Occurrence of IgE antibody-recognizing N-linked glycan moiety of a soybean allergen, Gly m Bd 28K.
BACKGROUND
It has been reported that N-linked glycan moieties of glycoproteins function as IgE-reactive determinants. Gly m Bd 28K, a soybean allergen, was a glycoprotein with glycan moieties, which are supposed to be the Man(3)GlcNAc(2) backbone with the beta1-->2 xylose and alpha1-->3 fucose branches. The purpose of the present study was to examine the IgE-binding ability of the glycan moiety of Gly m Bd 28K in the binding reaction with patients' sera.


METHODS
A peptide containing the glycan moiety was prepared from Gly m Bd 28K by digestion with lysyl endopeptidase. The binding site of the glycan moiety was determined by amino acid sequence analyses. The glycan moiety of the allergen was characterized using anti-horseradish peroxidase antibody (anti-HRP) recognizing the N-linked glycan moieties of glycoproteins. The binding of patients' IgE antibodies with their glycan moiety was examined by an immunostaining technique using the glycopeptide and its deglycosylated peptide derived from Gly m Bd 28K.


RESULTS
The binding site of the glycan moiety in Gly m Bd 28K was shown to be its Asn20 residue. Gly m Bd 28K did react with anti-HRP and the sera of soybean-sensitive patients, but the binding of IgE antibodies was inhibited by the preincubation with anti-HRP. Moreover, the glycopeptide also reacted with the sera of soybean-sensitive patients, but its deglycosylated peptide did not react with any IgE antibodies of patients' sera.


CONCLUSIONS
The specific IgE antibodies recognizing the N-linked glycan moieties of Gly m Bd 28K and other glycoproteins with homologous glycan moieties occur in the sera of soybean-sensitive patients. It was indicated that the N-linked glycan moieties such as that of Gly m Bd 28K may be one of the common IgE-reactive determinants distributed in various plant food proteins.
Hiemori
M
M
Department of Nutrition, School of Medicine, The University of Tokushima, Tokushima, Japan.
Bando
N
N
Ogawa
T
T
Shimada
H
H
Tsuji
H
H
Yamanishi
R
R
Terao
J
J
D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D000595:Amino Acid Sequence; D052179:Antigens, Plant; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D000939:Epitopes; D005512:Food Hypersensitivity / Q000209:etiology; D006020:Glycopeptides / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism; D006023:Glycoproteins / Q000737:chemistry / Q000276:immunology*; D006031:Glycosylation; D006735:Horseradish Peroxidase / Q000378:metabolism; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology*; D008969:Molecular Sequence Data; D010455:Peptides / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism; D010940:Plant Proteins / Q000009:adverse effects / Q000737:chemistry / Q000276:immunology*; D011134:Polysaccharides / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D030262:Soybean Proteins; D013025:Glycine max / Q000009:adverse effects* / Q000276:immunology
D000485:Allergens; D052179:Antigens, Plant; D000939:Epitopes; C107967:Gly m Bd 28K allergen, Glycine max; D006020:Glycopeptides; D006023:Glycoproteins; D010455:Peptides; D010940:Plant Proteins; D011134:Polysaccharides; D030262:Soybean Proteins; D007073:Immunoglobulin E; D006735:Horseradish Peroxidase