title: Semiquinone radicals of methylamine dehydrogenase, methoxatin, and related o-quinones: a pulse radiolysis study.
abstract: Methoxatin is a novel o-quinone coenzyme found in a variety of dehydrogenases and oxidases. In this paper we present the visible absorption spectra, apparent pKa, and midpoint potentials of the methoxatin and two analogous phenanthrolinedione semiquinones. We have also obtained absorption spectra for the semiquinone forms of the methoxatin-containing holoenzyme methylamine dehydrogenase and of its resolved methoxatin-containing subunit. The two protein and the methoxatin semiquinone spectra all differ from one another.
authors.affiliation: Department of Chemistry, Ohio State University, Columbus 43210.
authors.forename: R B
authors.initials: RB
authors.lastname: McWhirter
authors.forename: M H
authors.initials: MH
authors.lastname: Klapper
mesh_terms: D016227:Benzoquinones; D003067:Coenzymes; D005609:Free Radicals; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D000587:Oxidoreductases Acting on CH-NH Group Donors; D045542:PQQ Cofactor; D011487:Protein Conformation; D011675:Pulse Radiolysis; D015363:Quinolones; D011809:Quinones
chemical_list: D016227:Benzoquinones; D003067:Coenzymes; D005609:Free Radicals; D015363:Quinolones; D011809:Quinones; C025232:semiquinone radicals; D045542:PQQ Cofactor; C021567:methylamine dehydrogenase; D000587:Oxidoreductases Acting on CH-NH Group Donors