Tryptophan-Accelerated Electron Flow Across a Protein−Protein Interface

0397877 - ÚFCH JH 2014 RIV US eng J - Článek v odborném periodiku
Takematsu, K. - Williamson, H. - Blanco-Rodríguez, A. M. - Sokolová, L. - Nikolovski, P. - Kaiser, J. T. - Towrie, M. - Clark, I. P. - Vlček, Antonín - Winkler, J. R. - Gray, H. B.
Tryptophan-Accelerated Electron Flow Across a Protein−Protein Interface.
Journal of the American Chemical Society. Roč. 135, č. 41 (2013), s. 15515-15525. ISSN 0002-7863. E-ISSN 1520-5126
Grant CEP: GA MŠMT LH13015
Institucionální podpora: RVO:61388955
Klíčová slova: PSEUDOMONAS-AERUGINOSA AZURINS * CYTOCHROME B(5) INTERFACE * LASER MASS-SPECTROMETRY
Kód oboru RIV: CF - Fyzikální chemie a teoretická chemie
Impakt faktor: 11.444, rok: 2013

We report a new metallolabeled blue copper protein, Re126W122CuI Pseudomonas aeruginosa azurin, which has three redox sites at well-defined distances in the protein fold: ReI(CO)3(4,7-dimethyl- 1,10-phenanthroline) covalently bound at H126, a Cu center, and an indole side chain W122 situated between the Re and Cu sites (Re- W122(indole) = 13.1 Å, dmp-W122(indole) = 10.0 Å, Re-Cu = 25.6 Å). Near-UV excitation of the Re chromophore leads to prompt CuI oxidation (<50 ns), followed by slow back ET to regenerate CuI and ground-state ReI with biexponential kinetics, 220 ns and 6 μs. From spectroscopic measurements of kinetics and relative ET yields at different concentrations, it is likely that the photoinduced ET reactions occur in protein dimers, (Re126W122CuI)2 and that the forward ET is accelerated by intermolecular electron hopping through the interfacial tryptophan: *Re//<-W122<-CuI, where // denotes a protein−protein interface. Solution mass spectrometry confirms a broad oligomer distribution with prevalent monomers and dimers, and the crystal structure of the CuII form shows two Re126W122CuII molecules oriented such that redox cofactors Re(dmp) and W122-indole on different protein molecules are located at the interface at much shorter intermolecular distances (Re-W122(indole) = 6.9 Å, dmp-W122(indole) = 3.5 Å, and Re- Cu = 14.0 Å) than within single protein folds. Whereas forward ET is accelerated by hopping through W122, BET is retarded by a space jump at the interface that lacks specific interactions or water molecules. These findings on interfacial electron hopping in (Re126W122CuI)2 shed new light on optimal redox-unit placements required for functional long-range charge separation in protein complexes.
Trvalý link: http://hdl.handle.net/11104/0225500