Machines molecular

This dynamics is regarded as a quantum-mechanical transmission of the reciprocating motion of the proton transfer to the rotation of methyl group, which can become one of the elements of the so-called molecular machine. 

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The question then is, to what degree can the microscopic motions influence the macroscopic ones is there a flow of infonnation between them [66] Biological systems appear to be nonconservative par excellence and present at least the possibility that random thermal motions are continuously injecting new infonnation into the macroscales. There is certainly no shortage of biological molecular machines for turning heat into correlated motion (e.g. [67] and section C2.14.5 note also [16]). 

Many key protein ET processes have become accessible to theoretical analysis recently because of high-resolution x-ray stmctural data. These proteins include the bacterial photosynthetic reaction centre [18], nitrogenase (responsible for nitrogen fixation), and cytochrome c oxidase (the tenninal ET protein in mammals) [19, 20]. Although much is understood about ET in these molecular machines, considerable debate persists about details of the molecular transfonnations. 

The development of efficient algorithms and the sophisticated description of long-range electrostatic effects allow calculations on systems with 100 000 atoms and more, which address biochemical problems like membrane-bound protein complexes or the action of molecular machines . 

In the 1950s, biologists (notably Francis Crick and James Watson) discovered the molecular basis for information coding in DNA and established that the workings of cells were molecular machines tvith understandable structure and function. Mathematician John von Neuman developed a mathematical theory of self-reproducing machines based on the biological theories. 

Iaing75a] Laing, R. Artificial Molecular Machines A Rapproachment Between Kinematic and Tessellation Automata, in Proceedings of the International Symposium on Uniformly Structured Automata and Logic, Tokyo (1975). 

Iaing75b] Laing, R. Some Alternative Reproduction Strategies in Artificial Molecular Machines, J. Theor. Biol, 54 (1975) 63-84. 

We are still years away from building molecular machines. In fact, using STM as a tool for molecular engineering has been compared to trying to build a wristwatch with a sharpened stick. 

Supposing that scientists succeed in constmcting molecular tools, they must overcome another obstacle for nanotechnology to be effective. A medical nanosubmarine is likely to contain about a billion (10 ) atoms. At an assembly speed of one atom per second, it would take 10 seconds to constmct one such device. That s almost 32 years If the assembly rate can be increased to one atom per micro-second, the constmction time for a 1-billion-atom machine drops to 1000 seconds, or just under 17 minutes. That s not bad if only a few machines are needed, but molecular machines are tiny, so large numbers of machines will be required for any practical application. Consequently, scientists will have to discover ways to mass-produce nanodevices. 

Another example of nanotechnology research is an attempt to develop biological molecules that can interact with fullerene, Cgo. By themselves, Cgo molecules are difficult to manipulate because they are greasy and inert. Scientists envision using proteins bound to Cgo, like the one illustrated here, as molecular machines that can deliver Cgo units to build larger carbon structures. 

The properties of these rotaxane dendrimers are quite different from those of the individual rotaxanes or dendrimers and often a blend of both. In view of the versatile characteristics that a dendron or dendrimer can manifest, several new properties can be imparted to the rotaxanes. For example, the solubility of rotaxanes in organic solvents as well as in water can be significantly improved when large dendrimer units are appended enhancing the prospects of their use as molecular machines. The dendritic units can also influence the photo/electro-chemical properties of the rotaxanes. Employing photo-receptive dendron units, photo chemically driven molecular machines may be developed, where the dendrons act as antenna for photo-harvesting [62]. 

In particular, rotaxane dendrimers capable of reversible binding of ring and rod components, such as Type II, pseudorotaxane-terminated dendrimers, can be reversibly controlled by external stimuli, such as the solvent composition, temperature, and pH, to change their structure and properties. This has profound implications in diverse applications, for instance in the controlled drug release. A trapped guest molecule within a closed dendrimeric host system can be unleashed in a controlled manner by manipulating these external factors. In the type III-B rotaxane dendrimers, external stimuli can result in perturbations of the interlocked mechanical bonds. This behavior can be gainfully exploited to construct controlled molecular machines. 

Richter OMH, Ludwig B. 2003. C)dochrDme c oxidase—Structure, function, and physiology of a redox-driven molecular machine. Rev Physiol Biochem Pharmacol 147 47-74. 

Baranoff E, Barigelletti F, Bonnet S, Collin J-P, Flamigni L, Mobian P, Sauvage J-P (2007) From Photoinduced Charge Separation to Light-Driven Molecular Machines. 123 41-78 Barbara B, see Curely J (2006) 122 207-250... 

R. Golestanian, T. B. Liverpool, and A. Ajdari, Propulsion of a molecular machine by asymmetric distribution of reaction products, Phys. Rev. Lett. 94, 220801 (2005). 

COlfen H (2007) Bio-inspired Mineralization Using Hydrophilic Polymers. 271 1-77 Collin J-P, Heitz V, Sauvage J-P (2005) Transition-Metal-Complexed Catenanes and Rotax-anes in Motion Towards Molecular Machines. 262 29-62 Collins BE, Wright AT, Anslyn EV (2007) Combining Molecular Recognition, Optical Detection, and Chemometric Analysis. 277 181-218 Collyer SD, see Davis F (2005) 255 97-124 Commeyras A, see Pascal R (2005) 259 69-122 Coquerel G (2007) Preferential Crystallization. 269 1-51 Correia JDG, see Santos I (2005) 252 45-84 Costanzo G, see Saladino R (2005) 259 29-68 Cotarca L, see Zonta C (2007) 275 131-161 Credi A, see Balzani V (2005) 262 1-27 Crestini C, see Saladino R (2005) 259 29-68... 

Karlen SD, Garcia-Garibay MA (2005) Amphidynamic Crystals Structural Blueprints for Molecular Machines. 262 179-227... 

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