Ecto-ADPase activity in the rat renal brush-border membranes

Scientific paper - Original scientific paper

• Author: Tihana Žanić-Grubišić
• Author: Lorena Griparić
• Author: Renata Zrinski
• Author: Mirna Floegel
• Author's institution: University of Zagreb; Faculty of Pharmacy and Biochemistry; (Department of medical biochemistry and haematology)
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Pharmacy; Medical Biochemistry

Abstract (english)

Brush-border membrane vesicles purified from rat kidney cortex exhibit an ectoenzyme activity responsible for the hydrolysis of both ATP and ADP, as well as of other nucleoside tri- and diphosphates. In the presence of Ca2+ ions, ADP hydrolysis follows the simple Michaelis-Menten kinetics assuming a single catalytic site.
The real substrate for ADPase is a divalent cation conjugated ADP.
The pH optimum for the hydrolysis is between 7.2 and 8.6.
ADP and ATP hydrolysis show similar heat denaturation curves, and are both resistant to limited proteolysis and to inhibitors of other known ATPases. The enzyme activity is inhibited by: diethyl py- rocarbonate, dithiothreitol, high concentrations of both IV-ethylmale- imide and azide. The diethyl pyrocarbonate inhibition could be reversed by hydroxylamine, indicating the involvement of histidine and/or tyrosine residues in the reaction. It is proposed that both ADPase and ATPase activities reside within the same enzyme protein.

• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: Croatica Chemica Acta
• Numbering: vol. 68, no. 3, pp. 491-510
• p-ISSN: 0011-1643
• e-ISSN: 1334-417X
• URN:NBN: urn:nbn:hr:163:516925
• Publication: 1995
• Document URL: https://hrcak.srce.hr/136710
• Type of resource: Text
• Access conditions: Open access
• Created on: 2020-04-29 14:59:53