ovomucoid
{{Short description|Protein found in egg whites}}
{{distinguish|Ovomucin}}
{{Infobox nonhuman protein
| Name = Ovomucoid
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| caption = The third Kazal domain of the turkey ovomucoid protein (orange) bound to subtilisin Carlsberg, a serine protease.{{cite journal | vauthors = Horn JR, Ramaswamy S, Murphy KP | title = Structure and energetics of protein-protein interactions: the role of conformational heterogeneity in OMTKY3 binding to serine proteases | journal = Journal of Molecular Biology | volume = 331 | issue = 2 | pages = 497–508 | date = August 2003 | pmid = 12888355 | doi = 10.1016/S0022-2836(03)00783-6 }}
| Organism = Meleagris gallopavo
| TaxID = 9103
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| UniProt = P68390
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{{Infobox nonhuman protein
| Name = Ovomucoid
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| Organism = Gallus gallus
| TaxID = 9103
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| UniProt = P01005
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Ovomucoid is a protein found in egg whites. It is a trypsin inhibitor with three protein domains of the Kazal domain family.{{cite journal | vauthors = Lineweaver H, Murray CW | title = Identification of the trypsin inhibitor of egg white with ovomucoid | journal = The Journal of Biological Chemistry | volume = 171 | issue = 2 | pages = 565–81 | date = December 1947 | doi = 10.1016/S0021-9258(17)41067-2 | pmid = 20272096 | doi-access = free }}{{cite journal | vauthors = Rimphanitchayakit V, Tassanakajon A | title = Structure and function of invertebrate Kazal-type serine proteinase inhibitors | journal = Developmental and Comparative Immunology | volume = 34 | issue = 4 | pages = 377–86 | date = April 2010 | pmid = 19995574 | doi = 10.1016/j.dci.2009.12.004 }} The homologs from chickens (Gallus gallus) and especially turkeys (Meleagris gallopavo) are best characterized. It is not related to the similarly named ovomucin, another egg white protein.
Chicken ovomucoid, also known as Gal d 1, is a known allergen. It is the protein most often causing egg allergy. At least four IgE epitopes have been identified.{{cite journal | vauthors = Järvinen KM, Beyer K, Vila L, Bardina L, Mishoe M, Sampson HA | title = Specificity of IgE antibodies to sequential epitopes of hen's egg ovomucoid as a marker for persistence of egg allergy | journal = Allergy | volume = 62 | issue = 7 | pages = 758–65 | date = July 2007 | pmid = 17573723 | doi = 10.1111/j.1398-9995.2007.01332.x | s2cid = 23540584 }} Three other egg white proteins are also identified as allergenic: ovalbumin (Gal d 2), ovotransferrin (Gal d 3) and lysozyme (Gal d 4).{{cite journal |vauthors=Caubet JC, Wang J |title=Current understanding of egg allergy |journal=Pediatr. Clin. North Am. |volume=58 |issue=2 |pages=427–43, xi |year=2011 |pmid=21453811 |pmc=3069662 |doi=10.1016/j.pcl.2011.02.014 }}