Reassessment of the active site quino-cofactor proposed to occur in the Aspergillus niger amine oxidase AO-I from the properties of model compounds
In: Biochemistry, Jg. 39 (2000-06-20), Heft 25
Online
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Zugriff:
Quino-cofactors have been found in a wide variety of prokaryotic and eukaryotic organisms. Two variants have, thus far, been demonstrated to derive from tyrosine precursors: these are the 2,4, 5-trihydroxyphenylalanine quinone (topa quinone or TPQ) [Janes, S. M. , et al. (1990) Science 248, 98] and an o-quinone analogue containing the side chain of a lysine residue (lysyltyrosine quinone or LTQ) [Wang, S. Z., et al. (1996) Science 273, 1078]. Additionally, a third variant of the family of tyrosine-derived cofactors has been reported to exist in an Aspergillus niger amine oxidase AO-I. This was described as an o-quinone cross-linked to the side chain of a glutamate residue [Frebort, I. (1996) Biochim. Biophys. Acta 1295, 59]. We have synthesized model compounds related to the proposed structure. Characterization of the redox properties for the model compound and spectral properties of its 4-nitrophenylhydrazine derivative lead us to conclude that the cofactor in A. niger amine oxidase AO-I has been misidentified. A TPQ carboxylate ester is considered an unlikely candidate for a biologically functional quino-cofactor.
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Reassessment of the active site quino-cofactor proposed to occur in the Aspergillus niger amine oxidase AO-I from the properties of model compounds
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Autor/in / Beteiligte Person: | Klinman, Judith P. ; Green, Edward L. ; Sanders-Loehr, Joann ; Melville, Chris R. |
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Zeitschrift: | Biochemistry, Jg. 39 (2000-06-20), Heft 25 |
Veröffentlichung: | 2000 |
Medientyp: | unknown |
ISSN: | 0006-2960 (print) |
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