AMINO-ACID RESIDUE - IS IT STRUCTURAL OR FUNCTIONAL

A new approach is suggested for delineating the structural and functio nal amino acid residues in proteins with known three-dimensional struc ture, basing on the involvement of residues in intramolecular hydropho bic and hydrophilic interactions and additional information about the conservativity of the residues, The approach is applied to the familie s of homologous neurotoxins and cardiotoxins. The results obtained con cerning the role of amino acid residues in both families of toxins acc ord well with the similarity of their fold, but different mechanisms o f action. Current approach can be used for detailed characterization o f protein spatial structures, as well as for rational protein engineer ing.