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Published June 2, 1999 | public
Journal Article

Mutations of the Weak Axial Ligand in the Thermus CuA Center Modulates Its Electronic Structure

Abstract

Here we report the first stable, axial ligand mutations, Met160Gln and Met160Glu, of a Cu_A center in the Thermus thermophilus (TtIICu_A) fragment of cytochrome ba3.2a The binuclear, delocalized (S = 1/2) Cu_A center serves as the initial electron acceptor in cytochrome c oxidases (COX) and nitrous oxide reductase (N_2OR). The Cu_A domains and the type 1 (T1) blue copper centers are members of the cupredoxin superfamily of electron transfer (ET) proteins. The Cu_A centers have two bridging Cys thiolates, two terminal His imidazole ligands, and one weak axial ligand to each copper, a Met thioether or the peptide carbonyl of Glu (Figure 1). The weak axial ligands give each Cu a distorted tetrahedral geometry, similar to the T1 centers.

Additional Information

© 1999 American Chemical Society. Received December 21, 1998. We are grateful to Dr. F. Neese and Prof. P. M. H. Kroneck for providing the EPR simulation program. This work was supported by a National Institutes of Health Grant GM16424 (J.H.R) and the German-Israel Foundation for Scientific Research (D.G. and I.P.). We thank Prof. I. Rubinstein for use of the Jasco V-570 UV/vis/NIR Spectrometer.

Additional details

Created:
August 19, 2023
Modified:
October 23, 2023