Determination of reaction mechanisms and macromolecular interactions using NMR with dissolution dynamic nuclear polarization

Seminar series
Physical Chemistry Seminar
When
Mon, Oct 2 4:00pm
Where
Young Hall 2033
Speaker Professor Christian Hilty
Texas A&M University
Chemistry
Description

Determination of reaction mechanisms and macromolecular interactions using NMR with dissolution dynamic nuclear polarization

Abstract: Nuclear spin hyperpolarization, achieved through dissolution dynamic nuclear polarization (D-DNP), enhances the sensitivity of NMR by several orders of magnitude. These signal enhancements enable the characterization of on-going chemical processes on the second to subsecond time scale, without signal averaging. Here, we describe the application of D-DNP for the characterization of both reactions and interactions involving macromolecules. First, we discuss the use of this method to characterize polymerization reactions carried out in-situ in the NMR spectrometer using hyperpolarized monomers. We illustrate the determination of kinetic mechanisms involving catalyst activation or deactivaton, from spectra measured of olefin polymerization catalyzed by metallocenes, as well as ring opening metathesis polymerization reactions using Grubbs catalysts. Second, hyperpolarization transfer through the nuclear Overhauser effect (NOE) can report sensitively on intermolecular interactions. We exploit this property to measure binding affinities, such as between a ligand and a protein. By comparing signals from hyperpolarized source and macromolecular target spins to simulations based on spin relaxation, structural information on the binding epitope can further be deduced. This is shown here for the complex of 1H hyperpolarized folic acid with the target protein dihydrofolate reductase. Using real-time NMR measurements of hyperpolarized samples, structural constraints can be obtained also of transient complexes. The source of these constraints is not limited solely to the NOE, but can include other NMR measurable paramters. In a reaction catalyzed by a paramagnetic form of the metalloenzyme pseudouridine monophosphate glycosidase, distance information is available from modeling the paramagnetic effect on the hyperpolarized nuclear spins.

Attachments