• Bulletin of the Korean Chemical Society
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• v.10 no.1
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• pp.69-71
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• 1989

Effects of SDS and temperature on the conformational changes of bacteriorhodopsin were studied using a, b, c bands of bacteriorhodopsin. In the SDS denaturation, bacteriorhodopsin in purple membrane was more labile than bacteriorhodopsin reconstituted into PC vesicles. These rather interesting results may be understood by effective SDS concentration in lipid layer.

• Journal of Photoscience
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• v.9 no.2
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• pp.118-121
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• 2002

A state of bacteriorhodopsin at high temperature was studied by various spectral measurements. The stability measurements indicated that the onset temperature of the denaturation was 70$^{\circ}C$ in the dark and 60$^{\circ}C$ under illumination. The reactivity of hydroxylamine with the Schiff's base also significantly increased in the temperature range between 60 and 70$^{\circ}C$. A spectral band at about 470 nm appeared in the temperature range higher than 60$^{\circ}C$. The circular dichroism spectra in the visible region started to change from a bilobed exiton type to a positive band at about 60$^{\circ}C$, suggesting that the two-dimensional configuration of bacteriorhodopsin molecules changed from crystalline to amorphous. All the measurements suggested a new state between 60 and 70$^{\circ}C$ in which bacteriorhodopsin is stable only in the dark.

• KSBB Journal
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• v.13 no.3
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• pp.268-271
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• 1998

Bacteriorhodopsin in the purple membrane (PM) of halobacteria has recently been attracting much attention to be used as a component of molecular electron device and optical computers. In order to increase the productivity of bacteriorhodopsin in high cell density cultures of Halobacterium halobium R1, an internal membrane cell-retention bioreactor system was employed. As a result, the production of cell mass at OD660 of 12 and of bacteriorhodopsin at 125-130 mg/L were obtained using the internal membrane bioreactor system at a dilution rate of 0.066 hr-1. The productivity achieved by the internal membrane system (0.7 mg/L$.$hr) was 3.5-fold higher than that obtained by the corresponding batch cultivations (0.2 mg/L$.$hr).

• Journal of Sensor Science and Technology
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• v.9 no.3
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• pp.208-212
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• 2000

A protein based vision biomembrane was fabricated by adsorbing bacteriorhodopsin into electrochemically polymerized polypyrrole film substrate mainly through strong electrostatic interaction. The immobilized bacteriorhodopsin on the polypyrrole film was demonstrated by SEM and SRET. The light signal transducing function from the bacteriorhodopsin which was adsorbed into Polypyrrole film was evaluated by electroretinogram(ERG). A wave form analysis of the electroretinogram indicated that the adsorbed bacteriorhodopsin retained its activity and light signal was obtained from the protein for at least one month.

• Journal of Photoscience
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• v.9 no.2
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• pp.299-301
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• 2002

Recent denaturation experiments of bacteriorhodopsin (bR) in the dark and under illumination at high temperatures revealed that irreversible thermal bleaching occurs above ~ 70°C and the preceding reversible structural changes in the dark above 60°C are closely related to irreversible photobleaching observed in the same temperature range (Yokoyama et al. (2002). J Biochem. 131,785). In this study, structural properties of bacteriorhodopsin (bR) at high temperatures were extensively probed by hydroxylamine reactivity with the Schiff base in the dark and hydrogen-deuterium (H-D) exchange in the peptide groups. In the Arrhenius plot from kinetics measurements of the hydroxylamine reaction, a good linear relationship between the reaction time constant and the inverse of the absolute temperature was observed below 60°C, while significant increase started above 60°C, suggesting that remarkable increase in water accessibility of the Schiff base in the temperature region. FT-IR spectroscopic studies on the H-D exchange suggested increase in the deuterium exchanges rate of the peptide hydrogen in the same temperature region.

• Journal of the Korean Chemical Society
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• v.37 no.11
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• pp.974-977
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• 1993

• Journal of the Korean Chemical Society
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• v.42 no.2
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• pp.143-149
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• 1998

When anesthetics were added to a bacteriorhodopsin (bR) in the purple membranes, the 570 nm absorption band shifts to 480 nm. This anesthetic-induced spectroscopic change is reversible. The apparent pKa (6.3) of this equilibrium depends on the nature of the anesthetics in which bR is dispersed. The electric orientation measurements showed that the native bR is easily achieved by relatively small electric field which is oriented at $60^\circ$, while anesthetic-treated bR is not the case. These results demonstrate that the subtle changes in the chromophore and the protein structure surrounding the chromophore by anesthetics influence the spatial orientation of the charged residues in the protein matrix surrounding chromophore.

• Korean Journal of Optics and Photonics
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• v.13 no.5
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• pp.414-420
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• 2002

We realized optical logic gates using a bacteriorhodopsin (bR) doped polymer film. The bR undergoes a complex photocycle characterized by several spectroscopically distinct intermediate states. We realized optical logic gates using a He-Ne laser (632.8 nm) and a He-Cd laser (413 nm) that consider B-state and absorption change of M-state in the photocycle of bR. Also, we realized high speed AND logic gate using He-Ne laser (632.8 nm) and the second harmonics at 532 nm from a pulsed Nd-YAG laser that considering absorption spectrum between B-state and K-state.

• Journal of the Korean Chemical Society
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• v.36 no.4
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• pp.504-510
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• 1992

Absorption properties of methylene blue (MB) in L-${\alpha}$-lecithin vesicle, bacteriorhodopsin and incorporated bacteriorhodopsin (InBR) vesicle systems at 20∼$60^{\circ}C$ has been studied by adsorption spectroscopy. The equilibrium of MB between monomer and dimer in lecithin vesicles has been existed at low concentration of MB, but oligomer has been formed in vesicle at higher concentration of MB. In most cases, the MB cluster was redistributed to monomer at the concentration of lecithin vesicles. Adding BR to constanr concentration of MB deceased the adsorption ratio (${\alpha}/{\beta}$) of MB, and MB was formed oligomeric aggregate. Absorption ratio (${\alpha}/{\beta}$) of MB was increased during phase transition of InBR vesicles, but independent of phase transition of lecithin vesicles. It suggested that aggregate of MB on the surfaces of InBR vesicles were redistributed to monomer under the influence of lipid phase transition.

• Journal of Photoscience
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• v.9 no.2
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• pp.296-298
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• 2002

Irreversible photobleaching of bacteriorhodopsin (bR), namely denaturation induced by illumination of visible light, was investigated by absorption kinetic measurements. The denaturation kinetics revealed that light illumination significantly enhanced the structural decay of bR. The kinetic analyses showed that the molecular structure of bR denatures according to a single-exponential decay, whereas irreversible photobleaching has two decay components. The decay constant of the slow component of photobleaching is almost same as that in the dark. An Arrhenius plot of the denaturation kinetic constants for the fast and slow components showed similar activation energies of approximately 19 kcal/mol.