JPH02247233A - Ion transmission membrane and ion transfer method using the membrane - Google Patents

Abstract

PURPOSE:To obtain the subject transmission membrane exhibiting selective ion-transmittance by light irradiation, having expanded active wavelength range and useful in an optical information processing industry by supporting a plurality of substance groups having different sensitive wavelength ranges on a lipid membrane. CONSTITUTION:The objective transmission membrane contains (A) two or more kinds of substance groups having different sensitive wavelength ranges and (B) an ionophore in a lipid membrane. Preferably, the component A is a photoreceptive protein or its derivative, especially bacteriorhodopsin or halorhodopsin and the component B is oligopeptide, etc. Furthermore, the component is preferably held in the lipid membrane in an oriented state to uniformize the ion transmission direction.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a selective ion permeable membrane by light irradiation using a group of substances that absorb light and transport ions, and an ion transport system using the membrane. It is about the method.

[Prior Art] Currently, it is known that one of the functions of biological membranes is selective permeation of ions, etc., and for example, this can be used to retain substances with active ion transport properties in thin membranes. Research is underway to obtain dialysis membranes and various sensors that have functions similar to those of biological membranes. Furthermore, a membrane using the above principle can be used in an element that has the function of easily converting the difference in ion concentration across the membrane into an electrical signal by combining it with an ion-sensitive electrode, etc., as a so-called membrane potential. A device using this film is expected to be applied as a chemical device that converts a chemical signal into an electrical signal. As an example of a device using a protein as an ion active transporting substance, a construction of a biochemical device such as a sensor for implantation in a living body is disclosed in Japanese Patent Laid-Open No. 62-41158.

By the way, if light irradiation is used to control ion permeability, it not only facilitates the external control method, but also
For example, it will become possible to realize a chemical element that performs photoelectric conversion with a small amount of heat. Ion permeable membranes, which have excellent volumetric and energy efficiency as well as good controllability, are promising as conversion elements in the field of optical communications.

In addition, in controlling membrane ion permeability by light incidence,
It is desirable to be able to arbitrarily set the wavelength of the incident light. Furthermore, it goes without saying that it is desirable to be able to select the direction of the membrane's ion permeability, rather than controlling it only in one direction, and to be able to select it in accordance with the wavelength of incident light.

However, at present, no element has been obtained in which ion permeability due to light irradiation is sufficiently controlled.

[Purpose of the invention]

Therefore, an object of the present invention is to provide an ion permeable membrane in which the control of ion permeation can be set arbitrarily by light irradiation.

[Means and actions to achieve the purpose]

That is, the present invention provides an ion-permeable membrane in which two or more types of substances that actively transport ions (that is, have different sensitive wavelength ranges) when irradiated with light in different wavelength ranges are supported in a lipid membrane, and the above-mentioned The present invention provides an ion-permeable membrane that supports ionophores that have ion transport ability using the driving force of the concentration gradient generated by active transport of ions.

Furthermore, the present invention provides an ion transport method for an ion permeable membrane in which the ion permeability of the ion permeable membrane is changed by selectively irradiating the ion permeable membrane with a wavelength of light.

The present inventors focused on the fact that the selectivity (specificity) and reaction efficiency of biochemical reactions observed in the living body are extremely high compared to physical or chemical reactions, and the irradiation wavelength range can be adjusted arbitrarily. An ion-permeable membrane and its control method that can be selected according to the irradiation energy, have high sensitivity, and control the ion permeability of the membrane for specific ions, as well as select the direction of ion transmission according to the incident wavelength. We have been considering the following.

In this process, the present inventors focused on photoreceptor proteins, which exist in the retina of animals and are substances that control light sensing by transporting substances with extremely high sensitivity and high resolution to visible light in living organisms. However, the use of a photoreceptor protein that has a similar structure and function and can exist relatively stably at room temperature is retained in a lipid membrane, and is a substance produced by microorganisms.
Focusing on antibiotics with ion-transporting ability, we aim to retain these antibiotics or ionophores, which are naturally or synthetically obtained ion-transporting substances (ionophores) with similar structures and functions, within the same lipid membrane. We have discovered that the above function can be achieved by performing the following steps.

Photoreceptor proteins can be mentioned as substances with the function of absorbing light and transporting various ions as referred to in the present invention, but as long as they have such functions, various photoreceptor proteins or their analogues may be used. can be used, and the types are not limited.

A typical example of a photoreceptor protein is a pigment protein that exists in the animal retina, so-called photoreceptor. Receive light at the nodes;
It has the effect of replacing this with some kind of change in membrane ion permeability. Examples of such substances include rhodopsin, polyphyllopsin, and iodopsin, which have been extracted and purified. In addition, there are bacteriorhodopsin and halorhodopsin, which are present in the cell membrane of halophilic bacteria, which have the same function as visual substances, and these are preferable because they are relatively easy to handle.

Bacteriorhodopsin is derived from Halobacterium (Halo
Halobacterium halobium (Hal.

It is a main component of protein in the cell membrane (purple membrane) of bacteria such as Bacterium halobium, contains retinal as a chromophore, and has the function of transporting hydrogen ions (proton pumping ability) in response to visible light [A, Danon, W.
5toeckenlus; Proc, Natl, Aca
d, 5ciUSA, Eyu, 1234 (1974)].

This bacteriorhodopsin is, for example, [D.

Oes terbe 1 t and W, 5toeck
-enius;Method in Enzy-
Mology, 3rd edition, 667 (1974), the purple membrane was extracted from highly halophilic bacteria, and further,
[K-8, Huang, H, Bay-1ey and
H, G, KhoranaProc, Nat 1. A
cad, sci.

It can be obtained by removing lipids from the purple membrane obtained using the method described in U.S.A., E.U., 323 (1980).

In addition, halorhodopsin is produced by highly halophilic bacteria such as R1, R,
A retinal protein discovered from bacteriorhodopsin-deficient strains such as L-h, which has the property of transporting sodium ions in response to visible light [A, Y, Matsuno
and Y.

Mukohata: Biochem, Bi.

T) hYS, Res, Common, +18,237 (
1977); R, E, Mac Donald.

R, U, Greene, R, D, C1ark.

E., V., Lindley: J., Biol., Ch-em.
, 254, 11831 (1979)].

This halorhodopsin is derived from highly halophilic bacteria, for example [Y, M
ukohata, Y., Sugiyama and Y.
Kaji, J., Usukura and E., Yama.
da; Photoch-em, Photobiol,,
33,539 (+981)].

Further, the structure of a natural photoreceptor protein isolated from a living body can be changed without impairing its function to form a derivative with a changed photosensitive wavelength, which can be used in the present invention.

Typically, the retinal moiety can be substituted to change the optical absorption wavelength. To give a specific example of the formation of such a derivative in rhodopsin, for example, bacteriorhodopsin with a maximum absorption wavelength of 570 nm by changing the retinal moiety to a) all-trans-retinal [
P, Town o r, W.

Gaerther, et al., Eur.

J.Biochem, 117, 353 (1981)
b) Bacteriorhodopsin with a maximum absorption wavelength of 550 nm by using 13-cis-retinal [same as above] c) Bacteriorhodopsin with a maximum absorption wavelength of 475 nm by using 5,6-cihydroretinal [
R,Mao,R,Gov-injee,et,al,
, Bioche-mistry, 20,428 (19
81)], d) Bacteriorhodopsin with maximum absorption wavelength of 430 nm by retro-γ-retinal [K-S, Huang, H, Baylay, et.
al,,Fed,Proc,.

40.1659 (1981)], e) bacteriorhodopsin with a maximum absorption wavelength of 593 nm by using 3,4-dihydroretinal [
F. Tokunaga.

T, Ebrey, Biochemistry.

Kamiyu, 1915 (1978)], etc.

Furthermore, the amino acid sequence of bacteriorhodopsin has already been clarified [Yu, A., Ovchinnikov
,N.G.,Abdula-ev,et,al,,Bio.
org, Khim.

Mutual, 1573 (1978)], and the nucleotide sequence of the basophilic bacteriorhodopsin gene [R, J.

Dunn, J. M., McCoy et al., Proc.

Natl. Acad. Sci., 78.6744 (19
81)]. Based on these findings, it has become possible to synthesize protein analogs in which the amino acid sequence of bacteriorhodopsin is substituted by constructing recombinant DNA [N, R.

Hackett, L. J., 5tern, et.

al,,J,Bi'o1. Chem,,262°927
7 (1987)], such photoreceptor protein-like substances can also be used in the present invention.

Depending on the configuration of the membrane ion-permeable membrane in which two or more proteins having different light absorption wavelength regions are desired, the photoreceptor proteins described above may be selected and used.

In the present invention, the lipid membrane holding the photoreceptor protein exhibits ion impermeability, the interior of the membrane is hydrophobic, and the surface of the membrane is hydrophilic. As the material for the lipid membrane, known amphipathic compounds that can form a monomolecular membrane or a multimolecular membrane can be used. These lipid molecules with membrane-forming ability are composed of a long-chain alkyl group with 8 or more carbon atoms and a hydrophilic group, and the hydrophilic group is a cation such as C1, (CI+, ), -QC. -CI.

Anions such as CH, (CH,), -0C-CI-SO, -Na" (2C, -3uccinyl-Son-), e.g. (2C, -glycero- (glycidoxy)
It may be either a nonion such as g) or a zwitterion such as (2C,,N''C,C,PO,'').

Among these lipid materials, glycerophospholipids such as phosphatidylcholine (lecithin), phosphatidylethanolamine, and dihu phosphatidylglycerol; sphingophospholipids such as sphingomyelin and ceramide syriatin; and sphingolipids such as cerebroside, sulfatide, and ceramide oligohexoside. and glyceroglycolipids such as glycosyldiacylglycerol that contain carbohydrates as hydrophilic groups are lipids that constitute biological membranes, so they incorporate the photoreceptive proteins mentioned above to form lipid membranes that retain photoreceptive proteins. It can be said that it is a particularly suitable material for making the protein function efficiently.

A typical example is soybean phospholipid lecithin.

This is [Y, Kagawa and E, Rack
er, J, Biol, Chem, 246°5477 (
1971)]. Various lipids can be used as long as they have the above-mentioned functions, and the type thereof is not limited.

In addition, the lipid membrane referred to in the present invention is one formed from the above-mentioned lipid materials and consists of a monolayer of lipids, or a membrane composed of two monolayers of lipids (lipid bilayer). (membrane) or a structure in which three or more lipid monomolecular films are laminated (lipid multilayer film) can be used. However, each monomolecular layer may be one that is polymerized by UV irradiation or ultraviolet irradiation.

Among these, retaining photoreceptive proteins within a lipid bilayer membrane is advantageous because the photosensitive pigment proteins can be reconstituted into a structure similar to that in vivo, and their functions can be effectively utilized. Furthermore, the aforementioned bacteriorhodopsin exists in halophilic bacteria as a complex with a lipid layer called the purple membrane, and it is convenient because it is possible to extract fragments of this lipid-protein complex.

For example, [E.

Packer and W, 5t=oecke −
n+us, J, Biol, Chem,, 249°662
(1974)] and [K-8, Huang.

H, Bayley and H, G, Kho-r
ana, Proc, Nat 1. Acad.

Sc I, USA, 77.323 (1980)], the above-mentioned lipids are suspended in a solution with an appropriate salt concentration, and liposomes are formed with sonication as necessary. It can be obtained using a method in which a desired photosensitive pigment protein is added to a solution during formation and incorporated into the formed lipid membrane.

The product thus obtained can be processed, for example, by column chromatography, [C.

Lind, B., Hojeberg and H.

G, Khorana, J, Biol, Chem.

Proteoliposomes incorporating photosensitive pigment proteins can be separated and purified using an ultracentrifugation method using a sucrose concentration gradient method as described in "Otsu" Yodan, 8298 (1981).

A lipid bilayer membrane layer in which the proteoliposomes purified in this manner are preformed is immersed in an appropriate solvent and adsorbed and fused within this membrane to form a photoresponsive ion-permeable membrane.

In addition, as is known for purple membranes, a protein-lipid bimolecular composite membrane can be formed by deploying proteoliposomes in a Langmuir tank and adhering them to the surface of a lipid bilayer membrane layer. In this case, a planar film can be obtained in which a hydrophilic surface is formed on the substrate side by horizontal deposition, and a hydrophobic surface is formed on the substrate side by vertical dipping. By immersing the thus constructed composite membrane in an appropriate solvent, it is possible to adsorb and fuse proteoliposomes holding a protein different from the protein in the membrane. According to this method, it is possible to form a composite membrane (photoresponsive ion permeable membrane) in which a photoreceptive protein that reverses the direction of ion permeation is incorporated into a single layer of membrane. Then, the composite membrane can incorporate different types of photoreceptor proteins into the lipid membrane in a uniform direction for each type of photoreceptor protein.

FIGS. 5 and 6 are schematic cross-sectional views showing the structure of an ion-permeable membrane holding two different photoreceptor proteins.

In the figure, numeral 1 represents an ion-permeable membrane, and 1a and 1b represent two different photoreceptor proteins.

Next, a method for controlling the photoresponsive ion-permeable membrane configured as described above will be explained with reference to the drawings.

(See Figure 5) By the method shown above, two photoreceptor proteins 1a and 1, each of which responds to different wavelength ranges, were
Photoresponsive transparent membrane 1 with b oriented in the same direction within two lipid molecules
form. Two different photoreceptor proteins 1a and 1b
For example, 1a is on the short wavelength side λ
1, 1b is selected to be located on the long wavelength side λ.

In the figure, a and b indicate incident light on the short wavelength side and incident light on the long wavelength side, respectively. The ion permeability of this membrane is achieved over a wider wavelength range than when 1a or 1b is present alone. Moreover, according to this configuration, the amount of ions transmitted can be controlled according to each wavelength.

FIGS. 6(A) and 6(B) are schematic cross-sectional views showing other configuration examples.

In this example, the transparent film 1 is 2 that responds to different wavelength ranges, respectively.
The two photoreceptor proteins 1a and 1b are oriented in different directions so that the ion transmission directions are opposite to each other. In this film, the directionality of ion transport is determined by changing the wavelength of incident light to λ, for example.
can be arbitrarily selected by switching from λ to λ.

In addition, by taking advantage of this difference in directionality, we further added 1a and l
photoreceptor protein 1 so that the light absorption bands of b overlap moderately.
By selecting a and 1b, it is also possible to significantly improve the wavelength selectivity for light having a wavelength near λ or A2.

Therefore, in the present invention, ionophores are incorporated into the above-mentioned ion-permeable membrane (an ion-permeable membrane in which two or more types of photoreceptor proteins each sensitive to different wavelength ranges are retained in a lipid membrane) to transport multiple types of ions. form an ion-permeable membrane that can

Ionophore as used in the present invention refers to a substance that simultaneously transports another type of ion using the concentration gradient generated as a driving force when the photoreceptor protein transports ions due to light irradiation (ion passive transport type). .

Specific examples of ionophores with ion transport ability include gramicidins, palinomycin, nonactin, monactin, nigericin, alamethicin, monensin,
A23187. In addition to natural oligopeptides derived from microorganisms such as X-537A, artificially synthesized cyclic oligopeptides and the like may be used. Also included are organic compounds such as cyclic polycorals (crown ethers), polyether polyamines (cryptands), and cyclams. Various ionophores can be used as long as they have the above-mentioned functions, and the type thereof is not limited.

FIG. 1, FIG. 2, FIG. 7, and FIG. 8 are schematic cross-sectional views showing the structure of the ion permeable membrane of the present invention.

In the figure, numeral 1 represents an ion permeable membrane, 1a and 1b represent two different photoreceptor proteins, 2 represents a porous support base, and 3 represents an ionophore. Collagen, cellulose, porous glass, etc. can be used as the substrate.

Next, a method for controlling the photoresponsive ion-permeable membrane configured as described above will be explained with reference to the drawings.

As shown in FIG. 3, two different photoreceptor proteins 1a and lb and an ionophore 3 are oriented within two lipid molecules to form an ion permeable membrane 1.

The ion transmission directions of two different photoreceptor proteins 1a and 1b are oriented in the same direction.

The two different photoreceptor proteins 1a and 1b are selected such that their maximum absorption wavelengths are located, for example, on the short wavelength side λ for 1a and on the long wavelength side λ for 1b. a, b in the figure
are the incident light on the shortwave side, respectively.

Indicates incident light on the long wavelength side. The ion permeability of this membrane is achieved over a wider wavelength range than when 1a or 1b is present alone.

Furthermore, by introducing an ionophore, the permeability of a second ion different from the first ion is also changed using the concentration gradient generated by the active transport of the first ion carried out by 1a or 1b by light irradiation as a driving force. be able to.

FIGS. 4(A) and 4(B) are schematic cross-sectional views showing other configuration examples of the present invention.

In this figure, two different photoreceptor proteins 1a and 1b are oriented so that their ion transmission directions are opposite.

In this film, the directionality of ion transport can be arbitrarily selected by, for example, switching the wavelength of incident light from A1 to λ. In addition, by utilizing this difference in directionality and selecting photoreceptor proteins 1a and 1b so that the light absorption bands of 1a and 1b suitably overlap, it is possible to Selectivity can also be significantly improved.

Furthermore, by introducing an ionophore, 1a
Alternatively, the directionality of the ion transport of the second ion, which is different from the first ion, can be selected using the concentration gradient generated by the active transport of the first ion carried out by 1b as a driving force.

〔Example〕

The present invention will be described in detail below with reference to Examples, but these are not intended to limit the scope of the present invention in any way.

(Example 1) Ha
lobacterium hal.

The purple membrane extracted from the Hua bium R1 strain was
Surfactant Tri-tonX according to the method of ng et al.
-100 (manufactured by Wako Pure Chemical Industries, Ltd.) to remove lipids from the resulting purple membrane to obtain bacteriorhodopsin, a photoreceptor protein. Using a portion of bacteriorhodopsin thus purified, its chromophore was extracted using the method of Tokunaga et al. [F.

Tokunaga and T, I was a
.

Membrane, 9.73 (1984)],
It was replaced with naphthyl retinal, which is a type of retinal analog. The maximum absorption wavelength of bacteriorhodopsin is 56
In contrast, the maximum absorption wavelength of analog bacteriorhodopsin using naphthyl retinal as a chromophore is distributed from 442 nm to 503 nm depending on the mixing ratio. Like bacteriorhodopsin, this analog bacteriorhodopsin exhibits active proton transport activity upon irradiation with light.

The analog bacteriorhodopsin using naphthyl retinal obtained as described above and the above-mentioned Y, Kag
The soybean phospholipids purified by the method of Awa et al. were reconstituted as proteoliposomes based on the method of S. Huang et al. mentioned above. This proteoliposome is 0
．． In a KCf solution with a concentration of 15 mol/l, irradiation with monochromatic visible light from a mercury lamp was carried out through a monochromator.
The pH change at that time was examined and compared with the pH change of proteoliposomes produced only by normal bacteriorhodopsin without the analog bacteriorhodopsin. As a result, proteoliposomes incorporating the analog bacteriorhodopsin showed equivalent proton active transport properties over the incident light range from around 440 nm to around 500 nm, and when coexisting with a system using normal bacteriorhodopsin, controlled incident light It has been shown that the range of use can be greatly expanded.

Next, bacteriorhodopsin purified according to the method of S. Huang et al. and palinomycin, one of the ionophores selectively permeable to potassium ions, were added at 2 μM per 0.1 mg/ml of bacteriorhodopsin.
, and the soybean phospholipid azolectin purified according to the method of Y. Kagawa et al.
The above three materials were reconstituted as a planar film using the method of M. and Montal et al. mentioned above.

Furthermore, as mentioned above, proteoliposomes containing the analog bacteriorhodopsin prepared by the method of S. Huang et al. I fused and adsorbed it so that it was. At this time, the directionality of proton transport was maintained.

FIGS. 9 to 12 are schematic diagrams best showing the features of the first embodiment of the present invention. In FIG. 9, 4 is an analog bacteriorhodopsin using naphthyl retinal, and 5 is a proteoliposome containing 4. In FIG. 10, 6 is bacteriorhodopsin, 7 is palinomycin, an ionophore, and 8 is a bimolecular lipid membrane consisting of soybean phospholipid. FIG. 11 shows 5 in FIG. 9 fused, adsorbed, and cleaved from the left side of 8 in FIG. 10. FIG. 12 shows the entire membrane in the same figure gently immersed in a bathtub 11 made of a light-transmitting material and left standing. In the same figure, bacteriorhodopsin moves protons from left to right.
The analog bacteriorhodopsin is kept in an orientation that transports protons from right to left. In the figure, potassium ions are contained on the left side of the membrane 10 immersed in the solution, and no potassium ions are contained on the right side. However, the osmotic pressure on both sides of 10 is made equal (pH electrodes 12.13 and potassium ion electrodes 14.15 are immersed on both sides of 10.

Next, when visible light of 560 nm was irradiated from the left side of the bathtub 11, the value of the pH electrode 12 increased, and the value of 5 decreased. On the other hand, the value of ion electrode 14 decreased, and the value of ion electrode 15 increased.

Next, when the 560 nm irradiation light was turned off and the pH electrode value returned to the value before irradiation, 442 nm light was irradiated from the left side of 11, the value of pH electrode 12 decreased, and the value of 13 increased. Also, the values of ion electrodes 14 and 15 continued to change.

Here, it has been shown that bidirectional proton transport is controlled by light irradiation with different wavelengths, and potassium ion permeability is also changed simultaneously by palinomycin, which uses the concentration gradient caused by proton transport as the driving force. Ta.

(Example 2) In Example 2, the changes in bidirectional proton transport and potassium ion permeability due to light irradiation with different wavelengths mentioned in Example 1 were investigated not only for potassium ions but also for sodium ion permeability. Changes were made.

In FIG. 10, a planar membrane was prepared in the same manner as in Example 4 using 2 μM of monensin (about 0.1 mg/mj' of bacteriorhodopsin), which is a sodium ionophore, as the ionophore. FIG. 11 shows a proteoliposome containing an analog bacteriorhodopsin using naphthyl retinal (5 in FIG. 9) fused, adsorbed, and cleaved from the left side of the planar membrane 8 in FIG. 10. FIG. 12 shows the entire layer shown in FIG. 12 being gently immersed in a bathtub 11 made of a light-transmitting material and left standing. In the figure, bacteriorhodopsin is held in a direction in which protons are transported from left to right, and analog bacteriorhodopsin is held in a direction in which protons are transported from right to left. In the figure, thorium ions are contained on the left side of the membrane 10 immersed in the solution, and no thorium ions are contained on the right side. However, the osmotic pressure on both sides of 10 should be equal. A pH electrode 12.13 and a sodium ion electrode 14.15 are immersed on both sides of the cell.

Next, when visible light of 560 nm was irradiated from the left side of the bathtub 11, the value of the pH electrode 12 increased, and the value of pH electrode 13 decreased. On the other hand, the value of ion electrode 14 decreased, and the value of ion electrode 15 increased.

Next, when the 560 nm irradiation light was turned off and the value of the pH electrode returned to the value before irradiation, 442 nm light was irradiated from the left side of 11, the value of pH electrode 2 decreased, and the value of 13 increased. . Also, the values of ion electrodes 14 and 15 continued to change.

Here, it was shown that bidirectional proton transport can be controlled by irradiation with light of different wavelengths, and that sodium ion permeability can also be changed simultaneously by monensin using the concentration gradient caused by proton transport as a driving force.

(Example 3) In Example 3, the changes in bidirectional proton transport and potassium ion permeability due to light irradiation with different wavelengths mentioned in Example 1 were investigated not only for potassium ions but also for magnesium ions. Changes were made.

In FIG. 10, a flat membrane was prepared in the same manner as in Example 4 using 2 μM (about 0.1 mg/mI of bacteriorhodopsin) of A23187, which is a magnesium ionophore, as the ionophore.

FIG. 11 shows a proteoliposome containing an analog bacteriorhodopsin using naphthyl retinal (5 in FIG. 9) fused, adsorbed, and cleaved from the left side of the planar membrane 8 in FIG. 10. FIG. 12 shows the entire layer shown in FIG. 12 being gently immersed in a bathtub 11 made of a light-transmitting material and left standing. In the figure, bacteriorhodopsin is held in a direction in which protons are transported from left to right, and analog bacteriorhodopsin is held in a direction in which protons are transported from right to left.

In the figure, magnesium ions are contained on the left side of the membrane 10 immersed in the solution, and no magnesium ions are contained on the right side. However, the osmotic pressure on both sides of 10 should be equal. 10
A pH electrode 12.13 and a magnesium ion electrode 14.15 are immersed on both sides.

Next, when visible light of 560 nm was irradiated from the left side of the bathtub 11, the value of the pH electrode 12 increased, and the value of pH electrode 13 decreased. On the other hand, the value of ion electrode 14 decreased, and the value of ion electrode 15 increased.

Next, when the 560 nm irradiation light was turned off and the pH electrode value returned to the value before irradiation, 442 nm light was irradiated from the left side of 11, the value of pH electrode 12 decreased, and the value of 13 increased. Also, the values of ion electrodes 14 and 15 continued to change.

Here, it was shown that bidirectional proton transport can be controlled by light irradiation with different wavelengths, and that the permeability of magnesium ions can also be changed simultaneously by A23187 using the concentration gradient caused by proton transport as a driving force.

〔Effect of the invention〕

According to the present invention, it is possible to construct an ion-permeable membrane that has selective ion permeability by light irradiation by using a group of substances that absorb light and transport ions, and to improve the membrane ion permeability by light irradiation. When controlling by irradiation, the wavelength range of incident visible light can be set over a wide range, and the effective wavelength range can also be expanded.

Furthermore, by holding the ionophore in the same membrane as the substance group that absorbs light and transports ions, the permeability of not only one type of ion but a plurality of types of ions can be controlled by light irradiation.

Furthermore, the direction of ion transmission through the transmission film of the present invention can be switched and reversibly changed depending on the incident wavelength. This also makes it possible to significantly improve the wavelength selectivity of ion permeability.

Since the difference in ion concentration between ion-permeable membranes can be easily converted into an electrical signal using an ion electrode, the present invention can be applied to the optical information processing industry, for example when converting an optical signal to an electrical signal. It is also highly expected that it will contribute to the construction of photoelectric conversion elements in the field of optoelectronics.

[Brief explanation of drawings]

Figures 1 and 2 are schematic cross-sectional views showing the structure of the ion permeable membrane of the present invention, and Figures 3 and 4 (A,) and (B) explain the principle of the ion permeable membrane of the present invention. Figures 5 and 6 (A) and (B) are schematic cross-sectional views of the ion-permeable membrane used to explain the principle of the ion-permeable membrane used in the present invention. 7 and 8 are cross-sectional views showing the structure of the ion-permeable membrane of the present invention, and FIGS. 9 to 12 are schematic views illustrating examples. 1... Ion permeable membrane 2... Porous support a... Short wavelength side incident light b... Long wavelength side incident light 1a... Short wavelength light receiving protein 1b... Long wavelength light receiving Protein 4...Analog bacteriorhodopsin 5...Proteoliposome 6...Batateriorhodobusin 7...Ionophore 8...Lipid planar membrane 9...Lipid planar membrane in which proteoliposomes are fused, adsorbed, and cleaved 10... Lipid planar membrane in which proteoliposomes are fused, adsorbed, and cleaved 11... Bathtub 12.13... pH electrode 1415... Iosi electrode 3rd opening h-< 0---=0 +- --〇o---1110o-m--< 0-111110o---1-0 5--O Q---1-0 0----=. o-11110 C--0 0---< 0--1.

Claims (10)

[Claims] (1) Two or more types of substance groups with different sensitive wavelength ranges,
An ion-permeable membrane characterized by having an ionophore supported in a lipid membrane and further having an ionophore supported in the lipid membrane. (2) The ion-permeable membrane according to claim 1, wherein the substance group that performs the active ion transport is a photoreceptor protein or a derivative thereof. (3) The ion-permeable membrane according to claim 2, wherein the photoreceptor protein is rhodopsin, polyphyllopsin, or iodopsin. (4) The ion permeable membrane according to claim 2, wherein the photoreceptor protein is bacteriorhodopsin or halorhodopsin. (5) The ion-permeable membrane according to claim 1, wherein the substance that actively transports ions is oriented and held in the lipid membrane so that ions permeate in the same direction. (6) The ion-permeable membrane according to claim 1, wherein the substance that actively transports ions is oriented and held in the lipid membrane so that the ion permeation direction is opposite between different types. (7) The ion permeable membrane according to claim 1, wherein the ion permeable membrane is formed on a porous substrate. (8) The ion-permeable membrane according to claim 7, wherein the porous substrate is collagen, cellulose, or porous glass. (9) The ion permeable membrane according to claim 1, wherein the ionophore is selected from oligopeptides, polycorals, polyethers, polyamines, or cyclams. (10) A method for transporting ions in an ion-permeable membrane, comprising changing the ion permeability of the ion-permeable membrane by selectively irradiating the ion-permeable membrane with the wavelength of the light.