Structural conservation in globular proteins.

Some well sequenced classes of homologous proteins have been analysed in the light of their representative tertiary structures to reveal the nature of structural conservation during protein evolution. Within 'the sphere of influence' around conserved residue sites preferential association of other conservative sites has been observed to be a feature of natural selection valid for all residue types. An information theory approach evolved to examine residue variability reveals that even some non-conservative sites scaffold clusters of high biochemical specificity and intermediate folding units.