Amino Acid Analyzer

Amino acid (AA) analysis of proteins is a method to determine the absolute amounts of individual amino acids in a sample. The method can be applied to samples containing free amino acids. However it may also be used on peptides and protein samples after hydrolysis into amino acids.

AA analysis can be used for determination of the relative composition of amino acids in a protein. It can also be used for determination of the absolute amount of a protein or peptide if the amino acid sequence is known. Finally, it is used for purity estimation of a purified protein.

There have been many AAA procedures developed over the years. The gold standard remains the post-column labeling method of Stein and Moore. This method involves protein hydrolysis, cation‐exchange chromatography of the released amino acids, followed by in-line post-column labeling with ninhydrin. Post-column methods are less affected by sample buffer constituents and sample handling variability than procedures based on precolumn labeling.

Common Applications

• Estimating amount of peptide/protein in different types of food samples
• Determination of physiological amino acids in biological fluids
• Estimating degree of purity of products
• Determination of amino acid composition
• Identifying proteins in databases
• Check of correct recombinant protein expression
• Estimating tryptophan and/or cysteine content of a peptide/protein