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At least 19 recordsLinked to original sources
PubMed1990

Enhanced proteolysis of glucose-6-phosphate dehydrogenase in the presence of palmitoyl coenzyme A.

Palmitoyl coenzyme A at concentrations below its critical micelle concentration increases the rate of proteolysis of baker's yeast glucose-6-phosphate dehydrogenase by proteinase A in the pH range 4-5. both glucose-6-phosphate and NADP protect glucose-6-phosphate dehydrogenase against proteolysis, but these protective effects are diminished in the presence of palmitoyl coenzyme A. Since palmitoyl coenzyme A is known to dissociate glucose-6-phosphate dehydrogenase into dimers, the results imply that the in vivo half life of glucose-6-phosphate dehydrogenase may be controlled by a process based on the regulation of the oligomeric structure of the enzyme by the collective actions of various molecules, including palmitoyl coenzyme A.

Aspartic Acid Endopeptidases↗
PubMed1983

Inhibition of DNA polymerases of sea urchin by palmitoyl coenzyme A.

Palmitoyl CoA noncompetitively inhibited the activities of DNA polymerase alpha and gamma, prepared from sea urchin germ cells, with Ki values of 28 microM and 116 microM, respectively. Myristoyl CoA also inhibited DNA polymerase alpha and gamma, while coenzyme A, short chain fatty acyl CoA's, Na-myristate and Na-palmitate failed to inhibit the enzymes. It was concluded that both the long hydrocarbon chain and CoA moiety of long chain fatty acyl CoA's are necessary for inhibition of DNA polymerase activity. DNA polymerase beta was not inhibited by long chain fatty acyl CoA's.

Acyl Coenzyme A↗
PubMed1993

Three-dimensional structure of the complex between acyl-coenzyme A binding protein and palmitoyl-coenzyme A.

Multidimensional 1H, 13C and 15N nuclear magnetic resonance spectroscopy has been used to study the complex between palmitoyl-coenzyme A and acyl-coenzyme A binding protein. The 1H and the 15N spectra of the holo-protein have been almost completely assigned and so has most of the 1H spectrum of the coenzyme A part of the protein-bound ligand. The palmitoyl part of the ligand has been uniformly labelled with 13C and the nuclear magnetic resonance signals of the carbon atoms and their protons have been assigned at the two ends of the hydrocarbon chain. A total of 1251 distance restraints from nuclear Overhauser effects and 131 dihedral angle restraints from three-bond coupling constants provided the basis for the structure calculation. A comparison of 20 structures calculated from these data to the average structure showed that they could be aligned with an atomic root-mean-square deviation of 1.3(+/- 0.2) A for all C, N, O, P and S atoms in protein and ligand. The apo-protein is a four-helix protein and this structure is maintained in the holo-protein. The four alpha-helices are Ac1 of residues 3 to 15, Ac2 from residue 20 to 36, Ac3 from 51 to 62, and Ac4 from 65 to 84. For the four alpha-helices of the peptide backbone of the holo-protein the root-mean-square deviation for the C, C alpha and N atoms was 0.42(+/- 0.08) A. The binding site for the palmitoyl-chain stretches between the N-terminal end of Ac3 where the carboxyl part binds, to the N-terminal of Ac3 where the omega-end of the palmitoyl part binds. The adenosine-3'-phosphate is bound near residues of each of the four helices in an arrangement where it can form salt bridges and/or hydrogen bonds to either backbone or side-chain atoms of Ala9, Tyr28, Lys32, Lys54 and Tyr73. The polar parts of the pantetheine and the pyrophosphate are structured in the bound ligand to form an interface with the solvent. Also the ligand forms a set of non-polar intramolecular interactions where the adenine, the pantetheine, and the palmitoyl-chain are associated, so overall the structure of the bound ligand seems to be organized to protect the lipophilic palmitoyl part from the polar solvent.

Amino Acid Sequence↗
PubMed1975

Reversible inhibition of the fatty acid synthetase complex from Mycobacterium smegmatis by palmitoyl-coenzyme A.

Palmitoyl-CoA dissociates the fatty acid synthetase complex from Mycobacterium smegmatis into inactive subunits of molecular weight 250,000 as determined by sucrose density gradient centrifugation. Palmitoyl-CoA binds to the subunits but the binding can be prevented and reversed by the mycobacterial 3-O-methylmannose-containing polysaccharide. When the palmitoyl-CoA containing inactive subunits were isolated by gel filtration on Sepharose 6B, and then concentrated and dialyzed against 0.5 M phosphate buffer, pH 7.0, containing 3 mM of the complexing agent heptakis-(2,6-di-O-methyl)-beta-cyclodextrin, activity was regenerated to the level of 40 percent of a control sample. The reversibility of the dissociation and inactivation of the synthetase by palmitoyl-CoA suggests that this end product might play a regulatory role by acting as a feedback inhibitor.

Coenzyme A↗
PubMed1984

Effect of atractylosides, palmitoyl coenzyme A, and anion transport inhibitors on translocation of nucleotide sugars and nucleotide sulfate into Golgi vesicles.

The effect of palmitoyl coenzyme A, atractylosides, and anion transport inhibitors on translocation into rat liver Golgi vesicles of adenosine 3'-phosphate 5'-phosphosulfate (PAPS), CMP-N-acetylneuraminic acid, and GDP-fucose was studied. Translocation of the above three nucleotide derivatives was inhibited by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS; 50% inhibition required 10-20 microM DIDS). The inhibition of translocation of PAPS by DIDS was used to demonstrate that sulfation of macromolecules within Golgi vesicles is preceded by translocation of PAPS into the vesicles. Palmitoyl coenzyme A, at concentrations below its critical micellar concentration, specifically inhibited translocation into Golgi vesicles of PAPS but not CMP-NeuAc and GDP-fucose. Inhibition of PAPS translocation by 50% required 9 microM palmitoyl coenzyme A. Translocation of PAPS but not of CMP-NeuAc or GDP-fucose was also inhibited by atractyloside or carboxyatractyloside with 50% inhibition requiring 15 microM either glycoside. This pattern of inhibition suggests structural similarities between the putative translocator of PAPS in Golgi membranes and the ATP/ADP translocator of mitochondria.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1993

Palmitoyl-coenzyme A hydrolyzing activity in rat kidney and its relationship to carboxylesterase.

Palmitoyl-coenzyme A (palmitoyl-CoA) hydrolase was obtained from rat kidney in an electrophoretically homogeneous form. The enzyme associated with carboxylesterase activity was purified by acetone precipitation of microsomes, followed by successive chromatographies on DEAE-cellulose, phenyl-Sepharose, and Sephadex G-100 gel. The two activities in rat kidney were associated as judged by their co-elution profiles, co-purification at different steps, co-precipitation by an antibody raised against the purified enzyme, and identical profiles of inhibition by diisopropylfluorophosphate. The enzyme catalyzed the hydrolysis of long- and medium-chain acyl-CoA, but not short-chain acyl-CoA. The N-terminal amino acid sequence of the first 27 residues of the purified enzyme was 80% identical with that of the carboxylesterase from rat adipose tissue. Using a polyclonal rabbit antibody against the rat kidney palmitoyl-CoA hydrolase, the enzyme was demonstrated in liver but not in adipose tissue. The antibody reacted with the carboxylesterase(s) (pI 6.3 and pI 6.6) in rat liver microsomes. The antibody removed the palmitoyl-CoA hydrolase in kidney (75%) and liver (68%). The antibody also removed the monoolein hydrolase in kidney (77%) and liver (61%). These results suggest that carboxylesterase contributes to the hydrolysis of long-chain acyl-CoA and monoglyceride in kidney and liver.

Adipose Tissue↗
PubMed1995

The membrane-perturbing properties of palmitoyl-coenzyme A and palmitoylcarnitine. A comparative study.

Fatty acyl-coenzyme A's are temporarily converted into fatty acylcarnitines while transferred across the inner mitochondrial membrane, in their catabolic pathway. In search of an explanation for the need of this coenzyme exchange, the present work describes comparatively the abilities of both kinds of fatty acyl derivatives (represented by palmitoyl-coenzyme A and palmitoylcarnitine) in binding to and perturbing the structure of phosphatidylcholine bilayers in the form of large unilamellar vesicles. Both palmitoyl-coenzyme A and palmitoylcarnitine partition preferentially into the bilayer lipids, so that their free concentration in water is in practice negligible. However, palmitoylcarnitine is able to disrupt the membrane barrier to solutes, leading to vesicle leakage, and, at higher concentrations, it produces complete membrane solubilization, while palmitoyl-coenzyme A produces neither leakage nor solubilization. Palmitoylcarnitine has the properties of many commonly used biochemical detergents. The different behavior of both fatty acyl derivatives helps to explain the need for the transitory coenzyme A/carnitine exchange, and provides a pathogenic mechanism for some genetic defects of mitochondrial fatty acid transport. Other pathophysiological processes in which palmitoylcarnitine has been putatively involved are examined in light of the above results.

Cell Membrane↗
PubMed1979

Differences between microsomal and mitochondrial-matrix palmitoyl-coenzyme A hydrolase, and palmitoyl-L-carnitine hydrolase from rat liver.

Palmitoyl-CoA hydrolase (EC 3.1.2.2) and palmitoyl-L-carnitine hydrolase (EC 3.1.1.28) activities from rat liver were investigated. 1. Microsomal and mitochondrial-matrix palmitoyl-CoA hydrolase activities had similar pH and temperature optima, although the activities showed different temperature stability. They were inhibited by Pb2+ and Zn2+. The palmitoyl-CoA hydrolase activities in microsomal fraction and mitochondrial matrix were differently affected by the addition of Mg2+, Ca2+, Co2+, K+ and Na+ to the reaction mixture. ATP, ADP and NAD+ stimulated the microsomal activity and inhibited the mitochondrial-matrix enzyme. The activity of both the microsomal and mitochondrial-matrix hydrolase enzymes was specific for long-chain fatty acyl-CoA esters (C12-C18), with the highest activity for palmitoyl-CoA. The apparent Km for palmitoyl-CoA was 47 microM for the microsomal enzyme and 17 microM for the mitochondrial-matrix enzyme. 2. The palmitoyl-CoA hydrolase and palmitoyl-L-carnitine hydrolase activities of microsomal fraction had similar pH optima and were stimulated by dithiothreitol, but were affected differently by the addition of Pb2+, Mg2+, Ca2+, Mn2+ and cysteine. The two enzymes had different temperature-sensitivities. 3. The data strongly suggest that palmitoyl-CoA hydrolase and palmitoyl-L-carnitine hydrolase are separate microsomal enzymes, and that the hydrolysis of palmitoyl-CoA in the microsomal fraction and mitochondria matrix was catalysed by two different enzymes.

Animals↗
PubMed1983

Effects of palmitoyl coenzyme A on rat skeletal muscle sarcoplasmic reticulum.

Palmitoyl coenzyme A (PCoA) inhibits Ca2+ uptake and stimulates Ca2+-activated ATPase in sarcoplasmic reticulum vesicles. The inhibitory effect on Ca2+-uptake is referable to a stimulation of Ca2+ release which is directly correlated to the concentration of PCoA added. The comparison of the Ca2+-releasing effect of PCoA in different experimental conditions indicates that concentrations of PCoA higher than 10 microM may be disruptive for the vesicles while concentrations of PCoA lower than this value can activate a Ca2+-releasing channel or more generally can increase the membrane permeability for Ca2+.

Acyl Coenzyme A↗
PubMed1994

Removal of Mg2+ inhibition of cardiac ryanodine receptor by palmitoyl coenzyme A.

45Ca2+ fluxes and planar bilayer recordings indicated that the fatty acid metabolite palmitoyl coenzyme A, but not free coenzyme A or palmitic acid, stimulated the cardiac ryanodine receptor channel of pig heart sarcoplasmic reticulum. Palmitoyl CoA reactivated channels inhibited by concentrations of cytoplasmic free Mg2+ in the physiological range. Reactivation by palmitoyl CoA in the presence of Mg2+ was stimulated by myoplasmic free Ca2+ in the micromolar range. Acyl coenzyme A derivatives may be utilized by cardiac muscle cells to compensate for the severe Mg2+ inhibition of ryanodine receptors which would otherwise leave Ca2+ stores unresponsive to Ca2+ and to other cytosolic ligands involved in signal transduction.

Animals↗
PubMed2001

Thioredoxin-linked lipid hydroperoxide peroxidase activity of human serum albumin in the presence of palmitoyl coenzyme A.

Human Serum Albumin (HSA) exerted a significant lipid peroxidase activity with the use of a thiol-reducing equivalent such as dithiothreitol (DTT). Carboxyl group-modified HSA (CM-HSA) showed a 10-fold stronger lipid peroxidase activity (1.6 nmol/min/mg) than that of HSA (0.17 nmol/min/mg). Instead of DTT, thioredoxin (Trx) also supported reducing equivalent to the reduction of lipid hydroperoxide by CM-HSA. Contrast to CM-HSA, HSA did not reduce lipid peroxide with the use of Trx. In the presence of palmitoyl coenzyme A (palmitoyl-CoA) however, HSA used Trx as an electron donor to the reduction of lipid hydroperoxide. The Trx-linked peroxidase activity of HSA sharply increased with elongation in the carbon chain of the acyl moiety of acyl-CoA, showing an optimum activity in the presence of palmitoyl-CoA. Fluorescence study indicates the conformational changes of HSA induced by palmitoyl-CoA. Together, these data suggest that palmitoyl-CoA-bound HSA has a capability to remove lipid peroxide with the use of electrons given by Trx system.

Dithiothreitol↗
PubMed1979

Factors affecting the activity and stability of the palmitoyl-coenzyme A hydrolase of rat brain.

Palmitoyl-CoA hydrolase (EC 3.1.2.2) catalyses the irreversible hydrolysis of long-chain acyl-CoA thioesters. This enzyme is found primarily in the postmicrosomal supernatant fraction prepared from homogenates of rat brain. Either of two forms of the hydrolase, a lower-molecular-weight species of approx. 70000 or a higher-molecular-weight species of approx. 130000 can be isolated by gel filtration. The higher-molecular-weight form is obtained from columns of Sephadex G-200 eluted with buffer containing 10mum-palmitoyl-CoA or 20% (v/v) glycerol, whereas the lower-molecular-weight form is obtained when the eluting buffer does not contain palmitoyl-CoA or glycerol. The two forms of the hydrolase have the same pH optimum of 7.5, are equally sensitive to the thiol-blocking reagents p-hydroxymercuribenzoate, HgCl(2), and 5,5'-dithiobis-(2-nitrobenzoic acid), and exhibit the same K(m) (1.8mum) with palmitoyl-CoA as substrate. The two forms differ in the availability or reactivity of certain external thiol groups, as determined by covalent chromatography with activated thiol Sepharose. Dilute solutions of the lower-molecular-weight form of the hydrolase rapidly lose activity (50% in 60min at 0 degrees C), but there is no change in the K(m) with palmitoyl-CoA as substrate during this progressive inactivation. Dilutions of the hydrolase in buffer containing 10mum-palmitoyl-CoA retain full activity. However, addition of palmitoyl-CoA to solutions of the lower-molecular-weight form will not restore previously lost hydrolase activity. The evidence supports the conclusion that the substrate palmitoyl-CoA promotes the formation of a relatively stable dimer from two unstable subunits. This process may not be reversible, since the removal of palmitoyl-CoA or glycerol from solutions of the higher-molecular-weight form does not result in the appearance of the lower-molecular-weight form of the hydrolase.

Animals↗
PubMed1975

Factors affecting the palmitoyl-coenzyme A desaturase of Saccharomyces cerevisiae.

The activity and stability of the palmitoyl-coenzyme A (CoA) desaturase complex of Saccharomyces cerevisiae was influenced by several factors. Cells, grown nonaerobically and then incubated with glucose, either in air or under N2, showed a marked increase in desaturase activity. Cycloheximide, added during such incubations, prevented the increase in activity, suggesting de novo synthesis. The stability of the desaturase from cells grown nonaerobically was affected by subsequent treatment of the cells; enzyme from freshly harvested cells, or from cells that were then shaken under nitrogen, readily lost activity upon washing or during density gradient analysis, whereas aerated cells, in the presence or absence of glucose, yielded stable enzyme preparations. The loss of activity in nonaerobic preparations could be reversed by adding soluble supernatant from these homogenates and could be prevented by growing the cells in the presence of palmitoleic acid and ergosterol, but not with several other lipids tested.

Aerobiosis↗
PubMed1990

In vitro regulation of mammary glucose-6-phosphate dehydrogenase activity by palmitoyl coenzyme A, acetate, and polyamines.

An in vitro study was conducted to determine whether bovine mammary glucose-6-phosphate dehydrogenase (G6PD) activity was regulated by palmitoyl coenzyme A (CoA), acetate, spermidine, and putrescine and whether these effects were dependent upon stage of lactation. Early lactation explants incubated in media containing palmitoyl CoA or acetate had reduced (P less than 0.01) G6PD activity compared with incubated control explants. G6PD activity in early lactation explants was reduced (P less than 0.05) when incubated with 5 microM palmitoyl CoA or 1 mM acetate compared with 25 microM palmitoyl CoA or 10 mM acetate. Spermidine (0.4 mM) reversed (P less than 0.05) palmitoyl CoA-induced inhibition of early lactation G6PD activity at 5 microM, but not at 25 microM palmitoyl CoA. G6PD activity in early lactation explants was decreased (P less than 0.05) when treated with putrescine (0.4 mM) compared with explants treated with spermidine. Addition of acetate in combination with 5 microM palmitoyl CoA reversed G6PD inhibition (P less than 0.05 for 1 mM and P less than 0.01 for 10 mM) while addition of either level of acetate in combination with 25 microM palmitoyl CoA failed to reverse G6PD inhibition. G6PD activity was higher (P less than 0.01) in early lactation than mid-lactation explants. No statistical differences (P greater than 0.1) were found among any treatments in explants from mid-lactation cows. We conclude that palmitoyl CoA and acetate will inhibit G6PD activity in early lactation, but not mid-lactation explants; addition of spermidine will reverse this inhibition.

Acetates↗
PubMed1986

Characterization of rat brain microsomal acyl-coenzyme A ligases: different enzymes for the synthesis of palmitoyl-coenzyme A and lignoceroyl-coenzyme A.

Palmitic acid solubilized with Triton WR-1339 was converted to palmitoyl-CoA by microsomal membranes but lignoceric acid solubilized with Triton WR-1339 was not an effective substrate even though the detergent dispersed the same amount of these fatty acids and was also not inhibitory to the enzyme [I. Singh, R. P. Singh, A. Bhushan, and A. K. Singh (1985) Arch. Biochem. Biophys. 236, 418-426]. This observation suggested that palmitoyl-CoA and lignoceroyl-CoA may be synthesized by two different enzymes. We have solubilized the acyl-CoA ligase activities for palmitic and lignoceric acid of rat brain microsomal membranes with Triton X-100 and resolved them into three separate peaks (fractions) by hydroxylapatite chromatography. Fraction A (palmitoyl-CoA ligase) had high specific activity for palmitic acid and Fraction C (lignoceroyl-CoA ligase) for lignoceric acid. Specific activity of palmitoyl-CoA ligase for palmitic acid was six times higher than in Fraction C and specific activity of lignoceroyl-CoA ligase for lignoceric acid was four times higher than in Fraction A. At higher concentrations of Triton X-100 (0.5%), lignoceroyl-CoA ligase loses activity whereas palmitoyl-CoA ligase does not. Lignoceroyl-CoA ligase lost 60% of activity at 0.6% Triton X-100. Palmitoyl-CoA ligase (T1/2 of 4.5 min) is more stable at 40 degrees C than lignoceroyl-CoA ligase (T1/2 of 1.5 min). The pH optimum of palmitoyl-CoA ligase was 7.7 and that of lignoceroyl-CoA ligase was 8.4. Similar to our results with intact membranes, palmitic acid solubilized with Triton WR-1339 was converted to palmitoyl-CoA by palmitoyl-CoA ligase whereas lignoceric acid when solubilized with Triton WR-1339 was not able to act as substrate for lignoceroyl-CoA ligase. Since solubilized enzyme activities for synthesis of palmitoyl-CoA and lignoceroyl-CoA from microsomal membranes can be resolved into different fractions by column chromatography and demonstrate different properties, we suggest that in microsomal membranes palmitoyl-CoA and lignoceroyl-CoA are synthesized by two different enzymes.

Acyl Coenzyme A↗
PubMed1975

Role of the surface excess of palmitoyl coenzyme A in the 1-acylglycerol-3-phosphate acyltransferase reaction catalyzed by microsomes.

Surface excess values for palmitoyl-coenzyme A have been determined at the air-water interface. In the bulk concentration range of 0.23 to 3.7 muM, the surface concentration of palmitoyl-CoA ranges from 0.7 to 1.4 times 10- minus 10 mol/cm-2. The molecules of palmitoyl-CoA in the surface layer behave as if they were in a monolayer with each molecule occupying a limiting molecular area of 79 A-2. The distribution of palmitoyl-CoA between bulk and surface phases can be described by a Langmuir adsorption isotherm with an equilibrium constant of 0.33 muM. This constant is identical to the apparent Km for palmitoyl-CoA in the 1-acylglycerol-3-phosphate acyltransferase reaction catalyzed by microsomes. The results of this study, together with those from earlier work, suggest that the observed saturation behavior of the enzymatic reaction reflects the formation of a positive surface excess of palmitoyl-CoA in the vicinity of the catalytic site.

Acyltransferases↗