Principles of Biochemistry Volume 1 - A. Lehninger 1985

Biomolecules
Water
The acid-base properties of amino acids serve as the basis for amino acid analysis

As we will see in Chapter 6, the first step in determining The Structure of a given protein is its hydrolytic Cleavage into its constituent Amino Acids. Following this, it is necessary to determine the quantity of each type of amino acid present in the protein. One might assume that separating the resulting amino acid mixture after Hydrolysis, identifying them, and quantitatively determining the content of each of the 20 amino acids would require a great deal of effort and patience. However, highly efficient and sensitive Methods have now been developed that make it possible to solve such problems quite rapidly. These methods include, in particular, Electrophoresis and Ion-exchange Chromatography. Both of these techniques are based on differences in the acid-base properties of amino acids—that is, on differences in the sign and magnitude of their net electrical charge at a given pH value, which can be readily predicted from the pK' values and titration curves of the amino acids under investigation.