Amino-acid sequence of the vitamin-K-dependent part of protein Z

After tryptic digestion of protein Z a peptide corresponding to residues 1-43 has been isolated and sequenced. Smaller peptides were generated by treatment of the peptide with pepsin and then separated by high-performance liquid chromatography. The purity of the peptides was sufficient for mass spectrometric measurement. Thirteen gamma-carboxyglutamic acid residues have been identified and the peptide shows strong homology to the corresponding domains of the classical vitamin-K-dependent blood clotting proteins.