Structural characterization of the 16-kDa allergen, RA17, in rice seeds. Prediction of the secondary structure and identification of intramolecular disulfide bridges.
The 16-kDa rice allergen, RA17, belonging to the alpha-amylase/trypsin inhibitor family was isolated from rice seed and structurally characterized by identifying cystine-containing peptides and predicting the secondary structure and hydrophobic regions. Eight peptides, which constitute three sets of cystine-containing peptides, were purified by HPLC from a thermolytic digest of RA17 and identified by their amino acid sequence and composition, indicating five intramolecular disulfide bridges: Cys34-Cys94, Cys26-(Cys50 or Cys51)-Cys110 and Cys12-(Cys62 or Cys64)-Cys122. Analyses of the CD spectrum and the Chou-Fasman prediction suggested that RA17 had some helical- and sheet-structure regions. Based on these experimental and predicted data, RA17 is proposed to be a globular molecule with a small hydrophobic core having folding restricted by five intramolecular disulfide bridges.
Izumi
H
H
Department of Food and Nutrition, Nagoya College of Nutrition, Japan.
Sugiyama
M
M
Matsuda
T
T
Nakamura
R
R
D000485:Allergens / Q000737:chemistry*; D000595:Amino Acid Sequence; D052179:Antigens, Plant; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D003545:Cysteine / Q000032:analysis; D004220:Disulfides / Q000737:chemistry; D008969:Molecular Sequence Data; D008970:Molecular Weight; D012275:Oryza / Q000276:immunology*; D017510:Protein Folding; D017433:Protein Structure, Secondary; D012639:Seeds / Q000276:immunology
D000485:Allergens; D052179:Antigens, Plant; D004220:Disulfides; C405344:RA17 allergen; D003545:Cysteine