Hypoxanthine and Xanthine: UV-Assay

Jørgensen, S.

doi:10.1016/b978-0-12-091304-6.50055-0

Cited by 5 publications

(2 citation statements)

References 21 publications

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“…Membrane preparations with a high concentration of active Na,K-ATPase (about 5000 pumps per Wm 2 ) were prepared from outer medulla of rabbit kidneys using procedure C of JÖrgensen [14]. For these preparations a speci¢c ATPase activity was measured in the range between 2000 and 2600 Wmol P i per hour and mg protein at 37³C.…”

Section: Methodsmentioning

confidence: 99%

Binding of the third Na⁺ ion to the cytoplasmic side of the Na,K‐ATPase is electrogenic

Domaszewicz

Apell

1999

FEBS Letters

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A new experimental setup was constructed to allow parallel measurements of total internal reflection fluorescence and of capacitance changes in Na,K-ATPase-containing membranes. Effects correlated with cytoplasmic sodium binding to Na,K-ATPase were investigated. Ion binding-induced fluorescence changes of the electrochromic dye RH421 in membrane fragments adsorbed on a transparent capacitative electrode corresponded perfectly to capacitance increases detected by a lock-in technique. From these electric measurements it was possible to estimate a dielectric coefficient of about 0.25 for the electrogenic binding of the third Na + ion. Binding of K + to cytoplasmic sites was electroneutral.z 1999 Federation of European Biochemical Societies.

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Section: Methodsmentioning

confidence: 99%

Binding of the third Na⁺ ion to the cytoplasmic side of the Na,K‐ATPase is electrogenic

Domaszewicz

Apell

1999

FEBS Letters

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“…The enzyme was isolated by a modification of the method of Jorgensen [12]. The preparation showed two major bands (112 kDa and 44 kDa) on SDS-gel electrophorsis corresponding to the two subunits of Na',K'-ATPase.…”

Section: Pur$ication Of Nu+ K'-a Tpasementioning

confidence: 99%

Effect of divalent cations on Na⁺,K⁺‐ATPase obtained from human placenta

Zolese¹,

Staffolani²,

Mazzanti³

et al. 1993

FEBS Letters

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Circular dichroism (CD) and acrylamide quenching studies of Na+,K+‐ATPase from human placenta showed that its incorporation into phosphatidylcholine vesicles increased the enzymic activity by 55%. Moreover, both with the purified and the vesicle‐reconstituted protein, Ca2+ and Mg2+ increased the activity, the effect being more pronounced after preincubation of the protein with Mg2+. CD data suggest that this activity increase may be linked to a change in the secondary structure of the ATPase, in particular β‐turn, β‐sheet and random coil. Acrylamide quenching studies suggest that ions could primarily interact with phospholipid head groups, but not directly with the protein.

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Inosine di‐ and triphosphate synthesis in erythrocytes and cell extracts

Vanderheiden

1979

Journal Cellular Physiology

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The ability to synthesize inosinetriphosphate was demonstrated in blood cells as well as in a variety of tissue extracts in spite of the presence of ITP pyrophohydrolase. At the expense of having sub-optimal conditions, an assay system was selected that completely repressed the hydrolyzing enzyme, thus permitting the accumulation of ITP. In an attempt to define the biosynthetic pathway of ITP, and since guanylate kinase has been implicated in the formation of ITP, the rate of synthesis of ITP and GTP in cell extracts was compared. The comparison of the specific activities of the [14C]-labeled hypoxanthine and guanine moieties of the inosine and guanosine phosphates formed during incubation with [8-14C]-inosine and [8-14C]-guanosine respectively, revealed striking differences in the relative rates of isotope incorporation. Tentative mechanisms are proposed to explain these differences. The data obtained thus far does not discard the possibility that ITP may be formed by stepwise phosphorylation and (or) by direct pyrophosphorylation of IMP.

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Hypoxanthine and Xanthine: UV-Assay

Cited by 5 publications

References 21 publications

Binding of the third Na⁺ ion to the cytoplasmic side of the Na,K‐ATPase is electrogenic

Binding of the third Na⁺ ion to the cytoplasmic side of the Na,K‐ATPase is electrogenic

Effect of divalent cations on Na⁺,K⁺‐ATPase obtained from human placenta

Inosine di‐ and triphosphate synthesis in erythrocytes and cell extracts

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Hypoxanthine and Xanthine: UV-Assay

Cited by 5 publications

References 21 publications

Binding of the third Na+ ion to the cytoplasmic side of the Na,K‐ATPase is electrogenic

Binding of the third Na+ ion to the cytoplasmic side of the Na,K‐ATPase is electrogenic

Effect of divalent cations on Na+,K+‐ATPase obtained from human placenta

Inosine di‐ and triphosphate synthesis in erythrocytes and cell extracts

Contact Info

Product

Resources

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Binding of the third Na⁺ ion to the cytoplasmic side of the Na,K‐ATPase is electrogenic

Binding of the third Na⁺ ion to the cytoplasmic side of the Na,K‐ATPase is electrogenic

Effect of divalent cations on Na⁺,K⁺‐ATPase obtained from human placenta