University of Sydney - July 1994
The X-ray crystallography laboratory at the University of Sydney traces its beginnings to the School of Chemistry in the 1950's when Hans Freeman was still a graduate student. His own research work has maintained a consistent theme, focussing on the structural characterisation of biologically interesting molecules.
Most stages of the crystallographic technology have been represented in the Sydney laboratory in the last forty years. Generators have evolved from early low-power continuously evacuated models, through standard sealed tube generators to the direct drive rotating anode generators currently in use. Intensities were first measured by visual comparison on films. A Weissenberg geometry diffractometer was constructed from a commercially available mix of components in the 1960's. It has since been replaced by several standard four circle instruments. Computing facilities represent the most obvious improvement in technology. Hans Freeman was a pioneer in the use of computers with several publications in the 1950's describing the use of SILIAC one of Australia's first computers to calculate Fourier summations. The Sydney crystallographers were users over a period of time of mainframe computers at the Department of Defence in South Australia, the Atomic Energy Commission at Lucas Heights and the CSIRO in Canberra. Access to these machines involved decks of cards and the precursor of Australia Post. The Silicon Graphics workstations in use today perform least-squares refinement cycles in very nearly real time. Most importantly this revolution in technology has been matched by the complexity of structural problems being studied. The first structures of copper peptide complexes (some twenty or thirty non-hydrogen atoms) were sufficiently large in their day to comprise an entire PhD thesis project. The copper protein plastocyanin whose structure was solved in 1977 contained 929 non-hydrogen atoms in the asymmetric unit. Protein structures currently in progress have up to 130 KDa, 1400 amino acid residues or 7000 non-hydrogen atoms in the asymmetric unit.
In 1994 there are two X-ray crystallography laboratories at the University of Sydney. Hans Freeman and Trevor Hambley remain in the School of Chemistry and Mitchell Guss has established a new laboratory in the Department of Biochemistry. The Chemistry groups continue research into metal complexes of biological ligands. There is a common interest in metal amino-acid and metal peptide complexes. Trevor Hambley uses both crystallography and molecular mechanics modelling to study platinum complexes bound to DNA and DNA fragments, and carries crystal structure analyses as contributions to a number of drug design projects. In addition Trevor Hambley supervises a structure determination facility which carries out more than 100 structure analyses per year for research groups in many departments throughout the University.
The new laboratory in the Department of Biochemistry is concerned entirely with protein structures. A collaboration with Professor Graeme Cox of the John Curtin School of Medical Research at the Australian National University has yielded crystals of several of the subunits of Escherichia coli adenosine triphosphatase (ATPase). A group under the direction of Professor John Hopwood at the Women's and Children's Hospital in Adelaide works on genetic diseases which result in excess storage of polysaccharides in lysosomes. One of these enzymes is being produced in large quantities by recombinant technology with the aim of its use in enzyme replacement therapy. We have crystallised this enzyme, N-acetyl-galactosamine-4-sulfatase. The work on metalloproteins continues in collaboration with Hans Freeman, with the present emphasis being placed on a class of copper-containing amine oxidases. We have crystallised the protein isolated from pea plants and several crystallographic forms of the equivalent protein from a bacterium, Arthrobacter globoformis.
The equipment available in the two laboratories includes: in Chemistry, a Rigaku AFC-7 diffractometer on a Rigaku RU-200 rotating anode generator, and an Enraf-Nonius CAD-4 diffractometer on a sealed tube generator; in Biochemistry, a Rigaku R-Axis IIc imaging plate detector system, with mirror optics on a Rigaku RU-200 rotating anode generator and a second RU-200 with precession and oscillation cameras. Both laboratories are equipped with Silicon Graphics computing and graphics facilities for use in small molecule and macromolecule structure analysis and refinement. The small molecule crystal structure analyses are carried out using the teXsan system. SHELX-76 and the Enraf-Nonius MOLEN system are also available. The software for protein structure analysis includes: DENZO for data reduction, PROTEIN and CCP4 for standard crystallographic calculations, PROLSQ for restrained refinement and X-PLOR for refinement with simulated annealing.
Staff, in addition to the academics already mentioned, include Research Associates Dr Peter Turner and Dr Vinay Kumar, Research Assistants Vilma Zubak and Michael Costello and eight research students.