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EPR spectroscopy of 5‐DOXYL‐stearic acid bound to the mitochondrial uncoupling protein reveals its competitive displacement by alkylsulfonates in the channel and allosteric displacement by ATP
Author(s) -
Ježek Petr,
Bauer Michael,
Trommer Wolfgang E.
Publication year - 1995
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(95)00201-j
Subject(s) - allosteric regulation , uncoupling protein , chemistry , biophysics , gating , electron paramagnetic resonance , stearic acid , biochemistry , biology , receptor , nuclear magnetic resonance , physics , organic chemistry , adipose tissue , brown adipose tissue
Competition of fatty acids (FA) and alkylsulfonates with 5‐DOXYL‐stearic acid (5‐SASL) binding to isolated mitochondrial uncoupling protein (UcP) is demonstrated using EPR spectroscopy. A distinct peak of the bound 5‐SASL (h +1I ) decreased with increasing concentration of competitors. Since alkylsulfonates are UcP substrates, it suggests that the FA binding site is located in the anion channel. Moreover, with increasing ATP the h +1I peak decreased and was smoothed with the ‘micellar’ peak into a single wider peak. A pH of 8.5 reversed this effect. It could reflect an allosteric release of 5‐SASL from the ATP binding site which mimics the ATP gating mechanism.