@article{MTMT:32869090, title = {Nonlinear electric response of the diffuse double layer to an abrupt charge displacement inside a biological membrane}, url = {https://m2.mtmt.hu/api/publication/32869090}, author = {Mostafa, Hamdy I.A. and Tóth-Boconádi, Rudolf and Dér, László and Fábián, László and Taneva, Stefka G. and Dér, András and Keszthelyi, Lajos}, doi = {10.1016/j.bioelechem.2022.108138}, journal-iso = {BIOELECTROCHEMISTRY}, journal = {BIOELECTROCHEMISTRY}, volume = {146}, unique-id = {32869090}, issn = {1567-5394}, year = {2022}, eissn = {1878-562X} } @article{MTMT:3211116, title = {Integrated optical investigation of two light-sensitive proteins}, url = {https://m2.mtmt.hu/api/publication/3211116}, author = {Fábián, László and Krekic, Szilvia and Tóth-Boconádi, Rudolf and G Taneva, Stefka and M Bálint, Agneta and Nánai, László and Dér, András}, doi = {10.1063/1.4972379}, journal-iso = {AIP CONF PROC}, journal = {AIP CONFERENCE PROCEEDINGS}, volume = {1796}, unique-id = {3211116}, issn = {0094-243X}, year = {2017}, eissn = {1551-7616} } @article{MTMT:3017997, title = {Time course of purple membrane bending during the photocycle of bacteriorhodopsins}, url = {https://m2.mtmt.hu/api/publication/3017997}, author = {Tóth-Boconádi, Rudolf and Keszthelyi, Lajos}, doi = {10.4024/29TO14A.jbpc.15.02}, journal-iso = {J BIOL PHYS CHEM}, journal = {JOURNAL OF BIOLOGICAL PHYSICS AND CHEMISTRY}, volume = {15}, unique-id = {3017997}, issn = {1512-0856}, year = {2015}, pages = {55-62} } @article{MTMT:2078393, title = {2D measurement of ion currents associated to the signal transduction of the phototactic alga Chlamydomonas reinhardtii}, url = {https://m2.mtmt.hu/api/publication/2078393}, author = {Kincses, András and Tóth-Boconádi, Rudolf and Dér, András}, doi = {10.1016/j.jphotobiol.2012.06.001}, journal-iso = {J PHOTOCH PHOTOBIO B}, journal = {JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY}, volume = {114}, unique-id = {2078393}, issn = {1011-1344}, abstract = {Our objective was to develop a simple procedure for the detection of light-induced ion currents of photomotile cells in two dimensions. The novel technique was based on the light gradient method (LGM), and the model object was Chlamydomonas reinhardtii, a phototactic unicellular alga, ideal for such experiments. The conventional LGM cuvette was modified such that the electrode pair could be rotated around the sample and pick up the electric signals from arbitrary directions. The experiments were performed with and without the application of an auxiliary light beam preorienting the motile cells. The analysis of the detected traces revealed two main vectorial components of the signal by the help of singular value decomposition (SVD), in concert with previous experimental findings and theoretical considerations suggesting different origins of the "fast" and "slow" components of the photoelectric response of Chlamydomonas and Haematococcus cells. Using plausible assumptions, our method allowed a quantitative analysis of the signal, assigning size and direction to the two vectorial components. The method allows a rapid and accurate way to measure electric signals of photomotive cells in 2D, and particularly, to test the physiological activity and in vivo-kinetics of site-directed mutants of ChR1 or ChR2, providing novel photo-electrophysiological methods with important quantitative information. (C) 2012 Elsevier B.V. All rights reserved.}, year = {2012}, eissn = {1873-2682}, pages = {147-152} } @article{MTMT:1552416, title = {Optical and electric signals from dried oriented purple membrane of bacteriorhodopsins}, url = {https://m2.mtmt.hu/api/publication/1552416}, author = {Tóth-Boconádi, Rudolf and Dér, András and Keszthelyi, Lajos}, doi = {10.1016/j.bioelechem.2010.12.003}, journal-iso = {BIOELECTROCHEMISTRY}, journal = {BIOELECTROCHEMISTRY}, volume = {81}, unique-id = {1552416}, issn = {1567-5394}, abstract = {All the intermediates of the bacteriorhodopsin photocycle are excitable with light of suitable wavelength. This property might regulate the activity in the cells when they are exposed in the nature to high light intensity. On the other hand this property is involved in many applications. In this study the ground state and M intermediate of dried oriented samples of wild-type bacteriorhodopsin and its mutant D96N were excited with 406 nm laser flashes. Substantial M populations were generated with quasi-continuous illumination. The decay of the absorption of M intermediate had three components: their lifetimes were very different for laser flash and quasi-continuous illuminations in cases of both bacteriorhodopsin species. The optical answer for the excitation of M intermediate had a lifetime of 2.2 ms. Electric signals for M excitation had large fast negative components and small positive components in the 100 mu s time domain. The results are expected to have important implications for bioelectronic applications of bacteriorhodopsin. (C) 2010 Elsevier B.V. All rights reserved.}, year = {2011}, eissn = {1878-562X}, pages = {17-21} } @article{MTMT:1324792, title = {Excitation of the M intermediates of wild-type bacteriorhodopsin and mutant D96N: temperature dependence of absorbance, electric responses and proton movements}, url = {https://m2.mtmt.hu/api/publication/1324792}, author = {Tóth-Boconádi, Rudolf and Dér, András and Taneva, SG and Keszthelyi, Lajos}, doi = {10.1007/s00214-009-0632-y}, journal-iso = {THEOR CHEM ACC}, journal = {THEORETICAL CHEMISTRY ACCOUNTS}, volume = {125}, unique-id = {1324792}, issn = {1432-881X}, abstract = {The simplest proton pump known in biological systems, bacteriorhodopsin (bR), is the first ion-transporting membrane protein, the function of which can be described at the atomic level, with the aid of molecular dynamics calculations. To get additional experimental support for the proposed atomic level description of the function of bR, we studied a quasi-stable state of the protein molecule, the so-called M intermediate that plays a crucial role in the proton pumping process. The temperature dependence of the light-induced events occurring in the photocycle of wild-type bacteriorhodopsin and its mutant D96N were followed in detail. Absorbance changes, electric signals generated by charge motion inside the protein, and movement of protons in the protein solution interface either forward (proton release due to excitation of bR) or backward (uptake of protons due to the M excitation: "back-take") were monitored. The obtained Arrhenius parameters indicate that the proton back-take is triggered by charge rearrangements in the protein similar to the proton release triggered by those during the L -> M transition. The time necessary for proton back-take determines the reconstitution time of the bR ground state. The data are expected to be used in theoretical modeling of the bR function. Based on these results, a more detailed photocycle model is established to describe the proton pumping mechanism, implying a formal principle ("domino model") that is expected to hold also for other charge transfer proteins.}, year = {2010}, eissn = {1432-2234}, pages = {365-373} } @article{MTMT:1411558, title = {Excitation of the M intermediates of bacteriorhodopsin}, url = {https://m2.mtmt.hu/api/publication/1411558}, author = {Tóth-Boconádi, Rudolf and Dér, András and Fábián, László and Taneva, S G and Keszthelyi, Lajos}, doi = {10.1111/j.1751-1097.2008.00521.x}, journal-iso = {PHOTOCHEM PHOTOBIOL}, journal = {PHOTOCHEMISTRY AND PHOTOBIOLOGY}, volume = {85}, unique-id = {1411558}, issn = {0031-8655}, abstract = {Protein electric response signals (PERS) of the M intermediates of wild-type bacteriorhodopsin (bR) were recorded. Contrary to earlier findings reporting on a single-phase response upon excitation of the M intermediates, a kinetic analysis of the signals revealed the existence of three components, the fastest and the slowest ones of negative, while the middle one of positive sign with respect to the normal direction of proton pumping. Based on proton motion indicator experiments and molecular dipole calculations, the components were assigned to proton transfer steps and conformational changes driving the bR molecule back from the M to the ground state upon blue light excitation. The fastest, negative pump component was assigned to the proton transfer from D85 to the Schiff base. The subsequent positive component was attributed to rearrangements in the protein core (in the vicinity of the retinal molecule), triggered by the primary proton transfer process. The slowest component was established to reflect charge rearrangements associated with proton uptake by the protein from the bulk. © 2009 The Authors.}, year = {2009}, eissn = {1751-1097}, pages = {609-613} } @article{MTMT:1920900, title = {pH-dependence of the photoelectric response of the M intermediate of bacteriorhodopsin}, url = {https://m2.mtmt.hu/api/publication/1920900}, author = {Tóth-Boconádi, Rudolf and Taneva, SG and Fábián, László and Dér, András and Keszthelyi, Lajos}, journal-iso = {J BIOL PHYS CHEM}, journal = {JOURNAL OF BIOLOGICAL PHYSICS AND CHEMISTRY}, volume = {7}, unique-id = {1920900}, issn = {1512-0856}, year = {2007}, pages = {147-151} } @article{MTMT:1090359, title = {Excitation of The L Intermediate of Bacteriorhodopsin: Electric Responses to Test X-ray Structures}, url = {https://m2.mtmt.hu/api/publication/1090359}, author = {Tóth-Boconádi, Rudolf and Dér, András and Taneva, SG and Keszthelyi, Lajos}, doi = {10.1529/biophysj.105.068817}, journal-iso = {BIOPHYS J}, journal = {BIOPHYSICAL JOURNAL}, volume = {90}, unique-id = {1090359}, issn = {0006-3495}, abstract = {The L intermediate of bacteriorhodopsin was excited, and its electrical response was measured. Two positive components were found in it with respect to the direction of proton pumping: an unresolved fast component, and a slower one (tau = mu s) of small amplitude. The fast component was assigned to a charge motion corresponding to reisomerization of the retinal moiety, whereas the slow one was attributed to charge rearrangements reestablishing the ground state. Because three x-ray crystallographic structures have recently been reported for the L intermediate, it seemed important to calculate the intramolecular dipole moment changes associated to bR-->L for all three structures, so as to compare them with similar quantities determined from the electrical signals. The results are discussed in terms of amino acid side chains possibly contributing to the observed effect. We propose to use electrical signals as a veri. cation tool for intermediate structures of the photocycle, and thus for molecular models of proton pumping.}, year = {2006}, eissn = {1542-0086}, pages = {2651-2655} } @article{MTMT:1090358, title = {Actinic Light-energy Dependence of Proton Release From Bacteriorhodopsin}, url = {https://m2.mtmt.hu/api/publication/1090358}, author = {Tóth-Boconádi, Rudolf and Taneva, SG and Keszthelyi, Lajos}, doi = {10.1529/biophysj.105.066431}, journal-iso = {BIOPHYS J}, journal = {BIOPHYSICAL JOURNAL}, volume = {89}, unique-id = {1090358}, issn = {0006-3495}, abstract = {Measuring the light-density (fluence) dependence of proton release from. ash excited bacteriorhodopsin with two independent methods we found that the lifetime of proton release increases and the proton pumping activity, defined as a number of protons per number of photocycle, decreases with increasing fluence. An interpretation of these results, based on bending of purple membrane and electrical interaction among the proton release groups of bacteriorhodopsin trimer, is presented.}, year = {2005}, eissn = {1542-0086}, pages = {2605-2609} }