Properties of staphylococcal enterotoxin A under limited proteolysis

1. Staphylococcal enterotoxin A (SEA) was exposed in a state of limited proteolysis to five kinds of proteolytic enzymes: papain, pepsin, pronase, trypsin and alpha-chymotrypsin. SEA was found to be sensitive to the action of three of them: papain, pepsin and pronase. 2. Four fragments were produced after papain proteolysis of SEA in the presence of beta-mercaptoethanol. 3. Papain processing of SEA does not influence its capacity to interact with antibodies to intact toxin, but the capacity of SEA to hydrolyse NAD to nicotinamide (NA) and adenosinediphosphatribose (ADP-ribose) completely disappears. 4. SEA under the action of pepsin and pronase has been hydrolysed to small peptides, which appear to be moving with the front of leading dye in disc-electrophoresis.