Quantitative structure-function relationships of the single-point mutants of haloalkane dehalogenase: A multivariate approach

The applicability of multivariate statistical methods for the systematic analysis of results from the site-directed experiments was tested. Dehalogenation data obtained with 15 single-point mutants of haloalkane dehalogenase of Xanthobacter autotrophicus GJ10 has been related to various physico-chemical properties of substituted amino acids. A two component model which explains 84% of activity data was derived. The most influential properties, required on position 172 in haloalkane dehalogenase were: aromaticity, main-chain flexibility, refractivity and bulkiness, and were related mainly to the transition state/halide stabilization. The general usage of multivariate techniques for quantitative structure-function relationships (QSFR) and protein engineering studies can be recommended. Score and loading plots from Principal Component Analysis (PCA) of physico-chemical properties of amino acids can be used for planning and design of site-directed mutagenesis experiments, while the models obtained from Projection to Latent Structures (PLS) can provide predictions on the effect of the mutations on protein functionality prior to its testing.