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A variable temperature spectroscopic study on Paracoccus pantotrophus pseudoazurin: protein constraints on the blue Cu site

Xie, Xiangjin and Hadt, Ryan G. and Pauleta, Sofia R. and González, Pablo J. and Un, Sun and Moura, Isabel and Solomon, Edward I. (2009) A variable temperature spectroscopic study on Paracoccus pantotrophus pseudoazurin: protein constraints on the blue Cu site. Journal of Inorganic Biochemistry, 103 (10). pp. 1307-1313. ISSN 0162-0134. doi:10.1016/j.jinorgbio.2009.04.012.

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The blue or Type 1 (T1) copper site of Paracoccuspantotrophus pseudoazurin exhibits significant absorption intensity in both the 450 and 600 nm regions. These are sigma and π S_(Cys) to Cu^(2+) charge transfer (CT) transitions. The temperature dependent absorption, EPR, and resonance Raman (rR) vibrations enhanced by these bands indicate that a single species is present at all temperatures. This contrasts the temperature dependent behavior of the T1 center in nitrite reductase [S. Ghosh, X. Xie, A. Dey, Y. Sun, C. Scholes, E. Solomon, Proc. Natl. Acad. Sci. 106 (2009) 4969-4974] which has a thioether ligand that is unconstrained by the protein. The lack of temperature dependence in the T1 site in pseudoazurin indicates the presence of a protein constraint similar to the blue Cu site in plastocyanin where the thioether ligand is constrained at 2.8 A. However, plastocyanin exhibits only π CT. This spectral difference between pseudoazurin and plastocyanin reflects a coupled distortion of the site where the axial thioether in pseudoazurin is also constrained, but at a shorter Cu-S_(Met) bond length. This leads to an increase in the Cu^(2+)-S_(Cys) bond length, and the site undergoes a partial tetragonal distortion in pseudoazurin. Thus, its ground state wavefunction has both sigma and pi character in the Cu^(2+)-S(Cys) bond.

Item Type:Article
Related URLs:
URLURL TypeDescription
Hadt, Ryan G.0000-0001-6026-1358
Solomon, Edward I.0000-0003-0291-3199
Additional Information:© 2009 Elsevier. Received 27 January 2009, Revised 20 March 2009, Accepted 24 April 2009, Available online 7 May 2009. his research was supported by NSF Grant CHE 0446304 (E.I.S.). X. X. is grateful for William S. Johnson fellowship.
Funding AgencyGrant Number
Stanford UniversityUNSPECIFIED
Subject Keywords:Blue copper; Axial ligand; Protein constraint; Coupled distortion; Temperature dependence
Issue or Number:10
Record Number:CaltechAUTHORS:20180612-155638279
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Official Citation:Xiangjin Xie, Ryan G. Hadt, Sofia R. Pauleta, Pablo J. González, Sun Un, Isabel Moura, Edward I. Solomon, A variable temperature spectroscopic study on Paracoccus pantotrophus pseudoazurin: Protein constraints on the blue Cu site, Journal of Inorganic Biochemistry, Volume 103, Issue 10, 2009, Pages 1307-1313, ISSN 0162-0134, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:87038
Deposited By: George Porter
Deposited On:12 Jun 2018 23:16
Last Modified:15 Nov 2021 20:44

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