Structure determination is a procedure by which the three-dimensional atomic coordinates of a molecule or biomolecule are solved using an analytical technique. Many techniques are used in structure determination, most commonly X-ray crystallography, NMR spectroscopy, electron microscopy and molecular modelling.Structure determination of biological macromolecules using x-ray crystallography has been greatly improved in recent years through the development of a number of key technologies and better integration with sample preparation steps. This has enabled the crystallization of large numbers of proteins, including integral membrane proteins.