DESCRIPTION: A complete description of protein folding and stability remains as one of the most important questions in modern biochemistry. To realize the full potential of Dr. Scholtz's growing knowledge of genome information, he must come to an understanding of the rules for protein folding. This proposal addresses some very fundamental issues in protein stability and folding ranging from the role of electrostatic interactions in defining the folded and unfolded conformations of proteins to the role that interactions between networks of polar residues have on the rate of protein folding, the stability of the final folded structure and the mechanism of folding. Dr. Scholtz's basic approach is to make quantitative comparisons between different proteins or variants that alter a specific property. These comparisons encompass global structural and stability measurements to detailed atomic level descriptions of interactions to kinetic studies on the folding reactions. A complete molecular and quantitative description of the rules for protein folding will only be achieved through studies such as those presented here. This proposal addresses two major topics in protein folding and stability: 1) What are the roles of electrostatic interactions in defining the structure and stability of the folded and unfolded conformations of a protein, and 2) How do complex networks of interactions between polar groups govern the stability and folding of globular proteins? Dr. Scholtz will use a variety of different experimental techniques to explore the molecular forces responsible for protein stability, folding and structure. The strength of the program is the use of comparisons-comparisons between single-site variants of proteins, between proteins and model peptides and between the properties of a protein under different solution conditions. This broad-based comparative approach will allow the PI to reach a better understanding of the rules for protein folding, stability and structure and these rules will help answer these very basic questions in molecular medicine.