Conformational Dynamics and Enzyme Catalysis

University Of California-San Diego, La Jolla CA

Investigators

Abstract

To facilitate chemical transformations, enzymes must possess sufficient flexibility to accommodate substrate and reaction intermediates while maintaining adequate structural rigidity. How enzymes perform this delicate balancing act is critical for a meaningful understanding of catalysis and recognition. This attribute is brilliantly expressed in the enzymes that catalyze protein phosphorylation in the cell, the protein kinases. These enzymes have been crystallized in many forms that differ by movements in the amino acid backbones comprising the essential three-dimensional structure. While it is believed that these motions are important for function, little is known about the nature and catalytic relevance of these conformational changes in solution. In this project, equilibrium- and pulsed- hydrogen deuterium exchange coupled with MALDI-TOF mass spectrometry will be used to understand the solution conformation of an essential protein kinase-cAMP-dependent protein kinase [PKA]. The goal is to determine what types of structural transitions occur when nucleotides, substrates and inhibitors bind to the enzyme. Once identified, the time frame for the structural transitions will be established and correlated with the catalytic mechanism for the enzyme. The long-range goal is to determine whether structural changes limit substrate phosphorylation and, if so, which regions of the enzyme are involved in these events.