title: Identification of the bile acid-binding region in the soy glycinin A1aB1b subunit.
abstract: Soy glycinin has five major subunits which are classified into two groups according to their homology in amino acid sequences (group I, A1aB1b, A1bB2 and A2B1a; group II, A3B4 and A5A4B3). It has been reported that the peptide fragments derived from the A1a and A2 chains of the A1aB1b and A2B1a subunits had bile acid-binding ability and that the region of 114-161 residues of the A1a chain was responsible for this bile acid-binding ability. In this study, we constructed A1a, A3 and 9 deletion mutants of A1a lacking various numbers of residues at the C-terminus, and evaluated their bile acid-binding ability by a cholic acid-conjugated column and fluorescence analysis. The bile acid-binding ability of A1a was higher than that of A3 and there was a remarkable decrease in the bile acid-binding ability between the delta[138-291] and delta[130-291] mutants. The 130-138 region is rich in hydrophobic residues. In this regard, when we constructed the delta[129-134] mutant lacking six contiguous hydrophobic residues (VAWWMY) and evaluated its bile acid-binding ability, a similar remarkable decrease in the bile acid-binding ability was observed. These results indicate that the 129-134 residue region (VAWWMY) with high hydrophobicity was important for bile acid-binding of A1a.
authors.affiliation: Laboratory of Food Quality Design and Development, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: Seon-Kang
authors.initials: SK
authors.lastname: Choi
authors.forename: Motoyasu
authors.initials: M
authors.lastname: Adachi
authors.forename: Shigeru
authors.initials: S
authors.lastname: Utsumi
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001647:Bile Acids and Salts / Q000378:metabolism*; D001665:Binding Sites; D019826:Cholic Acid / Q000737:chemistry / Q000378:metabolism; D002846:Chromatography, Affinity / Q000379:methods; D004591:Electrophoresis, Polyacrylamide Gel; D017353:Gene Deletion; D005916:Globulins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000235:genetics; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D021122:Protein Subunits; D030262:Soybean Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001647:Bile Acids and Salts; D005916:Globulins; D009841:Oligonucleotides; D010446:Peptide Fragments; D021122:Protein Subunits; D030262:Soybean Proteins; C011474:glycinin; D019826:Cholic Acid