Vectorial insertion of bacteriorhodopsin for directed orientation assays in various polymeric biomembranes

Lee, Hyeseung; Ho, Dean; Kuo, Karen; Montemagno, Carlo

doi:10.1016/j.polymer.2006.02.082

Cited by 13 publications

(8 citation statements)

References 31 publications

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“…Using pyranine, the internal pH change of the liposome was measured as a function of time (Figure 4E). Pyranine was also used to confirm the activity of bR reconstituted in LUVs, GUVs, large proteoliposomes, and ABA block copolymer vesicles [83,86,127,128]. Pyranine has been used to monitor the proton-pumping activity of different types of rhodopsins: sensory rhodopsin-I and II [129,130], xR [131], ChR [132], aR [133], pR [134], and xanthorhodopsin [135,136].…”

Section: Membrane-impermeable Dye-based Assaysmentioning

confidence: 99%

Fluorescence Approaches for Characterizing Ion Channels in Synthetic Bilayers

2021

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Ion channels are membrane proteins that play important roles in a wide range of fundamental cellular processes. Studying membrane proteins at a molecular level becomes challenging in complex cellular environments. Instead, many studies focus on the isolation and reconstitution of the membrane proteins into model lipid membranes. Such simpler, in vitro, systems offer the advantage of control over the membrane and protein composition and the lipid environment. Rhodopsin and rhodopsin-like ion channels are widely studied due to their light-interacting properties and are a natural candidate for investigation with fluorescence methods. Here we review techniques for synthesizing liposomes and for reconstituting membrane proteins into lipid bilayers. We then summarize fluorescence assays which can be used to verify the functionality of reconstituted membrane proteins in synthetic liposomes.

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Section: Membrane-impermeable Dye-based Assaysmentioning

confidence: 99%

Fluorescence Approaches for Characterizing Ion Channels in Synthetic Bilayers

2021

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“…Nevertheless, the successful reconstitution of membrane proteins into polymer membranes has been demonstrated for several types of polymers (see Review [40]), but the functional integration is dependent on both, the nature of the polymer and the membrane thickness [41]. The polymer that has been used most extensively for the integration of membrane proteins, usually for the establishment of a highly selective mass transport into and out of the vesicles, is poly(2-methyloxazoline)-poly(dimethylsiloxane)-poly(2-methyloxazoline) (PMOXA-PDMS-PMOXA) [30,34,[41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57]. In this case, the ability to accommodate membrane proteins easily and in functional form, is due to the high flexibility and high fluidity of the PDMS-based polymers [41,58,59], as well as to their broad polydispersity [60,61].…”

Section: Advantages and Challenges Of Using Polymersomesmentioning

confidence: 99%

Light-Driven Biocatalysis in Liposomes and Polymersomes: Where Are We Now?

Wang

Castiglione

2018

Catalysts

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The utilization of light energy to power organic-chemical transformations is a fundamental strategy of the terrestrial energy cycle. Inspired by the elegance of natural photosynthesis, much interdisciplinary research effort has been devoted to the construction of simplified cell mimics based on artificial vesicles to provide a novel tool for biocatalytic cascade reactions with energy-demanding steps. By inserting natural or even artificial photosynthetic systems into liposomes or polymersomes, the light-driven proton translocation and the resulting formation of electrochemical gradients have become possible. This is the basis for the conversion of photonic into chemical energy in form of energy-rich molecules such as adenosine triphosphate (ATP), which can be further utilized by energy-dependent biocatalytic reactions, e.g. carbon fixation. This review compares liposomes and polymersomes as artificial compartments and summarizes the types of light-driven proton pumps that have been employed in artificial photosynthesis so far. We give an overview over the methods affecting the orientation of the photosystems within the membranes to ensure a unidirectional transport of molecules and highlight recent examples of light-driven biocatalysis in artificial vesicles. Finally, we summarize the current achievements and discuss the next steps needed for the transition of this technology from the proof-of-concept status to preparative applications.

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“…Lee et al (2006) used chemical treatment protocols to modify the electrostatic characteristics of bR protein surfaces in an effort to enhance the monolayer surface connect ability to polymeric planar membranes and vesicles. The key step in their chemical treatment process is the extraction of each bR molecule from its biological membrane and exposing its surfaces to a sequence of pH changes between acidic and basic solutions.…”

Section: Embedded Br Proton Pumpsmentioning

confidence: 99%

“…The actual response amplitude of bR molecules embedded in the polymeric membrane, however, was much lower than the estimated values. The authors attributed the decrease in efficiency to the chemical protocols used and the possible molecular shielding effect because the transmembrane channels that connect the cytoplasmic side to the extracellular side would become partially blocked (Lee et al 2006). …”

Section: Embedded Br Proton Pumpsmentioning

confidence: 99%

Fabrication of an optically driven pH gradient generator based on self-assembled proton pumps

Al-Aribe

Knopf

Bassi

2011

Microfluid Nanofluid

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Optically manipulating the local pH of a target solution in a microchannel, or reservoir, provides a mechanism for activating and controlling a variety of biological and chemical processes on Lab-on-a-Chip (LOC) devices and micro-total analysis systems (l-TAS). A microscale pH gradient generator that exploits the lightactivated molecular proton pumps found in the purple membranes (PM) of bacteriorhodopsin is described in this paper. The photo-electro-chemical transducer is an ultrathin layer (*13 nm) of oriented PM patches self-assembled on an Au-coated porous substrate. A biotin labeling and streptavidin molecular recognition technique is used to ensure that the extracellular side of all PM patches is attached to the porous substrate enabling unidirectional and efficient transport of ions across the transducer surface. The photo-induced proton pumps generate a flow of ions that produce a measurable change in pH between the separated solutions. The self-assembly procedure is experimentally quantified based on the capacitance characteristics of the bR membranes. The investigation confirms that the transducer is covered with the bR proton pumps at a mass density of 2.33 ng/cm 2 . Experimental tests also show that the proposed transducer can repeatedly generate pH gradients as high as 0.42 and absolute voltage differences as high as 25 mV when illuminated by an 18 mW, 568 nm light source. Furthermore, the DpH is observed to be nonlinear with respect to light intensity and exposure time. The DpH of the target solution is sufficient to cause a phenolphthalein indicator dye to change color or an ionic hydrogel micro-valve to expand.

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Vectorial insertion of bacteriorhodopsin for directed orientation assays in various polymeric biomembranes

Cited by 13 publications

References 31 publications

Fluorescence Approaches for Characterizing Ion Channels in Synthetic Bilayers

Fluorescence Approaches for Characterizing Ion Channels in Synthetic Bilayers

Light-Driven Biocatalysis in Liposomes and Polymersomes: Where Are We Now?

Fabrication of an optically driven pH gradient generator based on self-assembled proton pumps

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