Über die DPN-Spaltung im Leberhomogenat

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Abstract
The nature of the enzymic degradation of diphosphopyridine nucleotide (DPN) and DPNH in liver homogenates was investigated. Mouse livers were rapidly homogenized at O[degree]C, and the DPN and DPNH concentrations measured enzymically after incubation at 0[degree]C and 40[degree]C. Fluorescence measurements were also carried out. Two distinct degradation mechanisms of DPN were detected: one was operative at 0[degree]C as well as at 40[degree]C and inhibited partially but not completely by nicotinamide (0.04[image]). The other did not take place at low temperatures and was unaffected by nicotinamide. Added DPN was almost completely destroyed after 60 minutes at 40[degree]C. The nicotinamide-sensitive process is assumed to be due to the DPNase, the resistant one to nucleotide pyrophosphatase. DPNH was also destroyed rapidly by incubation of homogenates; nicotinamide had no effect on this process, which was not further characterized.