Low frequency EPR of Pseudomonas aeruginosa azurin. Analysis of ligand superhyperfine structure from a type 1 copper site. Biophys J 1993 Jan;64(1):267-72
Date
01/01/1993Pubmed ID
8381679Pubmed Central ID
PMC1262323DOI
10.1016/S0006-3495(93)81363-8Scopus ID
2-s2.0-0027511133 (requires institutional sign-in at Scopus site) 21 CitationsAbstract
The type 1 copper in Pseudomonas aeruginosa azurin was studied by electron paramagnetic resonance (EPR) spectroscopy at low microwave frequencies. Partially resolved ligand hyperfine structure was observed in the perpendicular region of the spectra at both S-band (2.4 GHz) and L-band (1.1 GHz). A trial and error method, requiring several hundred simulations, has been used to simulate the low frequency EPR data and yield an optimum value of 30 MHz for ACUx, more than one half that previously reported. The fit between the simulated and experimental data is sensitive to changes in the Euler angles and, in particular, to the angle alpha which rotates the Cu A-tensor about the z-axis. Thus, the A- and g-tensors for copper in P. aeruginosa azurin do not appear to be coincident. A value for the Euler angle beta of at least 10 degrees does not disturb the fit between the simulated and experimental data. These studies demonstrate the advantage of evaluating EPR parameters from simulations at more than one frequency, especially at low frequencies where ligand superhyperfine structure may be resolved for type 1 copper.
Author List
Antholine WE, Hanna PM, McMillin DRMESH terms used to index this publication - Major topics in bold
AzurinBinding Sites
Biophysical Phenomena
Biophysics
Computer Simulation
Copper
Electron Spin Resonance Spectroscopy
Ligands
Molecular Structure
Pseudomonas aeruginosa
