Purification of clofibrate-induced carnitine acetyltransferase from rat liver mitochondria

Mittal, Balraj; Kurup, C. K. Ramakrishna

doi:10.1016/0005-2760(80)90245-3

Cited by 26 publications

(11 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1 revealed a negative relationship between intramuscular lipid accumulation and CrAT activity. Relevant to this observation, earlier studies reported that LCACoAs inhibited the activity of purifi ed pigeon CrAT (14)(15)(16). Here, we sought to examine the inhibitory actions of palmitoyl-CoA on the activity of rat and mouse CrAT when assayed in a more native environment.…”

Section: Lcacoas Inhibit Crat Activitymentioning

confidence: 91%

Obesity and lipid stress inhibit carnitine acetyltransferase activity

Seiler

Martin

Noland

et al. 2014

Journal of Lipid Research

View full text Add to dashboard Cite

L -Carnitine is a conditionally essential nutrient that serves as a substrate for a family of acyltransferase enzymes that catalyze the interconversion of acyl-CoAs and acylcarnitines. Unlike their acyl-CoA precursors, acylcarnitines can be transported across cellular membranes. Accordingly, carnitine is best known for its obligatory role in shuttling long-chain acyl-CoAs (LCACoAs) from the cytoplasm into the mitochondrial matrix for fatty acid oxidation, a function that is mediated by the outer mitochondrial membrane enzyme, carnitine palmitoyltransferase 1 (CPT1). The long-chain acylcarnitine (LCAC) products of CPT1 are transported across the inner mitochondrial membrane by carnitine acylcarnitine translocase and then converted back to LCACoAs by carnitine palimitoyltransferase 2 (CPT2), also localized to the inner membrane. By contrast, carnitine acetyltransferase (CrAT) resides in the mitochondrial matrix and has strong preference for short-chain acyl-CoA (SCACoA) intermediates of fatty acid, glucose, and amino acid catabolism. Thus, CrAT facilitates traffi cking and effl ux of carbon intermediates from the mitochondrial compartment to other cellular and extracellular sites.Recent animal studies have established important roles for L -carnitine and CrAT in regulating glucose homeostasis and mitochondrial substrate switching ( 1 ). By converting acetyl-CoA to acetylcarnitine, CrAT not only buffers the mitochondrial acetyl-CoA pool but also regenerates free CoA, both of which infl uence the activities of several oxidative enzymes. Carnitine supplementation promotes

show abstract

Section: Lcacoas Inhibit Crat Activitymentioning

confidence: 91%

Obesity and lipid stress inhibit carnitine acetyltransferase activity

Seiler

Martin

Noland

et al. 2014

Journal of Lipid Research

View full text Add to dashboard Cite

show abstract

“…Detailed studies on the properties of peroxisomal and mitochondrial carnitine acetyltransferases may offer one of the clues to solve the mechanism of biogenesis and development of cellular organelles, especially that of peroxisomes. Little information had been available about the isolation and characterization of the enzyme from distinct organelles in the same eukaryotic cells [5,6,20] before our previous paper [8] reporting the isolation of peroxisomal and mitochondrial carnitine acetyltransferases from alkane-grown C. tropicalis cells.…”

Section: Discussionmentioning

confidence: 99%

Characterization of peroxisomal and mitochondrial carnitine acetyltransferases purified from alkane‐grown Candida tropicalis

Ueda

Tanaka

Fukui

1984

European Journal of Biochemistry

View full text Add to dashboard Cite

Properties of peroxisomal and mitochondrial carnitine acetyltransferases purified from an alkane-grown yeast, Candida tropicalis, were compared each other. The molecular weight of both enzymes was estimated to be about 420000 by analytical ultracentrifugation and gel filtration chromatography with Sepharose 6B. However, each enzyme gave two subunits on the polyacrylamide slab gel electrophoresis in the presence of sodium dodecyl sulfate : the peroxisomal enzyme (64000 and 57000) and the mitochondrial enzyme (64000 and 52000). The subcellularly distinct enzymes gave a similar amino acid composition except for the contents of some amino acids : glycine, valine, glutamic acid and aspartic acid. Their isoelectric point was somewhat different: 5.11 for the peroxisomal enzyme and 5.22 for the mitochondrial enzyme. Both enzymes had the same amino-terminal residue (glutamic acid or glutamine) and the heat stability, and was indistinguishable immunochemically. These results suggest that peroxisomal and mitochondrial carnitine acetyltransferases of C. tropicalis cells may be products of the same nuclear gene. Differences in the molecular weight of the subunits of the enzymes would result from modification or processing of the common protein in the step of distribution to the respective organelles, that is, so-called posttranslational modification.Carnitine acetyltransferase, which catalyzes the reversible transfer of acetyl group between CoA and I -carnitine, has an important role in the metabolism of fatty acids in eukaryotic cells, because acetyl-CoA, a final product of j-oxidation of fatty acids, is not permeable through the various organelle membranes but acetylcarnitine is permeable through these membranes [l -41. This enzyme has been detected in peroxis o m a and microsomes as well as in mitochondria of mammalian cells, and isolated from pigeon breast muscle and rat liver mitochondria [I -61. However, there is no information about the molecular identity of peroxisomal and mitochondrial carnitine acetyltransferases isolated from the same cells.In this connection, a variety of interesting problems remain to be elucidated: whether or not peroxisomal and mitochondrial carnitine acetyltransferases are products encoded by the same gene; how these two enzymes are distributed into two subcellular compartment if they are the same gene products ; what relationships exist between these two enzymes and the biogenesis of organelles, especially peroxisomes and so on. To acquire useful information on these matters, it is necessary to compare the molecular properties of peroxisomal and mitochondrial carnitine acetyltransferases.In a previous paper [7], we have demonstrated that carnitine acetyltransferases induced in alkane-grown cells of Candida tropicalis are localized in peroxisomes and mitochondria and that both enzymes take an essential part in the transfer of acetyl units from peroxisomes to mitochondria for the complete operation of the glyoxylate cycle. These enzymes in both organelles were separated by DEAE-Sephacel column...

show abstract

“…These results indicate that carnitine acetyltransferase is a monomer, similar to mouse liver carnitine acetyltransferase [9]. Carnitine acetyltransferase was previously proposed to have a heterodimeric structure [7] but Miyazawa et al demonstrated that the dimer is the consequence of proteolytic degradation during purification [8]. We used the proteolytic inhibitor, phenylmethylsulphony1 fluoride, during human liver homogenization and ammonium sulphate fractionation which significantly limited the degradation of carnitine acetyltransferase.…”

Section: Purification and Physical Properties Of Carnitine Acetyltranmentioning

confidence: 97%

Purification and properties of carnitine acetyltransferase from human liver

Bloisi

Colombo

Garavaglia

et al. 1990

European Journal of Biochemistry

View full text Add to dashboard Cite

Carnitine acetyltransferase was purified from the supernatant obtained after centrifugation of human liver homogenate to a final specific activity of 78.75 unit . mg-' with acetyl-CoA as a substrate. Human carnitine acetyltransferase is a monomer of 60.5 kDa with maximum activity in the presence of propionyl-CoA and a pH optimum of 8.7. Apparent K , values for acetyl-CoA are three times lower than for decanoyl-CoA. K,,, values for L-carnitine in the presence of acetyl-CoA are six times lower than in the presence of decdnoyl-CoA. K, values for acetylcarnitine are three times lower than for octanoylcarnitine.The polyclonal antibodies against human carnitine acetyltransferase recognize a 60.5-kDa peptide in the purified preparation of human liver and brain homogenates and in immunoblots of mitochondrial and peroxisomal fractions from human liver.Immunoprecipitation and SDSjPAGE analysis of 35S-labelled proteins produced by human fibroblasts indicate that mitochondrial carnitine acetyltransferase is synthesized as a precursor of 65 kDa.We also purified carnitine acetyltransferase from the pellet obtained after centrifugation of liver homogenate. The pellet was extracted by sonication in the presence of 0.5% Tween 20. The chromatographic procedures for the purification and the kinetic, physical and immunological properties of pellet-extracted carnitine acetyltransferase are similar to those of carnitine acetyltransferase purified from the supernatant of human liver homogenate.

show abstract

Purification of clofibrate-induced carnitine acetyltransferase from rat liver mitochondria

Cited by 26 publications

References 27 publications

Obesity and lipid stress inhibit carnitine acetyltransferase activity

Obesity and lipid stress inhibit carnitine acetyltransferase activity

Characterization of peroxisomal and mitochondrial carnitine acetyltransferases purified from alkane‐grown Candida tropicalis

Purification and properties of carnitine acetyltransferase from human liver

Contact Info

Product

Resources

About