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Redox Properties of Human Medium-Chain Acyl-CoA Dehydrogenase, Modulation by Charged Active-Site Amino Acid Residues

Redox Properties of Human Medium-Chain Acyl-CoA Dehydrogenase, Modulation by Charged Active-Site Amino Acid Residues

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MANCINI-SAMUELSON, Gina J., Volker KIEWEG, Kim Marie SABAJ, Sandro GHISLA, Marian T. STANKOVICH, 1998. Redox Properties of Human Medium-Chain Acyl-CoA Dehydrogenase, Modulation by Charged Active-Site Amino Acid Residues. In: Biochemistry. 37(41), pp. 14605-14612. ISSN 0006-2960. eISSN 1520-4995

@article{Mancini-Samuelson1998Redox-8636, title={Redox Properties of Human Medium-Chain Acyl-CoA Dehydrogenase, Modulation by Charged Active-Site Amino Acid Residues}, year={1998}, doi={10.1021/bi981414w}, number={41}, volume={37}, issn={0006-2960}, journal={Biochemistry}, pages={14605--14612}, author={Mancini-Samuelson, Gina J. and Kieweg, Volker and Sabaj, Kim Marie and Ghisla, Sandro and Stankovich, Marian T.} }

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:bibo="http://purl.org/ontology/bibo/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:xsd="http://www.w3.org/2001/XMLSchema#" > <rdf:Description rdf:about="https://kops.uni-konstanz.de/rdf/resource/123456789/8636"> <dc:contributor>Mancini-Samuelson, Gina J.</dc:contributor> <dc:contributor>Kieweg, Volker</dc:contributor> <dc:contributor>Ghisla, Sandro</dc:contributor> <dc:language>eng</dc:language> <dcterms:abstract xml:lang="eng">The modulation of the electron-transfer properties of human medium-chain acyl-CoA dehydrogenase (hwtMCADH) has been studied using wild-type and site-directed mutants by determining their midpoint potentials at various pH values and estimating the involved pKs. The mutants used were E376D, in which the negative charge is retained; E376Q, in which one negative charge (pKa ≈ 6.0) is removed from the active center; E99G, in which a different negative charge (pKa ≈ 7.3) also is affected; and E376H (pKa ≈ 9.3) in which a positive charge is present. Em for hwtMCADH at pH 7.6 is -0.114 V. Results for the site-directed mutants indicate that loss of a negative charge in the active site causes a +0.033 V potential shift. This is consistent with the assumption that electrostatic interactions (as in the case of flavodoxins) and specific charges are important in the modulation of the electron-transfer properties of this class of dehydrogenases. Specifically, these charge interactions appear to correlate with the positive Em shift observed upon binding of substrate/product couple to MCADH [Lenn, N. D., Stankovich, M. T., and Liu, H. (1990) Biochemistry 29, 3709-3715], which coincides with a pK increase of Glu376-COOH from ~6 to 8-9 [Rudik, I., Ghisla, S., and Thorpe, C. (1998) Biochemistry 37, 8437-8445]. From the pH dependence of the midpoint potentials of hwtMCADH two mechanistically important ionizations are estimated. The pKa value of ~6.0 is assigned to the catalytic base, Glu376-COOH, in the oxidized enzyme based on comparison with the pH behavior of the E376H mutant, it thus coincides with the pK value recently estimated [Vock, P., Engst, S., Eder, M., and Ghisla, S. (1998) Biochemistry 37, 1848-1860]. The pKa of ~7.1 is assigned to Glu376-COOH in reduced hwtMCADH. Comparable values for these pKas for Glu376-COOH in pig kidney MCADH are pKox = 6.5 and pKred = 7.9. The Em measured for K304E-MCADH (a major mutant resulting in a deficiency syndrome) is essentially identical to that of hwtMCADH, indicating that the disordered enzyme has an intact active site.</dcterms:abstract> <dcterms:title>Redox Properties of Human Medium-Chain Acyl-CoA Dehydrogenase, Modulation by Charged Active-Site Amino Acid Residues</dcterms:title> <dc:rights>deposit-license</dc:rights> <dcterms:rights rdf:resource="https://creativecommons.org/licenses/by-nc-nd/2.0/legalcode"/> <dc:contributor>Stankovich, Marian T.</dc:contributor> <dc:creator>Mancini-Samuelson, Gina J.</dc:creator> <dc:creator>Kieweg, Volker</dc:creator> <dcterms:issued>1998</dcterms:issued> <dcterms:bibliographicCitation>First publ. in: Biochemistry ; 37 (1998), 41. - S. 14605-14612</dcterms:bibliographicCitation> <dc:creator>Sabaj, Kim Marie</dc:creator> <dc:contributor>Sabaj, Kim Marie</dc:contributor> <dc:format>application/pdf</dc:format> <dc:date rdf:datatype="http://www.w3.org/2001/XMLSchema#dateTime">2011-03-24T17:45:17Z</dc:date> <dc:creator>Stankovich, Marian T.</dc:creator> <dc:creator>Ghisla, Sandro</dc:creator> <bibo:uri rdf:resource="http://kops.uni-konstanz.de/handle/123456789/8636"/> </rdf:Description> </rdf:RDF>

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