Nucleotídeos contendo Selênio
The most simple method currently used for solution of the macromolecular phase problem, single wavelength anomalous dispersion (SAD), still involves the incorporation of heavy atoms into protein crystals. After crystallization, finding such derivatives is the second major bottleneck in the determination of the 3D structure of bio-macromolecules.
Most labeling procedures focus on the protein itself in a "trial and error" fashion.
Selenium-containing nucleotides provide an alternative method that allows rational incorporation of the heavy atom into a large number of physiologically relevant ATP-binding enzymes like kinases, motor proteins and chaperones. Selenium derivative crystals are well suitable for SAD and MAD experiments. Please note that it is recommended one selenium atom per 50 amino acids for weakly diffraction crystals.