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Identification and characterization of a basic thaumatin‐like protein ( TLP 2) as an allergen in sapodilla plum ( M anilkara zapota )
Author(s) -
Hegde Venkatesh L.,
Ashok Kumar Hassan G.,
Sreenath Kundimi,
Hegde Muralidhar L.,
Venkatesh Yeldur P.
Publication year - 2014
Publication title -
molecular nutrition and food research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.495
H-Index - 131
eISSN - 1613-4133
pISSN - 1613-4125
DOI - 10.1002/mnfr.201300261
Subject(s) - allergen , thaumatin , oral allergy syndrome , pathogenesis related protein , allergy , immunoglobulin e , food allergy , immunology , medicine , chemistry , biochemistry , antibody , gene , gene expression
Scope Cases of oral allergy syndrome following the ingestion of sapodilla plum ( M anilkara zapota ) have been reported rarely. As the causative allergens are not known, the main objective of this study was to identify and characterize the important allergens in sapodilla. Methods and results Allergy to sapodilla was diagnosed by case history, skin prick test, and serum allergen–specific I g E . The allergen was detected by I g E immunoblotting, purified on SP – S epharose and characterized by native/ SDS – PAGE , IEF , MS , and amino acid composition. Several cases of allergy to sapodilla fruit were identified; majority of the sapodilla‐allergic subjects (6/7) experienced typical oral allergy syndrome symptoms, and allergen–specific I g E to the purified protein was positive. The allergen has a p I ≥9.5 and high contents of arginine, threonine, glycine, and cysteine. Circular dichroism revealed a secondary structure rich in beta sheets/turns. Based on its N ‐terminal sequence of A‐T‐F‐D‐I‐Q‐N‐N‐C‐X‐Y ‐, the allergen (21 578 Da) was identified as a thaumatin‐like protein by homology. Conclusion The causative allergen in sapodilla plum has been identified and characterized as a highly basic thaumatin‐like protein belonging to the pathogenesis‐related protein ( PR –5) family, which has been recognized as a new family of conserved, cross‐reactive plant allergens.