4762
Biochemistry 1989, 28, 4762-4771
Ca2+-DependentStructural Changes in Bovine Blood Coagulation Factor Va and Its Subunits? Thomas M. Laue,t*s Ruiliang L u , ~Ute C. Krieg,f Charles T. Esmon,l'iL!# and Arthur E. Johnson*J Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104, Department of Pathology and Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73190, and Howard Hughes Medical Institute, Oklahoma City, Oklahoma 73104 Received November 16. 1988; Revised Manuscript Received February 14, 1989
ABSTRACT: The calcium dependence of the structures of bovine blood coagulation factor Va and its subunits
(Vh and V1) has been examined spectroscopically in order to characterize the conformational changes which accompany the binding of Ca2+ to Vh and VI to form factor Va. The far-UV C D spectra of the isolated subunits indicate that the secondary structures of both Vh and V1 are predominantly @sheet (>45%), with little a-helix content (
