Expression and characterisation of a highly repetitive peptide derived from a wheat seed storage protein
Expression and characterisation of a highly repetitive peptide derived from a wheat seed storage protein
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DOI：
10.1016/s0167-4838(00)00059-5
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发表时间：
2000-06-15
期刊：
影响因子：
--
通讯作者：
Tatham, AS
中科院分区：
文献类型：
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作者：
Gilbert, SM;Wellner, N;Tatham, AS
小麦种子贮藏蛋白的高分子量（HMW）亚基组赋予小麦面团和面筋弹性。它们由三个领域组成：非重复的N-和C-末端结构域，其含有用于共价交联的半胱氨酸残基，以及由重复序列组成的中心结构域。一个完整的HMW亚基的圆二色性和红外（IR）光谱进行了比较与那些对应于在大肠杆菌中表达的中央重复结构域的肽。这允许在不存在N-和C-末端结构域的情况下研究中心结构域的结构，并确定这些结构域对整个蛋白质结构的贡献。在溶液中，肽显示出β-转角和聚脯氨酸II样结构的存在。变温研究表明这两种结构之间的平衡，聚脯氨酸II构象在低温下占主导地位，在较高温度下的β-转角构象。在水合固体状态下的IR也表明β-转角和分子间β-折叠结构的存在。相反，整个亚基的光谱显示在N-和C-末端结构域中存在α-螺旋。β折叠的含量在整个亚基中也较高，表明N-和C-末端结构域可能促进重复序列之间分子间β折叠结构的形成，这可能是通过对齐分子以促进相互作用。(C)2000 Elsevier Science B. V.保留所有权利。
The high molecular weight (HMW) subunit group of wheat seed storage proteins impart elasticity to wheat doughs and glutens. They consist of three domains: non-repetitive N- and C-terminal domains, which contain cysteine residues for covalent cross-linking, and a central domain consisting of repeated sequences. The circular dichroism and infrared (IR) spectra of an intact HMW subunit were compared with those of a peptide corresponding to the central repetitive domain expressed in Escherichia coli. This allowed the structure of the central domain to be studied in the absence of the N- and C-terminal domains and the contributions of these domains to the structure of the whole protein to be determined. In solution the peptide showed the presence of beta-turns and polyproline II-like structure. Variable temperature studies indicated an equilibrium between these two structures, the polyproline II conformation predominating at low temperatures and the beta-turn conformation at higher temperatures. IR in the hydrated solid state also indicated the presence of beta-turns and intermolecular beta-sheet structures. In contrast, spectroscopy of the whole subunit showed the presence of alpha-helix in the N- and C-terminal domains. The content of beta-sheet was also higher in the whole subunit, indicating that the N- and C-terminal domains may promote the formation of intermolecular beta-sheet structures between the repetitive sequences, perhaps by aligning the molecules to promote interaction. (C) 2000 Elsevier Science B.V. All rights reserved.