Effects of protein engineering of canola procruciferin on its physicochemical and functional properties.
The primary structure of Brassica napus procruciferin 2/3a was engineered to elucidate structure-function relationships and to improve the functionality of cruciferin. The following mutants were constructed: (1) C287T, (2) DeltaII, variable region II was deleted; (3) C287T/DeltaII, mutation involving (1) and (2); (4) DeltaIV + A1aIV; and (5) DeltaIV + A3IV, variable region IV was replaced with variable region IV containing many charged residues from soybean glycinin A1aB1b and A3B4 subunits. Differential scanning calorimetry analysis revealed that the A1aIV region has a more favorable interaction with the procruciferin molecule than does A3IV as well as the original regions. On the basis of heat-induced precipitation analysis, it was concluded that replacement of the free cysteine residue with threonine (C287T) and insertion of charged regions (DeltaIV + A1aIV and DeltaIV + A3IV) could lead procruciferin to form soluble aggregates after heating. Low solubility was observed in mutants DeltaIV + A3IV, DeltaII, and C287T/DeltaII, especially between pH 4 and 6 at mu = 0.08, but not in DeltaIV + A1aIV, indicating that the number of acidic amino acid residues and the high number of glutamine residues are important factors for solubility at mu = 0.08. None of the mutants showed any improvements in emulsifying ability, indicating that destabilization and addition of the hydrophilic region are not effective for emulsification. The insertion of the A1aIV region in procruciferin made the molecule more susceptible to alpha-chymotrypsin.
Tandang
Mary Rose G
MR
Laboratory of Food Quality Design and Development, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan.
Adachi
Motoyasu
M
Inui
Nauko
N
Maruyama
Nobuyuki
N
Utsumi
Shigeru
S
D000485:Allergens; D052179:Antigens, Plant; D029688:Brassica napus / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D011232:Chemical Precipitation; D002918:Chymotrypsin / Q000378:metabolism; D045703:Emulsifying Agents; D004926:Escherichia coli; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D016296:Mutagenesis; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D015202:Protein Engineering; D011498:Protein Precursors / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D011994:Recombinant Proteins; D055314:Seed Storage Proteins; D012995:Solubility; D013329:Structure-Activity Relationship; D013816:Thermodynamics
D000485:Allergens; D052179:Antigens, Plant; D045703:Emulsifying Agents; D010940:Plant Proteins; D011498:Protein Precursors; D011994:Recombinant Proteins; D055314:Seed Storage Proteins; C059777:cruciferin protein, Brassica napus; D002918:Chymotrypsin; C117608:alpha-chymotrypsin