Synthetic factor VIII peptides with amino acid sequences contained within
the C2 domain of factor VIII inhibit factor VIII binding to
phosphatidylserine
PA Foster, CA Fulcher, RA Houghten and TS Zimmerman
Division of Experimental Hemostasis, Roon Research Center for
Arteriosclerosis and Thrombosis, Scripps Clinic and Research Foundation, La
Jolla, CA 92037.
The effective activation of factor X by factor IXa requires the co- factor
activity of activated factor VIII (FVIII). Factor Xa formation is also
dependent on the presence of negatively charged phospholipid. A
phospholipid binding domain of FVIII has been reported to be present on the
FVIII light chain. Recent observations on a subset of human FVIII
inhibitors have implicated the carboxyl-terminal C2 domain of FVIII as
containing a possible phospholipid binding site. The purpose of this study
was to investigate directly the role of the C2 domain in phospholipid
binding. Twenty-six overlapping peptides, which span the entire C2 domain
of FVIII, were synthesized. The ability of these peptides to inhibit the
binding of purified human FVIII to immobilized phosphatidylserine was
evaluated in an enzyme-linked immunosorbent assay. Three overlapping
synthetic FVIII peptides, 2303-2317, 2305- 2332, and 2308-2322, inhibited
FVIII binding to phosphatidylserine by greater than 90% when tested at a
concentration of 100 mumols/L. A fourth partially overlapping peptide,
2318-2332, inhibited FVIII binding by 65%. These results suggest that the
area described by these peptides, residues 2303 to 2332, may play an
important role in the mediation of FVIII binding to phospholipid.
Volume 75,
Issue 10,
pp. 1999-2004,
05/15/1990
Copyright © 1990 by The American Society of Hematology
