Sancho A I, Rigby N M, Zuidmeer L, Asero R, Mistrello G, Amato S, González-Mancebo E, Fernández-Rivas M, van Ree R, Mills E N C
Institute of Food Research, Norwich Research Park, Colney, Norwich, UK.
Allergy. 2005 Oct;60(10):1262-8. doi: 10.1111/j.1398-9995.2005.00876.x.
Non-specific lipid transfer proteins (LTPs) are involved in allergy to fresh and processed fruits. We have investigated the effect of thermal treatment and glycation on the physico-chemical and IgE-binding properties of the LTP from apple (Mal d 3).
Mal d 3 was purified from apple peel and the effect of heating in the absence and presence of glucose investigated by CD spectroscopy, electrospray and MALDI-TOF mass spectrometry. IgE reactivity was determined by RAST and immunoblot inhibition, SPT and basophil histamine release test.
The identity and IgE reactivity of purified Mal d 3 was confirmed. Mild heat treatment (90 degrees C, 20 min) in the absence or presence of glucose did not alter its IgE reactivity. More severe heat treatment (100 degrees C, 2 h) induced minor changes in protein structure, but a significant decrease in IgE-binding (30-fold) and biological activity (100- to 1000-fold). Addition of glucose resulted in up to four glucose residues attached to Mal d 3 and only a 2- and 10-fold decrease of IgE-binding and biological activity, respectively.
Only severe heat treatment caused a significant decrease in the allergenicity of Mal d 3 but glycation had a protective effect. The presence of sugars in fruits may contribute to the thermostability of the allergenic activity of LTP in heat-processed foods.
非特异性脂质转移蛋白（LTPs）与新鲜水果和加工水果过敏有关。我们研究了热处理和糖基化对苹果LTP（Mal d 3）的物理化学性质和IgE结合特性的影响。
从苹果皮中纯化Mal d 3，通过圆二色光谱、电喷雾和基质辅助激光解吸电离飞行时间质谱研究在有无葡萄糖存在下加热的影响。通过放射性变应原吸附试验和免疫印迹抑制、皮肤点刺试验和嗜碱性粒细胞组胺释放试验测定IgE反应性。
证实了纯化的Mal d 3的身份和IgE反应性。在有无葡萄糖存在下进行温和热处理（90℃，20分钟）不会改变其IgE反应性。更剧烈的热处理（100℃，2小时）会引起蛋白质结构的微小变化，但IgE结合显著降低（30倍），生物活性降低（100至1000倍）。添加葡萄糖导致多达四个葡萄糖残基附着在Mal d 3上，IgE结合和生物活性分别仅降低2倍和10倍。
只有剧烈热处理才会导致Mal d 3的致敏性显著降低，但糖基化具有保护作用。水果中糖的存在可能有助于热加工食品中LTP致敏活性的热稳定性。
