UM Biophysics Faculty | E Neil G Marsh

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E Neil G Marsh

Enzymes: structure, mechanism and specificity; protein engineering and molecular recognition

Neil Marsh

Associate Professor

Chemistry and Biological Chemistry

Ph.D., University of Cambridge

Dept: Chemistry

Office Address: 4537 Chemistry

Phone: (734) 763-6096

Email: nmarsh@umich.edu

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My laboratory focuses on two areas of chemical biology. In one area, we seek to understand the remarkable catalytic prowess of enzymes, in particular those that use free radicals in catalysis. Recently, we have also begun to explore the potential for developing novel biological catalysts and therapeutic agents offered by the de-novo design and synthesis of novel proteins incorporating highly fluorinated amino acids. Our research is inherently inter-disciplinary in nature and draws on a synergistic combination of bio-organic, bio-inorganic and bio-physical chemistry.

Our major interest is in enzymes that use free radicals (a carbon with an unpaired electron) to catalyze a variety of unusual reactions, many of which have no ready counterpart in organic chemistry. Normally, organic radicals are thought of as highly reactive species that are dangerous to biological systems. However, enzymes can profoundly alter the reactivity of free radicals so that a radical with a lifetime of microseconds in free solution may be stable for days when generated within a protein! Enzymes are therefore able to exploit free radicals as "sparks" with which to ignite reactions on otherwise un-reactive substrate molecules.

We are studying a class of enzymes that use the cobalt-containing organo-metallic coenzyme B₁₂ to generate free radicals. These enzymes provide excellent model systems with which to study free radical catalysis. We are using a variety of kinetic and spectroscopic techniques, together with site-specific mutagenesis to understand how the enzymes generate and control reactive organic radical species.

In a new area of research, we are exploring the interface between biological macromolecules and materials chemistry though the de-novo design of extensively fluorinated "Teflon" proteins. Perfluorocarbons exhibit unique and useful physical properties that are not found in nature. For example, Teflon derives its highly inert and non-stick properties from the perfluorinated polymer polytetrafluoroethylene. We are examining the effects of replacing "greasy" hydrophobic amino acids that are found in the interior of proteins with extensively fluorinated analogs to create a "Teflon" interior. We expect that such proteins may exhibit useful new properties such as increased thermal stability, resistance to unfolding in organic solvents, and resistance to degradation by proteases. Teflon proteins may also exhibit novel protein:protein interactions and provide model systems to test theories of protein folding.

Representative Publications

H.-Y. Lee, K.-H. Lee, H. Al Hashimi and E.N.G. Marsh (2006) “Modulating Protein Structure with Fluorous Amino Acids: Increased Stability and Native-like Structure Conferred on a 4-Helix Bundle Protein by Hexafluoroleucine” J. Am. Chem. Soc., 128, 337-343

A.J. Brooks, C.C. Fox, E.N.G. Marsh, M. Vlasie, R. Banerjee and T. C. Brunold (2005) “Electronic structure studies of the adenosylcobalamin cofactor in glutamate mutase” Biochemistry, 44, 15167-15181

R.J. Sension, A.D. Harris, A. Stickrath, A.G. Cole, C.C. Fox, and E.N.G. Marsh (2005) “Time-resolved measurements of the photolysis and recombination of adenosylcobalamin bound to glutamate mutase” J. Phys. Chem. B, 109, 18146-18152

C. Qiao and E.N.G. Marsh (2005) “Mechanism of benzylsuccinate synthase: stereochemistry of toluene addition to fumarate and maleate ” J. Am. Chem. Soc., 127, 8608-8609

M.-C. Cheng and E.N.G. Marsh (2005) “Isotope effects for the transfer of deuterium between glutamate and 5’-deoxyadensosine in adenosylcobalamin-dependent glutamate mutase ” Biochemistry, 44, 2686-2691

E.N.G. Marsh, A. Patwardhan and M.S. Huhta (2004) “S-adenosylmethionine radical enzymes” Bioorganic Chem, 32, 326-340

K.-H. Lee, M. Matzapetakis, S. Mitra, E.N.G. Marsh and V.L. Pecoraro (2004) “Control of metal coordination number through subtle sequence modifications of designed peptides” J. Am. Chem. Soc, 126, 9178-9179

M.S. Slutsky and E.N.G. Marsh (2004) “Contribution of cation-pi interactions to protein folding studies in a model coiled-coil peptide” Protein Science, 13: 2244-2251

L Xia, D.P. Ballou and E.N.G. Marsh (2004) “The role of Arg100 in the active site of adenosylcobalamin-dependent glutamate mutase” Biochemistry, 43 3238-3245

R.J. Sension, A.G. Cole, A.D. Harris, C.C. Fox, N. Woodbury, S. Lin, and E.N.G. Marsh (2004) “Photolysis and Recombination of Adenosylcobalamin Bound to Glutamate Mutase” J. Am. Chem. Soc, 126, 1598-1599

M.-C. Cheng and E.N.G. Marsh (2004) “Pre-steady state measurement of intrinsic secondary tritium isotope effects associated with the homolysis of adenosylcobalamin and the formation of 5’-deoxyadensosine in glutamate mutase ” Biochemistry, 43, 2155-2158

P. Madhavapeddi, D.P. Ballou and E.N.G. Marsh "Pre-Steady State Kinetic studies on the Gly171Gln Active Site Mutant of Adenosylcobalamin-dependent Glutamate Mutase" Biochemistry, 2002 41, 15802-15809

E.N.G. Marsh and W.F. DeGrado. "Non-covalent self assembly of a heterotetrameric diiron protein" Proc. Natl. Acad. Sci., 2002, 99, 5150-5154

E.N.G. Marsh and C. L. Drennan. "Adenosylcobalamin-dependent isomerases: new insights into structure and mechanism" Curr. Opin. Chem. Biol., 2001, 5, 499-505

E.N.G. Marsh. "Towards the non-stick egg: designing fluorous proteins" Chemistry and Biology, 2000, 7, R153-R157

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Biophysics Research Division University of Michigan 4028 Chemistry Building 930 North University Avenue Ann Arbor, MI 48109-1055 UMsitemaker	Phone: (734) 763-6722 Fax: (734) 764-3323 E-mail: biophysics@umich.edu Last Updated: 2/1/2006 © Copyright 2006 University of Michigan