Amino acids are important biochemicals, as they are the building blocks from which proteins and polypeptides are assembled. We begin this chapter with an examination of some of the fundamental chemistry of amino acids: their structures, stereochemistry and synthesis. We then discuss the nature of peptides and of the peptide bond, and present the complex issue of determining the order in which the various amino‑acid residues occur in a given peptide. Once a chemist knows the exact order the of the residues in a given peptide, the next challenge is to determine a method by which the same peptide can be prepared in the laboratory. Thus, two sections are devoted to the problem of protein synthesis. The final sections in the chapter deal with the classification, overall structure and denaturation of proteins. 7.1: Introduction 7.2: Structures of Amino Acids 7.3: Amino Acids, the Henderson-Hasselbalch Equation, and Isoelectric Points 7.4: Synthesis of Amino Acids 7.5: Peptides and Proteins 7.6: Peptide Synthesis 7.7: Protein Structure 7.8: Enzymes and Coenzymes 7.9: How do Enzymes Work? Citrate Synthase 7.10: Chapter Objectives 7.11: Amino Acid Analysis of Peptides 7.12: The Edman Degradation Edman degradation is the process of purifying protein by sequentially removing one residue at a time from the amino end of a peptide. To solve the problem of damaging the protein by hydrolyzing conditions, Pehr Edman created a new way of labeling and cleaving the peptide. Edman thought of a way of removing only one residue at a time, which did not damage the overall sequencing. This was done by adding Phenyl isothiocyanate, which creates a phenylthiocarbamoyl derivative with the N-terminal. 7.13: The Merrifield Solid-Phase Technique