title: Degradation of soluble proteins including some allergens in brown rice grains by endogenous proteolytic activity during germination and heat-processing.
abstract: The effect of germination and subsequent heat-processing on the degradation of soluble proteins, including some allergenic proteins, in brown rice grains was investigated. The content of soluble proteins, including 14-16-kDa and 26-kDa allergens, in the germinated and processed brown rice grains (GPR) was much lower than that of non-germinated brown rice. These proteins in brown rice grains were also much lower after subsequent heat-processing during the manufacturing process. The protease activity of germinated brown rice (GR) was detected and increased 1.5 times after germination. The optimum pH values for degradation of the 26-kDa and 14-16-kDa allergens in the GR grains were 4 and between 5 and 7, respectively. These results suggest that the decrease in the soluble proteins and allergens was induced in part by proteolytic degradation. The presence of a detergent enhanced the proteolytic degradation of the soluble proteins, especially of the 26-kDa allergen, in the brown rice grains. The degradation of the 26-kDa allergen was weakly inhibited by NEM, suggesting cysteine protease(s) may have been involved in its degradation. These results suggest that the two abundant allergens were degraded in a different manner and probably by different proteases in the grains during germination.
authors.affiliation: School of Nutritional Sciences, Nagoya University of Arts and Sciences, Nissin, Aichi, Japan.
authors.forename: Chikako
authors.initials: C
authors.lastname: Yamada
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Izumi
authors.forename: Junko
authors.initials: J
authors.lastname: Hirano
authors.forename: Aya
authors.initials: A
authors.lastname: Mizukuchi
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Kise
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Matsuda
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Kato
mesh_terms: D000485:Allergens / Q000378:metabolism*; D003546:Cysteine Endopeptidases / Q000378:metabolism; D003902:Detergents / Q000494:pharmacology; D005511:Food Handling; D005512:Food Hypersensitivity / Q000517:prevention & control; D018525:Germination; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D012275:Oryza / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism; D012639:Seeds; D012995:Solubility
chemical_list: D000485:Allergens; D003902:Detergents; D010940:Plant Proteins; D010447:Peptide Hydrolases; D003546:Cysteine Endopeptidases