Premium
Detection of the local H + gradients on the internal mitochondrial membrane
Author(s) -
Krasinskaya Inna P,
Lapin Mikhail V,
Yaguzhinsky Lev S
Publication year - 1998
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(98)01463-x
Subject(s) - submitochondrial particle , valinomycin , chemistry , nigericin , biophysics , chemiosmosis , deprotonation , respiration , inner membrane , electrochemical gradient , membrane , mitochondrion , inner mitochondrial membrane , photochemistry , biochemistry , atp synthase , biology , organic chemistry , ion , botany , enzyme
Respiration‐dependent responses of a pH probe (fluorescein isothiocyanate, FITC), covalently bound to the membrane proteins of mitochondria and submitochondrial particles (SMP) have been studied. A spectral shift indicating FITC deprotonation was observed when respiration was activated in coupled mitochondria. Such a response was increased by valinomycin and reduced by uncoupler. Some FITC deprotonation was detected in the presence of excess of an uncoupler, but the response was smaller and insensitive to valinomycin. FITC deprotonation was also observed in submitochondrial particles after succinate addition. In this case it was not affected by uncoupler. Increase in the buffer concentration was found to (i) decrease the FITC response and (ii) increase the rate of uncoupled respiration in both mitochondria and submitochondrial particles. The results are consistent with the assumption that respiration initiates appearance of local H + activity gradients on the inner side of the internal mitochondrial membrane during the steady‐state H + pumping. We suggest that the formation of this gradient is due to kinetic barrier to proton transfer from the bulk phase to the respiratory proton pump vicinity.