Grant: Research Tools and Instruments - Category 1 (<$150,000)

The functional status of proteins is critically dependent on their structure and most proteins go through a series of structural changes in the course of their functional cycle. Protein characterization involves being able to correlate the protein of interest's structural status and its functional state. Circular dichroism spectroscopy provides a powerful and relatively simple tool to assess a protein for its folded state and whether or not it has undergone a structural change upon ligand binding, enzyme turnover, or interaction with a protein binding partner.     Circular dichroism (i.e., CD) spectroscopy measures the inherent optical activity of any molecular center that absorbs light (i.e., chromophore) and has some inherent structural asymmetry. Protein molecules possess chromophores across the UV-visible spectrum. In the short ultraviolet the peptide linkage itself absorbs light, in the near UV aromatic residues such as tryptophan absorb light and there are prosthetic groups such as heme centers that absorb light in the visible and near infrared regions. Each of these chromophores may give rise to CD, and the nature of the signal is sensitive to the environment in which the chromophore resides. For example, the CD signal of a peptide bond is modified when it is in a secondary structure such as an a-helix and it is different when in a ß-sheet, or if the protein is unstructured. CD will be used to distinguish different conformational states of proteins of interest to our research groups. Understanding the evolution of a protein's structure over its functional cycle is a critical component to being able to predict, control and regulate a protein's activity.       The equipment requested here will provide an opportunity for the research personnel in our laboratories (students, technicians and post-doctoral fellows) to gain valuable training with one of the most widely used approaches in modern protein structure studies. Improving the training of young Canadians researchers in these areas is an important element in the development of our fundamental science and technology base.