Endogenous inhibitors of cyclic adenosine 3',5'-monophosphate-phosphodiesterase in rat epididymis. 1986

D Benau, and E I Szabo, and C Terner

Stabilization of cyclic adenosine 3',5'-monophosphate (cAMP)-phosphodiesterase (PDE) in 50% glycerol made possible the removal of endogenous inhibitors from tissue extracts by dialysis and the storage of the extracts at -20 degrees C without loss of PDE activity. Dialysates of heat-inactivated epididymal extracts were fractionated by liquid chromatography, and 4 fractions-F2, F5, F7, and F12-were found to contain endogenous inhibitors of PDE. The masses of the fractions required to inhibit low-Km PDE activity by ca. 50% in 430-microliter incubation mixtures were F2, 89 micrograms; F5, 23 micrograms; F7, 275 micrograms; and F12, 1.2 mg. The mechanisms of inhibition of low-Km PDE by the endogenous inhibitors were investigated by kinetic analysis of enzyme-inhibitor interaction. F2 and F12 inhibited PDE competitively; F5 and F7 decreased both apparent Km and Vmax, suggesting an uncompetitive mechanism of inhibition. The high potency of F5 in low concentration suggests that it may be a physiological modulator of low-Km cAMP-PDE activity.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D008297 Male Males
D010726 Phosphodiesterase Inhibitors Compounds which inhibit or antagonize the biosynthesis or actions of phosphodiesterases. Phosphodiesterase Antagonists,Phosphodiesterase Inhibitor,Phosphoric Diester Hydrolase Inhibitors,Antiphosphodiesterases,Inhibitor, Phosphodiesterase
D004795 Enzyme Stability The extent to which an enzyme retains its structural conformation or its activity when subjected to storage, isolation, and purification or various other physical or chemical manipulations, including proteolytic enzymes and heat. Enzyme Stabilities,Stabilities, Enzyme,Stability, Enzyme
D004822 Epididymis The convoluted cordlike structure attached to the posterior of the TESTIS. Epididymis consists of the head (caput), the body (corpus), and the tail (cauda). A network of ducts leaving the testis joins into a common epididymal tubule proper which provides the transport, storage, and maturation of SPERMATOZOA.
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D015105 3',5'-Cyclic-AMP Phosphodiesterases Enzymes that catalyze the hydrolysis of CYCLIC AMP to form adenosine 5'-phosphate. The enzymes are widely distributed in animal tissue and control the level of intracellular cyclic AMP. Many specific enzymes classified under this heading demonstrate additional spcificity for 3',5'-cyclic IMP and CYCLIC GMP. 3',5'-Cyclic AMP 5'-Nucleotidohydrolase,3',5'-Cyclic-Nucleotide Phosphodiesterase,CAMP Phosphodiesterase,3',5' Cyclic AMP Phosphodiesterase,3',5'-Cyclic AMP Phosphodiesterase,3',5'-Cyclic Nucleotide Phosphodiesterase,3',5'-Cyclic-AMP Phosphodiesterase,3',5'-Nucleotide Phosphodiesterase,3,5-Cyclic AMP 5-Nucleotidohydrolase,3,5-Cyclic AMP Phosphodiesterase,3',5' Cyclic AMP 5' Nucleotidohydrolase,3',5' Cyclic AMP Phosphodiesterases,3',5' Cyclic Nucleotide Phosphodiesterase,3',5' Nucleotide Phosphodiesterase,3,5 Cyclic AMP 5 Nucleotidohydrolase,3,5 Cyclic AMP Phosphodiesterase,5'-Nucleotidohydrolase, 3',5'-Cyclic AMP,5-Nucleotidohydrolase, 3,5-Cyclic AMP,AMP 5'-Nucleotidohydrolase, 3',5'-Cyclic,AMP 5-Nucleotidohydrolase, 3,5-Cyclic,AMP Phosphodiesterase, 3',5'-Cyclic,AMP Phosphodiesterase, 3,5-Cyclic,Nucleotide Phosphodiesterase, 3',5'-Cyclic,Phosphodiesterase, 3',5'-Cyclic AMP,Phosphodiesterase, 3',5'-Cyclic Nucleotide,Phosphodiesterase, 3',5'-Cyclic-AMP,Phosphodiesterase, 3',5'-Cyclic-Nucleotide,Phosphodiesterase, 3',5'-Nucleotide,Phosphodiesterase, 3,5-Cyclic AMP,Phosphodiesterase, CAMP,Phosphodiesterases, 3',5'-Cyclic-AMP
D051381 Rats The common name for the genus Rattus. Rattus,Rats, Laboratory,Rats, Norway,Rattus norvegicus,Laboratory Rat,Laboratory Rats,Norway Rat,Norway Rats,Rat,Rat, Laboratory,Rat, Norway,norvegicus, Rattus

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