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Phase determination by multiple-wavelength x-ray diffraction: crystal structure of a basic "blue" copper protein from
J M Guss1, E A Merritt, R P Phizackerley
1Department of Inorganic Chemistry, University of Sydney, New South Wales, Australia.
Science (New York, N.Y.)
|August 12, 1988
Summary
A new X-ray diffraction method, multiple-wavelength anomalous dispersion (MAD) phasing, determined the structure of a cucumber blue copper protein. This technique offers a direct solution to the phase problem in crystallography.
Area of Science:
- Protein crystallography
- Structural biology
- Biophysics
Background:
- The "phase problem" hinders X-ray crystallography for unknown protein structures.
- Conventional methods like isomorphous replacement or molecular replacement have limitations.
- Blue copper proteins are vital metalloproteins with diverse biological roles.
Purpose of the Study:
- To determine the de novo protein structure of a blue copper protein from cucumber seedlings.
- To showcase the utility of multiple-wavelength anomalous dispersion (MAD) phasing for structure determination.
- To gain insights into the properties of blue copper proteins.
Main Methods:
- Application of multiple-wavelength anomalous dispersion (MAD) phasing.
- Utilizing intense, polychromatic synchrotron radiation.
- Accurate data collection with multiwire electronic area detectors.
Main Results:
- Successful de novo structure determination of the cucumber blue copper protein.
- Demonstrated MAD phasing as a viable alternative to conventional methods.
- Provided new insights into the spectroscopic and redox properties of blue copper proteins.
Conclusions:
- MAD phasing is a powerful technique for solving the X-ray crystallography phase problem.
- This method is particularly advantageous for metalloproteins where derivatives are difficult to obtain.
- The determined structure enhances understanding of blue copper protein function.