MAD phasing

Atliappilly, F. K., and Hendrickson, W. A., 1995. Structure of die biotinyl domain of acetyl-CoA carboxyla.se determined by MAD phasing. Structure 3 1407. 

Coehlo AV, Matias P,Fiilop V,et al. 1997. Desulfoferrodoxin structure determined by MAD phasing and rehnement to 1.9-A reveals a unique combination of a tetrahedral FeS4 centre with a square pyramidal FeSN4 centre. J Biol Inorg Chem 2 680-9. 

Burla, M. C., et al. (2004). MAD phasing choosing the most informative wavelength combination. Acta Crystallogr. D 60,1683-1686. 

Deacon, A. M. and EaUck, S. E. (1999). Selenium-based MAD phasing setting the sites on larger structures. Structure Fold Des. 7, R161-166. 

Fanchon, E. and Hendrickson, W. A. (1990). Effect of the anisotropy of anomalous scattering on the MAD phasing method. Acta Crystallogr. A 46, 809-820. 

Peterson, M. R., et al. (1996). MAD Phasing strategies explored with a brominated oligonucleotide crystal at 1.65A resolution. J. Synchrotron Radiation 3,24-34. 

TerwiUiger, T. C. (1994b). MAD phasing treatment of dispersive differences as isomorphous replacement information. Acta Crystallogr. D 50,17-23. 

Alternative methods of solving the phase problem are also used now. When a transition metal such as Fe, Co, or Ni is present in the protein, anomolous scattering of X-rays at several wavelengths (from synchrotron radiation) can be used to obtain phases. Many protein structures have been obtained using this multiple wavelength anomalous diffraction (MAD phasing) method.404 407 408 Selenocysteine is often incorporated into a protein that may be produced in... 

Direct methods work if the molecules, and thus the unit cells and numbers of reflections, are relatively small. Isomorphous replacement works if the molecules are large enough that a heavy atom does not disturb their structures significantly. The most difficult structures for crystallographers are those that are too large for direct methods and too small to remain isomorphous despite the intrusion of a heavy atom. If a medium-size protein naturally contains a heavy atom, like iron or zinc, or if a selenomethionine derivative can be produced, the structure can often be solved by MAD phasing (Section IV.E). [NMR methods (see Chapter 10) are also of great power for small and medium-size molecules ]... 

Brodersen DE, Etzerodt M, Madsen P, Celis JE, Thogersen HC, Nyborg J, Kjeldgaard M. 1998. EF-hands at atomic resolution the structure of human psoriasin (S100A7) solved by MAD phasing. Structure 6(4) 477-489. 

Ishikawa K, Nakagawa A, Tanaka I, Suzuki M, Nishihira J. 2000. The structure of human MRP8, a member of the SI00 calcium-binding protein family, by MAD phasing at 1.9 A resolution. Acta Crystallogr D Biol Crystallogr 56(Pt 5) 559-566. 

Ennifar, E., Walter, P., and Dumas, P. (2001). An efficient method for solving RNA structures MAD phasing by replacing magnesium with zinc. Acta Crystallogr. D Biol. Crystallogr. 57, 330-332. 

Iwata, S., Saynovits, M., Link, T. A., and Michel, H., 1996, Structure of a water soluble fragment of the iRieskei iron-sulfur protein of the bovine heart mitochondrial cytochrome bcl complex determined by MAD phasing at 1.5 resolution. Structure 4 567n579. 

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