All enzyme that destroys DPN has been found in fractionated and highly concentrated streptococcal preparations that also contain streptolysin O. The enzyme—streptococcal DPNase—was shown by electrophoretic separation and by other means to be distinct from streptolysin O. It is non-dialyzable, heat-labile, and has optimal activity in the pH range 7.2 to 7.8. The enzyme has a high degree of specificity for DPN, which it splits at the nicotinamide-ribose linkage.

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