Assembling-disassembling process

The occurrence of the redox-driven reversible assembling-disassembling process involving copper complexes of 16 has been verified through cyclic voltammetry experiments at a platinum electrode in a MeCN solution. Figure 2.17 shows the CV profile obtained with a solution of the double-strand helicate complex [ Cu 21 (16)212 +. 

By contrast with the straight arrangement of tubulin subunits in protofilaments both in Zn-induced sheets and in MT, the T2R complex is curved. Interestingly, the curvature of T2R is very similar to that of the depolymerization products of MT, suggesting that the structure of tubulin in T2R reflects the structures of GDP/tubu-lin in oligomers and in curved tubulin protofilaments. Therefore, comparison of the structures of curved and straight tubulins can help one to understand the mechanism of the MT assembly-disassembly process. 

One may define molecular and supramolecular dynamic materials as materials whose components are linked through reversible covalent or non-covalent connections and undergo spontaneous and continuous change in constitution by assembly/disassembly processes in a given set of conditions. Such materials may in principle respond to multiple physical or chemical stimuli by constitutional variation and thus act as adaptive materials. 

It is not known if this difference reflects a real difference in the magnitude of the assembly-disassembly process in different types of smooth muscle cells. 

Tubulin is a heterodimeric protein consisting of a and p subunits which polymerises to form microtubules. These microtubules have a number of functions within eukaryotic organisms including chromosome segregation, motility and the maintenance of cellular morphology. The assembly-disassembly process (see Fig. 1) is critical for the proper functioning of microtubules within the cell. ... 

Amendola, V. Fabbrizzi. L. Pallavicini, P. Controlling the assembling/disassembling process of metal-containing superstructures. Coord. Chem. Rev. 2001. 216. 435. 

Consequently, supramolecular materials are by nature dynamic materials, defined as materials whose constituents are linked through reversible connections (covalent or noncovalent) and undergo spontaneous and continuous assembly/disassembly processes in a given set of conditions [47], Because of their intrinsic ability to exchange their constituents, they also have combinatorial character so that they may be considered as dynamic combinatorial materials (DCMs). Supramolecular materials thus are instructed, dynamic, and combinatorial, they may in principle select their constituents in response to external stimuli or environmental factors and therefore behave as adaptive materials [45],... 

In preliminary experiments Muller et al. [35] have shown that it is possible to encapsulate a M036 cluster within a big wheel M0154 cluster. This means that it is possible to imagine that the cluster assembly-disassembly process can be used to template or amplify the selection of other clusters, forming a complex library of interconverting species that can adapt to a given fitness landscape, see Fig. 5.4 [36]. 

Such a new binding motif in DNA duplex will influence research in such diverse areas as medicinal chemistry, materials science, and bionanotechnology. Introduction of metal-induced base pairs into DNA would not only affect the assembly-disassembly processes and the structure of DNA double strands but also confer a variety of metal-based functions on DNA. Examples of one-dimensional metal arrays in solution are quite limited and, for the most part, are found only in the solid state. This strategy represents a new method for arranging metal ions in solution in a discrete and predictable fashion, leading to the possibility of metal-based molecular devices such as molecular magnets and wires. 

Wegner also treated the case wherein assembly is coupled to nucleotide hydrolysis. Here, we consider a slight modification of his model to deal with the microtubule process. Normally, the concentration of GTP is maintained by use of a GTP-regenerating system (MacNeal et ai, 1977), and the system at the steady-state plateau of assembly can be described as in Scheme II. Under these conditions, the assembly-disassembly reactions are no longer reversible, and the primed rate constants are used to emphasize that we are dealing with a different case. The rate equations for the two ends are now given as ... 

Biochemical processes such as protein unfolding/refold-ing and supramolecular assembly/disassembly take place on a time scale of seconds to minutes after readjusting the temperature of a system. Most commercially available glass-jacketed cuvettes are not suitable for temperature jumps on this time scale, as a result of the slow kinetics of heat transfer across substances with characteristically high dielectric constants, and their use can convolute the time scale of the temperature change onto the time scale... 

The interaction of actin and myosin is key to the generation of contractile forces in skeletal muscles. Skeletal muscles are composed of thick and thin filaments the thick filaments are composed primarily of myosin and thin filaments contain actin. The interaction between the two is a reversible self-assembly process that is followed by disassembly that separates actin from myosin. This separation initiates movement of myosin with respect to actin and results in shortening of the muscle, causing force generation. It is the assembly and disassembly process that we are interested in in this section. 

Smith and co-workers prepared the dendritic assembly 190 from two L-lysine dendrons, bearing a benzo-18-crown -6 unit at the focal point, and l,4-bis(aminomethyl)benzene dihydrochloride. They then studied by NMR analysis the disassembly process induced by addition of potassium ions <2002AGE3254, 2003T3999>. 

Fig. 2. Schematic light-induced assembly and disassembly process. Reproduced with the permission of Wiley-VCH (41).

On the other hand, incineration is employed on a large scale in the stockpile program. The U.S. Army s baseline incineration system includes a process for reverse assembly (disassembly) of the stored munitions and collection of the contained agent. As such, it constitutes a complete munition processing system for munitions that have been properly stored. Agent drained from these munitions is sent to a liquid incinerator for destruction, while energetics and munition bodies are sent to separate furnaces for destruction or decontamination. This baseline system is now in use at... 

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