Electric signals during the bacteriorhodopsin photocycle, determined over a wide pH range

Krisztina Ludmann, Csilla Gergely, A. Dér, G. Váró

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Abstract

From the electric signals measured after photoexcitation, the electrogenicity of the photocycle intermediates of bacteriorhodopsin were determined in a pH range of 4.5-9. Current measurements and absorption kinetic signals at five wavelengths were recorded in the time interval from 300 ns to 0.5 s. To fit the data, the model containing sequential intermediates connected by reversible first-order reactions was used. The electrogenicities were calculated from the integral of the current signal, by using the time-dependent concentrations of the intermediates, obtained from the fits. Almost all of the calculated electrogenicities were pH independent, suggesting that the charge motions occur inside the protein. Only the N intermediate exhibited pH-dependent electrogenicity, implying that the protonation of Asp96, from the intracellular part of the protein, is not from a well-determined proton donor. The calculated electrogenicities gave good approximations of all of the details of the measured electric signals.

Original languageEnglish
Pages (from-to)3120-3126
Number of pages7
JournalBiophysical Journal
Volume75
Issue number6
Publication statusPublished - Dec 1998

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Bacteriorhodopsins
Protons
Proteins

ASJC Scopus subject areas

  • Biophysics

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Electric signals during the bacteriorhodopsin photocycle, determined over a wide pH range. / Ludmann, Krisztina; Gergely, Csilla; Dér, A.; Váró, G.

In: Biophysical Journal, Vol. 75, No. 6, 12.1998, p. 3120-3126.

Research output: Contribution to journalArticle

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