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Gambetta C, Massad WA, Nesci AV, García NA. Vitamin B2-sensitized degradation of the multifunctional drug Evernyl, in the presence of visible light – microbiological implications. PURE APPL CHEM 2015. [DOI: 10.1515/pac-2015-0407] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractTaking into consideration the importance of the photooxidative effects in complex bio- environments, this paper reports on the visible-light-promoted interactions between Evernyl (methyl 2, 4-dihydroxy-3,6-dimethylbenzoate, Ev) and vitamin B2 (riboflavin, Rf). Ev is a phenolic derivative, transparent to visible light, that possesses important antimicrobial activity. This compound is the first known natural, complete and specific human androgen receptor antagonist. Ev is profusely employed in personal-care products and synthesized as a secondary metabolite by several lichen and plant species. In both sceneries, acting Ev as a cosmetic component for topic applications or as a lichen constituent, may Rf behave as a native visible-light absorber pigment. In this context, kinetic and mechanistic aspects of the Rf-sensitized photooxidation of Ev, has been studied in aqueous solution, irradiating with blue LED light (463–471 nm) and employing stationary and time resolved methods. Results indicate that Ev reacts with the photogenerated reactive oxygen species (ROS) singlet molecular oxygen with a rate constant of kr=1.1±0.2×106 M−1s−1. In parallel Ev also quenches the electronically excited singlet and triplet excited states of Rf with rate constants close to the difussion limit. As a result the ROS superoxide radical anion and hydrogen peroxide are generated and the latter subsequently reacts with Ev. Possible implications of these photoreactions on the antimicrobial activity of Ev have been investigated employing a Candida albicans (CA) strain, isolated from human skin infection. The simultaneous presence of Rf, Ev in a sub-MIC, and blue-light irradiation produced a significant antimycotic effect, attributed to ROS photogeneration.
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Affiliation(s)
- Carolina Gambetta
- 1Departamento de Química, Universidad Nacional de Río Cuarto, 5800, Río Cuarto, Argentina
| | - Walter A. Massad
- 1Departamento de Química, Universidad Nacional de Río Cuarto, 5800, Río Cuarto, Argentina
| | - Andrea V. Nesci
- 2Departamento de Microbiología e Inmunología, Universidad Nacional de Río Cuarto, 5800, Río Cuarto, Argentina
| | - Norman A. García
- 1Departamento de Química, Universidad Nacional de Río Cuarto, 5800, Río Cuarto, Argentina
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Dioumaev AK, Lanyi JK. Two bathointermediates of the bacteriorhodopsin photocycle, from time-resolved nanosecond spectra in the visible. J Phys Chem B 2009; 113:16643-53. [PMID: 19994879 PMCID: PMC3808455 DOI: 10.1021/jp907393m] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Time-resolved measurements were performed on wild-type bacteriorhodopsin with an optical multichannel analyzer in the spectral range 350-735 nm, from 100 ns to the photocycle completion, at four temperatures in the 5-30 degrees C range. The intent was to examine the possibility of two K-like bathochromic intermediates and to obtain their spectra and kinetics in the visible. The existence of a second K-like intermediate, termed KL, had been postulated (Shichida et al., Biochim. Biophys. Acta 1983, 723, 240-246) to reconcile inconsistencies in data in the pico- and microsecond time domains. However, introduction of KL led to a controversy, since neither its visible spectrum nor its kinetics could be confirmed. Infrared data (Dioumaev and Braiman, J. Phys. Chem. B 1997, 101, 1655-1662) revealed a state which might have been considered a homologue to KL, but it had a kinetic pattern different from that of the earlier proposed KL. Here, we characterize two distinct K-like intermediates, K(E) ("early") and K(L) ("late"), by their spectra and kinetics in the visible as revealed by global kinetic analysis. The K(E)-to-K(L) transition has a time constant of approximately 250 ns at 20 degrees C, and describes a shift from K(E) with lambda(max) at approximately 600 nm and extinction of approximately 56,000 M(-1) x cm(-1) to K(L) with lambda(max) at approximately 590 nm and extinction of approximately 50,000 M(-1) x cm(-1). The temperature dependence of this transition is characterized by an enthalpy of activation of DeltaH(++) approximately 40 kJ/mol and a positive entropy of activation of DeltaS(++)/R approximately 4. The consequences of multiple K-like states for interpreting the spectral evolution in the early stages of the photocycle are discussed.
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Affiliation(s)
- Andrei K Dioumaev
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697, USA.
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Gaertner W, Oesterhelt D, Vogel J, Maurer R, Schneider S. Photocycles of bacteriorhodopsins containing 13-alkylsubstituted retinals. Biochemistry 2002. [DOI: 10.1021/bi00409a055] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Dioumaev AK, Braiman MS. Nano- and microsecond time-resolved FTIR spectroscopy of the halorhodopsin photocycle. Photochem Photobiol 1997; 66:755-63. [PMID: 9421962 DOI: 10.1111/j.1751-1097.1997.tb03220.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Step-scan Fourier transform infrared spectroscopy with 50 ns time resolution was applied to the early stages of the photocycle of halorhodopsin (hR) for the temperature range 3-42 degrees C. Kinetic data analysis with global fitting revealed two distinct kinetic processes associated with relaxations of the early red-shifted photoproduct hK; these processes have time constants tau 1 approximately equal to 280 ns and tau 2 approximately equal to 360 microns at 20 degrees C. Spectral features demonstrate that the tau 1 process corresponds to a transition between two distinct bathointermediates, hKE and hKL. The vibrational difference bands associated with both tau 1 and tau 2 transitions are spread throughout the whole 1800-900 cm-1 range. However, the largest bands correspond to ethylenic C=C stretches, fingerprint C-C stretches and hydrogen out-of-plane (HOOP) wags of the retinal chromophore. The time evolution of these difference bands indicate that both the tau 1 and tau 2 decay processes involve principally a relaxation of the chromophore and its immediate environment. The decay of the intense HOOP vibrations is nearly equally divided between the tau 1 and tau 2 processes, indicating a complex chromophore relaxation from a twisted nonrelaxed conformation in the primary (hKE) bathointermediate, to a less-twisted structure in hKL, and finally to a roughly planar structure in the hypsochromically shifted hL intermediate. This conclusion is also supported by the unexpectedly large positive entropy of activation observed for the tau 1 process. The two relaxations from hKE to hL are largely analogous to corresponding relaxations (KE-->KL-->L) in the bacteriorhodopsin photocycle, except that the second step is slowed down by over 200-fold in hR.
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Affiliation(s)
- A K Dioumaev
- University of Virginia Health Sciences Center, Biochemistry Department, Charlottesville 22908, USA
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Dioumaev AK. Evaluation of intrinsic chemical kinetics and transient product spectra from time-resolved spectroscopic data. Biophys Chem 1997; 67:1-25. [PMID: 17029887 DOI: 10.1016/s0301-4622(96)02268-5] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/1996] [Revised: 12/17/1996] [Accepted: 12/17/1996] [Indexed: 11/19/2022]
Abstract
This communication is devoted to the evaluation of true spectra and intrinsic (microscopic) rate constants from apparent kinetics measured in time-resolved spectroscopic experiments monitoring complex relaxation dynamics of multi-intermediate systems. Retinal proteins, cytochrom c oxidase, phytochrome, hemoglobin, and photoactive yellow protein are examples of natural systems in which several transient states (intermediates) overlap so strongly, both in time and spectral domains, that their isolation and full characterization by classical biochemical methods is impossible, and mathematical evaluation of their true spectra and microscopic kinetic constants is required. Most of the popular methods for analysis of kinetic data, global fitting (GF), singular value decomposition (SVD), principal component analysis (PCA) and factor analysis (FA), are applicable to two-dimensional (2D, in time and spectral domains) arrays of data. All these methods produce only a phenomenological description of data, that approximates the measured data only with apparent kinetics. A fundamental limitation, namely, insufficient information in 2D data, does not allow any of these methods to reach the final goal: to recalculate from apparent to intrinsic values in any but the most trivial cases. A strategy was proposed (J.F. Nagle, Biophys. J.. 59 (1991) 476-487) to include an additional (third) information-rich dimension, temperature, into the simultaneous computer analysis. A simultaneous direct fitting of 3D data arrays to systems of differential rate equations allows recalculation of apparent kinetics into true spectra and intrinsic rate constants. In spite of its evident theoretical advantages, this strategy has not been successful on real data. Here we describe another custom-built program, SCHEMEFIT, developed for the same purpose: to fit measured kinetics directly to the system of coupled differential rate equations describing the photochrome's relaxation dynamics. Though sharing the main strategy with the previous approach, SCHEMEFIT is based on a different set of numeric algorithms, and its application requires different tactics. Its performance is illustrated on synthetic data, and compared with GF and SVD. An example of applying SCHEMEFIT to the photocycle of halorhodopsin is also reported.
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Affiliation(s)
- A K Dioumaev
- Department of Physiology and Biophysics, University of California, Irvine, CA 92697, USA.
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Groma GI, Bogomolni RA, Stoeckenius W. The photocycle of bacteriorhodopsin at high pH and ionic strength. I. Effects of pH and buffer on the absorption kinetics. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1319:59-68. [PMID: 9107316 DOI: 10.1016/s0005-2728(96)00116-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A fitting analysis resolved the kinetics in the microsecond to second time range of the absorption changes in the bacteriorhodopsin photocycle at pH = 8.0-9.5 in 3 M KCl into seven exponential components. The time constants and/or amplitudes of all components are strongly pH-dependent. In the pH range studied, the logarithms of the pH-dependent time constants varied linearly with pH. The maximum absolute value of the corresponding slopes was 0.4, in contrast with the theoretically expected value of 1 for unidirectional reactions coupled directly to proton exchange with the bulk phase. This indicates that the extracted macroscopic rate constants are not identical to the microscopic rate constants for the elementary photocycle reaction steps. Unexpected differences were found in the kinetic parameters in CHES and borate buffers.
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Affiliation(s)
- G I Groma
- Department of Chemistry and Biochemistry, University of California, Santa Cruz 95064, USA.
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Dioumaev AK, Braiman MS. Two Bathointermediates of the Bacteriorhodopsin Photocycle, Distinguished by Nanosecond Time-Resolved FTIR Spectroscopy at Room Temperature. J Phys Chem B 1997. [DOI: 10.1021/jp961512w] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Andrei K. Dioumaev
- Department of Biochemistry, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908
| | - Mark S. Braiman
- Department of Biochemistry, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908
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Conformational flexibility of arginine-82 as source for the heterogeneous and pH-dependent kinetics of the primary proton transfer step in the bacteriorhodopsin photocycle: An electrostatic model. Chem Phys 1996. [DOI: 10.1016/s0301-0104(96)00192-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Henry E, Hofrichter J. [8] Singular value decomposition: Application to analysis of experimental data. Methods Enzymol 1992. [DOI: 10.1016/0076-6879(92)10010-b] [Citation(s) in RCA: 447] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Milder SJ, Thorgeirsson TE, Miercke LJ, Stroud RM, Kliger DS. Effects of detergent environments on the photocycle of purified monomeric bacteriorhodopsin. Biochemistry 1991; 30:1751-61. [PMID: 1993191 DOI: 10.1021/bi00221a004] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Time-resolved difference spectra have been obtained for the photocycle of delipidated bacteriorhodopsin monomers (d-BR) in six different detergent micelle environments that were prepared by two new detergent-exchange techniques. A global kinetic analysis of the photocycle spectra for d-BR in each detergent environment was performed. Comparison of these results with those obtained for the photocycle of bacteriorhodopsin in purple membrane (PM) shows that there is one fewer kinetically distinguishable process for monomeric BR between the decay of the K intermediate and the rise of the M intermediate. Assuming a sequential pathway occurs in the photocycle, it appears that the equilibrium between the L and M intermediates is reached much more rapidly in the detergent micelles. This is attributed to a more direct interaction between Asp-85 and the proton on the nitrogen of the Schiff base of retinal for BR in the detergents. Equilibrium concentrations of late photocycle intermediates are also altered in detergents. The later steps of the photocycle, including the decay of the M intermediate, are slowed in detergents with rings in their hydrocarbon region. This is attributed to effects on conformational changes occurring during the decay of M and/or other later photocycle intermediates. The lifetime of dark adaptation of light-adapted d-BR in different detergent environments increases in environments where the lifetime of the M intermediate increases. These results suggest that the high percentage of either unsaturated or methyl-branched lipids in PM and the membranes of other retinal proteins may be important for their effective functioning.
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Affiliation(s)
- S J Milder
- Department of Chemistry, University of California, Santa Cruz 95064
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Chernavskii DS, Chizhov IV, Lozier RH, Murina TM, Prokhorov AM, Zubov BV. Kinetic model of bacteriorhodopsin photocycle: pathway from M state to bR. Photochem Photobiol 1989; 49:649-53. [PMID: 2756001 DOI: 10.1111/j.1751-1097.1989.tb08437.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A model of the last parts of the bacteriorhodopsin (bR) photocycle is proposed on the basis of experimental data for the kinetic behavior of the 'O' intermediate during a temperature pulse in distilled water suspension. The model includes the previously proposed (but not well characterized) intermediate 'N' between the 'M' and 'O' states of bR. This intermediate exists in fast temperature-dependent quasi-stationary equilibrium with the red-shifted intermediate 'O' and has a maximum of absorption close to the bR spectrum.
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Laser-flash photolysis of 124 kDa oat phytochrome: Studies concerning the late steps of Pfr formation. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 1989. [DOI: 10.1016/1011-1344(89)80063-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Grossjean MF, Tavan P. Wavelength regulation in bacteriorhodopsin and halorhodopsin: A Pariser–Parr–Pople multireference double excitation configuration interaction study of retinal dyes. J Chem Phys 1988. [DOI: 10.1063/1.454701] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Simultaneous analysis of single-photon timing data with a reference method: Application to a poisson distribution of decay rates. Chem Phys 1988. [DOI: 10.1016/0301-0104(88)90028-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Maurer R, Vogel J, Schneider S. ANALYSIS OF FLASH PHOTOLYSIS DATA BY A GLOBAL FIT WITH MULTI-EXPONENTIALS–I. DETERMINATION OF THE MINIMAL NUMBER OF INTERMEDIATES IN THE PHOTOCYCLE OF BACTERIORHODOPSIN BY THE ‘STABILITY CRITERION’. Photochem Photobiol 1987. [DOI: 10.1111/j.1751-1097.1987.tb04763.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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