Kirsten Wolthers

Associate Professor

Biochemistry and Molecular Biology, Chemistry
Office: SCI 377
Phone: 250.807.8663
Email: kirsten.wolthers@ubc.ca

Graduate student supervisor



Research Summary

Enzyme guided radical-chemistry; use of fast reaction and spectroscopic methods to probe the interplay between protein dynamics, function and structure; rationale-design of biocatalysts; study of vitamin-derived cofactors by biological systems.

Courses & Teaching

Enzymology; biochemistry.

Degrees

PhD, Oregon State University
BSc, University of British Columbia

Research Interests & Projects

Enzymes are large macromolecules that serve as biological catalysts for an immense number of biochemical reactions. Given that enzymes catalyze reactions with a high level of stereo- and regio-specificity under mild conditions, they can serve as valuable tools for the synthesis of new drugs and other high commodity chemicals. Knowledge of enzyme structure and function can also lead to the treatment of diseases including bacterial infections, cancer and metabolic disorders. My research group is interested in unravelling the complexities of enzymatic reactions, as this knowledge can lead to advances in biotechnology and human health.

Current Projects

Bioengineering of Flavin-Dependent Monooxygenases

BioengineeringOur research group investigates acetone monooxygenase (ACMO), which preferentially catalyzes the Baeyer-Villiger oxidation of small (a)cyclic ketones to esters or lactones using molecular oxygen and reducing equivalents from NADPH.

We are specifically interested in structural features that control substrate specificity and the stability of key catalytic intermediates in ACMO and related flavin-dependent monooxygenases.

Bifunctional Ornithine Decarboxylase/Arginase

Fusobacterium nucleatum is a Gram-negative bacterium that is ubiquitous to the oral cavity. Recent research has shown that this bacterium is an opportunistic pathogen that is implicated in preterm births, colorectal cancer and periodontal disease. The organism encodes a novel bifunctional enzyme that fuses the activities of arginase and ornithine decarboxylase. The unique properties of this enzyme make it a potential therapeutic drug target to treat F. nucleatuminfections. We are currently in the early stages of characterizing this novel enzyme.

Bifunctional

Radical-Mediated Enzymology

RadicalOnce thought to be a rarity, free-radical chemistry is becoming a more mainstream event in enzyme catalysis. Radicals are highly reactive species that enable the enzyme to perform difficult reactions with high activation energy barriers (e.g. cleavage of C-C, C-N and C-H bonds on chemically inert substrates).

We study radical chemistry mediated by coenzyme B12- and PLP-dependent aminomutases. In particular, we investigate how the protein, in concert with the two cofactors, initiates and controls radical chemistry with high fidelity.

Research Infrastructure

Our research infrastructure supports large-scale isolation (mg quantities) of recombinant enzymes. We also have instrumentation for studying fast reactions using spectroscopic techniques.

Protein Expression and Purification Facility

Facilities 1To produce large quantities of protein, we have two temperature controlled growth shakers that have the capacity to grow 12 L of bacterial culture each.

A super speed and ultracentrifuge with five rotors (JA10, JA 25.50, Type 50.2 Ti, Type 90 Ti and SW 32.1 swinging bucket rotor) can be used to fractionate cellular debris or isolate small particulates. A sonicator and incubator are also part of this facility.

An AKTA FLPC (situated in a cold cabinet) is employed for protein purification. A number of ion exchange, affinity and gel filtration columns are compatible with the FLPC.

Facilities 2

Fast Reaction and Spectroscopic Techniques

Our group has three UV-visible spectrophotometers (Lambda 25, Lambda 265 and Lambda 365), with one placed in an anaerobically-maintained glove box for O2-sensitive reactions. In addition, we have a TgK Scientific dual mixing stopped-flow that is capable of single and multi-wavelength detection. The stopped-flow also comes with a quench-flow accessory (for isolation and analytical analysis of intermediates) and an automatic shutter to minimize photobleaching. Both fluorescence and absorbance detection options are available. The sample-handling unit is housed in a clear acrylic glovebox from Belle Technology.

Facilities 4

 

Selected Publications & Presentations

Google Scholar

 

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