A method for the purification of human α1-fetoprotein from the ascites fluid of a hepatoma-bearing patient is described that is capable of yielding large quantities of pure α1-fetoprotein within a relatively short period of time. The technique is based entirely on the physicochemical properties of the α1-fetoprotein molecule and uses sequential purification steps: ion-exchange chromatography on DEAE-Sephadex A-50, molecular-sieve chromatography on Sephadex G-200, negative-affinity chromatography on Sepharose-Blue Dextran, positive-affinity chromatography on concanavalin A-Sepharose and, finally, molecular-sieve chromatography on Sephadex G-100. The efficiency of the entire procedure in its present form is 15% of the α1-fetoprotein activity of the starting preparation from ascites fluid. The purity of the final product was shown by polyacrylamide gel electrophoresis, radioimmunoelectrophoresis, and determinations of the NH2-terminal and COOH-terminal amino acid residues of the α1-fetoprotein isolated. Amino acid analysis of the final product revealed a composition very similar to those reported for α-fetoprotein preparations that have been previously isolated by the use of immunochemical technology.

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This investigation was supported by grants from the Medical Research Council of Canada, Ottawa, Ontario, Canada, and the National Cancer Institute of Canada, Toronto, Ontario, Canada.

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