H+-ATPase of crude homogenate of the outer mantle epithelium of Anodonta cygnea

• Type: Article in International Scientific Journal
• Date: 2004

Authors

Oliveira, PF (Author) Other; Lopes, IA (Author) Other; Barrias, C (Author) Other; da Costa, AMR (Author) Other

Journal

Title: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology

Vol. 139

Pages: 425-432

ISSN: 1095-6433

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 12 Citations

Scopus - 12 Citations

Other information

Authenticus ID: P-000-7EB

DOI: 10.1016/j.cbpb.2004.07.004

Abstract (EN): The outer mantle epithelium of the freshwater bivalve, Anodonta cygnea, is responsible for the mineralisation of the shell. Under short circuit conditions, it generates a current that is due to the operation of an electrogenic proton pump located in the apical barrier of that epithelium. Bafilomycin A, and Concanamycin A inhibited the short circuit current. The IC50 and maximum inhibition dose were 0.17 and 0.5 muM for Bafilomycin A(1), and 0.7 and 5 muM for Concanamycin A. The present work was undertaken to further characterise V-type ATPase of the outer mantle cells. The V-ATPase enzymatic activity of crude homogenate, measured as the amount of inorganic phosphorous released, due to ATP hydrolysis, in the presence of Na2SO3 (200 mM) was found to be 4.6 +/- 1.1 mumol Pi/mg protein/h, at 27degreesC, pH 7.0-7.4 and ATP 4.5-6.0 muM. Bafilomycin A, and Concanamycin A inhibit the V-ATPase activity with an IC50 of 14 and 8 nmol mg(-1), respectively. Dicyclohexylcarboddmide (DCCD; 100 mM) and NaNO3 (100 muM) inhibited the V-type ATPase in what it seems a non-specific manner and NEM (100 mM) was unable to do it. Bafilomycin A(1) (10 muM) and Concanamycin A (10 muM), inhibited 50-40% of the total activity.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8