The invention provides methods for determining a set of critical features that serves as a “map” of attributes critical for maintaining the structure and function of a biologic. The map can serve as a development tool, e.g., as a guide or target during the development of expression, purification, and formulation protocols, a quality assurance tool during manufacturing, or as a definitive identifier of the specific biologic. The map can also serve as the definition of the biologic thereby providing a means by which a given product may be reliably characterized as a biosimilar of another biologic product.
