prosthetic group 
noun Biochemistry
A non-protein group forming part of or combined with a protein.Serum albumin is a highly soluble multidomain protein, without prosthetic groups or bulky appending carbohydrates, that is very stable and available at high purity and low cost....
- We believe that the Q-splitting, when carefully identified, represents an informative spectral parameter that can be used to understand how the biochemical activity of a prosthetic group is regulated in proteins.
- Proteins have high affinities for their substrates or co-factors or prosthetic groups or receptors or antibodies raised against them.