Protein Z was purified from human plasma by a four-step procedure which included barium citrate adsorption, ammonium sulfate fractionation, DEAE-Sepharose chromatography, and blue agarose chromatography with a yield of 20%. It is a 62,000 mol wt protein with an extinction coefficient of 12.0. The concentration of Protein Z in pooled, citrated plasma is 2.2 micrograms/ml and its half-life in patients starting warfarin anticoagulation therapy is estimated to be less than 2.5 d. The NH2-terminal sequence is Ala-Gly-Ser-Tyr-Leu-Leu-(Gla)-(Gla)-Leu-Phe-(Gla)-Gly-Asn-Leu. Neither Protein Z nor its cleavage products, which were obtained by treatment of Protein Z with thrombin or plasmin, incorporated [3H]diisopropyl fluorophosphate. The physiological function of Protein Z remains unknown.
G J Broze Jr, J P Miletich
The Editorial Board will only consider comments that are deemed relevant and of interest to readers. The Journal will not post data that have not been subjected to peer review; or a comment that is essentially a reiteration of another comment.