Prak Krisna, Mikami Bunzo, Itoh Takafumi, Fukuda Takako, Maruyama Nobuyuki, Utsumi Shigeru
Laboratory of Food Quality Design and Development, Graduate School of Agriculture, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2013 Aug;69(Pt 8):937-41. doi: 10.1107/S1744309113019684. Epub 2013 Jul 27.
Glycinin is one of the most abundant storage-protein molecules in soybean seeds and is composed of five subunits (A1aB1b, A1bB2, A2B1a, A3B4 and A5A4B3). A1bB2 was purified from a mutant soybean cultivar containing glycinin composed of only A5A4B3 and A1bB2. At 281 K the protein formed hexagonal, rectangular and rod-shaped crystals in the first [0.1 M imidazole pH 8.0, 0.2 M MgCl₂, 35%(v/v) MPD], second [0.1 M sodium citrate pH 5.6, 0.2 M ammonium acetate, 30%(v/v) MPD] and third (0.1 M phosphate-citrate pH 4.2, 2.0 M ammonium sulfate) crystallization conditions, respectively. X-ray diffraction data were collected to resolutions of 1.85, 1.85 and 2.5 Å from crystals of the three different shapes. The crystals belonged to space groups P6₃22, P2₁ and P1, with unit-cell parameters a = b = 143.60, c = 84.54 Å, a = 114.54, b = 105.82, c = 116.67 Å, β = 94.99° and a = 94.45, b = 94.96, c = 100.66 Å, α = 107.02, β = 108.44, γ = 110.71°, respectively. One, six and six subunits of A1bB2 were estimated to be present in the respective asymmetric units. The three-dimensional structure of the A1bB2 hexamer is currently being determined.
大豆球蛋白是大豆种子中最丰富的储存蛋白分子之一，由五个亚基（A1aB1b、A1bB2、A2B1a、A3B4和A5A4B3）组成。A1bB2是从一个突变大豆品种中纯化得到的，该品种的大豆球蛋白仅由A5A4B3和A1bB2组成。在281 K时，该蛋白分别在第一[0.1 M咪唑pH 8.0、0.2 M MgCl₂、35%（v/v）MPD]、第二[0.1 M柠檬酸钠pH 5.6、0.2 M醋酸铵、30%（v/v）MPD]和第三（0.1 M磷酸盐-柠檬酸盐pH 4.2、2.0 M硫酸铵）结晶条件下形成六边形、矩形和棒状晶体。从三种不同形状的晶体收集到的X射线衍射数据分辨率分别为1.85、1.85和2.5 Å。这些晶体分别属于空间群P6₃22、P2₁和P1，晶胞参数分别为a = b = 143.60，c = 84.54 Å，a = 114.54，b = 105.82，c = 116.67 Å，β = 94.99°以及a = 94.45，b = 94.96，c = 100.66 Å，α = 107.02，β = 108.44，γ = 110.71°。估计在各自的不对称单元中分别存在一个、六个和六个A1bB2亚基。目前正在确定A1bB2六聚体的三维结构。
