Circular Dichroism Measurements at Millisecond Time-Resolution; Stopped-Flow CD and Temperature-Jump CD Systems

Abstract

Circular Dichroism is an optical parameter uniquely sensitive to molecular conformation which finds widespread use in structural studies in many branches of chemistry. It is determined by the optical configuration at asymmetric centres, and in macromolecular systems by the overall conformation which derives from the stereospecific linkage together of asymmetric units such as peptides, nucleotides and carbohydrates. In biochemical systems, biological activity is generally dependent upon a specific conformation and modulation of this structure (for example by a conformational change in an enzyme following the binding of a substrate or coenzyme as ligand) is thought to play a central role in control of the conformational process. This provides a model for the regulation of biological function such as activation or inhibition of catalytic activity. Conformational effects are also thought to be involved in the sequential binding and release of reactants and products in ordered processes such as a dehydrogenase reaction.