出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.34, no.6, pp.294-303, 2009 (Released:2015-06-14)

All living organisms on the earth rely solely on a single molecule as an energy currency, ATP (adenosine triphosphate). This small molecule supports nearly all the activities that require energy, and our body synthesizes roughly as much ATP every day as our body weight. In the biological world, ATP synthesis is certainly the most prevalent chemical reaction and the enzyme, ATP synthase, responsible for most of this task, is one of the most ubiquitous, abundant proteins on the earth. ATP synthase uses physical rotation of its own subunits as a step of catalysis - a novel mechanism, different from any other known enzymes. Rotation is not a favourite motion in living organisms; there is no animal with wheels, no bird with a propeller, and no fish with a screw. The crystal structures of the main part of ATP synthase show in atomic detail how the appearance of this world tiniest motor made of protein is remarkably reminiscent of the man–made motors. The driving force that spins ATP synthase is trans-membrane gradient of hydrogen ion concentration that is generated by respiration (burning the food) or by sunshine. We have videoimaged the rotary motion of ATP synthase that spins as fast as several hundred revolutions per second. The mechanism of the motor is completely different from the man–made motor. ATP synthase is bi–particle structure with a common rotary shaft. The flow of hydrogen ions through the lower particle drives the rotation of the central rotor that then forces upper particle to make the bending motion for synthesis of ATP. Imagine billions of billion rotary motors are spinning in our body, day and night, without rest. When the motors stop, we die.
著者
林 久由 鈴木 裕一
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.36, no.6, pp.293-299, 2011 (Released:2012-05-18)
参考文献数
38

Chloride ions play many physiological roles, including regulation of cell volume, fluid secretion and acid.base balance. An efficient absorption of Cl- in the intestine is important to maintain the optimal levels of Cl- in the body. Three chloride absorptive pathways have been proposed : 1) a paracellular pathway, which is dependent on potential difference; 2) an electroneutral pathway involving parallel functioning of Na+/H+ exchange and Cl-/HCO3- exchange; 3) an HCO3- dependent Cl- absorptive pathway, which is not coupled to a parallel Na+/H+ exchange. Among these chloride absorptive mechanisms, the second electroneutral NaCl absorption is thought to be a predominant pathway. At least six Cl-/HCO3- exchangers (SLC4A1, SLC4A2, SLC4A3, SLC26A2, SLC26A3, SLC26A6) have been found in intestinal epithelial cells. However, the role of each exchanger and regulatory mechanisms in the intestine have not been well studied. This review in particular focuses on the role and regulation of SLC26A3 in the gastrointestinal tract.
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.34, no.6, pp.328-335, 2009 (Released:2015-06-14)
被引用文献数
1 1

It was previously considered that the practical application of liposomal medicines was very difficult. The pharmaceutical technologies for mass production, long term stability during storage, encapsulation efficiency of the drug, etc. were seemed big problems to be solved, and it was well known that the liposomal particles are apt to be entrapped in vivo by the reticuloendothelial system (RES) such as liver, spleen, etc. Fortunately, owing to the progress of science, about 10 liposomal medicines containing the anticancer agents, the antifungal agents, etc. were launched out and are now contributed to medical treatment in the world. Recently liposomes are expected to be useful as the vectors for in vivo nucleic acid (plasmid DNA, siRNA, etc.) therapy and as the tools for target validation in the area of drug discovery. There are already many liposomal reagents for transfection, and some clinical trials are performed using liposomes. It is considered that liposomes, the membrane–structure particles, have unlimited potential in the medical field.
著者
須郷 高信 斎藤 恭一
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.13, no.5, pp.272-282, 1988-09-01 (Released:2011-03-04)
参考文献数
72
被引用文献数
5 2

Many methods of recovery of uranium from seawater have been suggested : coprecipitation, adsorption, ion flotation, solvent extraction, and others. Of these, only the adsorption method using a suitable solid adsorbent seems to be feasible with regard to economic and envirom ental impacts. Extensive investigations of adsorbents have been carried out. Among the various organic resins, chelating resins containing amidoxime groups have been selected. A novel amidoxime-group-containing adsorbent of hollow-fiber form was prepared by radiation-induced graft polymerization of acrylonitrile onto a polyethylene hollow fiber, followed by chemical conversion of the produced cyano group to an amidoxime group. The fixed-bed adsorption column, 30 cm in length and charged with the bundle of amidoxime hollow-fibers, was found to adsorb uranium from seawater at a sufficiently high rate : 0.66 mg uranium per g of adsorbent in 25 days.
著者
酒井 清孝
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.14, no.1, pp.31-44, 1989-01-01 (Released:2011-03-04)
参考文献数
24

Various materials are presently available for hollow fiber dialysis membranes which satisfy technical and medical requirements such as high permeability to uremic toxins and water, biocompatibility, resistance to sterilization, and high mechanical strength. New dialysis membranes with high permeability to β2-microglobulin and with biocompatibility leading to low complement activation have been developed for more optimal hemodialysis. Data on structure and permeability are then required to prepare the new dialysis membranes. Much attention should be paid also to the geometry of hollow fiber dialysis membranes available for chronic renal failure patients with elevated hematocrits caused by the administration of erythropoietin.
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.33, no.3, pp.94-101, 2008 (Released:2015-06-18)

Serotonin transporter (SERT), a member of Na+/Cl– - dependent transporter family, is predicted to be a protein with a twelve membrane-spanning structure, which terminates the serotonergic neural transmission by re-uptaking serotonin into pre-synapse. It has been well-known that SERT is a target of antidepressants and abusive drugs. Although the pathogenesis of depression and mechanism underlying antidepressants action remains unclear, recent accumulated evidences have revealed that antidepressants promote the regeneration of neurons, which was damaged by repeated stress and recurrences of depression. In addition, analysis of crystal structure of bacterial leucine transporter, a homologue of mammalian Na+/Cl– - dependent neurotransmitter transporter, provides us a new information concerning the interactions of tricyclic antidepressants with serotonin transporter.
著者
田中 一宏 酒多 喜久
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.36, no.3, pp.113-121, 2011 (Released:2012-09-14)
参考文献数
48
被引用文献数
2

The recent research circumstances of photocatalytic overall splitting of H2O and the membrane separation of H2 and O2 for constructing the hydrogen production system by applying photocatalytic H2O splitting are introduced. Here, the principle of photocatalytic H2O splitting and photocatalysts for the reaction are explained on the historical aspect. Furthermore, the photocatalysts with high photocatalytic ability to the reaction, not only the photocatalysts and photocatalytic systems work under solar irradiation but also those show high efficiency are introduced. Incorporating gas separation membranes into the photocatalytic reactor leads to a safe and energy-efficient hydrogen production process. Since any research of application of gas separation membrane to this purpose has not been found in the literature, our research is introduced. The goal performance that the membrane should achieve to produce safe H2 and O2 streams have been determined by a simple model of a membrane module. Permeability and selectivity of H2 over O2 for silica membranes, carbon membranes, and polyimide membranes have been examined in a temperature range from 35 to 100 °C. Some silica membranes have passed the goal at 100 °C for a wet mixture of H2/O2(2/1).
著者
長井 孝紀 田中 滋康 高田 真理
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.29, no.3, pp.154-160, 2004-05-01 (Released:2011-03-04)
参考文献数
20

Amphibians regulate the osmotic and ionic composition of their body fluids by water and ion transport across their skin. When dehydrated, desert toads press down the pelvic region of ventral skin on moist surfaces to achieve maximal water absorption. Aquaporins (AQP) are trans-membrane proteins permeable to water. We cloned three isoforms of AQP (AQP-h1, -h2, -h3) in tissues of tree frogs. AQP-h3 was abundantly expressed in the pelvic region of ventral skin, facilitating water absorption across the skin. Antibodies to AQP-h3 labeled the cell membrane of the granulosum cells in the skin. AQP-h3 was progressively expressed during metamorphosis of larval frogs. Expression of AQP-h3 was facilitated by and diuretic hormone, argine vasotocin. Collectively, AQP-h3 is a molecule to play a positive role in water absorption across the amphibian skin. In bullfrogs short circuit current across the skin was suppressed by amiloride, a blocker for epithelial Na+ channel (ENaC), showing that transport of sodium ions occurs through ENaC. Na+ transport increased in parallel with metamorphosis of the tadpole. In cultured skins of the tadpole Na+ transport was facilitated by aldosterone, but counteracted by prolactin. Such counteraction seemed to be removed by thyroid hormone (T3) during metamorphosis to adapt a terrestrial environment.
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.31, no.4, pp.221-223, 2006 (Released:2015-07-01)
著者
大場 哲彦 渡名喜 力 大木 和夫
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.29, no.3, pp.169-179, 2004-05-01 (Released:2011-03-04)
参考文献数
22
被引用文献数
1 1

Laurdan, one of the environment-sensitive fluorescent probes, is useful for monitoring membrane fluidity and is widely used for spectroscopic and imaging applications. In the imaging applications, the generalized polarization parameter (GP), defined by two fluorescent intensities at characteristic wavelengths, is used as a measure of membrane fluidity and polarity. However, time-resolved fluorescent spectra of laurdan revealed that the three excited states concern with the emission spectra. We have measured the steady-state fluorescence spectra and the fluorescence anisotropy of laurdan, prodan and NBD-PE in the DPPC and DLPC bilayers at various temperatures. The spectral dependence on the excitation wavelength is interpreted as the red edge effects that are related to the existence of excited-state distribution of fluorophores on their interaction energy with the environment and the slow dielectric relaxation of this environment. The emission peak of laurdan in the liquid-crystalline phase is independent of the red edge excitation, while prodan and NBD-PE show significant red edge effects. This results strongly suggest that laurdan changes its electronic excited state by the specific interaction with a few water molecules in the bilayers and that in addition the non-specific solvent relaxation causes further spectral shifts in the case of prodan in the bilayers and laurdan in the micella. A new three state model for the absorption and emission of laurdan is proposed. The availability and limitation of the GP method are disscussed.
著者
浅野 真司
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.36, no.6, pp.278-285, 2011 (Released:2012-05-18)
参考文献数
35

Gastric acid secretion in parietal cells is performed by proton pump, H+, K+- ATPase, in combination with several related ion transporters located on the apical and basolateral membranes. In this review I will introduce several recent topics about molecular basis of gastric acid secretion in parietal cells. First, I wish to introduce 3D structures of H+, K+-ATPase resolved recently. The structures demonstrated the interaction between the α- and β- subunits fixes and favors the E2P conformation (the “rachet effect”). The binding site of a K+-competitive inhibitor SCH 28080 on the α- subunit of H+, K+-ATPase was also identified in the 3D structure. Secondly, I wish to introduce ion transporters on the apical membrane necessary for gastric acid secretion. Among others KCNQ1/KCNE2 was identified as a K+ channel involved in K+ recycling and replenishment of K+ in the lumen. Thirdly, I wish to introduce actin-binding proteins, ezrin and Huntingtin interacting protein 1 related (Hip1r), which are necessary for gastric acid secretion. Ezrin is involved in membrane fusion between tubulovesicles and apical membrane whereas Hip1r is involved in endocytosis and regeneration of tubulovesicles from apical membrane. Finally, the roles of parietal cells in differentiation of gastric epithelial cells as well as gastric acid secretion will be introduced.
著者
酒井 清孝
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.37, no.1, pp.2-9, 2012 (Released:2012-09-14)
参考文献数
34

The most commonly used artificial organ is the artificial kidney using dialysis membrane, a machine that performs a treatment known as hemodialysis. This process cleanses the bodies of renal failure patients by dialysis, filtration and adsorption which are simple physicochemical processes. Dialysis membranes account for the largest volume of artificial membranes, far outstripping other fields. Worldwide, the consumption of dialysis membranes has reached some 300 million square meters a year. More than 70% of the dialysis membranes in use are made of polysulfone. This paper describes dialyzers and dialysis membranes so far developed for blood purification.
著者
秋澤 忠男 越川 昭三
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.17, no.1, pp.12-18, 1992-01-01 (Released:2011-03-04)
参考文献数
17
被引用文献数
2 2

Phosphate (P) retention, resulted from renal insufficiency directly or indirectly provides pathogenetic roles to the human body. P related signs and symptoms include osteodystrophy, metastatic calcification, central or peripheral neuropathy, anemia, cardiomyopathy, lipid and carbohydrate mal-metabolisms, immunodysfunctions and so on. From these pathological effects of P, P is regarded as one of the major uremic toxins. In spite of the small molecular weight of P, P always shows lower dialysis efficiency than urea. This result can be partially explained by the interaction between negatively charged P and dialysis membrane. Although computer simulation model represented the increase in dialysis efficiency of P across the positively charged membranes, these membranes have not been clinically available. Dialysis membrane with larger membrane pore size and increased porosity significantly stimulated the P removal, however dialysis efficiency of P remained still lower than urea. From these results, it is strongly expected that membrane technology will succeed in the development of new dialysis membrane with more effective P removal.
著者
福島 義博 熊沢 紀之
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.13, no.2, pp.73-82, 1988-03-01 (Released:2011-03-04)
参考文献数
90

Plasma membrane (Na, K) -ATPase transports 3 Na+ out of and 2 K+ into the cell, and thus the pump is electrogenic. This review describes experiments on topical aspects of the cation movement mechanism of (Na, K) -ATPase, putting emphasis on electrogenic properties, reconstitution, and cation occlusion or deocclusion from the transport enzyme molecule.
著者
青木 隆史
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.22, no.3, pp.145-148, 1997-05-01
参考文献数
11

This paper describes that the optically active moieties, ((S) -<I>sec</I>-butylacrylamide (BAAm)), in <I>N</I>-isopropylacrylamide (IPAAm) copolymer chains affected the phase transition behavior and resulted in lower critical solution temperature (LCST) changes responding to foreign tryptophan (Trp). Copolymerization of (S) -<I>sec</I>-BAAm and IPAAm were carried out in DMF at 70&deg;C for 25 h using AIBN. The copolymer was water-soluble and showed the characteristic LCST near 27&deg;C. LCSTs of PIPAAm chains are affected by hydrophobic or hydrophilic nature of comonomers. Since sec-BAAm is insoluble in water, the component exhibited hydrophobic property. Therefore, poly ((S) -<I>sec</I>-BAAm-co-IPAAm) showed lower LCST as compared with that of PIPAAm. The LCSTs of the copolymer in the presence of L-Trp weve higher than those in the absence of the amino acid. It was understood that the optically active moieties in the copolymer stereospecifically interact with L-Trp, relatively enhancing hydrophilic property of the polymer chains. The copolymer increased the LCSTs in response to increasing L-Trp concentration. Hydrogels consisting of these comonomers will exhibit reversible swelling/ deswelling behavior in response to L-amino acids such as L-Trp. The polymers with the optically active moieties demonstrate the chiral discrimination to L-amino acids and are also good candidates to perform chiral separation.
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.32, no.3, pp.129-138, 2007 (Released:2015-06-18)

Oxygen is essential to most forms of life, but too much oxygen is harmful and can elicit tissue damage. Living creatures, therefore, have a tightly regulated system to deliver the necessary amount of oxygen to specific tissues at the right time. Red blood cells are ideal vehicles for delivering oxygen to tissues. Band 3 protein is the major membrane protein of red blood cells. The major membrane protein supports the oxygen delivering system by its anion exchange activity, cooperating with carbonic anhydrase and hemoglobin. Band 3 protein has unique structure within the molecule. Here, we briefly review the structure and function of band 3 protein.
著者
高野 幹久 湯元 良子
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.36, no.4, pp.145-153, 2011 (Released:2011-12-13)
参考文献数
25
被引用文献数
3 3

The lung is expected as a promising administration route for protein and peptide drugs. However, information concerning alveolar absorption mechanisms of these high molecular weight drugs is lacking. The alveolar region of the lung is lined with a continuous epithelium comprising of type I and type II epithelial cells, and squamous type I cells cover 90~95% and cuboidal type II cells cover 5~10% of the alveolar surface area. Using primary cultured alveolar type II and transdifferentiated type I cells, however, it was found that type II cells would play a significant role in albumin and insulin endocytosis from the alveolar space. Functional and siRNA studies suggest that albumin is taken up by clathrin-mediated endocytosis in type II cells, while clathrin- and caveolae-independent but dynamin-dependent pathway is involved in insulin endocytosis. The approach to enhance insulin uptake by the alveolar epithelial cells and absorption from the lung is also discussed.
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.33, no.5, pp.208-214, 2008 (Released:2015-06-14)

We reviewed scientific methods for measuring erythrocyte deformability such as micro pipette aspiration tech-nique, ektacytometry and nickel mesh filtration technique, from a quantitative and sensitive point of view. Then werepresented deformability of sickle cells and hereditary spherocytes including effects of medical treatments.Moreover, we showed a strong correlation between blood flow in vivoand erythrocyte deformability. Thus, we clari-fied physiological and medical significances of erythrocyte deformability.