Glutamic acid molecular mechanism

S. W. Fox (from 1984, director of the Institute for Molecular and Cellular Evolution of the University of Miami) made the highly controversial suggestion that the amino acid sequences in the proteinoids are not random. Nakashima prepared a thermal polymer from glutamic acid, glycine and tyrosine the analysis showed that two tyrosine-containing tripeptides had been formed pyr-Glu-Gly-Tyr and pyr-Glu-Tyr-Gly (Nakashima et al 1977). The result was confirmed (Hartmann, 1981). A closer examination of the reaction mechanism showed that the formation of these two tripeptides under the reaction conditions used depends on three parameters ... 

Polymorphs and solvated crystals is generally observed in pharmacentical indnstry [1], The bioavailability, stability, solnbility, and morphology of the pharmacentical products are very influenced by polymorphs [2-7], therefore the control of the polymorphic crystallization is very important. The crystallization process of polymorphs and solvated crystals is composed of competitive nucleation, growth, and transformation from a meta-stable form to a stable form [4], Furthermore, the crystallization behavior is influenced by various controlling factors such as temperature, supersaturation, additives and solvents [8], In order to perform the selective crystallization of the polymorphs, the mechanism of each elementary step in the crystallization process and the key controlling factor needs to be elucidated [8], On the other hand, we reported for L-Glutamic acid and L-Histidine system previously [4] that the nucleation and transformation behaviors of polymorphs depend on the molecular stractures. If the relationship between molecular stmcture and polymorphic crystallization behavior is known, the prediction of the polymorphism may become to be possible for the related compound. However, detail in such relationship is not clearly understood. 

Photomechanical effects have been also observed in monolayers obtained from poly(L-glutamic acid) modified with carbocyanine1831 and spiropyran dyes.184 In the latter case, irradiation at 254 nm produced changes in the molecular conformation, which in turn caused photomodulation of the surface pressure and surface area of the films. From all these examples, it appears that photoresponsive monolayers are quite fascinating systems, which may eventually come to be regarded as a machine to transform light into mechanical energy . 81 ... 

However, since the proportion of most metabohtes present as free acid at pH 7 is low, it is likely that the carriers have separate binding sites for protons and anions. The relationships between proton concentrations, substrate concentrations and rates of transport have been examined in order to gain insight into the molecular mechanisms of transport for the glutamate, pyruvate and phosphate carriers. 

In standard molecular mechanics methods, all atoms and bonds between atoms are explicitly defined, i.e., they are either present or not. In order to model the changes in pH, one must therefore alter the protonation states of ionizable amino acid side chains. For a decrease in pH, the relevant side chains are those of histidine, glutamate, and aspartate. Their pXa values in solution are 6.08, 4.15, and 3.71, respectively [98]. The local protein environment can, however, change the pKa of individual residues significantly. Langella et al. [99] calculated theoretical pKa values of the relevant side-chains based on the coordinates deposited for human recPrP obtained by protein NMR at pH 4.5 and pH 7.0 [39, 76]. Although differences in the local conformation of residues between the various structures lead to a... 

Our present knowledge of the helix-coil transition in synthetic polypeptides, with particular reference to the poly-y-benzyl-h-glutamate-dichloroacetic acid-1,2-dichloroethane system, is briefly reviewed. Recent results concerning the effect of solvent composition and of polypeptide and solvent deuteration on the thermodynamic properties of the transition show that both the thermodynamics and presumably the molecular mechanism of the transition are generally more complicated than had been previously supposed. 

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