**1. Introduction**

Peptide science is presently witnessing an enormous growth in its synthetic developments. Many synthetic peptides have commercial and pharmaceutical applications. But the synthesis of these peptides is a difficult task. The advent of solid-phase peptide synthesis has changed the face of peptide synthesis by opening the way to the extensive use of synthetic peptides in chemical and biomedical applications. Along with this landmark discovery, many other developments such as improved synthetic strategies, selection of protecting groups, automated synthetic methods, and advanced purification and analytical techniques were also evolved [1]. This book is intended essentially for those investigators who wish to make use of synthetic and antimicrobial peptides in their research and also provide practical information regarding the synthesis of difficult sequence-containing peptides. At the same time, it is addressing the common problems relating the synthesis and applications of synthetic peptides.

## **2. Methods of peptide synthesis**

Methods for the chemical synthesis of peptides are divided into two groups: classical solution phase and solid-phase peptide synthesis (SPPS). Solution phase is the traditional way for large-scale synthesis of peptides. But these methods are labor-intensive and time-consuming because of its intermediate purification procedures and unforeseeable solubility issues. Hence many researchers who need to synthesize peptides choose the more convenient solid-phase approach. One of the main difficulties in solid-phase assembly of peptides is that of obtaining reasonable quantities of pure peptides. Investigations dealing with the quantitative aspects of polymer-supported reactions have shown that the insoluble support does have a significant dynamic influence on the bound substrates. An efficient polymeric support for peptide synthesis should have optimum hydrophobic-hydrophilic balance compatible with the peptide being synthesized. Systematic studies on the polymersupported reactions show that the use of a flexible polymer support enhances the reactivity [2]. But the design and development of polymer supports having appropriate hydrophobic-hydrophilic balance is a difficult task.
