A streptococcal enzyme that acts specifically upon diphosphopyridine nucleotide: characterization of the enzyme and its separation from streptolysin O

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.

Selective inhibition by preparations of streptococcal filtrates of the oxidative metabolism of mitochondria procured from rabbit myocardium

When solutions of streptolysin O were added to Warburg flasks containing, among other constituents, suspensions of mitochondria from the myocardium of rabbits and citrate, fumarate, or alpha-ketoglutarate as the substrate, there followed regularly a sharp reduction, and eventually complete cessation, of oxygen consumption. This phenomenon was not observed when succinate was the substrate in the flasks, the finding pointing to a selective interference with DPN as the underlying change. The agent in the solutions of streptolysin O responsible for this effect was shown to be a streptococcal product, and to be non-dialyzable and heat-labile. It differed from streptolysin O in that it did not appear to require prior activation with cysteine, and its effectiveness was not diminished by treatment with cholesterol or antistreptolysin globulins.