Chemical Biology 3OA3, September 2009 Page 39 In this experiment, you will synthesize a simple peptide amide. 1.2 Peptide Synthesis: Activation and Protection Because amines only react with carboxylic acids under extreme conditions, the standard strategy for forming amide bonds is to prepare a chemically active functional derivative of the carboxylic acid and allow it to react with an amine. For example, a carboxylic acid can be activated by converting to an acyl chloride, which, on treatment with an amine, gives an amide: This simple strategy, so effective for monofunctional components, fails miserably when applied to making amide bonds between amino acids. With such bifunctional compounds, the initial activation step produces an intermediate that reacts with itself to produce a polymer before the amine component is added. For example, the amino acid glycine, on conversion to glycyl chloride, polymerizes to polyglycine and other condensation products, such as the
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