A number of enzymes capable of splitting the pyridine nucleotides have been found in animal tissues. A portion of the DPNase (1) that hydrolyzes the nicotinamide ribose bond of DPN and TPN was reported in the microsomes of rat liver (1). The DPN pyrophosphorylase, first described by Kornberg (2), has been found by Hogeboom and Schneider to be largely localized in the nucleus (3). In previous investigations (4) an enzyme from pigeon liver which splits DPNH and not DPN at the pyrophosphate linkage was described. The present communication deals with the intracellular distribution of enzymes from various species that attack the pyridine coenzymes at the pyrophosphate linkage. The distribution and properties of DPNases from different species and tissues will also be presented
