Estimation of adenylic acid deaminase in tissue extracts

Hayashi, Taizo; Olmsted, Peter S.

doi:10.1016/0003-2697(65)90277-0

Cited by 6 publications

(1 citation statement)

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“…The present study shows that the human term placenta contains high levels of ATPase and adenylate kinase, which ensure that placental ATP can be readily hydrolyzed to ADP and that 2 moles of ADP can be readily equilibrated to 1 mole each of AMP and ATP. In confirmation of an earlier observation (24), no adenylate deaminase was detected; consequently, the only catabolic pathway for AMP is via phosphohydrolysis to adenosine. Both alkaline phosphatase and 5'-nucleotidase are present in the placental homogenates and catalyze the hydrolysis of AMP.…”

Section: Discussionsupporting

confidence: 85%

Presence of Adenosine in the Human Term Placenta: DETERMINATION OF ADENOSINE CONTENT AND PATHWAYS OF ADENOSINE METABOLISM

Maguire

1972

Circulation Research

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Adenosine, inosine, and hypoxanthine were isolated from human term placentas by paper chromatography of the diaJyzates of aqueous placental homogenates and quantified by ultraviolet spectroscopy. Placentas obtained upon vaginal delivery contained 230 ± 18 nmoles adenosine/g tissue, 300 ± 29 nmoles inosine/g, and 250 ± 19 nmoles hypoxanthine/g. Three prelabor placentas obtained by cesarean section contained 44 =t 3 nmoles inosine/g and 277 ± 22 nmoles hypoxanthine/g, but adenosine was not detected in two of the placentas and was present only at 4 nmoles/g in the third. The activities of placental enzymes catabolizing ATP were determined in homogenates of term placentas. No adenylate deaminase or xanthine oxidase activity was found. Adenosinetriphosphatase, adenylate kinase, and 5'-nucleotidase were more active than were adenosine kinase, adenosine deaminase, and purine nucleoside phosphorylase. The results indicate that in the placenta both the formation of adenosine from adenosine monophosphate and the fate of adenosine, i.e., salvage or catabolism, are influenced by the level of adenosine triphosphate. Possibly, during labor, placental ischemia favors the enzymatic production of adenosine. Methods PLACENTASHuman placentas were obtained immediately upon normal vaginal delivery or upon delivery by CircaUtio* Risfrcb, Vol. XXXI, Novtmber 1972 779 by guest on June 17, 2015 http://circres.ahajournals.org/ Downloaded from 780 SIM, MAGUIRE cesarean section and processed at once. No complications were associated with the pregnancies, and all placentas were of normal size, color, and weight. by guest on June 17, 2015 http://circres.ahajournals.org/ Downloaded from ADENOSINE IN THE HUMAN PLACENTAAdenine nucleotide salvage synthesis in the rat heart: Pathways of adenosine salvage. Biochim

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Section: Discussionsupporting

confidence: 85%