PHOTO‐INDUCED ELECTRON EJECTION FROM THE REDUCED COPPER OF Pseudomonas aeruginosa AZURIN

Corin, Alan F.; Gould, Ian R.

doi:10.1111/j.1751-1097.1989.tb04178.x

Cited by 4 publications

(5 citation statements)

References 41 publications

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“…The observed redox chemistry of the Cu center can be attributed to several mechanisms that may be occurring in solution, and shown in Figure 5: path A, ET from Cu I to photogenerated W48• + ; path C, direct electron ejection 60 from Cu I to generate Cu II ; and path D, ET from Cu I to photogenerated W48*. 55 Protein degradation is also possible.…”

Section: ■ Discussionmentioning

confidence: 99%

Photogeneration and Quenching of Tryptophan Radical in Azurin

et al. 2015

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Tryptophan and tyrosine can form radical intermediates that enable long-range, multistep electron transfer (ET) reactions in proteins. This report describes the mechanisms of formation and quenching of a neutral tryptophan radical in azurin, a blue-copper protein that contains native tyrosine (Y108 and Y72) and tryptophan (W48) residues. A long-lived neutral tryptophan radical W48• is formed upon UV-photoexcitation of a zinc(II)-substituted azurin mutant in the presence of an external electron acceptor. The quantum yield of W48• formation (Φ) depends upon the tyrosine residues in the protein. A tyrosine-deficient mutant, ZnIIAz48W, exhibited a value of Φ = 0.080 with a Co(III) electron acceptor. A nearly identical quantum yield was observed when the electron acceptor was the analogous tyrosine-free, copper(II) mutant; this result for the ZnIIAz48W:CuIIAz48W mixture suggests there is an interprotein ET path. A single tyrosine residue at one of the native positions reduced the quantum yield to 0.062 (Y108) or 0.067 (Y72). Wild-type azurin with two tyrosine residues exhibited a quantum yield of Φ = 0.045. These data indicate that tyrosine is able to quench the tryptophan radical in azurin.

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Section: ■ Discussionmentioning

confidence: 99%

Photogeneration and Quenching of Tryptophan Radical in Azurin

et al. 2015

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“…Experimentally, electron-transfer processes can be examined by adding exogenous oxidants and reductants or by using photons to try to induce electron transfer. 4,11 For azurin numerous studies have concentrated on Trp-48 because it may be involved in electron trnasfer to the Cu site.3,5,7 Many of the unique absorption and fluorescence spectral features of Pae azurin (as well as Pseudomonas fluorescens ATCC-13525-2 (Pfl) azurin5,7) can be attributed to this single Trp residue. 3,5,[12][13][14][15] Several groups have investigated the Trp fluorescence behavior in azurins from different bacterial strains with the expectation of characterizing the Trp environment and interactions between the Trp and potential redox partners involved in the electrontransfer conduit.…”

Section: Introductionmentioning

confidence: 99%

UV resonance Raman examination of the azurin tryptophan environment and energy relaxation pathways

Sweeney¹,

Harmon²,

Asher³

et al. 1991

J. Am. Chem. Soc.

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“…When Corren et al (1987) observed the NO binding to Az, they suggested that it formed a charge transfer complex, Cu+-NO+, partly based on their observation of bleaching of the main absorption bands, which is also observed in reduction of the copper. However, the azurin spectra in Figure la show an isosbestic point at ~530 nm and increasing absorbance below that wavelength, indicating that a band appears around 400 nm, which does not exist in reduced Az (Corin & Gould, 1989). Halocyanin shows the same behavior, as evident from the spectra in Figure lb,c.…”

Section: Discussionmentioning

confidence: 55%

Ligand Binding and Protein Dynamics in Cupredoxins

Ehrenstein

Filiaci²,

Scharf³

et al. 1995

Biochemistry

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Type 1 copper sites bind nitric oxide (NO) in a photolabile complex. We have studied the NO binding properties of the type 1 copper sites in two cupredoxins, azurin and halocyanin, by measuring the temperature dependence of the ligand binding equilibria and the kinetics of the association reaction after photodissociation over a wide range of temperature (80-280 K) and time (10(-6)-10(2) s). In both proteins, we find nonexponential kinetics below 200 K that do not depend on the NO concentration. Consequently, this process is interpreted as geminate recombination. In azurin, the rebinding can be modeled with the Arrhenius law using a single pre-exponential factor of 10(8.3) s-1 and a Gaussian distribution of enthalpy barriers centered at 22 kJ/mol with a width [full width at half-maximum (FWHM)] of 11 kJ/mol. In halocyanin, a more complex behavior is observed. About 97% of the rebinding population can also be characterized by a Gaussian distribution of enthalpy barriers at 12 kJ/mol with a width of 6.0 kJ/mol (FWHM). The pre-exponential of this population is 1.6 x 10(12) s-1 at 100 K. After the majority population has rebound, a power-law phase that can be modeled with a gamma-distribution of enthalpy barriers is observed. Between 120 and 180 K, an additional feature that can be interpreted as a relaxation of the barrier distribution toward higher barriers shows up in the kinetics. Above 200 K, a slower, exponential rebinding appears in both cupredoxins. Since the kinetics depend on the NO concentration, this process is identified as bimolecular rebinding.(ABSTRACT TRUNCATED AT 250 WORDS)

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PHOTO‐INDUCED ELECTRON EJECTION FROM THE REDUCED COPPER OF Pseudomonas aeruginosa AZURIN

Cited by 4 publications

References 41 publications

Photogeneration and Quenching of Tryptophan Radical in Azurin

Photogeneration and Quenching of Tryptophan Radical in Azurin

UV resonance Raman examination of the azurin tryptophan environment and energy relaxation pathways

Ligand Binding and Protein Dynamics in Cupredoxins

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