Use of a selective inhibitor of liver carnitine palmitoyltransferase I (CPT I) allows quantification of its contribution to total CPT I activity in rat heart. Evidence that the dominant cardiac CPT I isoform is identical to the skeletal muscle enzyme

This study was designed to compare the activity of skeletal muscle carnitine palmitoyltransferase I (CPT I) in trained and inactive men ( n = 14) and women ( n = 12). CPT I activity was measured in intact mitochondria, isolated from needle biopsy vastus lateralis muscle samples (∼60 mg). The variability of CPT I activity determined on two biopsy samples from the same leg on the same day was 4.4, whereas it was 7.0% on two biopsy samples from the same leg on different days. The method was sensitive to the CPT I inhibitor malonyl-CoA (88% inhibition) and therefore specific for CPT I activity. The mean CPT I activity for all 26 subjects was 141.1 ± 10.6 μmol ⋅ min−1 ⋅ kg wet muscle (wm)−1 and was not different when all men vs. all women (140.5 ± 15.7 and 142.2 ± 14.5 μmol ⋅ min−1 ⋅ kg wm−1, respectively) were compared. However, CPT I activity was significantly higher in trained vs. inactive subjects for both men (176.2 ± 21.1 vs. 104.1 ± 13.6 μmol ⋅ min−1 ⋅ kg wm−1) and women (167.6 ± 14.1 vs. 91.2 ± 9.5 μmol ⋅ min−1 ⋅ kg wm−1). CPT I activity was also significantly correlated with citrate synthase activity (all subjects, r = 0.76) and maximal oxygen consumption expressed in milliliters per kilogram per minute (all subjects, r = 0.69). The results of this study suggest that CPT I activity can be accurately and reliably measured in intact mitochondria isolated from human muscle biopsy samples. CPT I activity was not affected by gender, and higher activities in aerobically trained subjects appeared to be the result of increased mitochondrial content in both men and women.

Download Full-text

Carnitine Palmitoyltransferase I (CPT I) Activity and Its Regulation by Malonyl-CoA Are Modulated by Age and Cold Exposure in Skeletal Muscle Mitochondria from Newborn Pigs

Journal of Nutrition ◽

10.1093/jn/128.5.886 ◽

1998 ◽

Vol 128 (5) ◽

pp. 886-893 ◽

Cited By ~ 17

Author(s):

Isabelle Schmidt ◽

Patrick Herpin

Keyword(s):

Skeletal Muscle ◽

Cold Exposure ◽

Carnitine Palmitoyltransferase ◽

Muscle Mitochondria ◽

Skeletal Muscle Mitochondria ◽

Malonyl Coa ◽

Carnitine Palmitoyltransferase I ◽

Newborn Pigs ◽

Cpt I

Download Full-text

Interaction of malonyl-CoA and related compounds with mitochondria from different rat tissues. Relationship between ligand binding and inhibition of carnitine palmitoyltransferase I

Biochemical Journal ◽

10.1042/bj2140083 ◽

1983 ◽

Vol 214 (1) ◽

pp. 83-91 ◽

Cited By ~ 85

Author(s):

S E Mills ◽

D W Foster ◽

J D McGarry

Keyword(s):

Skeletal Muscle ◽

Site Occupancy ◽

Carnitine Palmitoyltransferase ◽

Rat Tissues ◽

Skeletal Muscle Mitochondria ◽

Malonyl Coa ◽

High Affinity Binding Site ◽

Carnitine Palmitoyltransferase I ◽

Cpt I ◽

Related Compounds

The sensitivity of carnitine palmitoyltransferase I (CPT I; EC 2.3.1.21) to inhibition by malonyl-CoA and related compounds was examined in isolated mitochondria from liver, heart and skeletal muscle of the rat. In all three tissues the same order of inhibitory potency emerged: malonyl-CoA much greater than succinyl-CoA greater than methylmalonyl-CoA much greater than propionyl-CoA greater than acetyl-CoA. For any given agent, suppression of CPT I activity was much greater in skeletal muscle than in liver, with the heart enzyme having intermediate sensitivity. With skeletal-muscle mitochondria a high-affinity binding site for [14C]malonyl-CoA was readily demonstrable (Kd approx. 25 nM). The ability of other CoA esters to compete with [14C]malonyl-CoA for binding to the membrane paralleled their capacity to inhibit CPT I. Palmitoyl-CoA also competitively inhibited [14C]malonyl-CoA binding, in keeping with its known ability to overcome malonyl-CoA suppression of CPT I. For reasons not yet clear, free CoA displayed anomalous behaviour in that its competition for [14C]malonyl-CoA binding was disproportionately greater than its inhibition of CPT I. Three major conclusions are drawn. First, malonyl-CoA is not the only physiological compound capable of suppressing CPT I, since chemically related compounds, known to exist in cells, also share this property, particularly in tissues where the enzyme shows the greatest sensitivity to malonyl-CoA. Second, malonyl-CoA and its analogues appear to interact with the same site on the mitochondrial membrane, as may palmitoyl-CoA. Third, the degree of site occupancy by inhibitors governs the activity of CPT I.

Download Full-text

Effects of pH on the interaction of substrates and malonyl-CoA with mitochondrial carnitine palmitoyltransferase I

Biochemical Journal ◽

10.1042/bj2190601 ◽

1984 ◽

Vol 219 (2) ◽

pp. 601-608 ◽

Cited By ~ 40

Author(s):

S E Mills ◽

D W Foster ◽

J D McGarry

Keyword(s):

Skeletal Muscle ◽

Binding Site ◽

Liver Mitochondria ◽

Fatty Acyl ◽

Carnitine Palmitoyltransferase ◽

Skeletal Muscle Mitochondria ◽

Malonyl Coa ◽

Effects Of Ph ◽

Carnitine Palmitoyltransferase I ◽

Cpt I

The kinetics of carnitine palmitoyltransferase I (CPT I; EC 2.3.1.21) were examined in mitochondria from rat liver, heart and skeletal muscle as a function of pH over the range 6.8-7.6. In all three tissues raising the pH resulted in a fall in the Km for carnitine, no change in the Km for palmitoyl-CoA or Octanoyl-CoA, and a marked decrease in the inhibitory potency of malonyl-CoA. Studies with skeletal-muscle mitochondria established that increasing pH was accompanied by an increase in the Kd of the malonyl-CoA binding site for this ligand, coupled with a decrease in the Kd for fatty acyl-CoA species to compete for malonyl-CoA binding. Three principal conclusions are drawn. (1) The pH-induced shift in malonyl-CoA sensitivity of CPT I is not a phenomenon restricted to liver mitochondria. (2) At any given pH within the range tested, the ability of malonyl-CoA (and closely related compounds) to inhibit enzyme activity is governed by the efficiency of their binding to the malonyl-CoA site. (3) The competitive interaction between fatty acyl-CoA substrates and malonyl-CoA as regards CPT I activity is exerted at the malonyl-CoA binding site. Finally, the possibility is strengthened that the malonyl-CoA binding site is distinct from the active site of CPT I.

Download Full-text

Vergleichende Untersuchungen zu ausgewählten Kriterien des Energiestoffwechsels in Skelettmuskulatur, Plasma und Lymphozyten bei gesunden und an Congenitaler Myofibrillärer Hypoplasie erkrankten Ferkeln

Archives Animal Breeding ◽

10.5194/aab-52-284-2009 ◽

2009 ◽

Vol 52 (3) ◽

pp. 284-298

Author(s):

A. Bull ◽

P. Engel ◽

V. Dzapo

Keyword(s):

Skeletal Muscle ◽

Enzyme Activity ◽

Carnitine Palmitoyltransferase ◽

Muscle Mitochondria ◽

Atp Production ◽

Healthy Siblings ◽

Carnitine Palmitoyltransferase I ◽

Cpt I ◽

Possible Cause ◽

Vergleichende Untersuchungen

Abstract. Title of the paper: Comparative investigations of selected criteria of energy metabolism in skeletal muscle, plasma and lymphocytes in healthy and in piglets with congenital myofibrillar hypoplasia Carnitine contents of skeletal muscle, plasma and lymphocytes, the capacity of ATPsynthesis in muscle mitochondria and lymphocytes, and the enzyme activity of carnitine palmitoyltransferase I (CPT I) in muscle mitochondria were determined in piglets with congenital myofibrillar hypoplasia (CMH) in comparision to their clinical healthy siblings and piglets from CMH-free litters. Tendentious differences in the relation of acylcarnitine to free carnitine in healthy piglets and piglets suffering from CMH could be detected. Healthy piglets showed in tendency superiority in the ATP-production of their lymphocytes compared with diseased animals. Depending on the applied substrate, muscle mitochondria showed tendentially differences in the ATP-production between CMH-affected and healthy litters, so that a connection between CMH and the lipid metabolism, particular the β-oxidation, is supposed. Differences in the carnitine palmitoyltransferase I-activity as a possible cause for CMH could be excluded.

Download Full-text

Expression of novel isoforms of carnitine palmitoyltransferase I (CPT-1) generated by alternative splicing of the CPT-Iβ gene

Biochemical Journal ◽

10.1042/bj3340225 ◽

1998 ◽

Vol 334 (1) ◽

pp. 225-231 ◽

Cited By ~ 11

Author(s):

Geng-Sheng YU ◽

Yi-Chun LU ◽

Tod GULICK

Keyword(s):

Alternative Splicing ◽

Donor Site ◽

Carnitine Palmitoyltransferase ◽

Membrane Topology ◽

Splice Donor Site ◽

The Novel ◽

Pcr Screening ◽

Mitochondrial Fatty Acid ◽

Carnitine Palmitoyltransferase I ◽

Cpt I

Carnitine palmitoyltransferase I (CPT-I) catalyses the rate-determining step in mitochondrial fatty acid β-oxidation. The enzyme has two cognate structural genes that are preferentially expressed in liver (α) or fat and muscle (β). We hypothesized the existence of additional isoforms in heart to account for unique kinetic characteristics of enzyme activity in this tissue. Hybridization and PCR screening of a human cardiac cDNA library revealed the expression of two novel CPT-I isoforms generated by alternative splicing of the CPT-Iβ transcript, in addition to the β and α cDNA species previously described. Ribonuclease protection and reverse transcriptase-mediated PCR assays confirmed the presence of mRNA species of each splicing variant in heart, skeletal muscle and liver, with differing relative concentrations in the tissues. The novel splicing variants omit exons or utilize a cryptic splice donor site within an exon. Deduced polypeptide sequences of the novel enzymes include omissions in the region of putative membrane-spanning and malonyl-CoA regulatory domains compared with the previously described CPT-Is, implying that the encoded enzymes will exhibit unique features with respect to outer mitochondrial membrane topology and response to physiological and pharmacological inhibitors.

Download Full-text