Download MendeleyX-ray structure determination and characterization of the Pseudomonas aeruginosa azurin mutant Met121Glu.
Karlsson, B.G., Tsai, L.C., Nar, H., Sanders-Loehr, J., Bonander, N., Langer, V., Sjolin, L.(1997) Biochemistry 36: 4089-4095
- PubMed: 9100002
- DOI: https://doi.org/10.1021/bi962416o
- Primary Citation of Related Structures:
1ETJ - PubMed Abstract:
The Met121Glu azurin mutant has been crystallized and the structure determined at a resolution of 2.3 A. In the crystal structure a carboxyl oxygen of Met121Glu is coordinated to the metal at a distance of 2.2 A. Single-crystal resonance Raman spectroscopy was used to show that the glutamic acid residue in the copper site was in the protonated state. Titration of this residue gives rise to a number of unusual, pH-dependent properties: as the pH is increased from 4 to 8, the S(Cys)-Cu ligand-to-metal charge transfer bands are blue shifted and their intensity ratio is reversed, the EPR signal changes from type 1 copper to a new form of protein-bound copper, and the redox potential changes from 370 to 180 mV. The spectroscopic changes in this pH interval are consistent with a two-state model. From the pH dependence of the optical and EPR spectra, pKa = 5.0 for the glutamic acid in the oxidized protein was determined.
Organizational Affiliation:
Department of Biochemistry and Biophysics, Goteborg University, Sweden. Goran.Karlsson@bcbp.gu.se
