8-Mercaptoflavins as Active Site Probes of Flavoenzymes


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MASSEY, Vincent, Sandro GHISLA, Edwin G. MOORE, 1979. 8-Mercaptoflavins as Active Site Probes of Flavoenzymes. In: Journal of Biological Chemistry. 254(19), pp. 9640-9650

@article{Massey19798-Mer-8392, title={8-Mercaptoflavins as Active Site Probes of Flavoenzymes}, year={1979}, number={19}, volume={254}, journal={Journal of Biological Chemistry}, pages={9640--9650}, author={Massey, Vincent and Ghisla, Sandro and Moore, Edwin G.} }

<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/123456789/8392"> <dc:rights>deposit-license</dc:rights> <dc:creator>Ghisla, Sandro</dc:creator> <dc:format>application/pdf</dc:format> <dc:creator>Massey, Vincent</dc:creator> <dc:contributor>Ghisla, Sandro</dc:contributor> <dcterms:available rdf:datatype="http://www.w3.org/2001/XMLSchema#dateTime">2011-03-24T17:43:15Z</dcterms:available> <dc:language>eng</dc:language> <dcterms:title>8-Mercaptoflavins as Active Site Probes of Flavoenzymes</dcterms:title> <dc:contributor>Moore, Edwin G.</dc:contributor> <dcterms:rights rdf:resource="https://creativecommons.org/licenses/by-nc-nd/2.0/legalcode"/> <dc:contributor>Massey, Vincent</dc:contributor> <dc:creator>Moore, Edwin G.</dc:creator> <dc:date rdf:datatype="http://www.w3.org/2001/XMLSchema#dateTime">2011-03-24T17:43:15Z</dc:date> <dcterms:issued>1979</dcterms:issued> <dcterms:abstract xml:lang="eng">Representative examples of the various classes of flavoproteins have been converted to their apoprotein forms and the native flavin replaced by 8-mercapto- FMN or 8-mercapto-FAD. The spectral and catalytic properties of the modified enzymes are characteristically different from one group to another; the results suggest that flavin interactions at positions N (1) or N(5) of the flavin chromophore have profound influences on the properties of the flavoprotein. 1. The 8-thiolate anion form of 8-mercaptoflavin has an absorption maximum in the region 520 to 550 nm (e ~30 mM-1 cm-1). This form is retained on binding to flavoproteins whose physiological reactions involve obligatory one-electron transfers (e.g. flavodoxin, NADPH-cytochrome P-450 reductase). In the native form these enzymes stabilize the blue neutral radical of the flavin. A radical form of 8-mercaptoflavin is also stabilized by these proteins. 2. The p-quinoid form of 8-mercaptoflavin has an absorption maximum in the range 560 to 600 nm (e ~30 mM-1 cm-1). This form is stabilized on binding to flavoproteins of the dehydrogenase-oxidase class (e.g. glucose oxidase, n-amino acid oxidase, lactate oxidase, Old Yellow Enzyme). These same enzymes in their native flavin form stabilize the red semiquinone, and have a pronounced reactivity with sulfite to form flavin N(5)- sulfite adducts. These properties of the native enzyme,including the ability to react with nitroalkane carbanions, are not exhibited by the 8-mercaptoflavoproteins. 3. A group of flavoenzymes fails to conform strictly to the above classification, exhibiting some properties of both classes. These include the examples of flavoprotein hydroxylases and transhydrogenases studied. 4. The riboflavin-binding protein of hen egg whites binds 8-mercaptoriboflavin preferentially in the unionized state, resulting in a shift in pK from 3.8 with free 8-mercaptoriboflavin to ≥ 9.0 with the protein-bound form.</dcterms:abstract> <dcterms:bibliographicCitation>First publ. in: Journal of Biological Chemistry 254 (1979), 19, pp. 9640-9650</dcterms:bibliographicCitation> <bibo:uri rdf:resource="http://kops.uni-konstanz.de/handle/123456789/8392"/> </rdf:Description> </rdf:RDF>

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