Human alpha-fetoprotein primary structure: a mass spectrometric study.


The amino acid sequence of human alpha-fetoprotein, a 67-kDa protein present in mammalian embryonic serum, was verified by fast atom bombardment mass spectrometric (FAB/MS) analyses of three different enzymatic digests of the protein. Human alpha-fetoprotein obtained from a large-scale cell culture was digested with trypsin and V-8 protease either separately on two different samples or combined on the same one. The V-8 protease digest of the protein was partially fractionated by HPLC; the other samples were directly analyzed by FAB/MS without previous purification steps. About 90% of the alpha-fetoprotein amino acid sequence was verified by mass spectrometric analysis; this also confirmed that the cell-derived protein is identical with the hepatoma-derived protein. FAB analysis revealed that the N terminus of the mature protein is arginine rather than threonine, with the threonine occupying the second position. Therefore, the processing site of the alpha-fetoprotein signal peptide during maturation of the protein occurs at the N-terminal side of the arginine residue formerly indicated as residue-1. Thus mature alpha-fetoprotein contains 591 amino acids rather than 590.

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@article{Pucci1991HumanAP, title={Human alpha-fetoprotein primary structure: a mass spectrometric study.}, author={Piero Pucci and Rosa Anna Siciliano and Antonio Malorni and Gennaro Marino and M. F. Tecce and Costante Ceccarini and Benedetto Terrana}, journal={Biochemistry}, year={1991}, volume={30 20}, pages={5061-6} }