期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2001
卷号：98
期号：25
页码：14268-14273
DOI：10.1073/pnas.241429098
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The crystal structure of the heterotrimeric quinohemoprotein amine dehydrogenase from Paracoccus denitrificans has been determined at 2.05-A resolution. Within an 82-residue subunit is contained an unusual redox cofactor, cysteine tryptophylquinone (CTQ), consisting of an orthoquinone-modified tryptophan side chain covalently linked to a nearby cysteine side chain. The subunit is surrounded on three sides by a 489-residue, four-domain subunit that includes a diheme cytochrome c. Both subunits sit on the surface of a third subunit, a 337-residue seven-bladed {beta}-propeller that forms part of the enzyme active site. The small catalytic subunit is internally crosslinked by three highly unusual covalent cysteine to aspartic or glutamic acid thioether linkages in addition to the cofactor crossbridge. The catalytic function of the enzyme as well as the biosynthesis of the unusual catalytic subunit is discussed.
