Differences in Properties between Multiple Forms of Enzymes

Abstract

Modern concepts of protein structure, with their emphasis on the uniqueness of the primary structure of each type of polypeptide chain from which follow its specific secondary and tertiary structures, imply that most modifications of the amino acid sequence of the one or more chains which constitute a given protein will result in some observable change in its properties. The extent of such changes is potentially very wide, depending on the nature of the amino acid substitution which distinguishes the modified protein from its parent form: e.g., if an amino acid in or near the active centre of an enzyme is replaced by another, a direct effect on catalytic function is likely, whereas replacement of a residue in a more distant region of the molecule by one with similar characteristics may produce only a minor change in properties.