Synthetic Methods for the Preparation of Polypeptides

Studies of protein structures and their functions in nature or mode of actions, as in the case of enzymes, are only part of various investigations. Much effort is also put into syntheses of different polypeptide. Such polymers can actually be formed from mixture of various amino acids by simply heating them together. The products, however, are complex polymeric materials with random distribution of amino acids and do not resemble any naturally occurring materials. 

Base catalyzed ring opening polymerization reactions of A -carboxy-a-amino acid anhydrides also result in formations of polypeptides  

Duplication of naturally occurring polypeptides is needed, however, to imderstand the details of structures that lead to biological activities. One of the early works consisted of assembling 23 amino acids to form synthetic pig corticotropin [43]. The molecules were built stepwise [43]. 

One technique used in these syntheses is to protect the terminal amino nitrogen by forming protective derivatives that can subsequently be easily cleaved. This is often done by converting them to amide groups  

The condensations can be carried out by a number of different techniques [26, 28]. A few of them will be shown below. One is to carry out amino acyl halide reactions  

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