ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS 164, 30-36 (1974) A Two-Step Procedure for Purification of Papain From Extract of Papaya Latex’

A method is presented for purifying papain from extracts of papaya latex. The procedure involves precipitation of theextract ofpapaya latex with sodium chloride followed by affinity chromatography of the redissolved pr cipitate. Precipitation of theprotein from the latex extract isnecessary to separate he papain from aterial which interferes withthe binding of papain to the affinity column. During affinity chromatography, t e affinity column is overloaded to insure absence inthe final product ofimpurities which are capable of binding tothe affinity column. The papain prepared by this procedure yielded an amino acid analysis and an N-terminal amino acid analysis expected for asample of pure papain. NoMet was detected on amino acid analysis norwas the presence ofN-terminal residues other than Ile detected. On polyacrylamide d scgel electrophoresis at pH 4.3, papain prepared bythe method described in this work was indistinguishable from crystalline papain which was prepared by the method of Kimmel and Smith, and further purified by affinity chromatography. Both disc gel patterns consisted of a single band and a trailing shadow hich was less than 5 % of the main band. In routine spectrophotometric assays, the specific activity towar