Proteins and conduction

I. Willner and E. Katz, Integration of layered redox proteins and conductive supports for bioelectronic applications. Anyrw Chem. Int. Ed. 39, 1180-1218 (2000). 

Cao, T.B., F. Wei, X.M. Jiao, J.Y. Chen, W. Liao, X. Zhao, and W.X. Cao. 2003. Micropattems of protein and conducting polymer molecules fabricated by layer-by-layer self-assembly and photolithography techniques. Langmuir 19 8127—8129. 

Microbial Electrosynthesis, Fig. 2 (a) Electron trans- pathway via multiheme proteins in Shewanella oneidensis fer pathway via multiheme proteins and conductive pili in (for further details, see text)... 

STM has, however, not only been applied to metals and semiconductors, but also to a wide variety of organic and biological systems, like thin films on conducting substrates [5.15, 5.16] as well as protein and DNA molecules [5.43-5.46]. 

The antimuscarinic drug atropine, and its derivative ipratropiumbromide, can also be used for antiarrhyth-mic treatment. Muscarinic receptors (M2 subtype) are mainly present in supraventricular tissue and in the AV node. They inhibit adenylylcyclase via G proteins and thereby reduce intracellular cAMP. On the other hand, activation of the M2 receptor leads to opening of hyperpolarizing Ik.acii and inhibits the pacemaker current If probably via the (3y-subunit of the Gi protein associated with this receptor. The results are hyperpolarization and slower spontaneous depolarization. Muscarinic receptor antagonists like atropine lead to increased heart rate and accelerated atrioventricular conduction. There are no or only slight effects on the ventricular electrophysiology. 

The axonal membrane is a lipid bilayer in the nerve fibre. Ionic channels and other proteins are located in the membrane to achieve electrical activity. Action potentials are generated and conducted along the membrane. 

In addition to intracellular heme-containing proteins, big-conductance calcium-dependent K+ (BKCa) channels and calcium-spark activated transient Kca channels in plasma membrane are also tar geted by CO [3]. As well known, nitric oxide (NO) also activates BKca channels in vascular smooth muscle cells. While both NO and CO open BKCa channels, CO mainly acts on alpha subunit of BKCa channels and NO mainly acts on beta subunit of BKca channels in vascular smooth muscle cells. Rather than a redundant machinery, CO and NO provide a coordinated regulation of BKca channel function by acting on different subunits of the same protein complex. Furthermore, pretreatment of vascular smooth muscle... 

Eleven controlled diet and environment experiments have been designed in a way that can be used to investigate the effects of protein nutrition and heat and/or water stress on diet-tissue A N. Laboratory rats were raised on purified, pelletized diets in which the isotopic composition of proteins, lipids and carbohydrates were well characterized and their proportions accurately and precisely measured (Ambrose and Norr 1993). Four experiments involved manipulation of temperature and/or water availability. Of these four experiments, one used a diet with high (70%) protein concentrations and heat/water stress (36°C) and three used normal (20%) protein concentrations. Seven experiments were conducted at normal temperature (21°C) with water ad libitum. Of these seven experiments, two used diets formulated with veiy low protein (5%), three with normal protein and two with high protein concentrations. 

Given the actual scenario, one can state that the emerging field of nanotechnology represents new effort to exploit new materials as well as new technologies in the development of efficient and low-cost solar cells. In fact, the technological capabilities to manipulate matter under controlled conditions in order to assemble complex supramolecular structures within the range of 100 nm could lead to innovative devices (nano-devices) based on unconventional photovoltaic materials, namely, conducting polymers, fuUerenes, biopolymers (photosensitive proteins), and related composites. 

The exact process(es) by which a2-adrenoceptors blunt release of transmitter from the terminals is still controversial but a reduction in the synthesis of the second messenger, cAMP, contributes to this process. a2-Adrenoceptors are negatively coupled to adenylyl cyclase, through a Pertussis toxin-sensitive Gi-like protein, and so their activation will reduce the cAMP production which is vital for several stages of the chemical cascade that culminates in vesicular exocytosis (see Chapter 4). The reduction in cAMP also indirectly reduces Ca + influx into the terminal and increases K+ conductance, thereby reducing neuronal excitability (reviewed by Starke 1987). Whichever of these releasecontrolling processes predominates is uncertain but it is likely that their relative importance depends on the type (or location) of the neuron. 

Myelin A protein and phospholipid sheath that surrounds the axons of certain neurons. Myelinated nerves conduct impulses more rapidly than nonmyelinated nerves. 

Metabolism. As noted in Section 3.4.3, the metabolism of americium consists of binding interactions with proteins and probably complex formation with various inorganic anions such as carbonate and phosphate, and carboxylic acids such as citrate and lactate (Durbin 1973 Taylor 1973 Webb et al. 1998). Experiments have not been conducted to determine whether americium binds to metallothionein, but such binding is not likely. 

Bakhshi, A. K., P. Otto, and J. Ladik. 1988. On the Electronic Structure and Conduction Properties of Aperiodic Proteins Study of Six-Component Polypeptide Chains. J. Mol. Struct. (Theochem) 180, 113-123. 

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