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.
D001216:Asparagine; D003545:Cysteine; D004220:Disulfides; D006639:Histidine; D006863:Hydrogen-Ion Concentration; D010206:Papain; D011725:Pyridines; D013438:Sulfhydryl Compounds
D004220:Disulfides; D011725:Pyridines; D013438:Sulfhydryl Compounds; D006639:Histidine; D001216:Asparagine; D010206:Papain; D003545:Cysteine