Purification of pneumolysin.

A procedure for the purification of pneumolysin has been developed. Its use results in a 96-fold increase in specific activity from the original crude pneumococcal extract to the final purified product. The purified material is heat-labile and is inactivated by trypsin and cholesterol; inactivation by p-hydroxymercuribenzoate can be reversed by mercaptoethanol. Intravenous administration of the material to rabbits results in crenation, increased osmotic fragility, and intravascular lysis of the erythrocytes of the animal.