Editing Factor XII (section)

== Structure ==

Human Factor XII is 596 [[amino acids]] long and consists of two chains, the heavy chain (353 [[Amino acid|residues]]) and light chain (243 residues) held together by a [[disulfide bond]]. It is 80,000 daltons in molecular weight. The heavy chain contains two [[fibronectin]]-type domains (type I and II), two [[epidermal growth factor]]-like domains, a kringle domain, and a proline-rich region, while the light chain contains the protease domain. FXII can be cleaved sequentially at two sites, Arg353 and Arg334, with the second cleavage liberating the light chain and forming β-FXIIa.<ref>{{cite journal | vauthors = Ivanov I, Matafonov A, Gailani D | title = Single-chain factor XII: a new form of activated factor XII | journal = Current Opinion in Hematology | volume = 24 | issue = 5 | pages = 411–418 | date = September 2017 | pmid = 28604413 | doi = 10.1097/MOH.0000000000000363 | pmc = 5762122 }}</ref> 

The structure of the FnI-EGF-like tandem [[Protein domain|domain]] of coagulation factor XII has been solved by [[X-ray crystallography]].<ref>{{cite journal | vauthors = Stavrou E, Schmaier AH | title = Factor XII: what does it contribute to our understanding of the physiology and pathophysiology of hemostasis & thrombosis | journal = Thrombosis Research | volume = 125 | issue = 3 | pages = 210–215 | date = March 2010 | pmid = 20022081 | pmc = 2851158 | doi = 10.1016/j.thromres.2009.11.028 }}</ref><ref>{{cite journal | vauthors = Beringer DX, Kroon-Batenburg LM | title = The structure of the FnI-EGF-like tandem domain of coagulation factor XII solved using SIRAS | journal = Acta Crystallographica Section F | volume = 69 | issue = Pt 2 | pages = 94–102 | date = February 2013 | pmid = 23385745 | pmc = 3564606 | doi = 10.1107/S1744309113000286 }}</ref> Crystal structures of the FXII light chain have also been determined, both unbound (β-FXII) and bound (β-FXIIa) to [[Enzyme inhibitor|inhibitors]].<ref>{{cite journal | vauthors = Dementiev A, Silva A, Yee C, Li Z, Flavin MT, Sham H, Partridge JR | title = Structures of human plasma β-factor XIIa cocrystallized with potent inhibitors | journal = Blood Advances | volume = 2 | issue = 5 | pages = 549–558 | date = March 2018 | pmid = 29519898 | pmc = 5851424 | doi = 10.1182/bloodadvances.2018016337 }}</ref><ref>{{cite journal | vauthors = Pathak M, Wilmann P, Awford J, Li C, Hamad BK, Fischer PM, Dreveny I, Dekker LV, Emsley J | title = Coagulation factor XII protease domain crystal structure | journal = Journal of Thrombosis and Haemostasis | volume = 13 | issue = 4 | pages = 580–591 | date = April 2015 | pmid = 25604127 | pmc = 4418343 | doi = 10.1111/jth.12849 }}</ref><ref>{{cite journal | vauthors = Pathak M, Manna R, Li C, Kaira BG, Hamad BK, Belviso BD, Bonturi CR, Dreveny I, Fischer PM, Dekker LV, Oliva ML, Emsley J | title = Crystal structures of the recombinant β-factor XIIa protease with bound Thr-Arg and Pro-Arg substrate mimetics | journal = Acta Crystallographica Section D | volume = 75 | issue = Pt 6 | pages = 578–591 | date = June 2019 | pmid = 31205020 | doi = 10.1107/S2059798319006910 | s2cid = 189944782 | url = https://nottingham-repository.worktribe.com/output/2390798 }}</ref>