 In reviewing the tertiary structure, what he calls the native shape, he talks about the non-covalent interactions that bind the amino acids and the folding that determines the molecules three-dimensional shape including the stereospecific binding site.The author then writes that a primary structure exists in a single (or a small number of related states, as is the case with allosteric proteins) precisely defined conformational native state under normal physiological conditions.Prior to folding there is no biological activity.