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.
Pucci
P
P
Servizio di Spettrometria di Massa, Consiglio Nazionale delle Ricerche, Napoli, Italy.
Siciliano
R
R
Malorni
A
A
Marino
G
G
Tecce
M F
MF
Ceccarini
C
C
Terrana
B
B
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000302:isolation & purification; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D016339:Spectrometry, Mass, Fast Atom Bombardment; D000509:alpha-Fetoproteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification
D010446:Peptide Fragments; D000509:alpha-Fetoproteins