Thromb Haemost 2001; 85(04): 655-660
DOI: 10.1055/s-0037-1615649
Review Articles
Schattauer GmbH

Protein Z Circulates in Plasma in a Complex with Protein Z-Dependent Protease Inhibitor

Amir Tabatabai
1   Division of Hematology, Barnes-Jewish Hospital at Washington University Medical Center, St. Louis, MO, USA
,
Ryan Fiehler
1   Division of Hematology, Barnes-Jewish Hospital at Washington University Medical Center, St. Louis, MO, USA
,
George J. Broze
1   Division of Hematology, Barnes-Jewish Hospital at Washington University Medical Center, St. Louis, MO, USA
› Author Affiliations
Further Information

Publication History

Received 10 October 2000

Accepted after revision 08 November 2000

Publication Date:
08 December 2017 (online)

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Summary

Protein Z (PZ) is a vitamin K-dependent plasma protein that forms a Ca++-dependent complex with factor Xa at phospholipid surfaces. This interaction between PZ and factor Xa enhances by >1000-fold the inhibition of factor Xa by the serpin called protein Z-dependent protease inhibitor (ZPI). These experiments show that PZ also binds ZPI in a process that does not require Ca++ or phospholipids. In pooled normal plasma, which contains excess ZPI relative to PZ, all the PZ appears to be bound in a complex with ZPI. The binding of PZ to ZPI reduces the rate and extent of factor XIa inhibition produced by ZPI. During the course of these studies, it was noted that a PZ purification procedure, that included NaSCN (2.0 M) elution of PZ from an immunoaffinity column, produced aggregated, inactive forms of PZ.