User:Natalie Mullins/Sandbox Wauwatosa West SMART Team
From Proteopedia
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Abstract
Fibrinogen is the precursor to fibrin, the last protein in the blood clotting process. Fibrin forms the clot that is stabilized by factor XIII, causing fibrin monomerss to link together. Without fibrin, a person would bleed to death. Fibrinogen is made up of three unique polypeptide chains: α, β, and γ. These chains are twisted together, forming two terminal barbell-like D domains with a smaller central E domain in between. Thrombin, another essential clotting protein, forms fibrin by removing alpha and beta chain amino termini peptides in the E domain, exposing amino acid knob-like protrusions that interact with depressions—“holes”—always present on D domains of neighboring molecules. Van der Waals forces keep the α and β chains together between the E and D domains. Cross-linking occurs between D domains of adjacent molecules at residues Gln398/399 of one D domain and Lys406 of the other. There is currently controversy within the scientific community over whether fibrin D domains cross-link longitudinally (end-to-end) or transversely (between parallel molecules). Cross-linking transversely allows for greater elasticity, allowing the clot to stretch with the skin or blood vessels. Studies with fibrinogen in physiological solution strongly suggest cross linking occurs in a transverse manner. Although the cross-linking residues (381-411) in the crystalline structure appear to be too short to link transversely, if the loop on the γ chain could flip out, it would provide an extension. Using 3D printer technology, the Wauwatosa West SMART Team (Students Modeling A Research Topic) designed a fibrinogen model to visualize this loop. Image:StretchyFibrin.jpg
History
Fibrinogen was one of the first proteins to be used in practical medical applications. Field doctors in WWI used unpolymerized fibrinogen sheets and powders to quickly stop bleeding while in the field.
Structure
This is the structure of human fibrinogen. It is only important for two reasons.This structure is created using things which make the thing a ma gig awesome.
