Advances in site-directed mutagenesis and other genetic engineering
techniques have made it possible to create novel proteins of interest. A
challenging aspect of these studies is to understand the effect of
substitution mutations on folding and stability of natural proteins. We
present an analysis of protein structure data, available from the
literature, for which substitution mutations have been made and changes in
stability characteristics are reported. Amino acid structural environment
parameters have been computed for a set of 304 non- homologous best
resolved protein structures. The structural environment parameters were
used to calculate each of the 20 amino acid propensities to a given
structural environment. The observed increase or decrease in stability upon
mutation was found to be correlated with the average residue structural
environment propensity of wild-type residue versus mutant residue. The
analysis presented here helps identification of less optimally placed
residues in a given protein structure, and suggests possible substitution
mutations to a residue with higher propensity to the corresponding local
structural environment. We propose that such substitution mutations,
suggested based on amino acid propensities to local structural
environments, should bestow higher stability to the protein structure.
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