Overhauser Dynamic Nuclear Polarization for the Study of Hydration Dynamics, Explained.

摘要: Abstract We outline the physical properties of hydration water that are captured by Overhauser Dynamic Nuclear Polarization (ODNP) relaxometry and explore insights ODNP yields about surface this is coupled to. As relies on pairwise cross-relaxation between electron spin a probe proton nuclear water, it captures dynamics single-particle diffusion an ensemble molecules moving near probe. principally utilizes same physics as other magnetic resonance (NMR) (i.e., relaxation measurement) techniques. However, in ODNP, paramagnetic (EPR) excites spins probes their high net polarization acts signal amplifier. Furthermore, renders parameters highly sensitive to at rates commensurate with EPR frequency (typically 10 GHz). Also, selectively enhances NMR contributions within close proximity label. result, can capture ps–ns movements waters sensitivity locality, even samples protein concentrations dilute 10 µM. To date, utility technique has been demonstrated for two major applications: characterization spatial variation layer proteins or surfaces displaying topological diversity, identification structural emerging from disordered domains. The former shown correlate well predicted MD simulations capable evaluating hydrophilicity hydrophobicity surface. latter studies interhelical loop proteorhodopsin, partial structure α-synuclein embedded lipid membrane surface, incipient structures adopted tau en route fibrils, profile transmembrane peptide. This chapter focuses offering mechanistic understanding measurement molecular encoded parameters. In particular, clarifies how electron–nuclear dipolar coupling encodes information self-relaxation and, more importantly, rates. clarification underlying should assist establishing connection theory computer simulation will offer far richer interpretations results future studies.