Wieser H
German Research Institute of Food chemistry, Garching.
Baillieres Clin Gastroenterol. 1995 Jun;9(2):191-207. doi: 10.1016/0950-3528(95)90027-6.
In recent years, remarkable progress has been made in the elucidation of cereal protein structure and its relation to coeliac toxicity. Gluten proteins of wheat can be classified according to their primary structure into high-, medium- and low-molecular-weight (HMW, MMW, LMW) groups. Each of these groups contains two or three different protein types having partly homologous, partly unique, structural elements: chi- and gamma-type HMW subunits of glutenin (HMW group), omega 5 and omega 1,2-type gliadins (MMW group) and alpha-type gliadins, gamma-type gliadins and LMW subunits of glutenin (LMW group). Numerous proteins from the same type do exist with only a few modifications of the amino-acid sequence. The structure of the HMW and LMW group proteins can be divided into three and five domains, respectively. Most typical for each type and unique for cereals are the glutamine- and proline-rich domains containing repetitive sequences (HMW group: domain B; LMW group: domain I). omega-type gliadins consist almost entirely of repetitive sequences. Rye and barley, closely related to wheat, have protein types homologous to those of wheat. Early investigations showed that wheat gluten and, in particular, the alcohol-soluble gliadin fraction contained the factor toxic for coeliac patients. Equivalent protein fractions of rye, barley and probably oats were also considered to be toxic. The effects of toxic proteins were not destroyed by digestion with pepsin, trypsin and pancreatin. In-vivo (instillation) testing established the toxicity of alpha-type gliadins, and in-vitro (organ culture) testing of gliadin peptides demonstrated that the N-terminal region (domain I) of alpha-type gliadins is involved in activating coeliac disease. The longest sequences common for toxic peptides were found to be -Pro-Ser-Gln-Gln- and -Gln-Gln-Gln-Pro-. Various in-vitro tests and two in-vivo studies on synthetic peptides support the importance of one or both of these sequences. They do not occur in non-toxic food proteins and are characterized by their ability to form a beta-turn conformation. Although these sequences are probably not sufficient for toxicity in themselves, and other amino-acid residues are additionally required, they could serve as the starting point for further investigation.
近年来，在阐明谷物蛋白结构及其与乳糜泻毒性的关系方面取得了显著进展。小麦的面筋蛋白可根据其一级结构分为高分子量、中分子量和低分子量（HMW、MMW、LMW）组。这些组中的每一组都包含两种或三种不同的蛋白质类型，它们具有部分同源、部分独特的结构元件：麦谷蛋白的chi型和γ型HMW亚基（HMW组）、ω5和ω1,2型醇溶蛋白（MMW组）以及α型醇溶蛋白、γ型醇溶蛋白和麦谷蛋白的LMW亚基（LMW组）。同一类型的众多蛋白质确实存在，只是氨基酸序列有一些修饰。HMW组和LMW组蛋白质的结构可分别分为三个和五个结构域。每种类型最典型且谷物特有的是含有重复序列的富含谷氨酰胺和脯氨酸的结构域（HMW组：结构域B；LMW组：结构域I）。ω型醇溶蛋白几乎完全由重复序列组成。与小麦密切相关的黑麦和大麦具有与小麦同源的蛋白质类型。早期研究表明，小麦面筋，特别是醇溶性醇溶蛋白部分含有对乳糜泻患者有毒的因子。黑麦、大麦以及可能燕麦的等效蛋白部分也被认为是有毒的。有毒蛋白质的作用不会被胃蛋白酶、胰蛋白酶和胰凝乳蛋白酶消化破坏。体内（灌注）试验确定了α型醇溶蛋白的毒性，体外（器官培养）对醇溶蛋白肽的试验表明，α型醇溶蛋白的N端区域（结构域I）参与激活乳糜泻。发现有毒肽最常见的最长序列是-Pro-Ser-Gln-Gln-和-Gln-Gln-Gln-Pro-。对合成肽的各种体外试验和两项体内研究支持了这些序列中一个或两个的重要性。它们不存在于无毒食物蛋白中，其特征在于能够形成β-转角构象。尽管这些序列本身可能不足以产生毒性，还需要其他氨基酸残基，但它们可作为进一步研究的起点。
