Funds have been provided for the purchase of a high performance static spectrofluorometer for shared use by a group of investigators. The instrument will be used for four different projects involving proteins, each of which utilizes fluorescence as a technique. Fluorescence intensity measurements will be used as a means of monitoring such processes as protein-protein and protein-nucleic acid interactions, ligand-induced conformational changes, and accessibility of fluorophors to quencher. Measurements of fluorescence anisotropy will also be used to study protein associations and conformational changes. Fluorescence energy transfer will be employed as a "spectroscopic ruler" to measure the separation of sites on a protein. Studies of the above kinds require an instrument with high sensitivity and stability, low background, and capability of providing corrected spectra. The individual projects are concerned with the properties and interactions of the Ca2+-binding regulatory proteins calmodulin and troponin C, the nature of the catalytic site of papain, the characteristics of nucleic acid-unwinding proteins, and the properties of the topoismerase enzymes which mediate alterations in the geometry of DNA. A central goal of molecular biology is to elucidate the structure of specific molecules and determine how their chemical characteristics influence their activity. One approach is fluorescence spectroscopy, which provides data about molecular subgroups and molecule-molecule interactions. This kind of information explains biological processes at their most basic level.
