Term: prosthetic group https://doi.org/10.1351/goldbook.P04893 Definition: 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. Related Terms: 1) cofactors (http://doi.org/10.1351/goldbook.C01128). 2) cytochromes (http://doi.org/10.1351/goldbook.C01510). 3) lipids (http://doi.org/10.1351/goldbook.L03571). 4) polysaccharides (http://doi.org/10.1351/goldbook.P04752). 5) lipoproteins (http://doi.org/10.1351/goldbook.L03575). 6) glycoproteins (http://doi.org/10.1351/goldbook.G02656). Source: PAC, 1992, 64, 143. 'Glossary for chemists of terms used in biotechnology (IUPAC Recommendations 1992)' on page 163 (https://doi.org/10.1351/pac199264010143) Citation: 'prosthetic group' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.P04893 License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.