English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT
  The basal Mg2+-dependent ATPase activity is not part of the (H++K+)-transporting ATPase reaction cycle

Van der Hijden, H. T., Kramer-Schmitt, S., Grell, E., & de Pont, J. J. H. (1990). The basal Mg2+-dependent ATPase activity is not part of the (H++K+)-transporting ATPase reaction cycle. Biochemical Journal, 267(3), 565-572. doi:10.1042/bj2670565.

Item is

Basic

show hide
Genre: Journal Article

Files

show Files

Locators

show

Creators

show
hide
 Creators:
Van der Hijden , Harry T.W.M.1, Author
Kramer-Schmitt, Sabine2, Author           
Grell, Ernst2, Author           
de Pont, Jan Joep H.H.M.1, Author
Affiliations:
1Department of Biochemistry, University of Nijmegen, The Netherlands, ou_persistent22              
2Molecular Biophysics Group, Max Planck Institute of Biophysics, Max Planck Society, ou_3264820              

Content

show
hide
Free keywords: -
 Abstract: Purified gastric (H++K+)-transporting ATPase [(H++K+)-ATPase] from the parietal cells always contains a certain amount of basal Mg2+-dependent ATPase (Mg2+-ATPase) activity. lin-Benzo-ATP (the prefix lin refers to the linear disposition of the pyrimidine, benzene and imidazole rings in the 'stretched-out' version of the adenine nucleus), an ATP analogue with a benzene ring formally inserted between the two rings composing the adenosine moiety, is an interesting substrate not only because of its fluorescent behaviour, but also because of its geometric properties. lin-Benzo-ATP was used in the present study to elucidate the possible role of the basal Mg2+-ATPase activity in the gastric (H++K+)-ATPase preparation. With lin-benzo-ATP the enzyme can be phosphorylated such that a conventional phosphoenzyme intermediate is formed. The rate of the phosphorylation reaction, however, is so low that this reaction with subsequent dephosphorylation cannot account for the much higher rate of hydrolysis of lin-benzo-ATP by the enzyme. This apparent kinetic discrepancy indicates that lin-benzo-ATP is not a substrate for the (H++K+)-ATPase reaction cycle. This idea was further supported by the finding that lin-benzo-ATP was unable to catalyse H+ uptake by gastric-mucosa vesicles. The breakdown of lin-benzo-ATP by the (H++K+)-ATPase preparation must be due to a hydrolytic activity which is not involved in the ion-transporting reaction cycle of the (H++K+)-ATPase itself. Comparison of the basal Mg2+-ATPase activity (with ATP as substrate) with the hydrolytic activity of (H++K+)-ATPase using lin-benzo-ATP as substrate and the effect of the inhibitors omeprazole and SCH 28080 support the notion that lin-benzo-ATP is not hydrolysed by the (H++K+)-ATPase, but by the basal Mg2+-ATPase, and that the activity of the latter enzyme is not involved in the (H++K+)-transporting reaction cycle (according to the Albers-Post formalism) of (H++K+)-ATPase.

Details

show
hide
Language(s): eng - English
 Dates: 1989-10-311989-09-011989-11-091990-05-01
 Publication Status: Published in print
 Pages: 8
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1042/bj2670565
PMID: 2160231
PMC: PMC1131334
 Degree: -

Event

show

Legal Case

show

Project information

show

Source 1

show
hide
Title: Biochemical Journal
Source Genre: Journal
 Creator(s):
Affiliations:
Publ. Info: -
Pages: - Volume / Issue: 267 (3) Sequence Number: - Start / End Page: 565 - 572 Identifier: -