To retain antibody bioactivity, mild, near-physiological conditions are often used for conjugation reactions. Under these conditions, endogenous amino acids such as Lys and Cys are chemically reactive and can be used as conjugation sites. Scientists at Creative Biolabs are experienced in performing Lysine conjugation (amine reaction) as well as Cysteine conjugation (thiol reactions) to create ADCs using these endogenous sites.