................................................................................................................................. 2 Abbreviations ........................................................................................................................ 3 Chapter One: Introduction ..................................................................................................... 6 1.1 Allostery ..............................................................................................................................................................6 1.2 Lysine biosynthesis pathway ......................................................................................................................7 1.3 DHDPS .............................................................................................................................................................. 10 1.3.1 Background ............................................................................................................................................. 10 1.3.2 Structure of DHDPS ............................................................................................................................ 10 1.3.2.1 The catalytic site ........................................................................................................... 11 1.3.2.2 The Allosteric site ........................................................................................................ 12 1.3.2.3 The A,B/C,D interfaces .............................................................................................. 12 1.3.2.4 The A,D/B,C interfaces .............................................................................................. 13 1.3.3 DHDPS-catalysed reaction ................................................................................................................ 13 1.3.4 DHDPS is allosterically inhibited by lysine ................................................................................. 14 1.4 Motivation for this research .................................................................................................................... 15 1.5 Aims and hypothesis ................................................................................................................................... 17 1.6 References ........................................................................................................................................................ 17 Chapter Two: Molecular Biology and Protein Purification................................................. 23 2.