Lechevalier Valérie, Croguennec Thomas, Pezennec Stéphane, Guérin-Dubiard Catherine, Pasco Maryvonne, Nau Françoise
UMR INRA-ENSAR Physico-Chimie et Technologie des Ovoproduits, CS 84215, 65 rue de Saint Brieuc, 35042 Rennes Cedex, France.
J Agric Food Chem. 2003 Oct 8;51(21):6354-61. doi: 10.1021/jf034184n.
Structural modifications of ovalbumin, ovotransferrin, and lysozyme at the air-water interface have been investigated using SDS-PAGE, both intrinsic and ANS fluorometry, and circular dichroism experiments. Ovalbumin contact with an interface induced an exposure of aromatic residues, a slight decrease in alpha-helix structures (-1.7%), and an increase in both beta-sheet (+3.4%) and beta-turn (+7.9%) structures. Moreover, these conformational changes led to the formation of insoluble polymers of ovalbumin through intermolecular disulfide bonds. Ovotransferrin contact with an interface led to an increase in its surface hydrophobicity (+30%) and modifications of its secondary structure (-33% of alpha-helices, +96.4% of beta-sheets, +13.2% of beta-turns, and +21.2% of random coils), characteristic of major conformational changes. On the other hand, lysozyme did not undergo any structural modification. These results clearly underscore that at the air-water interface proteins are susceptible to denaturation.
利用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）、固有荧光和1-苯胺基萘-8-磺酸（ANS）荧光测定法以及圆二色性实验，对卵清蛋白、卵转铁蛋白和溶菌酶在气-水界面的结构修饰进行了研究。卵清蛋白与界面接触会导致芳香族残基暴露、α-螺旋结构略有减少（-1.7%），β-折叠（+3.4%）和β-转角（+7.9%）结构均增加。此外，这些构象变化通过分子间二硫键导致卵清蛋白形成不溶性聚合物。卵转铁蛋白与界面接触导致其表面疏水性增加（+30%）及其二级结构发生改变（α-螺旋减少33%，β-折叠增加96.4%，β-转角增加13.2%，无规卷曲增加21.2%），这是主要构象变化的特征。另一方面，溶菌酶未发生任何结构修饰。这些结果清楚地表明，在气-水界面蛋白质易发生变性。
