1. Center for Molecular Genetics, University of California, San Diego, La Jolla, California 92093-0634, USA
2. These authors contributed equally to this work.

Correspondence to: Russell F. Doolittle¹ Correspondence and requests for materials should be addressed to R.D. (e-mail: Email: rdoolittle@ucsd.edu).Coordinates have been deposited in the Brookhaven Protein Data Bank (accession nos: fragmentD, 1FZA; double-D,1FZB).

Abstract

In blood coagulation, units of the protein fibrinogen pack together to form a fibrin clot, but a crystal structure for fibrinogen is needed to understand how this is achieved. The structure of a core fragment (fragment D) from human fibrinogen has now been determined to 2.9 Å resolution. The 86K three-chained structure consists of a coiled-coil region and two homologous globular entities oriented at approximately 130 degrees to each other. Additionally, the covalently bound dimer of fragment D, known as 'double-D', was isolated from human fibrin, crystallized in the presence of a Gly-Pro-Arg-Pro-amide peptide ligand, which simulates the donor polymerization site, and its structure solved by molecular replacement with the model of fragment D.