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N I Swislocki

Publications and source records attributed to N I Swislocki.

At least 37 records · Page 2Linked to original sources
PubMed1981

ATP-dependent activation of adenylate cyclase.

Incubation of rat liver plasma membranes with MgCl2, ATP, and an ATP-regenerating system at 4 degrees C provides a 4-7-fold persistent activation of adenylate cyclase. Enzyme activation is time-dependent and 48 h of incubation is usually required to achieve maximal stimulation of adenylate cyclase activity. The activation described is not affected by GTP, cAMP, or cGMP, and does not occur when ATP is replaced by a nonphosphorylating analogue, adenyl-5'-imidodiphosphate. In addition to ATP, the activation requires Mg2+ and an ATP-regenerating system. The activation described is not additive with that produced by fluoride and analysis of basal and fluoride activities following extended incubation for 48 h reveals identical activities which decay at the same rate. These results are consistent with our model (11) which invokes phosphorylation-dephosphorylation mechanisms in regulating adenylate cyclase activity.

Adenosine Triphosphate↗
PubMed1979

Activation of adenylate cyclase by molybdate.

The effect of molybdate on adenylate cyclase (EC 4.6.1.1) in rat liver plasma membranes has been examined. The apparent K alpha for molybdate activation of the enzyme is 4.5 mM, and maximal, 7-fold stimulation is achieved at 50 mM. The observed increase in cAMP formation in the adenylate cyclase assay is not due to: (a) an inhibition of ATP hydrolysis; (b) a molybdate-catalyzed conversion of ATP to cAMP; (c) an inhibition of cAMP hydrolysis; or (d) an artifact in the isolation of cAMP formed in the reaction. Molybdate activation of adenylate cyclase is a general phenomenon exhibited by the enzyme in brain, cardiac, and renal tissue homogenates and in erythrocyte ghosts. However, like fluoride and guanyl-5'-yl imidodiphosphate (Gpp(NH)p), molybdate does not activate the soluble rat testicular adenylate cyclase. Molybdate is a reversible activator of adenylate cyclase. Activation is not due to an increase in ionic strength and is independent of the salt used to introduce molybdate. Molybdate does not activate adenylate cyclase previously stimulated with Gpp(NH)p or fluoride. At concentration greater than 20 mM, molybdate inhibits fluoride-stimulated adenylate cyclase, and at concentrations greater than 100 mM, molybdate stimulation of basal adenylate cyclase activity is diminished.

Adenylyl Cyclases↗
PubMed1975

Effect of methylazoxymethanol acetate on adenylate cyclase and 5'-nucleotidase in rat liver plasma membranes.

A single tumorigenic dose of methylazoxymethanol acetate increased adenylate cyclase activity in total liver homogenates 70-100% by the seventh day after treatment. The increased activity occurred in the plasma membranes rather than in the nuclei and was accompanied by a significant increase in 5'-nucleotidase activity. The data indicate that the carcinogen may alter the structure of the plasma membrane.

3',5'-Cyclic-AMP Phosphodiesterases↗