Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.3.1.21 (CPT)
4,580 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have investigated the contribution of peroxisomes and mitochondria to the beta-oxidation of palmitate (C16:0) and cerotate (C26:0) in intact human skin fibroblasts. The oxidation of both fatty acids was found to be inhibited by rotenone plus antimycin and cyanide, respectively, although to a different extent. When 2-[5-(4-chlorophenyl)pentyl]-oxirane-2-carboxylate (POCA) was used to specifically block carnitine palmitoyltransferase I, it was found that palmitate beta-oxidation was inhibited almost completely whereas cerotate beta-oxidation was not affected. Since carnitine palmitoyltransferase is essential for the oxidation of fatty acids in mitochondria this result provides conclusive evidence that oxidation of very-long-chain fatty acids is initiated in peroxisomes and not in mitochondria.
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PMID:Conclusive evidence that very-long-chain fatty acids are oxidized exclusively in peroxisomes in human skin fibroblasts. 187 64

We studied the effect of sodium 2-[5-(4-chlorophenyl)pentyl]oxirane-2-carboxylate (POCA), a potent inhibitor of mitochondrial carnitine palmitoyltransferase I, on fatty acid oxidation by rat brain cells. In cultured glial cells as well as in dissociated brain cells from adult rats palmitic acid (16:0) oxidation was inhibited by about 85% of control values when 25 microM POCA was added to the medium, whereas no inhibition of cerotic acid (26:0) oxidation was observed. Furthermore, omission of carnitine from the culture medium resulted in a 57.7% decrease in palmitic acid oxidation in cultured glial cells, whereas cerotic acid oxidation was not influenced. These results indicate that rat brain peroxisomes contribute only little (about 15%) to palmitic acid oxidation and provide conclusive evidence that cerotic acid is oxidized exclusively in rat brain peroxisomes.
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PMID:Oxidation of very-long-chain fatty acids in rat brain: cerotic acid is beta-oxidized exclusively in rat brain peroxisomes. 191 73

14(R,S)-[18F]Fluoro-6-thia-heptadecanoic acid (FTHA) is a new radiolabeled long-chain fatty acid (LCFA) analog designed to undergo metabolic trapping subsequent to its commitment to the beta-oxidation pathway. Sulfur-substitution at the sixth carbon of FTHA causes a prolonging of myocardial clearance half-time (T 1/2 approximately 2 hr) in mice with little diminution of myocardial uptake (39.8 +/- 3.0% ID/g at 5 min). Heart-to-blood ratios were 20 +/- 6 and 82 +/- 16 at 1 and 60 min, respectively. In contrast, the 3-thia analog, 13(R,S)-[18F]-fluoro-3-thia-hexadecanoic acid, showed lower uptake and poor retention by heart. Myocardial uptake of FTHA was reduced by 81% (p less than 10(-5) and 87% (p less than 5 x 10(-4] in mice pretreated with the carnitine palmitoyltransferase I inhibitor, 2[5(4-chlorophenyl)pentyl]oxirane-2-carboxylate (POCA) at 1 and 60 min, respectively. Radioanalytical studies showed the major metabolic fate of FTHA in control and POCA treated myocardium to be unidentified metabolite(s) that bind to tissue protein. Smaller amounts of 18F radioactivity were present in myocardium as complex lipids, fatty acid, and unidentified soluble metabolites. The results indicate metabolic trapping of FTHA in myocardium subsequent to its entry into the mitochondrion and encourage its further evaluation as a PET tracer of myocardial LCFA utilization.
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PMID:14(R,S)-[18F]fluoro-6-thia-heptadecanoic acid (FTHA): evaluation in mouse of a new probe of myocardial utilization of long chain fatty acids. 191 27

The effects of sodium 2-[5-(4-chlorophenyl)pentyl]oxirane-2-carboxylate (POCA), a potent inhibitor of carnitine palmitoyltransferase I, on fatty acid oxidation were investigated using fibroblasts from control subjects and from patients with peroxisomal disorders. [1-14C]Palmitate oxidation was inhibited by 8% of the control value when 15 microM POCA was added to the medium. The inhibition by POCA was significantly (P less than 0.05) stronger in fibroblasts from patients with Zellweger syndrome or with neonatal adrenoleukodystrophy, in which peroxisomes and peroxisomal beta-oxidation enzymes were absent. However, the inhibition in fibroblasts from patients with X-linked adrenoleukodystrophy, in which a specific defect of peroxisomal lignoceroyl-CoA synthetase was speculated, was similar to that in the controls. [1-14C]Lignocerate oxidation was not influenced by the addition of POCA, in samples from the controls and from the patients. These results indicate that peroxisomes account for a small but demonstrable proportion of palmitate oxidation, and add new evidence to the concept that lignocerate is oxidized exclusively in the peroxisomes. Our findings also support the hypotheses that the activity of palmitoyl-CoA synthetase and the enzymes of beta-oxidation cycle in peroxisomes are normal in patients with X-linked adrenoleukodystrophy and that a specific defect of lignoceroyl-CoA synthetase is responsible for the accumulation of very long chain fatty acids in these patients.
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PMID:Effects of sodium 2-[5-(4-chlorophenyl)pentyl]-oxirane-2-carboxylate (POCA) on fatty acid oxidation in fibroblasts from patients with peroxisomal diseases. 199 2

The acylcarnitine transferase blocking agent, sodium 2(5-(4-chlorophenyl)-pentyl)-oxirane-2-carboxylate (Clomoxir, INN), effectively inhibits free fatty acid oxidation, thereby decreasing myocardial oxygen consumption in the normally perfused myocardium without influencing cardiodynamic parameters. As a consequence, however, arterial free fatty acid levels increase significantly. In an acute dog model, we investigated the hypothesis that the sodium 2(5-(4-chlorophenyl)-pentyl)-oxirane-2-carboxylate-induced decrease in myocardial oxygen consumption may also improve the energetic situation in the underperfused myocardium. Regional myocardial function was assessed by means of subendocardially inserted ultrasonic crystals, and changes in metabolism were measured regionally by means of a catheter inserted into a local myocardial vein in the underperfused area. The flow in the circumflex coronary artery was reduced on average by 53.5% followed 30 min later by an infusion of sodium 2(5-(4-chlorophenyl)-pentyl)-oxirane-2-carboxylate (dosage: 20 mg/kg over 20 min). Arterial free fatty acid levels continuously increased, whereas arterial glucose levels decreased. In accordance with the situation in the normally perfused myocardium, free fatty acid uptake and oxygen uptake were also reduced in the underperfused area. However, sodium 2(5-(4-chlorophenyl)-pentyl)-oxirane-2-carboxylate induced a further, transient increase in end-diastolic segment length and a sustained decrease in systolic shortening in the underperfused area, indicating a further deterioration in regional myocardial function. Control experiments with infusion of 9 g/l sodium chloride showed no change in the degree of regional myocardial dysfunction throughout the observation period.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of acylcarnitine transferase blockade on metabolism and function in the normally and underperfused canine myocardium. 238 Jun 72

Myocardial extraction and the characteristic tissue clearance of radioactivity following bolus injections of a radioiodinated (125I) long chain fatty acid (LCFA) analog 15-p-iodophenylpentadecanoic acid (IPPA) were examined in the isolated perfused working rat heart. Radioactivity remaining in the heart was monitored with external scintillation probes. A compartmental model which included nonesterified tracer, catabolite, and complex lipid compartments successfully fitted tissue time-radioactivity residue curves, and gave a value for the rate of IPPA oxidation 1.8 times that obtained from steady-state release of tritiated water from labeled palmitic acid. The technique was sensitive to the impairment of LCFA oxidation in hearts of animals treated with the carnitine palmitoyltransferase I inhibitor, 2[5(4-chlorophenyl)pentyl]oxirane-2-carboxylate (POCA). IPPA or similar modified fatty acids may be better than 11C-labeled physiological fatty acids such as palmitate in this type of study, because efflux of unoxidized tracer and catabolite(s) from the heart are kinetically more distinct, and their contributions to the early data can be reliably separated. This technique may be suitable for extension to in vivo measurements with position tomography and appropriate modified fatty acids.
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PMID:Quantitative analysis of myocardial kinetics of 15-p-[iodine-125] iodophenylpentadecanoic acid. 273 2

The use of 15-p-iodophenyl-beta-methyl-pentadecanoic acid (beta Me-IPPA) as an indicator of long chain fatty acid (LCFA) utilization in nuclear medicine studies was evaluated in the isolated, perfused, working rat heart. Time courses of radioactivity (residue curves) were obtained following bolus injections of both beta Me-IPPA and its straight chain counterpart 15-p-iodophenyl-pentadecanoic acid (IPPA). IPPA kinetics clearly indicated flow independent impairment of fatty acid oxidation caused by the carnitine palmitoyltransferase I inhibitor 2[5(4-chlorophenyl)pentyl]oxirane-2-carboxylate (POCA). In contrast, beta Me-IPPA kinetics were insensitive to changes in fatty acid oxidation rate and net utilization of long chain fatty acid. Analysis of radiolabeled species in coronary effluent and heart homogenates showed the methylated fatty acid to be readily incorporated into complex lipids but a poor substrate for oxidation. POCA did not significantly alter metabolism of the tracer, suggesting that the tracer is poorly metabolized beyond beta Me-IPPA-CoA in the oxidative pathway.
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PMID:beta-Methyl-15-p-iodophenylpentadecanoic acid metabolism and kinetics in the isolated rat heart. 235 Nov 85

Treatment of rats by beta,beta'-methyl-substituted hexadecanedioic acid (MEDICA 16) resulted in a dose- and time-dependent increase in liver peroxisomal enoyl-CoA hydratase and cyanide-insensitive palmitoyl-CoA oxidation with a concomitant increase in the volume density of peroxisomes as determined by morphometry. The induced peroxisomal proliferation was sustained as long as treatment was maintained and was accompanied by an increase in liver weight. Incubation of cultured rat hepatocytes in the presence of MEDICA 16 added to the culture medium resulted in a dose-dependent increase in peroxisomal beta-oxidation activities with a concomitant elevation of the volume density of peroxisomes. The induction of peroxisomal proliferation by MEDICA 16 in culture could be prevented in the presence of carnitine palmitoyltransferase inhibitors added to the culture medium, e.g. 2-bromopalmitate, 2-tetradecylglycidic acid or 2-[5-(4-chlorophenyl)-pentyl]oxirane-2-carboxylate. The induction of liver peroxisomes by MEDICA 16 conforms to the previously defined requirement for an amphipathic carboxylate in initiating peroxisomal proliferation. The prevention of peroxisomal proliferation by carnitine acyltransferase inhibitors may implicate the involvement of this acyltransferase in the induction of peroxisomal proliferation by xenobiotic or native amphipathic carboxylates.
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PMID:The induction of liver peroxisomal proliferation by beta,beta'-methyl-substituted hexadecanedioic acid (MEDICA 16). 317 72

Chlorpromazine and related drugs including trifluoperazine, clopenthixol, and fluphenazine are in vitro inhibitors of mitochondrial carnitine palmitoyltransferase and cytochrome c oxidase and of peroxisomal carnitine octanoyltransferase from mouse heart and liver. By contrast with 0.1% ethyl 2(5(4-chlorophenyl)pentyl) oxiran-2-carboxylic acid or 0.1% clofibrate-containing diets, the treatment of mice with 0.1% chlorpromazine-containing diet fails to induce peroxisomal proliferation in liver and heart. An 0.5% chlorpromazine-containing diet did induce peroxisomal proliferation. Inhibition of peroxisomal beta-oxidation presumably via the reduction of carnitine octanoyltransferase by chlorpromazine elicits the appearance in liver of lamellar structures resembling those seen in human peroxisomal disorders and induces accumulation of very long-chain fatty acids in plasma. The peroxisomal proliferation induced by administration of high dose chlorpromazine is ascribed to its ability to depress mitochondrial fatty acid oxidation by impairing cytochrome c oxidase and carnitine palmitoyltransferase activities.
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PMID:Peroxisomal proliferation in heart and liver of mice receiving chlorpromazine, ethyl 2(5(4-chlorophenyl)pentyl) oxiran-2-carboxylic acid or high fat diet: a biochemical and morphometrical comparative study. 343 62

1. The induction of peroxisomal beta-oxidation activities by bezafibrate in cultured rat hepatocytes and in the rat in vivo was prevented by inhibitors of carnitine acyltransferase, e.g. 2-bromopalmitate, 2-[5-(4-chlorophenyl)pentyl]oxirane-2-carboxylate or 2-tetradecylglycidic acid. 2. The prevention of peroxisomal proliferation by carnitine palmitoyltransferase inhibitors could not be accounted for by inhibition of mitochondrial beta-oxidation, since 2-bromo-octanoate, acting as an inhibitor of beta-oxidation, did not prevent the induction of peroxisomal activities in cultured rat hepatocytes. 3. The putative role of the acylcarnitine derivative of bezafibrate was analysed by studying the formation of bezafibroylcarnitine with bezafibroyl-CoA as substrate. However, no bezafibroylcarnitine formation was demonstrated in the presence of rat liver preparations capable of catalysing transfer to carnitine of medium- or long-chain fatty acids. 4. The prevention of peroxisomal proliferation by carnitine acyltransferase inhibitors may help in dissecting the causal relationship between the multiple effects mediated by peroxisomal proliferators.
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PMID:Prevention of peroxisomal proliferation by carnitine palmitoyltransferase inhibitors in cultured rat hepatocytes and in vivo. 366 64


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