Abstract

Protein engineering aims to provide insights into the interplay of forces that relate protein structure to stability and function. Genetic engineering techniques allow the identity of an amino acid residue within a protein to be altered, typically replacing one residue systematically with others that differ in only one functional aspect, such as size, charge, hydrogen-bonding capacity, etc. De novo design of proteins is being used to help understand the forces that stabilize specific protein structural motifs. Applications of de novo protein design to the construction of -helical bundles and all -sheet proteins are discussed. The power of mutagenic analysis for the identification of the structural determinants of biological function are illustrated through protein engineering studies of the proteolytic enzyme subtilisin, and of the G-protein-coupled -adrenergic receptor. Methods that allow for the replacement of an amino acid residue within a protein by unnatural amino acids are described.