prosthetic group
The non-amino acid portion of a conjugated protein. Examples include cofactors such as flavines or cytochromes as well as lipids and polysaccharides, which are the prosthetic groups of lipoproteins and glycoproteins, respectively.
PAC, 1992, 64, 143. 'Glossary for chemists of terms used in biotechnology (IUPAC Recommendations 1992)' on page 163 (