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2025/10/31
Zebrafish Xenograft Model for Predicting Cisplatin Efficacy in Muscle-Invasive Bladder Cancer
tSeparation and characterization of a novel isoenzyme of cyclic nucleotide phosphodieterase from rat cerebrum. .
1994/02/01
Mukai J, Asai T, Naka M, Tanaka T.
Br J Pharmacol. 1994 Feb;111(2):389-90.
Abstract
Anion-exchange chromatography on a Mono-Q column of the supernatant fraction, after ultracentrifugation, from a homogenate of rat cerebrum, prepared under isotonic conditions in the presence of protease inhibitors, yielded a novel isoenzyme of cyclic nucleotide phosphodiesterase (PDE) with properties unlike those of known PDEs. The isoenzyme was insensitive to stimulation by Ca2+/calmodulin and cyclic GMP, and it hydrolyzed both cyclic AMP and cyclic GMP with KM values of 0.109 +/- 0.008 microM and 1.78 +/- 0.04 microM, respectively. The ratio of Vmax of hydrolysis of cyclic GMP to that of cyclic AMP was 1.90 +/- 0.07. Nicardipine (PDE I inhibitor), SK&F 94120 (PDE III inhibitor), rolipram (PDE IV inhibitor) and zaprinast (PDE V inhibitor) had very weak inhibitory effects on the PDE activity of the isoenzyme. These results suggest that the isoenzyme is a novel and previously unreported species of PDE, which we tentatively designate PDE VIII.