Premium
Inhibition of the H + ‐ATPase in bovine adrenal chromaffin granule ghosts by diethylstilbestrol Evidence for a tight coupling between ATP hydrolysis and proton translocation
Author(s) -
Grønberg Martin,
Flatmark Torgeir
Publication year - 1988
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(88)80793-2
Subject(s) - atp hydrolysis , granule (geology) , chemistry , atpase , biophysics , chromaffin cell , biochemistry , adrenal medulla , enzyme , biology , endocrinology , paleontology , catecholamine
Diethylstilbestrol (DES) was found to inhibit reversibly the hydrolysis of MgATP (80% at 100μM) and proton pump activity ( I 50 ⋍15 μM, complete at 100 μM) in chromaffin granule ghosts. The parallel inhibition suggests a tight kinetic coupling between the two activities. The Mg 2+ ‐ATPase activity, but not proton pumping, was partially restored by N , N′ ‐dicyclohexylcarbodiimide,indicating that the two inhibitors in combination cause a partial uncoupling. The non‐competitive type of inhibition shows that the action of DES is distal to the site of ATP binding and hydrolysis. Although unspecific, the interaction of DES with the chromaffin granule membrane seems primarily to affect the H + ‐ATPase.