TY - JOUR
T1 - Characterization of cyclic 3', 5'-nucleotide phosphodiesterase activity in an islet cell tumor of the syrian hamster
AU - Schubart, Ulrich K.
AU - Udem, Linda
AU - Baum, Stephen G.
AU - Rosen, Ora M.
N1 - Funding Information:
We thank Mr. Dennis Baiser for valuable technical assistance. We are indebted to Drs. A. J. Whitty and P. P. Foa, Sinai Hospital of Detroit and Dr. Ira Goldfine, National Institutes of Health for their generous gifts of tumor-bearing animals. This work was supported in part by a grant from The New York Diabetes Association and a Genetics Research Center Grant (5 PO 1 GM 19100)f rom The National Institutes of Health.
PY - 1974/6
Y1 - 1974/6
N2 - During the purification of cyclic nucleotide phosphodiesterase (diesterase) activity from an insulin-secreting islet cell tumor of the syrian hamster, two soluble diesterases (diesterase I and diesterase II) and a particulate diesterase were resolved. Based on gel filtration, the estimated molecular weights of diesterases I and II were approximately 180,000. All of the diesterases had 'low' (approximately 1 μM) and 'high' (10-20 μM) KM's for both cAMP and cGMP. A heat-stable protein activator was partially separated from the soluble diesterases upon DEAE-cellulose chromatography. The activator enhanced the activity of the soluble diesterase 2 1 2-fold at cyclic nucleotide concentrations of 5 μM. No stimulation of diesterase activity was observed at higher (50-500 uM) substrate concentrations. The following compounds (in order of decreasing potency) inhibited both the soluble and particulate diesterases: papaverine, SQ 20009, xanthine derivatives, diphenylhydantoin, diazoxide, sulfonylureas, nicotinamide and catecholamines. Insulin, proinsulin, prostaglandins E1 and F1α, secretin, glucagon, colchicine, glucose, streptozotocin and imidazole were all without effect. Sulfhydryl-containing compounds and a number of amino acids enhanced the activity of soluble and paniculate diesterases. These investigations coupled with studies of adenylate cyclase and protein kinase activities, intracellular cyclic nucleotide levels and insulin secretion will provide a basis for understanding the role of cAMP in insulin secretion.
AB - During the purification of cyclic nucleotide phosphodiesterase (diesterase) activity from an insulin-secreting islet cell tumor of the syrian hamster, two soluble diesterases (diesterase I and diesterase II) and a particulate diesterase were resolved. Based on gel filtration, the estimated molecular weights of diesterases I and II were approximately 180,000. All of the diesterases had 'low' (approximately 1 μM) and 'high' (10-20 μM) KM's for both cAMP and cGMP. A heat-stable protein activator was partially separated from the soluble diesterases upon DEAE-cellulose chromatography. The activator enhanced the activity of the soluble diesterase 2 1 2-fold at cyclic nucleotide concentrations of 5 μM. No stimulation of diesterase activity was observed at higher (50-500 uM) substrate concentrations. The following compounds (in order of decreasing potency) inhibited both the soluble and particulate diesterases: papaverine, SQ 20009, xanthine derivatives, diphenylhydantoin, diazoxide, sulfonylureas, nicotinamide and catecholamines. Insulin, proinsulin, prostaglandins E1 and F1α, secretin, glucagon, colchicine, glucose, streptozotocin and imidazole were all without effect. Sulfhydryl-containing compounds and a number of amino acids enhanced the activity of soluble and paniculate diesterases. These investigations coupled with studies of adenylate cyclase and protein kinase activities, intracellular cyclic nucleotide levels and insulin secretion will provide a basis for understanding the role of cAMP in insulin secretion.
KW - cAMP
KW - insulin secreting tumor
KW - insulin secretion
KW - islet cell tumor
KW - phosphodiesterase
KW - phosphodiesterase activator
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U2 - 10.1016/0303-7207(74)90031-8
DO - 10.1016/0303-7207(74)90031-8
M3 - Article
AN - SCOPUS:49349139863
SN - 0303-7207
VL - 1
SP - 227
EP - 247
JO - Molecular and Cellular Endocrinology
JF - Molecular and Cellular Endocrinology
IS - 3
ER -