Brocklehurst, K., & Little, G. (1972). Reactivities of the various protonic states in the reactions of papain and of L-cysteine with 2,2'- and with 4,4'- dipyridyl disulphide: Evidence for nucleophilic reactivity in the un-ionized thiol group of the cysteine-25 residue of papain occasioned by its interaction with the histidine-159-asparagine-175 hydrogen-bonded system.

Brocklehurst, K., and G. Little. Reactivities of the Various Protonic States in the Reactions of Papain and of L-cysteine With 2,2'- and With 4,4'- Dipyridyl Disulphide: Evidence for Nucleophilic Reactivity in the Un-ionized Thiol Group of the Cysteine-25 Residue of Papain Occasioned By Its Interaction With the Histidine-159-asparagine-175 Hydrogen-bonded System. 1972.

Brocklehurst, K., and G. Little. Reactivities of the Various Protonic States in the Reactions of Papain and of L-cysteine With 2,2'- and With 4,4'- Dipyridyl Disulphide: Evidence for Nucleophilic Reactivity in the Un-ionized Thiol Group of the Cysteine-25 Residue of Papain Occasioned By Its Interaction With the Histidine-159-asparagine-175 Hydrogen-bonded System. 1972.