ABSTRACT
The basic ideas and techniques of MR originated in the early days of protein crystallography, from the interest in exploiting the so-called noncrystallographic symmetry (NCS) that occurs fairly often in protein crystals (1). Nowadays, the purpose of MR methods is different: It usually involves relating a search model, derived from a known crystal structure, to the molecule (or molecules) in an unknown crystal. When an appropriate search model is available, MR can directly provide the structure solution without the need for tedious preparations of heavy-atom or selenomethionine derivatives. The MR methods can thus be expected to play a central role in this new era of protein crystallography, when the number of known macromolecular structures will increase dramatically, fueled by structure-based biopharmaceutical discovery and ongoing structural genomics initiatives.
