The application of protein structure determination by X-ray crystallography coupled to molecular biology and biochemistry to probe biological mechanisms and to target specific disease pathways. We have ongoing research in 1) signal transduction 2) physical basis of protein carbohydrate interactions 3) pathogenic bacteria glycan assembly, we have cloned and crystallised a number of the enzymes involved in key steps of glycan synthesis in pathogenic bacteria. 4) viral replication, we are purifying and crystallising a heterodimer crucial to replication of viruses in vivo, 5) the biosynthesis of unusual natural products.