Water-mediated molecular recognition

If roow is much smaller than tcc, then recognition become an efficient procedure with structural integrity. The loss of order in the picosecond timescale is significant in changing the entropy, and this contribution to the free energy is possibly controlled by the change in the rotations of water molecules. 

An essential chemical for life processes water in biological functions 

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Series of various mono,- bi-, and poly-(thio)urea-functionalized (poly)saccha-rides have already been synthesized and studied for molecular recognition of, e.g., dimethyl and phenylphosphate as model compounds for monoanionic and polyanionic phosphate esters, respechvely [111]. Thiourea derivatives such as 195-197 were analyhcally identified to provide double hydrogen bonding mediated host-guest complexes of well-defined dimension and orientations and were also reported to serve as phosphate binders even in the hydrogen bonding environment of water (Figure 6.57) [111]. 

Levy Y, Onuchic JN. Water mediation in protein folding and molecular recognition. Ann. Rev. Biophys. Biomol. Struct. 2006 35 389-415. 

However, lipid bilayers are impermeable to ions and most polar molecules, with the exception of water, so they cannot, on their own, confer the multiple dynamic processes which we see in the function of biological membranes. All of this comes from proteins, inserted into the essentially inert backbone of the phospholipid bilayer (Figure 3.27), which mediate the multiple functions which we associate with biological membranes, such as molecular recognition by receptors, transport via pumps and channels, energy transduction, enzymes, and many more. Biomembranes are noncovalent assemblies of proteins and hpids, which can best be described as a fluid matrix, in which lipid (and protein molecules) can diffuse rapidly in the plane of the membrane, but not across it. 

The aminoacylation reaction of t-RNA is a key step in the translation of genetic information. The general molecular mechanism reported by Moras and co-workers highlights the role of water molecules in the recognition of t-RNA, which entails water-mediated hydrogen-bond interactions [12]. They showed that more than 20... 

Robinson CR, Sligar SG (1993) Molecular recognition mediated by bound water a mechanism f(OT star activity of the restrictirai enzyme endonuclease EcoRI. J Mol Biol 234 302-306... 

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