lysylsubstituted

Lysylsubstituted is an adjective used in biochemistry and organic chemistry to describe a molecule that bears a lysyl substituent, i.e., a lysine-derived moiety covalently attached to the molecule. The lysyl group may be the lysine side chain or a lysine residue linked through a functional group such as an amide, ester, or through a linker used in bioconjugation. The term is most often encountered in discussions of protein conjugates, synthetic polymers, or small-molecule ligands that have been modified to introduce lysine-based functionality. In protein chemistry, lysyl substitutions can result from deliberate bioconjugation strategies or from post-translational modifications where lysine residues are linked to dyes, drugs, or crosslinkers.

Enzymatic examples include transglutaminase-catalyzed crosslinking that yields bonds involving lysine residues; synthetic routes include amide coupling of N-ε-protected lysine derivatives to activated carboxyl groups. Lysyl substitutions are also used to improve solubility or to provide functional handles for further chemistry.

Analytical methods such as mass spectrometry or NMR are used to confirm the presence and location of lysyl substituents. Because the term is not universally standardized, its precise meaning can vary by field; consult primary literature when encountering the term.