Dipartimento di Scienze Molecolari Agroalimentari, Università degli Studi di Milano, Milano, Italy.
Plant Foods Hum Nutr. 2012 Mar;67(1):24, 30. doi: 10.1007/s11130-012-0274-4.
Maize is used as an alternative to wheat to elaborate food stuffs for celiac patients in a gluten-free diet.However, some maize prolamins (zeins) contain amino acid sequences that resemble the wheat gluten immunodominant peptides and their integrity after gastrointestinal proteolysisis unknown. In this study, the celiac IgA-immunoreactivity to zeins from raw or nixtamalized grains, before and after peptic/tryptic digestion was evaluated and their possible immunogenicity was investigated by in silico methods.IgA from some celiac patients with HLA-DQ2 or DQ8 haplotypes recognized two alpha-zeins even after peptic/ tryptic proteolysis. However, digestion affected zeins after denaturation, reduction, and alkylation, used for identification of prolamins as alpha-zein A20 and A30 by MS/MS sequencing. An in silico analysis indicated that other zeins contain similar sequences, or sequences that may bind even better to the HLA-DQ2/DQ8 molecules compared to the already identified ones. Results concur to indicate that relative abundance of these zeins, along with factors affecting their resistance to proteolysis, may be of paramount clinical relevance, and the use of maize in the formulation and preparation of gluten-free foods must be reevaluated in some cases of celiac disease.
玉米被用作小麦的替代品，用于为无麸质饮食中的乳糜泻患者精心制作食品。然而，一些玉米醇溶蛋白（zein）含有类似于小麦面筋免疫优势肽的氨基酸序列，其在胃肠道蛋白水解后的完整性尚不清楚。在这项研究中，评估了 raw 或 nixtamalized 谷物中原有的或经胃蛋白酶/胰蛋白酶消化后的玉米醇溶蛋白（zein）对乳糜泻 IgA 的免疫反应性，并通过计算方法研究了其可能的免疫原性。一些具有 HLA-DQ2 或 DQ8 单倍型的乳糜泻患者的 IgA 即使在胃蛋白酶/胰蛋白酶消化后也能识别两种 alpha-zein。然而，消化会影响变性、还原和烷基化后的醇溶蛋白，这些方法用于通过 MS/MS 测序鉴定醇溶蛋白为 alpha-zein A20 和 A30。计算分析表明，其他醇溶蛋白含有类似的序列，或者与已经鉴定的序列相比，可能与 HLA-DQ2/DQ8 分子结合得更好。结果表明，这些醇溶蛋白的相对丰度以及影响其对蛋白水解抗性的因素，在某些乳糜泻病例中可能具有至关重要的临床意义，因此必须重新评估玉米在无麸质食品配方和制备中的使用。
