Chemical Synthesis modify target structure

In Section 15, details are provided for the chemical modification of peptide C-terminal carboxylic acids. Many of these C-terminally modified peptides possess important biological activities and the wide range of experimental procedures may be applicable to the synthesis of novel peptide target structures. 

After synthesis of a protein has been completed, a few amino acid residues in the primary sequence may be further modified in enzyme-catalyzed reactions that add a chemical group, oxidize, or otherwise modify specific amino acids in the protein. Because protein synthesis occurs by a process known as translation, these changes are called posttranslational modification. More than 100 different posttranslation-ally modified amino acid residues have been found in human proteins. These modifications change the structure of one or more specific amino acids on a protein in a way that may serve a regulatory function, target or anchor the protein in membranes, enhance a protein s association with other proteins, or target it for degradation (Fig. 6.14). 

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