Proteomic Analysis of Oil-Roasted Cashews Using a Customized Allergen-Focused Protein Database

Cashews are one of the most prevalent
causes of tree nut allergies. However, the cashew proteome is far
from complete, which limits the quality of peptide identification
in mass spectrometric analyses. In this study, bioinformatics tools
were utilized to construct a customized cashew protein database and
improve sequence quality for proteins of interest, based on a publicly
available cashew genome database. As a result, two additional isoforms
for cashew 2S albumins and five other isoforms for cashew 11S proteins
were identified, along with several other potential allergens. Using
the optimized protein database, the protein profiles of cashew nuts
subjected to different oil-roasting conditions (139 and 166 °C
for 2–10 min) were analyzed using discovery LC-MS/MS analysis.
The results showed that the cashew 2S protein is most heat-stable,
followed by 11S and 7S proteins, though protein isoforms might be
affected differently. Preliminary target peptide selection indicated
that out of the 29 potential targets, 18 peptides were derived from
the newly developed database. In the evaluation of thermal processing
effects on cashew proteins, several Maillard reaction adducts were
also identified. The cashew protein database developed in this study
allows for comprehensive analyses of cashew proteins and development
of high-quality allergen detection methods.

腰果是引发坚果类过敏最常见的诱因之一。然而，当前腰果蛋白质组（proteome）的完整度仍有欠缺，这限制了质谱分析中肽段鉴定的质量。本研究基于公开可用的腰果基因组数据库，借助生物信息学工具构建了定制化腰果蛋白质数据库，并优化了目标蛋白的序列质量。最终，本研究鉴定得到2种新增的腰果2S清蛋白（2S albumin）亚型、5种腰果11S蛋白亚型，同时还发现了其他数种潜在过敏原。利用优化后的蛋白质数据库，本研究采用鸟枪法液相色谱-串联质谱（LC-MS/MS）分析了经不同油焙条件（139℃、166℃下处理2~10 min）处理的腰果蛋白质组谱。结果显示，腰果2S蛋白的热稳定性最强，其次为11S蛋白与7S蛋白，不过不同蛋白亚型受热影响的程度存在差异。初步靶肽筛选实验表明，在29个潜在靶标中，有18条肽段来自本次新构建的数据库。在评估热加工对腰果蛋白质的影响时，本研究还鉴定到了数种美拉德反应加合物。本研究构建的腰果蛋白质数据库，可用于腰果蛋白质的全面分析以及高质量过敏原检测方法的开发。