New opportunities in biological and chemical crystallography

Abstract

Banerjee [Proc. R. Soc. (1933), 141, 188–193] offered a new way of approaching the crystallographic phase problem which not only broke new ground beyond the `trial and error' structure solution method of that time but also heralded the extremely powerful direct methods of crystallography of the modern era from the 1970s onwards in chemical crystallography. Some 200000 crystal structures are known today. More complex crystal structures such as proteins required new experimental and theoretical methods to solve the phase problem. These are still evolving, and new methods and results involving synchrotron radiation at softer X‐ray wavelengths (2 Å) are reported. In addition, an overview is given of the new opportunities that are possible for biological and chemical crystallography, especially via harnessing synchrotron radiation and neutron beams.

Synchrotron and neutron techniques in biological crystallography

“…There is a small penalty of utilising a longer wavelength in having a less favourable monochromator transmission polarization correction but overall an increase from 1 A ˚to 2.5 A ˚wavelength offers an order of magnitude increase in E hkl , and a smaller crystal volume possibility by an equivalent factor. 8 The variation of the noise in the data as a function of wavelength must also be considered; systematic error due to absorption would be a problem if too big a crystal were used. At the opposite end of the available SR spectrum, the use of ultra-short wavelengths, down to 0.3 A ˚, was suggested, and early tests conducted, as a method to remove the systematic error of absorption in the X-ray data, and to reduce radiation damage.…”

Focusing optics for molybdenum radiation: a bright laboratory source for small-molecule crystallography

“…Developments in synchrotron science at dedicated central facilities, such as Station 9.8 (SRS, UK; Cernik et al, 1997; http://srs.dl.ac.uk/xrd/9.8), XRD1 (Elettra, Italy; http:// www.elettra.trieste.it/experiments/beamlines/xrd1/index.html) and ChemMatCARS (APS, USA; http://cars9.uchicago.edu/ chemmat/forNNusers/chemhomenn.html), have allowed small-molecule crystallographers to study increasingly small crystals (Clegg, 2000, and references therein) and enabled experiments that are more complex and advanced (Helliwell, 2002). The huge difference in the capabilities of synchrotron facilities compared with the conventional facilities in the home laboratory has allowed chemical sciences to benefit greatly so that, in many cases, studies have been performed that otherwise would have been impossible.…”

Resonant elastic X-ray scattering: Where from? where to?

“…Since the early days, MAD methods have matured as a routine tool and can deliver rapid solutions for biological structures [49]. Once again, this has been made possible through the combination of progress in instrumentation [52], in particular automation, and software development.…”

“…The MAD phasing methods have revolutionised the field of macromolecular crystallography. As predicted 20 years ago [50], the MAD techniques have now become a routine tool to solve the 'phase problem' in order to reveal the molecular arrangement in a large variety of proteins of great biological interest [51,52]. Since the early days, MAD methods have matured as a routine tool and can deliver rapid solutions for biological structures [49].…”