Glutamic acid folding

The functionalization of folded motifs is based on an understanding of secondary and tertiary structures (Fig. 2) and must take into account the relative positions of the residues, their rotamer populations and possible interactions with residues that do not form part of the site. For example, glutamic acid in position i has a strong propensity for salt-bridge formation, and thus reduced reactivity, if there is a Lys residue available i-4 in the sequence, but the probabihty is much less if the base is i-3 [60]. Fortunately, there is a wealth of structural information on the structural properties of the common amino acids from studies of natural proteins that provides considerable support for the design of new proteins. The naturally occurring amino acids have so far been used to construct reactive sites for catalysis [11-13], metal- and heme-binding sites [14,15,19,21,22] and for the site-selective functionalization of folded proteins [24,25]. 

GAA encodes a glutamic acid residue. If this glu is essential for the catalytic activity of the protein, any mutation (except GAA to GAG) will be harmful to the activity of the protein. If the glu residue is not essential for catalysis or proper folding, the possible mutations, in order of increasing potential severity, are ... 

Method. To 1—5 nmoles of amine in 0.1-0.5 ml of water are added three volumes of a solution of DNS-C1 in acetone (usually 5—45 mg/ml). The DNS-C1 should be present in a several fold molar excess. The reaction mixture is then saturated with sodium bicarbonate and permitted to stand for 30-60 min until reaction is complete. Occasional heating at 35-45 °C may be required for some amines of lower reactivity. The excess of DNS-C1 is then removed by adding an excess of proline or glutamic acid. The DNS derivatives are then... 

In conclusion, troponin binds Ca2+ in six-fold coordination and all oxygen ligands are provided from amino acids. No water is needed for the coordination complex. Aspartic acid and glutamic acid occupy key positions in the four calcium binding regions of the molecule. Transfer of calcium to tropomyosin and the actin filament during contraction is achieved by coordination changes. 

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