Popular products by category
Rigaku nano3DX is a true X-ray microscope (XRM) with ultra-wide field of view, 25X larger volume than comparable systems, and three X-ray wavelengths for different matrices.Read more...
HyPix-3000 is a next-generation two-dimensional hybrid pixel array semiconductor detector designed specifically to meet the needs of the home lab diffractionist.Read more...
Analytical solutions by industry
New papers of interest
Special Feature: Pharmaceutical Analysis (5): Analysis of trace impurities in pharmaceutical products using polarized EDXRF spectrometer NEX CG.Read more...
Phasing protein structures
Solve the phasing problem at home with Cr-radiation
The single-wavelength anomalous dispersion method (SAD) is frequently used to solve protein structures from synchrotron data by taking advantage of the tunable wavelength to collect heavy atom derivatives near the metal's absorption edge. For methionine-containing proteins, selenomethionine derivates may be prepared to take advantage of the anomalous Se signal.
However, some proteins will not crystallize as SeMet derivatives, and not all proteins contain methionine. Sulfur, on the other hand, is present in almost all proteins in cysteine residues. The process of structure solution is greatly simplified if SeMet substitution or heavy-atom soaks are not necessary.
The structure of crambin was solved in 1981 using the resolved atom S-SAD method and Cu Kα radiation and a number of other proteins have been solved using Cu or synchrotron radiation tuned to near-Cu wavelengths.
Chromium phasing macromolecular X-ray crystallography system