This project is in the Chemistry of Life Processes Initiative (COLP) and supported jointly by Chemistry and Biophysics. Fundamental studies of protein structure-function relationships will be carried out. Iso-cytochrome c from yeast is used to study how amino acid replacements and deletions affect key parameters such as electron transfer rates, binding strength, specificity to protein partners of cytochrome c, and protein stability. Detailed intracellelar measurements will be made for comparison with the in vitro work, using growth in lactate medium as a measure of relative specific activity. Specific mutations have been generated for each of the studies. Along with the experimental work, a variety of theoretical approaches are being developed to aid in the design and interpretation of experiments. This project is a continuation of that previously supported under the COLP Initiative.