Detail of "146-91-8"

Reference

Opiate binding to membrane preparations of neuroblastoma X glioma hybrid cells NG108-15: effects of ions and nucleotides

Opiate binding to membrane preparations of neuroblastoma X glioma hybrid cells NG108-15: effects of ions and nucleotides. Blume, Arthur J. (Dep. Physiol. Chem. Pharmacol., Roche Inst. Mol. Biol., Nutley, N. J., USA). Life Sci., 22(20), 1843-52 (English) 1978. CODEN: LIFSAK. ISSN: 0024-3205. DOCUMENT TYPE: Journal CA Section: 3 (Biochemical Interactions) Interaction of a no. of opiate agonists with the opiate receptors in NG108-15 cell membranes was influenced by ions, as well as certain nucleotides. Steady-state binding of tritiated leu-enkephalin [58822-25-6] was increased by Mg++ and decreased by Na+, GMP-P(NH)P [34273-04-6], GTP [86-01-1], GDP [146-91-8], ITP [132-06-9], and IMP-P(NH)P [61371-89-9]. Half-maximal inhibition produced by GMP-P(NH)P occurred at 4.6 mM. The dissocn. of tritiated leu- and metenkephalin [58569-55-4], as well as etorphine [14521-96-1], from these opiate receptors was also shown to be altered by both ions and nucleotides.

Adenylate cyclase system of human skeletal muscle

Adenylate cyclase system of human skeletal muscle. Characteristics of catecholamine stimulation and nucleotide regulation. Reddy, N. Bojji; Oliver, Katharine L.; Festoff, Barry W.; Engel, W. King (Natl. Inst. Neurol. Commun. Disord. Stroke, NIH, Bethesda, Md., USA). Biochim. Biophys. Acta, 540(3), 389-401 (English) 1978. CODEN: BBACAQ. ISSN: 0006-3002. DOCUMENT TYPE: Journal CA Section: 2 (Hormone Pharmacology) Human skeletal muscle plasmalemmal adenylate cyclase [9012-42-4] activation by catecholamines and guanyl nucleotides was investigated. The enzyme was selectively stimulated by different b-adrenergic catecholamines. Their order of potency was isoproterenol (I) [7683-59-2] > epinephrine [51-43-4] > norepinephrine [51-41-2]. Phenylephrine, an a-adrenergic agonist, showed no effect. Stimulation of the enzyme by b-agonists was stereospecific as (-)-isomers of I and epinephrine were at least 2 orders of magnitude more potent than their corresponding (+)-isomers. The b-adrenergic blocking agents, propranolol and alprenolol, completely abolished the stimulation of adenylate cyclase by (-)-I. Inhibition by b-blockers was also stereospecific, (-)-isomers being more effective inhibitors than their corresponding (+)-isomers. This selectivity and stereospecificity suggests that the human plasmalemmal adenylate cyclase is closely assocd. with the b-adrenergic receptors. Purine nucleotides, particularly GTP [86-01-1] and to a lesser extent ITP [132-06-9], further enhanced the catecholamine-sensitive, but not the basal, adenylate cyclase. Pyrimidine nucleotides, UTP and CTP, were without any effect on the enzyme activity. Of the guanosine compds. tested only GTP, and to a lesser extent GDP [146-91-8] enhanced the enzyme activity in the presence of (-)-I, whereas guanosine, GMP, and cyclic GMP were ineffective. 5'-Guanylyl imidodiphosphate (GMP-PNP) [34273-04-6] a nonphosphorylating analog of GTP, was a more profound activator of catecholamine-sensitive adenylate cyclase than GTP. In contrast to GTP, GMP-PNP stimulated the basal enzyme activity. The plasmalemmal adenylate cyclase showed greater affinity towards GTP (Km 3 x 10-7 M) than towards GMP-PNP (Km 2 x 10-6 M). Profound augmentation by GTP and GMP-PNP of plasmalemmal adenylate cyclase in the presence of (-)-I appeared to be a function of the b-adrenergic receptor because propranolol completely abolished their effects; GTP competitively inhibited that marked augmentation caused by GMP-PNP, suggesting that both nucleotides interact at similar sites on the enzyme system. Kinetic studies revealed that the predominant effect of guanyl nucleotides was to enhance the catalytic activity of the enzyme without altering its affinity for ATP, (-)-I, or Mg2+. Thus, the human plasmalemmal adenylate cyclase is closely assocd. with the b-adrenergic receptor and the guanyl nucleotides are potent regulators of the plasmalemmal enzyme.