Faculty

Our laboratory is interested in enzymology and protein design.  Our research is inherently inter-disciplinary in nature and draws on a synergistic combination of bio-organic, bio-inorganic and bio-physical chemistry.  We are fortunate to enjoy various productive collaborations with other research groups at Michigan. 

Our interest in protein design led us to explore the properties of novel ‘Teflon-like’ proteins that incorporate highly fluorinated amino acids within their hydrophobic cores.  We have designed a series of model proteins that contain the fluorinated amino acid hexafluoroleucine to examine how fluorination can be used to modulate the physical and biological properties of proteins.  We found that fluorinated proteins exhibit remarkable stability that allows them to resist unfolding by heat and organic solvents and degradation by proteases.  We are applying these design principles to the development of fluorinated antimicrobial peptides, short peptides that kill bacteria by selectively disrupting their membranes.  We aim to design fluorous antimicrobial peptides that will have enhanced selectivity for bacterial membranes and better resist degradation by proteases.  We are also developing methods to follow the fate of peptides in vivo using fluorine NMR as a probe.

We are currently studying three enzymes that catalyze unusual and chemically difficult reactions that involve metal cofactors and/or reactive free radical intermediates.  Benzylsuccinate synthase is a free radical-containing enzyme that catalyzes the first step in the metabolism of toluene – anaerobic bacteria that contain this enzyme can live on toluene as their sole carbon source!  Glutamate mutase catalyzes an unusual carbon skeleton rearrangement involved in glutamate fermentation; it uses coenzyme B12, a cobalt-containing organo-metallic complex, to generate reactive free radicals that initiate the reaction mechanism.  Lastly, we have begun to study aldehyde decarbonylase, an enzyme that catalyzes the conversion of long-chain aldehydes to alkanes and carbon monoxide, which is involved in hydrocarbon biosynthesis in plants and algae. 

Increasingly, our attention is focused on enzymes involved in hydrocarbon metabolism as these may prove useful for the synthesis of new biofuels and bioremediation of hydrocarbon-contaminated soils.  Our primary goal is to understand how these enzymes generate and control chemically reactive intermediates to catalyze their reactions; we then aim to apply what we learn to engineer new pathways for hydrocarbon metabolism.

Awards

Research Fellow of the Royal Society
Fellow of the Royal Society of Chemistry
Sc.D., University of Cambridge

Representative Publications

1. Lei, L., Patterson, D.P., Fox, C.C., Lin, B., Coschigano, P.W., and Marsh, E.N.G., "Subunit Structure of Benzylsuccinate Synthase", Biochemistry, 2009, 48, 1284-1292. [Full Article]

2. Gottler, L.M., se la Salud-Bea, R., Shelburne, C.E., Ramamoorthy, A., and Marsh, E.N.G., "Using Fluorous Amino Acids to Probe the Effects of Changing Hydrophobicity on the Physical and Biological Properties of the β-Hairpin Antimicrobial Peptide Protegrin-1", Biochemistry 2008, 47, 9243-9250. [Full Article]

3. Gottler, L.M., de la Salud-Bea, R., and Marsh, E.N.G., "The Fluorous Effect in Proteins: Properties of α₄F₆, a 4-α-Helix Bundle Protein with a Fluorocarbon Core", Biochemistry, 2008, 47, 4484-4490. [Full Article]

4. Gottler, L.M., Lee, H.-Y, Shelburne, C.E., Ramamoorthy, A., and Marsh, E.N.G., "Enhancing the biological activity of an antimicrobial peptide using fluorous amino acids", ChemBioChem, 2008, 9, 370-373. [Full Article]

5. Yoon, M., Kalli, A., Lee, H.-Y, Hakansson, K., and Marsh, E.N.G. "Intrinsic deuterium kinetic isotope effects in glutamate mutase measured by an intramolecular competition experiment", Angew. Chem., 2007, 46, 8455-8459. [Full Article]

6. Cheng, M.C. and Marsh, E.N.G. "Evidence for coupled motion and hydrogen tunneling the reaction catalyzed by glutamase mutase", Biochem., 2007, 46, 883-888. [Full Article]

7. Li, L. and Marsh, E.N.G. "Mechanism of benzylsuccinate synthase probed by substrate exchange", J. Am. Chem. Soc., 2006, 128, 16056-16058. [Full Article]