FlgJ belongs to Carbohydrate Active enZyme (CAZy) family GH73 and facilitates passage of the bacterial flagellum through the peptidoglycan (PG) layer by cleaving the glycosidic bonds within glycan strands of PG. In this thesis I present the structure of the GH73 enzyme FlgJ from bacterial pathogenSalmonella typhimurium (St FlgJ). The St FlgJ active site was found to be blocked by the C-terminus of a neighbouring symmetry mate. To investigate if the C-terminus of FlgJ inhibits enzymatic activity similarly to the N-terminus of GH73 enzyme Auto, the glycolytic activity of St FlgJ was measured with and without its C-terminus. The assays revealed St FlgJ activity to be unaffected by the presence of the C-terminal sequence. Removal of the C-terminus did, however, allow a crystal structure of the domain to be obtained where a β-hairpin known to accommodate critical catalytic residues was found capable of opening widely, which likely aids in substrate capture and turnover. / February 2016

X-ray diffraction has been used to investigate the structure and structural behaviour of several inorganic solids under variable pressure and temperature conditions. A brief description of the diamond anvil cell (d.a.c.) and its applications to the high- pressure investigations is given. A spectroscopic system built for pressure calibration is discussed, plus an account of powder diffraction data analysis including a detailed description of a software package engineered for the specific reduction of powder data obtained under variable pressure. Potassium nitrate (KNO3) has seven polymorphs in the pressure range 0.0-4.0 GPa. This material has been studied with energy dispersive powder diffraction (EDXRD) to 9.3 GPa. The structure of the non-ambient phase IV refined by neutron diffraction at 0.36 GPa has been confirmed, the compressibility of the high-pressure phase measured and found to be anisotropic with axial compression ratios a:b:c = 1.0:0.64:0.50. The valence induced structural transition at 0.8 GPa in EuPd2Si2 has been studied using EDXRD and uni-axial compressibilities calculated. A basic explanation of the electronic theory which accompanies the subtle shortening of the a lattice parameter in the tetragonal asymmetric unit is also given. The structures of two compounds CH3HgX (X = I, Cl) have been investigated using single crystal and angle-dispersive powder techniques respectively. The crystal structure of methyl mercuric iodide is reported. CH3HgCl has been observed above and below the temperature induced I/II phase boundary at 162.5 K. A hypothesis detailing the iso-structural nature of CH3HgCl low temperature phase II and the ambient phase I of the analogous methyl mercuric bromide is also tested.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.