α-Amylase Inhibition: Towards Therapies for Diabetes and Obesity
Through a long standing collaboration with Gary Brayer (UBC) and others we have developed a detailed structural and mechanistic understanding of the principal enzyme responsible for starch digestion in humans – the pancreatic α-amylase. Useful inhibitors for structural and mechanistic studies have been developed by design and synthesis. However, of greatest therapeutics interest has been our discovery of the plant natural product Montbretin A (MbA0 as a poten (Ki=8M) amylase inhibitor through screening of a library of 60,000 natural product extracts with our in-house robot. In conjunction with the UBC Centre for Drug Research & Development (CDRD), we have cultivated this plant, isolated large quantities of MbA and shown excellent efficacy in vivo. Further development is underway through a newly formed company. (Ran Zhang, Anjuman Begum, Shin Numao, Chris Tarling, Christina Tysoe, Anna Win-Mason, Xiahua Zhang)
Neuraminidase Inhibition: Influenza Therapeutics
While drugs such as Tamiflu are currently used to treat influenza, development of resistance is lessening their value. We have developed a new class of mechanism-inspired neuraminidase inhibitors, and have demonstrated both specificity and efficacy in vitro and in cell-based assays and in animals (Kim et al. Science 2013). This work has been done in conjunction with CDRD, the BC Centre for Disease Control, and Dr. Masahiro Niikura (Simon Fraser University). We are now working with CDRD Ventures Inc. to further develop it. In parallel we are developing new imaging tools and potential diagnostics for influenza infections. (Jin Hyo Kim, Tom Wennekes, Ricardo Resende, Stefan Weck, Zhizeng Gao)
Lysosomal Storage Diseases
Genetic diseases such as Tay Sachs, Gaucher and MPS-I are caused by mutations in lysosomal glycosidases that lower enzyme activity levels, resulting in harmful accumulation of glycolipids and glycosaminoglycans. Previous work focused upon kinetic, mechanistic and structural studies of many such enzymes. Current efforts are focusing upon therapies such as the chemical chaperones that we are developing for Tay Sachs and Gaucher’s Disease in conjunction with the Hospital for Sick Children in Toronto and Dr. Lorne Clarke at CFRI in Vancouver. Novel PET-imaging methodologies have also been developed. (Hongming Chen, Brian Rempel, Steve Reid, Tara Hill, Ethan Goddard-Borger, Andrés Gonzalez-Santana)
High-Throughput Methodologies
As founding members of the Centre for High-Throughput Biology (CHiBi) at UBC we are involved in several projects that involve use of high-throughput methodologies. Examples include: directed evolution of enzymes, universal blood.
Directed Evolution of Enzymes
It is now feasible to mimic the processes of natural selection in the laboratory to improve the performance of enzymes. This involves creating large (104 – 108) libraries of mutant genes encoding the enzymes of interest transforming these into a host (typically E. coli) and then screening for the activities of interest. Multiple iterative cycles result in improvements. We have focused upon development of new screens and have applied this to improvement of activities of
- Glycosidases for conversion of blood type (A+B to O)
- Glycosynthases and glycosyl transferases for efficient assembly of oligosaccharides and glycolipids
Towards Universal Blood
The antigens present on red blood cells that are responsible for the A +B antigenicity are simple sugars. Removal by selective glycosides converts the red blood cells to universal O-type blood. We are improving the activities of such enzymes by directed evolution, in collaboration with Dr. Jay Kizhakkedathu, and through the use of molecular crowders (Chapanian et al. Nature Commun. 2014). (Fathima Shaikh, David Kwan)