Structure of proteins with single-site mutations: a minimum perturbation approach.

A large number of mutant proteins with single amino acid substitutions are now being produced. The ability to predict the structural changes expected from such mutations would aid greatly in the efficient utilization of the mutagenic techniques and in the interpretation of the changes in stability and function that result. A minimum perturbation approach is suggested as a first step in such structural predictions and is tested by application to a recently isolated variant of the hemagglutinin glycoprotein. The agreement between the predicted structure and that inferred from the x-ray refinement is encouraging and provides support for the proposed modeling procedure.