Multiwavelength Anomalous Diffraction as a Direct Phasing Vehicle in Macromolecular Crystallography
The possibility for definitive phase determination from diffraction measurements made at multiple wavelengths from crystals that contain anomalous scatterers has long been recognized (Okaya and Pepinsky, 1956). This potential is easy to appreciate since multiwavelength anomalous diffraction (MAD) experiments can be thought of as in situ multiple isomorphous replacements (MIR) arising from the variations in scattering factors that accompany changes of wavelengths. These variations, known as anomalous scattering, result from the resonance that occurs between the oscillations of atomic orbitals and x-ray-induced electronic vibrations. With synchrotron radiation such experiments are now quite feasible, and with recently developed methods for analyzing MAD measurements, accurate phases can be obtained for macromolecular crystal structures. Anomalous scattering centers appropriate for MAD experiments can be introduced as for conventional heavy atom derivatives or they may occur naturally in metalloproteins. In addition, selenomethionyl proteins produced biologically are suitable for MAD phasing. Since a single crystalline species (and often a single crystal) suffices for MAD analysis of such molecules, the MAD method serves as a vehicle for direct structure determination.
KeywordsCrystal Structure Analysis Anomalous Signal Anomalous Scattering Photon Factory Macromolecular Crystallography
Unable to display preview. Download preview PDF.
- Adman, E. T., Sieker, L. C., and Jensen, L. H., 1973, The structure of a bacterial ferredoxin, J. Biol. Chem., 248: 3987.Google Scholar
- Hendrickson, W. A., 1985, Analysis of protein structure from diffraction measurements at multiple wavelengths. Trans. Amer. Cryst. Assn. 21: 11–21.Google Scholar
- Hendrickson, W. A., 1987, Anomalous scattering in macromolecular structure analysis, in: “Crystallography in Molecular Biology,” D. Moras, J. Drenth, B. Strandberg, D. Suck and K. Wilson, eds., Plenum Press, New York.Google Scholar
- Holmgren, A., Soderberg, B.-0., Eklund, H., and Branden, C.-I., 1975, Three-dimensional structure of Escherichia coli thioredoxin-S2 to 2.8 Angstroms resolution, Proc. Natl. Acad. Sci., USA 72: 2305.Google Scholar
- Karle, J., 1980, Some developments in anomalous dispersion for the structure investigation of macromolecular systems in biology, Int. J. Quant. Chem., 7: 357.Google Scholar
- Le Master, D. M., and Richards, F. M., 1985, 1H–15N heteronuclear NMR studies of Escherichia coli thioredoxin in samples isotropically labelled by residue type, Biochemistry, 24: 7263.Google Scholar
- Pahler, A., Hendrickson, W. A., Gawinowicz-Kolks, M. A., Argarana, C. E.., and Cantor C. R., 1987, Characterization and crystallization of core streptavidin, J. Biol. Chem. 262: 13933.Google Scholar
- Satow, Y., 1984, Photon factory data collection systems for x-ray crystallography using synchrotron radiation, in: “Methods and Applications in Crystallographic Computing,” S. R. Hall and T. Ashida, eds. Oxford Univ. Press, Oxford.Google Scholar