Primary amine group on protein

Primary amine groups on proteins refer to the free –NH₂ groups found at the N-terminus of each polypeptide chain and in the side-chain of lysine residues within protein sequences. These groups are highly nucleophilic and are positively charged at physiological pH, making them chemically reactive and located primarily on protein surfaces. They are the major sites for chemical conjugation, biotinylation, crosslinking, fluorescent labeling, and other covalent modifications using specialized reagents such as NHS esters, isothiocyanates, and aldehydes. Primary amine groups are not a protein, enzyme, or receptor in themselves, but rather a widespread chemical functionality present on most proteins; they serve as universal chemical handles for protein chemistry applications but do not act as biological targets for drugs in the conventional sense. Note: - This is not a receptor, enzyme, transporter, or true therapeutic target, but a chemical group common to many proteins. Searches for drugs or disease associations return reagents and chemical uses, not true medicinal targeting. - The entry as a target is incorrect for most drug discovery purposes (e.g., not suitable for standard database entries focused on proteins/genes as targets).

Other names

Primary amino group on proteinFree amine on proteinAmine group on lysineN-terminal amine

Covalent modification/addition to primary amines (often via acylation or alkylation) Protein labeling for detection, immobilization, or crosslinking