Properties of apyrase and inorganic pyrophosphatase inStreptomyces aureofaciens

Abstract

Apyrase (ATP-diphosphohydrolase, EC 3.6.1.5) and inorganic pyrophosphatase (EC 3.6.1.1) were partially purified from S. aureofaciens RIA 57 and characterized. Apyrase degrades, in addition to ATP, other nucleoside triphosphates and nucleoside diphosphates, diphosphate, thiamine diphosphate, phosphoenolpyruvate and oligophosphates of chain length n less than 90. The apyrase activity was detected in the membrane and supernatant fractions. Its properties (substrate specificity. effect of inhibitors, pH optimum and effect of Mg2+ ions) were similar in both fractions except for the effect of oligomycin that inhibited only the membrane fraction. Pyrophosphatase exhibited a strict substrate specificity, substrates other than diphosphate being degraded relatively slowly. Of other enzymes exhibiting the phosphatase activity acid phosphatase (EC 3.1.3.2) and alkaline phosphatase (EC 3.1.3.1), trimetaphosphatase (EC 3.6.1.2) and exopolyphosphatase (EC 3.6.1.11) degrading oligophosphatase of chain length n = 15, 40 and 60, were detected.

Ca2+ signalling by recombinant human CXCR2 chemokine receptors is potentiated by P2Y nucleotide receptors in HEK cells

“…It has been shown previously that Ca 2+ ‐signalling by δ‐opioid receptors in stirred suspensions of SH‐SY5Y cells is sensitive to apyrase (ATP diphosphohydrolase, which converts nucleotide polyphosphates to nucleoside monophosphates (Curdova et al ., 1982)), suggesting that endogenous ATP release may act as a potentiating factor (Yeo et al ., 2001). We therefore investigated the possibility that release of endogenous nucleotides from the cell monolayer following addition of buffer was responsible for the effects of vehicle pre‐treatment.…”

“…Addition of vehicle (BSS) alone also revealed [Ca 2+ ] i responses to IL-8 and (+)-arterenol although these were signi®cantly less than the responses observed in the presence of 1 mM ATP (P50.05 for both pEC 50 and E max values) (Figure 2a 8.4+0.4 and E max 34+3% whilst arterenol elevated [Ca 2+ ] i with a pEC 50 of 6.2+0.1 and E max of 11+1%. It has been shown previously that Ca 2+ -signalling by dopioid receptors in stirred suspensions of SH-SY5Y cells is sensitive to apyrase (ATP diphosphohydrolase, which converts nucleotide polyphosphates to nucleoside monophosphates (Curdova et al, 1982)), suggesting that endogenous ATP release may act as a potentiating factor (Yeo et al, 2001). We therefore investigated the possibility that release of endogenous nucleotides from the cell monolayer following addition of buer was responsible for the eects of vehicle pre-treatment.…”

Απομόνωση Και Ιδιότητες Της ATP Διφωσφουδρολάσης Από Ανθρώπινο Πλακούντα

“…Ακολούθησε ψηφοφορία, όπου εγκρίθηκε η διδακτορική διατριβή με βαθμό "ΑΡΙΣΤΑ". (Vara and Serrano 1981), μίσχος μπιζελιού (TognoΜ andMarre 1981, Tognoli 1984), λάχανο (Mazelis 1959), αναριχούμενο φυτό (Ishikawa et al 1984) και κίτρινο λούπινο (Guranovski et al 1991) Η απυράση έχει επίσης ανιχνευτεί σε μύκητες και βακτήρια (Krishnan 1952, Curdova et al 1982 1.2 2. ATP-DPH στα ασπόνδυλα.…”