Timon Geib, Ph.D

Chemistry, Université du Québec à Montréal (UQAM)

Quantifying reactive metabolite modifications of target proteins by LC-MS

Abstract

Chemically reactive metabolites can be derived from oxidative stress or from drug administration. These electrophilic species can react with proteins and other macromolecules, affecting their biological function, and potentially resulting in toxic effects or tissue injury. Identifying these modified biomolecule targets is one important step in the complete understanding of related adverse effects and toxicity.

These types of analyses are often challenging due to low quantities of modified targets, a large variety of targets with different physicochemical properties in complex biological samples and technological hurdles. One effective technique for the analysis of reactive metabolite-modified proteins is liquid chromatography-tandem mass spectrometry (LC-MS/MS), which combines the separation of complex samples by LC, and comprehensive mass spectral analysis and structural elucidation by MS/MS.

The goal of this thesis was to develop and utilize different LC-MS/MS strategies to study the formation of reactive metabolites, their reactivity and the resulting covalent binding to proteins in different tissues, presumed to play an important role in adverse effects and toxicity. In order to yield the best results, sample preparation, data acquisition and data analysis were carefully optimized. The reactive metabolite formation of the drugs acetaminophen, clozapine and olanzapine was studied in liver microsomes. Then, covalent protein binding of their reactive metabolites to important glutathione S-transferase enzymes was investigated in vitro. In addition, acetaminophen-related liver toxicity was monitored in acute liver failure patients by quantifying the amount of circulating, modified human serum albumin. Furthermore, the endogenous reactive metabolite, 4-hydroxynonenal, was studied with regards to binding to histones and other proteins in cartilage of osteoarthritis patients.

Biosketch

Timon is a Senior Scientist in the R&D Proteomics group at CellCarta, specializing in using mass spectrometry to analyze proteins and peptides to support clinical trials. He manages and conducts method development, assay validation and deployment using LC-MS strategies.

Timon has a Ph.D. in Chemistry from the Université du Québec à Montréal (UQAM) in Mass Spectrometry. He completed the Bachelor’s and Master’s Program in Chemistry at the Saarland University in Saarbrucken, Germany.

Date
Date(s) - November 16, 2023
6:00 pm - 8:30 pm

Emplacement / Location
Université de Montréal - Campus MIL (Beer and pizza at 18h, conference at 19h in A-4502)