Topic
Cyclase
About: Cyclase is a research topic. Over the lifetime, 10162 publications have been published within this topic receiving 388566 citations.
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TL;DR: Four compartments of adenylate cyclase in B. pertussis are proposed; soluble enzyme in the culture supernatant (up to 20% of the total activity); enzyme associated with intact cells and measurable without cell disruption (20-45%); extracytoplasmic enzyme sensitive to trypsin, but not measurable in intact cells at standard substrate concentrations (40-60%); and intracellular enzyme (7-9%).
Abstract: Soluble adenylate cyclase [EC 4.6.1.1] accumulates in the culture medium of exponentially growing Bordetella pertussis (300-900 pmol of cAMP formed/min per ml of 24 hr culture supernatant). In addition, there is an extracytoplasmic adenylate cyclase which enables the intact organisms to form [32P] cAMP (adenosine 3':5'-cyclic monophosphate) from exogenous [alpha-32P] ATP (200-1200 nmol of cAMP formed/min per g wet weight of cells) and which comprises 20-45% of the total adenylate cyclase activity. In contrast, only 1.7 and 2.4% of the total cell malate dehydrogenase [EC 1.1.1.37] and alkaline phosphatase [EC 3.1.3.1], respectively, are detectable in the intact cell. Trypsin treatment of intact organisms destroys 96% of the extracytoplasmic adenylate cyclase, but does not reduce the total cell malate dehydrogenase or a small pool of intracellular adenylate cyclase. Four compartments of adenylate cyclase in B. pertussis are proposed; (A) soluble enzyme in the culture supernatant (up to 20% of the total activity); (B) enzyme associated with intact cells and measurable without cell disruption (20-45%); (C) extracytoplasmic enzyme sensitive to trypsin, but not measurable in intact cells at standard substrate concentrations (40-60%); and (D) intracellular enzyme (7-9%). In comparison with previously studied bacterial adenylate cyclases, the extracytoplasmic location appears to be unique to the B. pertussis enzyme.
141 citations
TL;DR: Capillaries were isolated from epididymal fat, and a catecholamine-sensitive adenylate cyclase found in these capillaries was characterized and the cyclase was found to exhibit mixed alpha and beta characteristics.
Abstract: Capillaries were isolated from epididymal fat, and a catecholamine-sensitive adenylate cyclase found in these capillaries was characterized. The effect of various hormones on the accumulation of adenosine 3′:5′-cyclic monophosphate in capillary endothelial cells was determined and the cyclase was found to exhibit mixed alpha and beta characteristics. Cyclase was cytochemically localized in these endothelial cells with 5′-adenylyl-imidodiphosphate as a specific cyclase substrate and alloxan as a specific cyclase inhibitor. Lead imidodiphosphate was precipitated at or near the site of cyclase activity upon hydrolysis of 5′-adenylyl-imidodiphosphate by cyclase. This reaction product was observed primarily on the luminal surface of intact capillaries, in micropinocytic invaginations, in free vesicles within the cytoplasm, and in the intracellular junctions.
141 citations
TL;DR: The development of a transplantable osteogenic sarcoma is reported, which has retained through many generations a parathyroid hormone-responsive adenylate cyclase, providing a system which can be used to evaluate the significance of hormone- responsiveness for tumour cell growth and differentiation.
Abstract: AN apparent paradox prevents accurate assessment of the role of cyclic AMP in the development and maintenance of tumours. Although cell culture experiments indicate that malignant transformation is associated with decreased adenylate cyclase activity and intracellular cyclic AMP levels1,2, the same is not true of in vivo studies with tumours, in which a range of results have been obtained, from low3 to normal4 and elevated5 tumour cell cyclic AMP levels. We report here the development of a transplantable osteogenic sarcoma which has retained through many generations a parathyroid hormone-responsive adenylate cyclase, providing a system which can be used to evaluate the significance of hormone-responsive adenylate cyclase for tumour cell growth and differentiation.
141 citations
TL;DR: The data suggest that adenylate cyclase from brain requires some metal in addition to added Mg2+ for full expression of activity and that the metal is bound tightly to the enzyme.
140 citations
01 Jan 1962
TL;DR: It was observed that the possible formation of other nucleo- side 3’) 5’-phosphates from the corresponding nucleoside triphos- phates by cyclase preparations could not be readily detected with existing methods.
Abstract: SUMMARY 1. Adenosine 3’) 5’-phosphate-Pz2 (cyclic 3’) 5’-AMP32) was formed by adenyl cyclase in the presence of AP32PP with a specific activity of 67 to 84% of the precursor. Little radio- active cyclic 3’) 5’-AMP was formed in the presence of SPP32P32. 2. When solubilized preparations of adenyl cyclase skele- tal muscle and cerebral cortex were employed, 0.8 to 2.5 pmoles of inorganic pyrophosphate per pmole of cyclic 3’,5’-AMP were formed. The accumulation of both products was inhibited by Zn++ ions. 3, When particulate preparations of adenyl cyclase from cardiac muscle were used, 1.5 to 2.1 pmoles of inorganic pyro- phosphate per pmole of cyclic 3’,5’-AMP were formed. The accumulation of both products was increased by epinephrine. 4. It was observed that the possible formation of other nucleo- side 3’) 5’-phosphates from the corresponding nucleoside triphos- phates by cyclase preparations could not be readily detected with existing methods. Inosine 3’,5’-phosphate had the great- est activity the assay system, which amounted to only ap-
140 citations