The domain/active site of a (former) native protein after all or most of its extraneous (unneeded) portions (peptides) have been removed. In 1995, Brian Cunningham and James A. Wells reduced the 28-residue (peptide) protein (hormone) Atrial Natriuretic Factor to 15-residues (peptides) size without reducing its potency (biological activity).
Minimized proteins—that retain their potency—hold the potential for medicines possessing a greater serum lifetime (when injected into a patient’s body), and as “models” for the creation of organic-chemical-synthesized mimetic drugs possessing the same therapeutic effect as the native protein did.