Cuesta-Herranz J, Pastor C, Figueredo E, Vidarte L, De las Heras M, Durán C, Fernández-Caldas E, de Miguel J, Vivanco F
Servicio de Alergia, Fundación Jiménez Díaz and C.B.F. Leti, SA. Tres Cantos, Madrid, Spain.
Clin Exp Allergy. 2003 Jun;33(6):827-33. doi: 10.1046/j.1365-2222.2003.01680.x.
Allergenic components in melon extracts have not been described in spite of the fact that melon (Cucumis melo) is a frequent allergy-eliciting fruit. The aim of this study was to evaluate allergenic components in melon extract and to report the identification of cucumisin as a major melon allergen.
Sera from 35 patients allergic to melon were selected on the basis of clinical symptoms, skin prick tests and oral challenge test. Allergenic components were detected by sodium dodecyl sulphate polyacrylamide gel electrophoresis and immunoblotting. Molecular characterization of IgE-binding bands was performed by N-terminal amino acid sequencing.
More than 10 IgE-binding bands, between 10 and 80 kDa, were identified in melon extract. Out of them, four IgE-binding bands were major allergens: 14 kDa, 36 kDa, 54 kDa and 67 kDa. These major allergens, except 14 kDa band, showed the same N-terminal sequence: T-T-R-S-W-D-F-L. Research conducted with protein databases identified this N-terminal sequence as cucumisin, an alkaline serine protease, which shares structural homology with microbial subtilisin. The molecular mass of the identified bands corresponds with different molecular forms of cucumisin produced during the processing or degradation of the enzyme: 67 kDa native cucumisin, 54 kDa mature cucumisin and 36 kDa NH2-terminal cucumisin fragment.
Cucumisin (Cuc m 1) and several N-terminal cucumisin fragments are the major allergens of melon. The ubiquitous distribution of this protein family (cucumisin-like proteases) in many plant species and its high structural similarity suggest its potential role as a new panallergen in plant foods.
尽管甜瓜（黄瓜属甜瓜种）是一种常见的引发过敏的水果，但甜瓜提取物中的变应原成分尚未得到描述。本研究的目的是评估甜瓜提取物中的变应原成分，并报告将黄瓜蛋白酶鉴定为主要甜瓜变应原。
根据临床症状、皮肤点刺试验和口服激发试验，从35名对甜瓜过敏的患者中选取血清。通过十二烷基硫酸钠聚丙烯酰胺凝胶电泳和免疫印迹检测变应原成分。通过N端氨基酸测序对IgE结合条带进行分子表征。
在甜瓜提取物中鉴定出10多条分子量在10至80 kDa之间的IgE结合条带。其中，四条IgE结合条带是主要变应原：14 kDa、36 kDa、54 kDa和67 kDa。除14 kDa条带外，这些主要变应原显示相同的N端序列：T-T-R-S-W-D-F-L。利用蛋白质数据库进行的研究将该N端序列鉴定为黄瓜蛋白酶，一种碱性丝氨酸蛋白酶，它与微生物枯草杆菌蛋白酶具有结构同源性。鉴定出的条带分子量与酶在加工或降解过程中产生的不同分子形式的黄瓜蛋白酶相对应：67 kDa天然黄瓜蛋白酶、54 kDa成熟黄瓜蛋白酶和36 kDa NH2端黄瓜蛋白酶片段。
黄瓜蛋白酶（Cuc m 1）和几个N端黄瓜蛋白酶片段是甜瓜的主要变应原。该蛋白质家族（类黄瓜蛋白酶）在许多植物物种中的广泛分布及其高度的结构相似性表明其在植物性食物中作为一种新的泛变应原的潜在作用。
