Information-transducing membranes

This chapter mainly concerns Itself with three major fields of blofunctlonal synthetic membranes (1) blocatalytlc, (2) energy-transducing and (3) Information-transducing membranes (Figure 1). 

In addition to blocatalytlc, energy-transducing and Information transducing membranes, there are, of course, other types of blofunctlonal synthetic membranes. However, this review concentrates on these three Important blofunctlonal membranes. The historical background of their development, the molecular mechanism In biological membranes on which blofunctlonal synthetic membranes are modelled, the methodology of membrane preparation and current trends In the research and development are described. 

In 1969, Chlbata and co-workers (20) succeeded in developing the first Industrial process Incorporating Immobilized enzymes. Since then a number of applications for Immobilized biocatalysts have appeared In various areas. Updike and Hicks (21) proposed a novel use for membrane-bound enzymes for an analytical device, an "enzyme electrode," which bases its selectivity on the membrane-bound enzyme. The details appear below In the section on "Information-transducing Membranes."... 

One striking characteristic of the coupling ATPase of energy-transducing membranes, apart from the extraordinarily large number of different polypeptide subunits, is the existence of two different polypeptides involved in the response of the enzyme to the inhibitor oligomycin. One binds the inhibitor, the other, separated in space from the former by possibly as much as 10 to 15 A, confers oligomycin sensitivity to the entire enzyme complex. How could the transfer of information between these two polypeptide subunits and their concerted interaction with the ATPase proper be visualized ... 

Maggio, B., Fanani, M.L., Rosetti, C.M., Wilke, N. 2006. Biophysics of sphingolipids II. Glycosphingolipids an assortment of multiple structural information transducers at the membrane surface. Biochim. Biophys. Acta 1758 1922-1944. 

PKC is a family of enzymes whose members play central roles in transducing information from external stimuli to cellular responses. Members of this family of serine/ threonine kinases respond to signals that cause lipid hydrolysis. PKC isozymes phosphorylate an abundance of substrates, leading to both short-term cellular responses such as regulation of membrane transport and long-term responses such as memory and learning. 

Some sensors may include a separator which is, for example a membrane. In the receptor part of a sensor the chemical information is transformed into a form of energy which may be measured by the transducer. The transducer part is a device capable of transforming the energy carrying the chemical... 

A unified model for mechanotransduction allows comparison of mechanoreceptors from many organisms and cell types. Mechanoreceptors nearly universally use ion channels for transducing sensory information. Mechanoreceptors are either neurons or are neuroepithelial cells with synapses, and the currency of the nervous system is the membrane potential. Opening an ion channel allows a cell quickly and extensively to modulate its membrane potential, and hence neurotransmitter release, the final step in mechanoreception at the cellular level. 

In these molecular communications an information molecule is selectively recognized and transduced by the corresponding receptor which is a characteristic protein assembly found on the cellular membrane surface as schematically illustrated in Fig.3. Major categories based on its constitutions are... 

In biological taste reception, taste substances are received by the biological membrane of gustatory cells in taste buds on tongue (Figure 1). Then the information on taste substances is transduced into an electric signal, which is... 

In the present study, therefore, lipid membranes were used as transducers of taste information. Artificial lipid materials, such as dioleyl phosphate (DOPH) or dioctadecyl-dimethyl-ammonium, were used to construct a lipid membrane and responses of electrical potential and resistance of the membranes were measured [9-15]. It was confirmed that the lipid membranes could discriminate five primary taste substances. Moreover, they could detect the interactions between taste substances observed in biological systems. The response properties were different in different types of lipids. If a hydrophobic part of a lipid was different, taste substances which can be detected were different. These facts indicate that the taste sensor can be realized by the use of various kinds of lipid membranes as transducers. 

Although the above lipid membranes had the ability to sense the taste by responding to many taste substances, information was insufficient to recognize quality of the taste. This weakness was overcome by means of a multichannel sensor, where transducers were composed of lipid membranes immobilized with a polymer [16-23]. We investigated responses of the sensors to various taste solutions. The electrode showed five different response patterns to five primary tastes with small experimental deviations. The patterns looked alike when the applied substance elicited the same taste in humans. 

Although there is some information on the effects of mechanical forces on the structure of collagen and the possible mechanism by which this is transduced at the cell membrane, very little information is available on the... 

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