Glutamic acid sidechains

Sidechain conservatism may be split up into at least two kinds 1) substitutions which conserve sidechain bonding forces - providing similar electrostatic, hydrophilic, or hydrogen bonding interactions, and 2) substitutions conserving secondary structure propensity. For instance, substitution of glutamic acid with aspartic acid conserves charge, but this could have a considerable effect upon the secondary structure propensity of the peptide. 

Figure 3. Some of the commonly occurring sidechains (a) glycine (Gly, G) (A) leucine (Leu, L) (c) glutamic acid (Glu, E) (d) lysine (Lys, K) (e) tyrosine (Tyr, Y) (/) tryptophan (Tip, W). All atoms, including hydrogens (black dots), are shown the a-carbons are indicated by lines, oxygens by dots, and nitrogens by crosshatching in the corresponding circles open circles are other carbon atoms and the flexible dihedral angles are indicated by arrows with the one nearest to the a-carbon called x1, the next x2> and so on.

Figure 23.1 Transamination. This process moves the amino group from one keto acid to another. Glutamate and cr-ketoglutarate are always one of the two pairs involved, so that glutamate serves as a clearing house for amino groups. The R in the two compounds on the left is not an unusual atom. It is the chemist s shorthand way of generalising - i.e. this could be any amino acid sidechain.

Itoh, M. Peptides. I. Selective protection of a- or sidechain carboxyl groups of aspartic and glutamic acid. A facile synthesis of p-aspartyl and y-glutamyl peptides. Chem. Pharm. Bull. 17, 1679 (1969). 

Amino acids have two functional groups, the carboxylic group and the amino group, which can be converted to surfactant with a reactive molecule bearing a hydrophobic chain. Amino acids with reactive sidechains, such as lysine, arginine, aspartic acid, and glutamic acid, offer opportunities for the molecular design of AAS. 

References to polypeptides bearing long alkyl sidechains are almost confined to the esters of poly(a,L-glutamic acid) (PyAG-n) and poly (a or p,L-asparfic acid) (PpAA-n or PaAA-n) whose chemical stmctures are depicted in Fig. 1. In these compounds the alkyl sidechain is connected to the mainchain by a carboxylate group that is directly anchored to the backbone in the case of poly(P-peptide)s and through a methylene or ethylene spacer in poly (a-aspartate)s and poly(a-... 

---