Protein crystallography is a technique that allows the determination of the 3-dimensional structures of biological macromolecules. Knowledge of the atomic structure of macromolecules such as enzymes, DNA binding proteins, t-RNAs and viruses is leading to a better understanding of the chemical reactions which take place in living organisms, how proteins are produced and how genetic information is forwarded. It is also helping to provide a basis for drug and vaccine design.
It is of course limited in that only macromolecules which crystallise can be studied. NMR spectroscopy has provided the structures of smaller proteins from samples in solution but crystallographic methods are still by far the most successful and widely used means of determining atomic structure.
This introductory chapter will give a brief overview of protein structure and the methods that have been developed to date to carry out structure solution. Particular attention will be paid to the method of Multiple wavelength Anomalous Dispersion (MAD) which is the main topic of this thesis.