Physicochemical approach to the purification of human alpha1-fetoprotein from the ascites fluid of a hepatoma-bearing patient.

A method for the purification of human alpha1-fetoprotein from the ascites fluid of a hepatoma-bearing patient is described that is capable of yielding large quantities of pure alpha1-fetoprotein within a relatively short period of time. The technique is based entirely on the physicochemical properties of the alpha1-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, positivepaffinity 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 alpha1-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 alphs1-fetoprotein isolated. Amino acid analysis of the final product revealed a composition very similar to those reported for alpha-fetoprotein preparations that have been previously isolated by the use of immunochemical technology.