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| {{STRUCTURE_1rf0| PDB=1rf0 | SCENE= }} | | {{STRUCTURE_1rf0| PDB=1rf0 | SCENE= }} |
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| '''Crystal Structure of Fragment D of gammaE132A Fibrinogen'''
| | ===Crystal Structure of Fragment D of gammaE132A Fibrinogen=== |
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| ==Overview==
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| Structural analysis of recombinant fibrinogen fragment D revealed that the calcium-binding site (beta2-site) composed of residues BbetaAsp261, BbetaAsp398, BbetaGly263, and gammaGlu132 is modulated by the "B:b" interaction. To determine the beta2-site's role in polymerization, we engineered variant fibrinogen gammaE132A in which calcium binding to the beta2-site was disrupted by replacing glutamic acid at gamma132 with alanine. We compared polymerization of gammaE132A to normal fibrinogen as a function of calcium concentration. Polymerization of gammaE132A at concentrations of calcium <or=1 mM exhibited an uncharacteristic 2-3-fold increase in lateral aggregation and fiber thickness compared to normal fibrinogen, while polymerization of variant and normal were indistinguishable at 10 mM calcium. These results suggest that the beta2-site controls the extent of lateral aggregation. That is, when the calcium anchor (beta2-site) is eliminated before "B:b" interactions occur then lateral aggregation is enhanced. We solved structures of fragment D of gammaE132A fibrinogen (rfD-gammaE132A) with and without Gly-His-Arg-Pro-amide (GHRPam) and found no change to the global structure. X-ray diffraction data showed GHRPam binding in the "a" and "b" polymerization sites and that calcium could still bind to the beta2-site of gammaE132A fibrinogen at 70 mM calcium. We found that the gamma2 calcium-binding site (in loop gamma294-301) did not have calcium bound in the structure of fragment D of gammaE132A fibrinogen with GHRPam bound (rfD-gammaE132A+GH). Analysis of structures rfD-gammaE132A+GH and rfD-BbetaD398A+GH indicated that differences in calcium occupation of the gamma2-site resulted from minor conformational changes provoked by crystal packing and GHRPam binding to the "a" site did not directly modulate calcium binding to this site.
| | The line below this paragraph, {{ABSTRACT_PUBMED_14992585}}, adds the Publication Abstract to the page |
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| | {{ABSTRACT_PUBMED_14992585}} |
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| ==Disease== | | ==Disease== |
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| [[Category: Recombinant fibrinogen fragment d]] | | [[Category: Recombinant fibrinogen fragment d]] |
| [[Category: Recombinant fibrinogen gammae132a]] | | [[Category: Recombinant fibrinogen gammae132a]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 07:24:51 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 19:48:42 2008'' |
