Bacteriorhodopsin film

Bromley, KM., Patil, A.J., Seddon, A. M., Booth, P. and Mann, S. (2007) Bio-functional mesolamellar nanocomposite based on inorganic/ polymer intercalation in purple membrane (Bacteriorhodopsin) films. Advanced Materials, 19, 2433—2438. 

Kothapalli SR, Wu PF, Yelleswarapu CS, Rao D (2004) Medical image processing using transient Fourier holography in bacteriorhodopsin films. Appl. Phys. Lett. 85(24) 5836-5838... 

Independent support for the validity of the foregoing component analysis is provided by experiments carried out with a mutant bacteriorhodopsin. Purple membranes were isolated from a mutant strain of Halobacterium halobium in which a point mutation at residue 212 (aspartic acid replaced by asparagine) was carried out by a new method of site-directed mutagenesis and expression (43, 44). The photosignal was found to be pH-independent in the range of pH 4-11 (45, 46). This photosignal was found to be a pure B1 component because its time course could be superimposed, after normalization, with that of the pure B1 component observed in a multilayered mutant bacteriorhodopsin film. Thus, Nature does indeed decompose the photosignal in accordance with the outlined component analysis. In other words, the B1 component as defined is indeed a natural entity. 

The apparent symmetry of proton uptake and release on either side of the purple membrane suggests that proton release at the extracellular side and its reverse reaction may be manifest as a displacement photocurrent (a hypothetical B2 component). This signal is blocked in a Trissl-Montal bacteriorhodopsin film because the Teflon film precludes access of aqueous protons at the extracellular side. If, however, bacteriorhodopsin is reconstituted in a lipid bilayer membrane, this hypothetical component, which represents proton release at the extracellular side, might be observable. A complication arises from the expected polarity of the B2 signal, which should be the same as that of the B2 component (both are of opposite polarity to the B1 component). Therefore, a method must be devised to distinguish the B2 from the B2 component. The following kinetic analysis provides the rationale for such a method. 

Juchem, T. and N. Hampp, Interferometric system for non-destructive testing based on large diameter bacteriorhodopsin films. Optics Lasers Eng., 2000,34 87-100. 

Yao, B., Ren, Z., Menke, N., Wang, Y, Zheng, Y, Lei, M., et al. (2005). Polarization holographic high-density optical data storage in bacteriorhodopsin film. Applied Optics, 44,7344—7348. 

Hampp, N., Popp, A., Brauchle, C., and Oesterhelt, D., Diffraction efficiency of bacteriorhodopsin films for holography containing bacteriorhodopsin wildtype BRwt and its variants BR jg and BRd96n.> / Phys. Chem., 96, 4679—4685,1992. 

TaUent, J., Song, Q.W, Li, Z., Stuart, J., and Birge, RR, Effective photochromic nonlinearity of dried blue-membrane bacteriorhodopsin films. Optics Lett., 21, 1339-1341,1996. 

Takei, H., Lewis, A., Chen, Z., and Nebenzahl, L, Implementing receptive fields with excitatory and inhibitory optoelectrical responses of bacteriorhodopsin films, Appl. Opt., 30, 500-509,1992. 

It is interesting to compare the thermal-treatment effect on the secondary structure of two proteins, namely, bacteriorhodopsin (BR) and photosynthetic reaction centers from Rhodopseudomonas viridis (RC). The investigation was done for three types of samples for each object-solution, LB film, and self-assembled film. Both proteins are membrane ones and are objects of numerous studies, for they play a key role in photosynthesis, providing a light-induced charge transfer through membranes—electrons in the case of RC and protons in the case of BR. 

The large intrinsic birefringence of the sarcoplasmic reticulum [143] and the polarized attenuated total reflectance FTIR spectroscopy data obtained on oriented films of sarcoplasmic reticulum [144] indicate that a sizeable portion of the secondary structural elements are arranged perpendicularly to the plane of the membrane in a manner reminiscent to the structure of bacteriorhodopsin [145-148]. 

Fig. 8.19 SEM images of mesolamellar thin films produced by intercalation of nanosheets of (A) aminopropyl-functionalized silica or (B) AMP between stacked purple membrane fragments containing bacteriorhodopsin (scale bars= 10pm).

He, J.A., Samuelson, L., Li, L., Kumar, J. and Tripathy, S.K. (1999) Bacteriorhodopsin thin film assemblies-immobilization, properties and applications. Advanced Materials, 11, 435-446. 

The infrared spectrum of a protein is dominated by its peptide backbone amide I (C=0) and amide II (C-N. NH) vibrations. Fig. 6.6-1 shows a typical IR absorption spectrum of a hydrated protein film, in this case bacteriorhodopsin. In addition to the strong amide I (1658 cm ) and amide II (1546 cm ) bands water also contributes largely to the absorption (3379 cm , 1650 cm ). 

Figure 6.6-1 Typical absorption spectrum of a hydrated protein film (bacteriorhodopsin).

In the case of bacteriorhodopsin, it was explicitly shown that such carefully hydrated thin protein film afford the same rate constants as suspensions (Gerwert et al., 1990). 

The function of bacteriorhodopsin as a light-driven proton pump is well established from studies [14,70,83-85,323] of whole H. halobium cells, cell envelope vesicles prepared from the cells [78,324], and liposomes [17,18,135,191,325-327] as well as planar films [328-339] into which purple membrane was incorporated. In all of these cases light-dependent net translocation of protons across the membrane is observed, whose magnitude exceeds the number of bacteriorhodopsin molecules in the system by up to two orders of magnitude. 

Figure 10.9 pH dependence of photosignals from TM films reconstituted from various mutant bacteriorhodopsins. (A) D212N (B) D115N (C) D96N (D) D85N, (Reproduced from [80].)... 

Stryer L 1986 Cyclic GMP cascade of vision Anna. Rev. Neurosci. 9 87-119 Cafiso D S and Hubbell W L 1980 Light-induced interfacial potentials in photoreceptor membrane Biophys. J. 30 243-63 Drain C M, Christensen B and Mauzerall D 1989 Photogating of ionic currents across a lipid bilayer Proc. Natl Acad. Sci. USA 86 6959-62 Vsevolodov N N, Druzhko A B and Djukova T V 1989 Actual possibilities of bacteriorhodopsin application Molecular Electronics Biosensors and Biocomputers ed F T Hong (New York Plenum) pp 381-4 Vsevolodov N N and Dyukova T V 1994 Retinal-protein complexes as optoelectronic components Trend. Biotechnol. 12 81-103 Vsevolodov N N, Djukova T V and Druzhko A B 1989 Some methods for irreversible write-once recording in Biochrom films Proc. Annu. Int. Conf IEEE Eng. Med. Biol. Soc. 11 1327... 

---