Characterization of low molecular weight allergens from English walnut (Juglans regia).
Although English walnut is a commonly allergenic tree nut, walnut allergens have been poorly characterized to date. The objective of this work was to characterize the natural, low molecular weight (LMW) allergens from walnut. A protocol was developed to purify LMW allergens (specifically 2S albumins) from English walnuts. In addition to 2S albumins, a series of peptides from the N-terminal region of the 7S seed storage globulin proprotein were also identified and characterized. These peptides comprised a four-cysteine motif (C-X-X-X-C-X10-12-C-X-X-X-C) repeated throughout the 7S N-terminal region. Upon IgE immunoblotting, 3/11 and 5/11 sera from walnut-allergic subjects showed IgE reactivity to the 7S N-terminal fragments and 2S albumin, respectively. The mature 7S protein and the newly described 7S N-terminal peptides represent two distinct types of allergens. Because the proteolytic processing of 7S globulins has not been elucidated in many edible plant species, similar protein fragments may be present in other nuts and seeds.
143 Food Industry Complex, Food Allergy Research and Resource Program, Department of Food Science and Technology, University of Nebraska-Lincoln , Lincoln, Nebraska 68583-0919, United States.
Melanie L
ML
Downs
Aida
A
Semic-Jusufagic
Angela
A
Simpson
Joan
J
Bartra
Montserrat
M
Fernandez-Rivas
Neil M
NM
Rigby
Steve L
SL
Taylor
Joseph L
JL
Baumert
E N Clare
EN
Mills
D000485:Allergens / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D000595:Amino Acid Sequence; D005916:Globulins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D031324:Juglans / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009754:Nuts / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D010449:Peptide Mapping; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D055314:Seed Storage Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D016415:Sequence Alignment; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D000485:Allergens; D005916:Globulins; D010940:Plant Proteins; D055314:Seed Storage Proteins
2S seed storage albumin; 7S seed storage globulin; food allergy; mass spectrometry; tree nut; walnut