Premium
Control of energy fluxes by the sarcoplasmic reticulum Ca 2+ ‐ATPase: ATP hydrolysis, ATP synthesis and heat production
Author(s) -
de Meis Leopoldo,
Bianconi M.Lucia,
Suzano Valdecir A
Publication year - 1997
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/s0014-5793(97)00244-5
Subject(s) - atp hydrolysis , endoplasmic reticulum , atpase , chemistry , hydrolysis , atp synthase , electrochemical gradient , adenosine triphosphate , chemiosmosis , vesicle , biochemistry , biophysics , enzyme , membrane , biology
The experiments described indicate that heat is released when Ca 2+ leaks through the Ca 2+ ‐ATPase of sarcoplasmic reticulum vesicles. In the presence of a transmembrane Ca 2+ concentration gradient, agents that modify the amount of ATP synthesized from ADP and P i also modify the amount of heat produced by the hydrolysis of each ATP molecule. Thus, in the presence of heparin, less ATP is synthesized and more heat is produced. Conversely, with dimethyl sulfoxide more ATP is synthesized and less heat is produced. The data indicate that between limits (−10 to −30 kcal/mol) the Ca 2+ ‐ATPase can regulate the interconversion of energy in such a way as to vary the fraction of energy derived from ATP hydrolysis which is converted into heat and that which is converted into other forms of energy.