleoyl-CoA . Pyridine nucleotides are required for the elongation reactions. Both NADH and NADPH are equally effective for the formation of 20:1, but NADPH is the preferred reductant for the formation of 22:1, which suggest the existence of separate elongase systems. Detergents, such as Triton X-100 and octyl thioglucoside, stimulate the elongation at low concentrations, but they are inhibitory at high concentrations. Partial solubilization of the elongase system using these detergents has been achieved.

Modulation of the transient outward current in adult rat ventricular myocytes by polyunsaturated fatty acids

1998 ◽  
Vol 274 (2) ◽  
pp. H571-H579 ◽  
Author(s):  
K. Y. Bogdanov ◽  
H. A. Spurgeon ◽  
T. M. Vinogradova ◽  
E. G. Lakatta
Keyword(s):  
Fatty Acids ◽  
Polyunsaturated Fatty Acids ◽  
Ventricular Myocytes ◽  
Outward Current ◽  
Transient Outward Current ◽  
Patch Clamp Technique ◽  
Rat Ventricular Myocytes ◽  
Adult Rat ◽  
Low Concentrations ◽  
High Concentrations

With the whole cell patch-clamp technique, we studied the effects of the n-3 and n-6 polyunsaturated fatty acids (PUFAs), linoleic (C18:2n-6), eicosapentaenoic (C20:4n-3), docosahexaenoic (C22:5n-3), and arachidonic (AA; C20:4n-6) acids, on K+ currents in rat ventricular myocytes. At low concentrations (5–10 μM) all PUFAs except AA inhibited, by ∼40%, the transient outward current ( I to) without affecting other K+ currents and markedly prolonged the action potential (AP). AA inhibited I to but also augmented a sustained depolarization-induced outward K+ current ( I sus); the latter effect did not occur in the presence of 4-aminopyridine or with eicosatetraynoic acid, a nonmetabolizable analog of AA. Higher concentrations of PUFAs (20–50 μM) further inhibited I to and also inhibited I sus. Thus, at high concentrations, PUFAs have a nonspecific effect on several K+ channels; at low concentrations, PUFAs preferentially inhibit I to and prolong the AP.

scholarly journals GPR120: A bi-potential mediator to modulate the osteogenic and adipogenic differentiation of BMMSCs

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Bo Gao ◽  
Qiang Huang ◽  
Qiang Jie ◽  
Wei-Guang Lu ◽  
Long Wang ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Unsaturated Fatty Acids ◽  
Adipogenic Differentiation ◽  
Dependent Manner ◽  
Signalling Molecules ◽  
Low Concentrations ◽  
High Concentrations ◽  
High Doses ◽  
Dose Dependent

Abstract Free fatty acids display diverse effects as signalling molecules through GPCRs in addition to their involvement in cellular metabolism. GPR120, a G protein-coupled receptor for long-chain unsaturated fatty acids, has been reported to mediate adipogenesis in lipid metabolism. However, whether GPR120 also mediates osteogenesis and regulates BMMSCs remain unclear. In this study, we showed that GPR120 targeted the bi-potential differentiation of BMMSCs in a ligand dose-dependent manner. High concentrations of TUG-891 (a highly selective agonist of GPR120) promoted osteogenesis via the Ras-ERK1/2 cascade, while low concentrations elevated P38 and increased adipogenesis. The fine molecular regulation of GPR120 was implemented by up-regulating different integrin subunits (α1, α2 and β1; α5 and β3). The administration of high doses of TUG-891 rescued oestrogen-deficient bone loss in vivo, further supporting an essential role of GPR120 in bone metabolism. Our findings, for the first time, showed that GPR120-mediated cellular signalling determines the bi-potential differentiation of BMMSCs in a dose-dependent manner. Additionally, the induction of different integrin subunits was involved in the cytoplasmic regulation of a seesaw-like balance between ERK and p38 phosphorylation. These findings provide new hope for developing novel remedies to treat osteoporosis by adjusting the GPR120-mediated differentiation balance of BMMSCs.

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