Structure and Mechanism of Hyoscyamine-6ß-Hydroxylase (H6H), an Enzyme that converts (-)-Atropine to Scopolamine: Prospects for Aerobic Epoxidation of Non-Activated Alkane Chains

• Applicant: Dr. Conrad Fischer
• Subject Area: Biochemistry ; Organic Molecular Chemistry - Synthesis and Characterisation
• Term: from 2014 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 257311736

The overall goal of this project is to determine the structure and mechanism of hyoscyamine-6ß-hydroxylase (H6H) and to do site specific mutations to expand its substrate specificity. The ultimate objective is to form new enzymes that can either make altered scopolamine analogs from accessible tropane derivatives or oxidize a variety of cyclic alkanes to corresponding useful expoxides. In preliminary work, the Vederas laboratory at the University of Alberta has already cloned H6H from Atropa belladonna (deadly nightshade) optimized for expression in E. coli, purified and characterized the enzyme. Their published work shows that this particular enzyme oxidized (-)-atropine (L-hyoscyamine) to 6ß-hydroxyhyoscyamine rapidly, but that the second step, namely closure to the epoxide (scopolamine) with retention of the new hydroxyl oxygen, is slow. Three additional corresponding enzymes with different but homologous sequences from scopolamine-producing plants such as Anisodus acutangulus and Hyoscyamus niger (henbane) have also been cloned and expressed. A collaboration has been established by the Vederas group with Prof. Christopher J. Schofield of the Chemistry Department at Oxford University to assist in crystallographic studies of these enzymes.

• DFG Programme: Research Fellowships
• International Connection: Canada
• Host: Professor John Christopher Vederas, Ph.D.