Master of Research
School of Chemistry and Molecular Bioscience
Cyclotransferases are a family of lyase enzymes present among a wide range of organisms both eukaryotic and prokaryotic. These enzymes catalyze the production of pyroglutamic acid (5-oxoproline) from differing γ-glutamyl-containing compounds. Enzymes that have cyclotransferase activity and fold have been shown to play a role in a variety of diseases including glutathione synthase deficiency, cancer and neurological diseases and have a potential use as biomarkers. Reviewing the current literature on this group of enzymes identifies a major gap in the substrate binding specificities of these proteins. This thesis aims to unravel some of these binding specificities by X-ray crystallography, bioinformatics and molecular docking of the enzymes; γ-glutamyl-amine-cyclotransferase (GGACT), γ-glutamylcyclotransferase (GGCT) and glutathione specific γ-glutamylcyclotransferase (ChaC1).
In this project, the cyclotransferase enzyme GGACT was used to reveal the structure of the protein-substrate complex. The catalytically inactive GGACT Glu82Gln mutant was co-crystalized in complex with its substrate γ-glutamyl-ε-lysine and X-ray diffraction data was collected, and the structure determined. A 1.2 Å resolution structure revealed the substrate γ-glutamyl-ε-lysine bound in the active site of GGACT at partial occupancy. The ligand is observed to be held in a cramped conformation by GGACT for catalysis.
El-Akruti, Eanwa, Structure and Functional Investigation of Cyclotransferases, Master of Research thesis, School of Chemistry and Molecular Bioscience, University of Wollongong, 2022. https://ro.uow.edu.au/theses1/1742
FoR codes (2008)
0601 BIOCHEMISTRY AND CELL BIOLOGY, 0605 MICROBIOLOGY, 0304 MEDICINAL AND BIOMOLECULAR CHEMISTRY
Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.