The meshwork of a blood clot is composed of fibrin fibers built up by the systematic assembly of fibrinogen molecules that have been proteolyzed by thrombin. During the process, the resulting polymers are further reinforced by the factor XIII-catalyzed introduction of crosslinks between various lysine and glutamine sidechains. Ultimately, the clot is digested by plasmin. The general nature of the clotting and lysis process has been appreciated for several decades, but a detailed knowledge of events was not possible because the three-dimensional structure of the starting fibrinogen units could not be determined at the atomic level. All this has changed during the past three years as a result of a series of high resolution crystal structures of fibrinogen fragments and a low resolution structure of a native fibrinogen. The structures have been very revealing and the possibility of a full understanding no longer seems remote. The immediate goals of this project are to obtain high-resolution crystal structures of native fibrinogens by X-ray diffraction, first of a chicken structure which is already well under way, and then the more daunting human molecule, crystals of which we have only recently observed and which are still too small for useful study. We also propose to solve separately the structure of an elusive but key part of fibrinogen that is very mobile and which has not yielded to other approaches. The proposal also describes plans for determining several complexes that can be isolated from crosslinked fibrin, including a moiety called """"""""D2E."""""""" Combined with the full structures of the native molecules at high resolution, these results should dispel much of the mystery of fibrin formation.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
2R01HL026873-21
Application #
6324129
Study Section
Biophysical Chemistry Study Section (BBCB)
Program Officer
Link, Rebecca P
Project Start
1981-05-01
Project End
2004-04-30
Budget Start
2001-05-01
Budget End
2002-04-30
Support Year
21
Fiscal Year
2001
Total Cost
$366,813
Indirect Cost
Name
University of California San Diego
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
077758407
City
La Jolla
State
CA
Country
United States
Zip Code
92093
Doolittle, Russell F (2003) Some notes on crystallizing fibrinogen and fibrin fragments. Biophys Chem 100:307-13
Doolittle, Russell F (2003) Structural basis of the fibrinogen-fibrin transformation: contributions from X-ray crystallography. Blood Rev 17:33-41
Jiang, Yong; Doolittle, Russell F (2003) The evolution of vertebrate blood coagulation as viewed from a comparison of puffer fish and sea squirt genomes. Proc Natl Acad Sci U S A 100:7527-32
Doolittle, R F (2003) X-ray crystallographic studies on fibrinogen and fibrin. J Thromb Haemost 1:1559-65
Yang, Zhe; Pandi, Leela; Doolittle, Russell F (2002) The crystal structure of fragment double-D from cross-linked lamprey fibrin reveals isopeptide linkages across an unexpected D-D interface. Biochemistry 41:15610-7
Yang, Zhe; Spraggon, Glen; Pandi, Leela et al. (2002) Crystal structure of fragment D from lamprey fibrinogen complexed with the peptide Gly-His-Arg-Pro-amide. Biochemistry 41:10218-24
Yang, Z; Kollman, J M; Pandi, L et al. (2001) Crystal structure of native chicken fibrinogen at 2.7 A resolution. Biochemistry 40:12515-23
Yang, Z; Mochalkin, I; Doolittle, R F (2000) A model of fibrin formation based on crystal structures of fibrinogen and fibrin fragments complexed with synthetic peptides. Proc Natl Acad Sci U S A 97:14156-61
Yang, Z; Mochalkin, I; Veerapandian, L et al. (2000) Crystal structure of native chicken fibrinogen at 5.5-A resolution. Proc Natl Acad Sci U S A 97:3907-12
Lin, Y C; Doolittle, R F (2000) A latent inhibitor of fibrin polymerization with ancillary anticoagulant activity. Thromb Res 97:375-8

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