Protein A is the most common method of immunoglobulin purification. However, there are certain types of antibodies, such as the single-chain antibodies IgE, IgY, and IgM, that cannot be purified using Protein A. An alternative antibody purification method, thiophilic affinity chromatography (TAC), is ideal for these types of applications, as well as immunoglobulin purification in general, including IgG, IgM, IgA, Fab and Fc fragments, and C3 and C4 complement factors.
TAC is a powerful and simple method for the purification of proteins—in particular, immunoglobulins. It is an economical alternative to Protein A for purifying antibodies from whole serum and tissue culture. In comparison to Protein A-based immunoadsorbents, thiophilic adsorbents have a broader affinity for immunoglobulins. Further, more than 99% of total proteins are recovered using a thiophilic adsorbent, in comparison to less than 92% for phenyl and 75% for octyl agarose adsorbents.
TAC has broad specificity for immunoglobulins of different classes and subclasses from a wide range of species and has capacity similar to that of other affinity methods.
Its advantages are the simplicity of the sample preparation, applicability with a range of source materials and protein concentration ranges, and gentle elution conditions, unlike the popular protein A/protein-G separation methods that require pH extremes for elution, to which the antibodies may not be sufficiently stable.