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J M Kilponen

Publications and source records attributed to J M Kilponen.

6 recordsLinked to original sources
PubMed1994

cDNA cloning and amino acid sequence of human mitochondrial delta 3 delta 2-enoyl-CoA isomerase: comparison of the human enzyme with its rat counterpart, mitochondrial short-chain isomerase.

We report the isolation of a cDNA encoding a mature human monofunctional delta 3 delta 2-enoyl-CoA isomerase and the determination of its nucleotide sequence. The purified uncleaved protein, as well as several internal tryptic and CNBr fragments, were subjected to N-terminal peptide sequencing. The deduced amino acid sequence of the mature protein consists of 260 amino acids with a predicted M(r) of 28735. The human mitochondrial isomerase exhibits a 74% (78%) sequence identity with the corresponding rat counterpart at amino acid (nucleotide) level(s). Many basic amino acid residues in rat isomerase have been changed to acidic or neutral residues in human enzyme, explaining the differences observed between these proteins.

Amino Acid Sequence↗
PubMed1993

Beta-oxidation of unsaturated fatty acids in humans. Isoforms of delta 3, delta 2-enoyl-CoA isomerase.

This investigation was undertaken in order to elucidate the human enzymes which participate in metabolism of the double bonds of unsaturated fatty acids during beta-oxidation. The results indicate that the human monofunctional delta 3, delta 2-enoyl-CoA isomerase (EC 5.3.3.8) with the native M(r) of 70,000 differed significantly from its rat counterpart [Palosaari et al. (1990) J. Biol. Chem. 265, 3347-3353]; the isoelectric point of the human isoform was over three pH-units more acidic, it showed different chromatographic behaviour, the human enzyme did not show any clear-cut substrate chain-length specificity and only a weak immunological cross-reactivity was detected with the antibody to rat liver mitochondrial short-chain enzyme. This explains the failure of attempts to apply the rat data directly to human beings. Another isomerase activity from human liver was found to be a part of the isomerase-hydratase-dehydrogenase polypeptide showing immunological cross-reactivity with the previously characterized peroxisomal multifunctional enzyme (MFE) from rat liver.

Animals↗
PubMed1992

Peroxisomal diseases.

The peroxisomal diseases, which are rare inborn metabolic errors, often have serious effects on the well being of the individual and many of them are fatal at an early age. The Zellweger cerebro-hepato-renal syndrome represents a group consisting of diseases with a generalized loss of peroxisomal functions and is considered as a prototype for peroxisomal dysfunction. The largest group includes those diseases where only a single peroxisomal function is impaired. The most common peroxisomal disease, x-linked adrenoleukodystrophy (ADL), belongs to this group, and neurological symptoms dominate among the patients. The primary diagnosis is usually based on clinical findings and measurement of accumulated or depleted metabolites in the body (e.g. very long chain fatty acids, bile acid intermediates or plasmalogens). Some progress has been made in treating of the peroxisomal diseases. Many patients with x-linked ALD have benefitted from the supplementation of the diet with long chain monounsaturated fatty acids like erucic acid or oleic acid with the simultaneous restriction of very long chain fatty acids. Docosahexenoate (C22:1) has also shown promising results in some studies.

Humans↗
PubMed1990

Occurrence of a long-chain delta 3,delta 2-enoyl-CoA isomerase in rat liver.

Isoproteins of delta 3,delta 2-enoyl-CoA isomerase (EC 5.3.3.8), an auxiliary enzyme in the beta-oxidation of unsaturated fatty acids having double bonds at odd-numbered positions, were studied in livers of control and clofibrate-treated rats. When liver extracts were applied to a hydroxyapatite column at pH 7.0, the previously characterized peroxisomal trifunctional hydratase-dehydrogenase-isomerase enzyme and the mitochondrial isomerase, which shows a preference for short-chain substrates, were eluted almost in parallel. In addition to these activities, a separate isomerase was observed to elute at a lower potassium phosphate concentration in the gradient. Experiments with extracts of purified mitochondria and peroxisomes demonstrated the mitochondrial origin of this third activity. Studies on the kinetic properties of the third isomerase showed that it has a preference for C10-C12 substrates. An Mr of 200,000 was obtained for the native protein by gel-filtration chromatography. Antibodies to mitochondrial short-chain isomerase and peroxisomal trifunctional enzyme did not recognize this novel mitochondrial isoenzyme. The immunological non-cross-reactivity can be interpreted as suggesting that the different isomerases are not closely related at the level of the primary structure of the polypeptide chain. The present data demonstrate that, similar to many other enzymes of beta-oxidation, delta 3,delta 2-enoyl-CoA isomerase has at least three isoenzymes in rat liver: mitochondrial short- and long-chain isomerases and an additional peroxisomal isoenzyme, which in this case is a part of a multifunctional protein.

Animals↗
PubMed1990

Delta 3,delta 2-enoyl-CoA isomerases. Characterization of the mitochondrial isoenzyme in the rat.

Delta 3,delta 2-Enoyl-CoA isomerase (EC 5.3.3.8), an obligatory auxiliary enzyme for the metabolism of double bonds at odd-numbered positions of fatty acids during their beta-oxidation, was studied in hearts and livers of normal and clofibrate-treated rats. Hepatic peroxisomal and mitochondrial isoenzymes were separable by dye-ligand chromatography. The mitochondrial one was further purified to apparent homogeneity. An isomerase was also purified from heart muscle, a peroxisome-poor tissue. These enzymes were dimeric basic proteins (pI 9.5) with a subunit molecular weight of 30,000. Both cis- and trans-enoyl-CoA served as substrates for the hepatic enzyme studied. The velocity ratio for the C6-, C10-, and C12-trans-3-enoyl substrates was 9:2.5:1. By immunoelectron microscopy the enzyme protein selected for purification was found to be mitochondrial both in liver and heart. Chromatographic evidence, immunoelectron microscopy, and immunoblotting indicated that in the liver but not in the heart, the enzyme underwent an induction of 1 order of magnitude during clofibrate treatment. Antibodies towards the rat isomerases detected cross-reactive proteins in bovine and pig liver and heart and human placenta. The estimated subunit sizes varied from species to species, being 31,000 in bovine liver and heart, 29,000 in pig liver and heart, and 30,000 in human placenta. The data are in accord with the notion of a dual location of the delta 3,delta 2-enoyl-CoA isomerase. Mitochondrial origin of one of the isoenzymes and its tissue-specific induction by clofibrate were verified by immunochemistry and the identity of the peroxisomal one revealed by the chromatographic behavior of the proteins.

Animals↗