Structure-function relationships of soybean proglycinins at subunit levels.
Structure-function relationships of soybean proglycinins at subunit levels.
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DOI：
10.1021/jf047811x
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发表时间：
2005-05
影响因子：
6.1
通讯作者：
K. Prak;K. Nakatani;T. Katsube-Tanaka;M. Adachi;N. Maruyama;S. Utsumi
中科院分区：
文献类型：
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作者：
K. Prak;K. Nakatani;T. Katsube-Tanaka;M. Adachi;N. Maruyama;S. Utsumi
大豆球蛋白由五种亚基组成，I组（A1 aB 1b、A1 bB 2和A2 B1 a）和II组（A3 B4和A5 A4 B3）。通过逆转录-聚合酶链反应方法克隆各个亚基的cDNA，并使用pET载体在大肠杆菌中表达。通过硫酸铵分级分离和柱层析以同源三聚体的形式纯化重组的前大豆球蛋白。物理化学性质，如分子尺寸，溶解度，表面疏水性，热稳定性，和乳化能力的个人大豆球蛋白进行了研究。除A2 B1 a外，所有前大豆球蛋白的分子尺寸与分子大小成正比。溶解度是每种大豆球蛋白原固有的。在离子强度为0.5时，除A1 aB 1b外的所有前大豆球蛋白在酸性pH下均显示出非常低的溶解度，但A1 aB 1b的溶解度高于60%。在离子强度0.08，所有的前大豆球蛋白表现出等电沉淀，虽然A2 B1 a和A1 bB 2不是完全不溶。表面疏水性（A5 A4 B3 <A1 aB 1b <或= A3 B4 <A1 bB 2 <A2 B1 a <或= A5 A4 B3 <A3 B4 <或= A1 aB 1b）和热稳定性（A1 bB 2 <<A2 B1 a <或= A5 A4 B3 <A3 B4 <或= A1 aB 1b）的乳化能力顺序不同。
Glycinin consists of five kinds of subunits, group I (A1aB1b, A1bB2, and A2B1a) and group II (A3B4 and A5A4B3). cDNAs for individual subunits were cloned by reverse transcription-polymerase chain reaction method and expressed in Escherichia coli using pET vector. The recombinant proglycinins were purified by ammonium sulfate fractionation and column chromatography in the form of homotrimers. Physicochemical properties such as molecular dimensions, solubility, surface hydrophobicity, thermal stability, and emulsifying ability of individual proglycinins were studied. Molecular dimensions were proportional to molecular size for all proglycinins except A2B1a. Solubility was intrinsic to each proglycinin. At the ionic strength of 0.5, all proglycinins except A1aB1b showed a very low solubility at acidic pH, but A1aB1b was soluble to higher than 60%. At ionic strength 0.08, all proglycinins exhibited isoelectric precipitation, although A2B1a and A1bB2 were not completely insoluble. The order of emulsifying ability (A1bB2 < A2B1a < A5A4B3 < A3B4 < or = A1aB1b) was not of the same for surface hydrophobicity (A5A4B3 < A1aB1b < or = A3B4 < A1bB2 < A2B1a) and thermal stability (A1bB2 << A2B1a < or = A5A4B3 < A3B4 < or = A1aB1b).