Purification, Characterization, and Crystallization of Single Molecular Species ofβ-Conglycinin from Soybean Seeds

Abstract

Four major molecular species of beta-conglycinin, alpha 3, alpha 2 beta, alpha beta 2, and beta 3, were isolated and purified from seeds of an alpha' subunit-deficient strain of soybeans (Glycine max). All components were found to be homogeneous by high pressure liquid chromatography, SDS-polyacrylamide gel electrophoresis, and amino acid and amino terminal sequence analyses. The amino acid compositions of the alpha 3 and beta 3 components agreed fairly well with the compositions deduced from the cDNA sequences, and all of the components were highly glycosylated. The alpha 3 and beta 3 components were compared regarding their secondary structures. The secondary structure of the alpha 3 component deduced from CD measurements showed a higher alpha-helix content than that of the beta 3 component. The beta 3 component was crystallized by decreasing the ionic strength from 0.5 to 0.14 in phosphate buffer, pH 7.3, and the crystals grew to a size (1.0 mm x 0.2 mm x 0.2 mm) suitable for X-ray crystallographic analysis. A preliminary X-ray analysis showed that the crystal belonged to an orthorhombic crystal system having the space group P2(1)2(1)2(1) and unit cell dimensions of a = 185.1 A, b = 107.9 A, and c = 97.6 A.

Developments in plant breeding for improved nutritional quality of soya beans I. Protein and amino acid content

“…Another subunit, named ∃', is present only in some soya bean varieties (Coates et al 1985;Morita et al 1996). The primary structure of the ∃' subunit is still unknown, but the data suggested that this subunit is rich in sulphur-containing amino acids (Coates et al 1985).…”

“…It contains three subunits (Sykes & Gayler 1981, Yamauchi et al 1981. Most recently, Morita et al (1996) succeeded in isolation and purification of four major molecular components of ∃-conglycinin, 3∀, 2∀1∃, 1∀2∃ and 3∃, from seeds of an ∀' subunit-deficient strain. By using such cultivars with a simple subunit composition and chromatography at intermediate ionic strengths over a period sufficient to reach an effective dissociation equilibrium between the monomer and dimer, they also succeeded in crystallization of single ∃-conglycinin components.…”

Development of a perfusion reversed‐phase HPLC method for the separation of soybean and cereal (wheat, corn, and rice) proteins in binary mixtures. Application to the detection of soybean proteins in commercial bakery products

“…Soybean proteins have been analysed by different methods, with HPLC in the reversed-phase, size-exclusion, and ion-exchange modes being the most widely employed [10,11]. In some cases, the analysis of soybean proteins by HPLC has been performed for varietal identification of soybean cultivars [12 -18].…”

Processing Foods without Soybean Ingredients

“…β -Conglycinin is a trimer composed of three major subunits, α , α ′ , and β , with MWs of 76, 72, and 53 kDa, respectively [65] . Another subunit, named β ′ , is present only in some soybean varieties [66,67] . All of the β -conglycinin subunits are glycoproteins and contain 4 -5% carbohydrate [68] .…”