Using NMR spectroscopy to elucidate the role of molecular motions in enzyme function

- NMR methods for characterizing ps-ns and μs-ms motions are reviewed.
- Applications of these methods to Ribonuclease A (RNase A) is reviewed with emphasis on the role of motions in product release.
- Mechanism of motions in catalytic cycle of RNase A is covered.
- Application of NMR methods to study active site loop dynamics in two protein tyrosine phosphatases is reviewed.

Conformational motions play an essential role in enzyme function, often facilitating the formation of enzyme-substrate complexes and/or product release. Although considerable debate remains regarding the role of molecular motions in the conversion of enzymatic substrates to products, numerous examples have found motions to be crucial for optimization of enzyme scaffolds, effective substrate binding, and product dissociation. Conformational fluctuations are often rate-limiting to enzyme catalysis, primarily through product release, with the chemical reaction occurring much more quickly. As a result, the direct involvement of motions at various stages along the enzyme reaction coordinate remains largely unknown and untested. In the following review, we describe the use of solution NMR techniques designed to probe various timescales of molecular motions and detail examples in which motions play a role in propagating catalytic effects from the active site and directly participate in essential aspects of enzyme function.

246