Experiment 3: Molecular Replacement of lysozyme

In this experiment, the structure of monoclinic hen-egg white lysozyme (HEWL) will be determined by Molecular Replacement (MR) using the structure of tetragonal HEWL as search model. MR is a method to determine a structure in cases where a similar structure is already known. If the similar structure can be correctly oriented and positioned in the unit cell of the structure to be solved, it can be used as a starting point for phase calculation and refinement. Currently about two thirds of all new structures deposited with the Protein Data Bank (PDB) are solved using MR.