Characterization of tyrosine sulfate residues in antihemophilic recombinant factor VIII by liquid chromatography electrospray ionization tandem mass spectrometry and amino acid analysis.

Recombinant Factor VIII (rFVIII) is involved in the cascade of biochemical reactions leading to blood coagulation and is used for the treatment of haemophilia A. Plasma-derived FVIII (pdFVIII) has been reported to be post-translationally modified by sulfation of tyrosine residues at positions 346, 1664, 1680, 718, 719 and 723. This report describes the quantitation of tyrosine sulfate residues in BHK-derived, human rFVIII by amino acid composition analysis and the identification of their positions in the polypeptide sequence using a combination of liquid chromatography and electrospray ionization mass spectrometry in the analysis of proteolytic digests of the protein.