IgE epitope: 55-QGPHVISRIYQTAT-68 (Monsalve et al., 1993 [121]). The epitope is common with Bra j 1E. Menendez-Arias et al. (1990) [109] reported that the single tyrosine of the large chain was involved in binding IgE.
Allergen stability: Process, chemical, enzymatic
Sin a 1, belonging to the 2S family of seed storage albumins, is a protein constituted by two subunits of about 9 and 5 kDa, linked by disulphide bridges. It is a very compact molecule, with a high percentage of alpha-helical conformation. It is resistant to proteolytic degradation, trypsin, chymotrypsin, and pepsin have been tested, (Astwood et al. 1996 [1160]) and to heating (exhibiting an unusually high thermal stability of up to 88 degrees C).
Nature of main cross-reacting proteins:
The 2S albumins are found as seed storage proteins throughout the Cruciferae family (e.g. Brassica and Arabidopsis). ELISA inhibition experiments show that mustard can cross reacts with rape seed, which has a very similar 2S seed storage protein (Monsalve et al. 1997 [649]).
Allergen properties & biological function:
2S albumins are seed storage proteins and are primarily used by the growing plant during germination. They may also have a defensive role against pathogens, since antifungal activity has been described for some of the members of this family. Trypsin inhibitor activity has been reported for the precursor of a mustard 2S albumin, Q42413, with 86% identity to Sin a 1 and 75% identity to Bra j 1-E (Mandal et al. 2002 [986]).
Allergen purification:
Purification process requires seed flour delipidation, aqueous extraction and gel filtration (Sephadex G50) to obtain the 2S fraction. Ion exchange chromatography is used next to separate isoforms (Menendez-Arias et al, 1987) [1159].
The gene sequences from Sinapis alba differ by 1-5 amino acids. The 2S storage proteins of Brassica nigra and Brassica juncea, Q42491 and Q42413, show up to 14 changes and interesting also a pentapeptide deletion at the same position as the tripeptide deletion of P15322. Bra j 1-E, P80207, shows 13 changes and only the removal of the linker.
References (10)
Astwood JD, Leach JN, Fuchs RL.
Stability of food allergens to digestion in vitro.
Nat Biotechnol. 14(10):1269-1273.
1996
PUBMED ID:
9631091
Gonzalez De La Pena MA, Monsalve RI, Batanero E, Villalba M, Rodriguez R.
Expression in Escherichia coli of Sin a 1, the major allergen from mustard.
Eur J Biochem 237: 827-832. 1996
PUBMED ID:
8647131
Mandal S, Kundu P, Roy B, Mandal RK.
Precursor of the inactive 2S seed storage protein from the Indian mustard Brassica juncea is a novel trypsin inhibitor. Charaterization, post-translational processing studies, and transgenic expression to develop insect-resistant plants.
J Biol Chem. 277(40):37161-37168. 2002
PUBMED ID:
12147695
Menendez-Arias L, Dominguez J, Moneo I, Rodriguez R.
Epitope mapping of the major allergen from yellow mustard seeds, Sin a I.
Mol. Immunol. 27: 143-150. 1990
PUBMED ID:
1690853
Menendez-Arias L, Moneo I, Dominguez J, Rodriguez R.
Primary structure of the major allergen of yellow mustard (Sinapis alba L.) seeds, Sin a I.
Eur. J. Biochem. 177:159-166. 1988
PUBMED ID:
3181153
Menéndez-Arias L, Monsalve RI, Gavilanes JG, Rodríguez, R.
Molecular and spectroscopic characterization of a low molecular weight seed storage protein from yellow mustard (Sinapis alba L.)
Int. J. Biochem. 19, 899-907
1987
PUBMED ID:
unknown
[1159]
Monsalve RI, Villalba M, Rodr¡guez. R
Allergy to Mustard Seeds: The Importance of 2S Albumins as Food Allergens.
Int Symp Food Allergens 3(2):57-69. 2001
PUBMED ID:
unknown
[119]
Monsalve RI, Gonzalez de la Pena MA, Lopez-Otin C, Fiandor A, Fernandez C, Villalba M, Rodriguez R.
Detection, isolation and complete amino acid sequence of an aeroallergenic protein from rapeseed flour.
Clin Exp Allergy 27(7):833-841 1997
PUBMED ID:
9249277
Monsalve RI, Villalba M, Lopez-Otin C, Rodriguez R.
Characterization of a new oriental-mustard (Brassica juncea) allergen, Bra j IE: detection of an allergenic epitope.
Biochem. J. 293: 625-632. 1993
PUBMED ID:
7688955
Onaderra M, Monsalve RI, Mancheno JM, Villalba M, Martinez del Pozo A, Gavilanes JG, Rodriguez R.
Food mustard allergen interaction with phospholipid vesicles.
Eur. J. Biochem. 225: 609-615. 1994
PUBMED ID:
7957175
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