ABSTRACT
The chemistry of modem solid-phase peptide synthesis [I] is well developed and is quite efficient, and aspects of this technique are described in this monograph as well as in several excellent reviews and books [2-6]. A few recent developments that have contributed to the production of high-quality peptides are briefly outlined here. Several different types of resins possessing the C-terminal amino acid already anchored to the support are commercially available, and methods for low-racemization attachment of this residue are available. Coupling reactions using carbodiimides, phosphonium salts, and uronium salts typically proceed in very high yield. Side-chain protecting groups for amino acids such as arginine, histidine, asparagine, and glutamine have reduced side reactions attributable to these residues. New, improved deprotection and cleavage cocktails are being reported that produce less byproducts. In spite of these advances, impurities such as truncated peptides, deletion sequences, peptides containing racemized residues, incompletely deprotected peptides, protecting group by-products, scavengers, and remnants of resins and linkers may be present in the crude product, thus necessitating purification steps.
