Advances in direct methods for protein crystallography

Recent advances in ab initio direct methods have enabled the solution of cr ystal structures of small proteins from native X-ray data alone, that is, w ithout the use of fragments of known structure or the need to prepare heavy -atom or selenomethionine derivatives, provided that the data are available to atomic resolution. These methods are also proving to be useful for loca ting the selenium atoms or other anomalous scatterers in the multiple wavel ength anomalous diffraction phasing of larger proteins at lower resolution.