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Internal Motion and Electron Transfer in Proteins: A Picosecond Fluorescence Study of Three Homologous Azurins
Biochemistry (1987)
  • Jacob W. Petrich, University of Chicago
  • James W. Longworth, Illinois Institute of Technology
  • Graham R. Fleming, University of Chicago
Abstract
We have carried out a picosecond fluorescence study of holo- and apoazurins of Pseudomonas aeruginosa (azurin Pae), Alcaligenes faecilis (azurin Afe), and Alcaligenes denitrificans (azurin Ade). Azurin Pae contains a single, buried tryptophyl residue; azurin Afe, a single surface tryptophyl residue; and azurin Ade, tryptophyl residues in both environments. From anisotropy measurements we conclude that the interiors of azurins Pae and Ade are not mobile enough to enable motion of the indole ring on a nanosecond time scale. The exposed tryptophans in azurins Afe and Ade show considerable mobility on a few hundred picosecond time scale. The quenching of tryptophan fluorescence observed in the holoproteins is interpreted in terms of electron transfer from excited-state tryptophan to Cu(II). The observed rates are near the maximum predicted by Marcus theory for the separation of donor and acceptor. The involvement of protein matrix and donor mobility for electron transfer is discussed. The two single-tryptophan-containing proteins enable the more complex fluorescence behavior of the two tryptophans of azurin Ade to be understood. The single-exponential fluorescence decay observed for azurin Pae and the nonexponential fluorescence decay observed for azurin Afe are discussed in terms of current models for tryptophan photophysics. 
Keywords
  • azurin,
  • bacterial protein,
  • copper,
  • Alcaligenes,
  • chemical structure,
  • electron transport,
  • kinetics,
  • metabolism,
  • protein conformation,
  • Pseudomonas aeruginosa,
  • spectrofluorometry
Disciplines
Publication Date
May, 1987
DOI
10.1021/bi00384a010
Publisher Statement
Reprinted (adapted) with permission from Biochemistry 26 (1987): 2711, doi: 10.1021/bi00384a010. Copyright 1987 American Chemical Society.
Citation Information
Jacob W. Petrich, James W. Longworth and Graham R. Fleming. "Internal Motion and Electron Transfer in Proteins: A Picosecond Fluorescence Study of Three Homologous Azurins" Biochemistry Vol. 26 Iss. 10 (1987) p. 2711 - 2722
Available at: http://works.bepress.com/jacob_petrich/14/