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Is Ca 2+ ‐ATPase a water pump?
Author(s) -
Dupont Yves
Publication year - 1983
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(83)80721-2
Subject(s) - atpase , calcium atpase , chemistry , calcium , chemiosmosis , transduction (biophysics) , biophysics , solvation , coupling (piping) , atp synthase , endoplasmic reticulum , ion transporter , enzyme , ion , biochemistry , membrane , biology , materials science , organic chemistry , metallurgy
The mechanism of free energy coupling in active transport is discussed with special reference to the sarcoplasmic reticulum Ca 2+ ‐ATPase. In the current working schemes for cation transport ATPases, free energy transduction is nearly always based on enzyme conformational changes. The principal objective of the present article is to examine whether recent experimental results on Ca 2+ ‐ATPase may in fact be better explained by assuming the existence of a direct chemiosmotic process. In the scheme proposed, free energy transduction between ATP and calcium is based on a transfer of solvation water between the acylphosphate bond and the bound calcium ions.