Enzyme and Enzyme Fragments Purifiation by Specific Immunoadsorbents

Chromatography of crude extracts of Escherichia coli K‐12 on an immunoadsorbent column prepared with antibodies directed against aspartokinase I‐homoserine dehydrogenase I and elution with 6 M urea results in the one‐step isolation of the denatured protein. The same immunoadsorbent has been used for the purification of a protein extracted from a nonsense mutant, carrying only the aspartokinase activity, characterized by a shortened polypeptide chain. The tryptic maps of the two proteins are identical with those of the same proteins obtained by conventional methods. The application to protein sequencing is discussed.