COMPARATIVE CHEMICAL STRUCTURES OF HUMAN ALPHA-FETOPROTEINS FROM FETAL SERUM AND FROM ASCITES-FLUID OF A PATIENT WITH HEPATOMA

Abstract

Human .alpha.-fetoproteins were purified from umbilical cord serum and ascites fluid of a patient with hepatoma by affinity chromatography, and their chemical compositions and terminal sequences were compared. The amino acid compositions of these .alpha.-fetoproteins were similar and in good agreement with the values reported by other investigators. The COOH-terminal 5-amino acid sequence determined by carboxypeptidase digestion and the NH2-terminal 20-amino acid sequence determined by an automated sequence analyzer revealed that both .alpha.-fetoproteins had the same terminal sequences of amino acids. The sequence analysis showed that a part of each of the proteins lacked its NH2-terminal residues for 1 or 3 amino acids. A small difference in the carbohydrate composition of each .alpha.-fetoprotein was observed. .alpha.-Fetoproteins from fetal serum and ascites fluid of a patient with hepatoma had very similar structures.