Lysine Sepharose 4B is L-lysine immobilized to Sepharose 4B by the cyanogen bromide method. L-lysine is coupled via its α-amino group, leaving both the ε-amino and α-carboxyl groups free to interact with sample substances during chromatography. It is designed for purification of molecules with biospecific or charge dependent affinity for L-lysine. Lysine Sepharose 4B is a group specific adsorbent and has been used for isolation of plasminogen and plasminogen activator, separation of ribosomal RNA (rRNA) and purification of doublestranded DNA. The precise mechanism by which separation occurs is not fully understood but both electrostatic and stereospecific effects may contribute to the separation, depending upon the application