Department of Biochemistry, Faculty of Chemistry, University of Belgrade, Studentski Trg 12-16, Belgrade, Serbia.
J Sci Food Agric. 2010 Aug 15;90(10):1702-8. doi: 10.1002/jsfa.4005.
The major peanut allergens are Ara h 1, Ara h 2 and Ara h 6. Proteolytic processing has been shown to be required for the maturation process of Ara h 6. The aim of this study was to examine whether Ara h 2 undergoes proteolytic processing and, if so, whether proteolytic processing influences its ability to bind human immunoglobulin E (IgE).
Ara h 2 isolated from peanut extract under conditions of protease inhibition revealed a single additional peak for its two known isoforms (Ara h 2.01 and Ara h 2.02), corresponding to a C-terminally truncated form lacking a dipeptide (RY). Ara h 2 isolated in the absence of protease inhibition, however, yielded two additional peaks, identified as C-terminally truncated forms lacking either a dipeptide (RY) or a single tyrosine residue. The IgE-binding capacity of the Ara h 2 truncated forms was not altered.
Ara h 2 undergoes proteolytic processing by peanut proteases that involves C-terminal removal of a dipeptide. Hence Ara h 2 isolated from peanut extract is a complex mixture of two isoforms expressed by different genes, Ara h 2.01 and Ara h 2.02, as well as truncated forms generated by the proteolytic processing of these isoforms.
主要的花生过敏原是 Ara h 1、Ara h 2 和 Ara h 6。蛋白水解加工已被证明是 Ara h 6 成熟过程所必需的。本研究旨在研究 Ara h 2 是否经历蛋白水解加工，如果是，蛋白水解加工是否会影响其与人免疫球蛋白 E（IgE）结合的能力。
在蛋白酶抑制条件下从花生提取物中分离出的 Ara h 2 揭示了其两个已知同工型（Ara h 2.01 和 Ara h 2.02）的单个额外峰，对应于缺乏二肽（RY）的 C 末端截断形式。然而，在没有蛋白酶抑制的情况下分离出的 Ara h 2 产生了另外两个峰，鉴定为缺乏二肽（RY）或单个酪氨酸残基的 C 末端截断形式。Ara h 2 截断形式的 IgE 结合能力没有改变。
Ara h 2 经历由花生蛋白酶介导的蛋白水解加工，涉及二肽 C 末端的去除。因此，从花生提取物中分离出的 Ara h 2 是由不同基因表达的两个同工型（Ara h 2.01 和 Ara h 2.02）以及这些同工型的蛋白水解加工产生的截断形式的复杂混合物。
