title: Binding interactions of β-conglycinin and glycinin with vitamin B12.
abstract: Vitamin B12 deficiency is a problem for many elderly people around the world that is caused by food-cobalamin malabsorption syndrome due to gastrointestinal problems. In this study, the molecular interactions of VB12 with two major soy protein fractions, β-conglycinin (7S) and glycinin (11S), were studied using fluorescence and far-UV circular dichroism spectroscopic techniques. The results show that the fluorescence of 7S and 11S was quenched by VB12 through binding-related quenching after correcting for the inner-filter effect. Both 7S and 11S had a good affinity to VB12 as indicated by their high binding constant 1.252 (±0.085) × 10(4) M(-1) for 7S and 0.952 (±0.04) × 10(4) M(-1) for 11S at 292 K, respectively. Such binding induced a more organized protein confirmation with increased β-sheet and β-turn structure components and a more folded tertiary structure. It is deduced that VB12 was bound in the interior of protein three-dimensional network mainly via hydrophobic interactions to form 7S-VB12 and 11S-VB12 complexes. The results suggest that soy protein has potential to be used as carrier of VB12.
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta , Edmonton, Alberta T6G 2P5, Canada.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Tian
authors.forename: Li
authors.initials: L
authors.lastname: Liang
authors.forename: Muriel
authors.initials: M
authors.lastname: Subirade
authors.forename: Lingyun
authors.initials: L
authors.lastname: Chen
mesh_terms: D052179:Antigens, Plant / Q000737:chemistry / Q000378:metabolism*; D002942:Circular Dichroism; D004735:Energy Transfer; D005916:Globulins / Q000737:chemistry / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D055314:Seed Storage Proteins / Q000737:chemistry / Q000378:metabolism*; D030262:Soybean Proteins / Q000737:chemistry / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013696:Temperature; D013816:Thermodynamics; D014805:Vitamin B 12 / Q000737:chemistry / Q000378:metabolism*
chemical_list: D052179:Antigens, Plant; D005916:Globulins; D055314:Seed Storage Proteins; D030262:Soybean Proteins; C013894:beta-conglycinin protein, Glycine max; C011474:glycinin; D014805:Vitamin B 12