Powder Diffraction Methods for Membrane Protein Structure Determination

Membrane proteins comprise a large proportion of all the proteins coded by human and other eukaryotic genomes, and are the targets of more than one-half of all the pharmaceutical drugs marketed today. Knowledge of their three-dimensional structure is important for understanding how they function, and for the development of new drugs for the treatment of diseases. Protein X-ray crystallographic studies, which require well-ordered, large single crystals of the protein, provide such structural information. However, one of the major obstacles to membrane protein structure determinations currently is the ability to produce crystals of a size and quality suitable for single crystal studies. Although often many much smaller crystals can be produced, there has yet to be a method developed to utilise these for the determination of the structure of membrane proteins. The aim of this project is to develop both the methodology and tools necessary to determine the structure of membrane proteins based on samples not of single crystals, but of bunches of very small (microcrystals) using powder diffraction techniques.

Membrane proteins comprise roughly one third of all the proteins coded by eukaryotic genomes, and are the targets of more than one-half of all currently marketed pharmaceuticals, although there is a relative dearth of crystal structures of this important class of proteins. A major obstacle to crystal structure determination is the ability to produce three-dimensional crystals of a size and quality suitable for single crystal structure determinations. Often, however, it is possible to produce showers of microcrystals which are not suitable for single crystals studies, and which resistant attempts to improve their size.
The aim of this project is the development of a method and associated tools for membrane protein structure determination based on powder diffraction of three-dimensional microcrystals.

Membrane proteins comprise roughly one third of all the proteins coded by eukaryotic genomes, and are the targets of more than one-half of all currently marketed pharmaceuticals. However, the number of crystal structures that have been determined for membrane proteins greatly lags behind the number of structures that have been determined for soluble proteins. One of the major obstacles to structure determination is the ability to produce crystals of a size and quality suitable for single crystal determinations. Often, however, it is possible to produce showers of microcrystals, which are not suitable for single crystals studies, and which resistant attempts to improve their size. The development of a method for structure determination that could enable the use of powder diffraction on microcrystals would provide a significant benefit for both academic and industrial labs. Both the methodologies developed and the structures produced would be of particular value in pharmaceutical, insecticide, and food industries.