Structural basis for the functional properties of food Proteins

球状蛋白质呈现不同的构象状态，即天然、变性和熔融球状状态。以蛋白质为模型蛋白，分析了白色卵清蛋白和卵转铁蛋白的构象转变模式，得到以下结果：1。关于卵清蛋白：在从脲不饱和状态作为中间体以及在酸性pH下二硫化物还原状态的重折叠过程中形成熔融小球状态。发现在大肠杆菌中产生的重组卵清蛋白呈现与卵白色卵清蛋白基本上相同的构象，但缺乏翻译后修饰。根据对重组蛋白的热稳定性的观察，该蛋白具有碱依赖性热稳定性，其热稳定机制不涉及翻译后修饰。发现卵清蛋白变体R339 T在P1-P1'位点裂解后转化为热稳定形式。关于卵转铁蛋白：作为结构转变的结构基础，测定了卵转铁蛋白的apo形式的晶体结构。发现热处理后鸡蛋白色的可成形性降低是由于卵转铁蛋白的变性，其可以通过添加一些阴离子来最小化。

Globular proteins assume different conformational states, namely the native, denatured, and molten-globule states. As model food proteins, we analyzed the mode of conformational transition of egg white ovalbumin and ovotransferrin and obtained the following results :1. About ovalbumin : the molten-globule state was formed during the refolding from the ureadenatured state as an intermediate and also in the disulfide-reduced state at acidic pH. Recombinant ovalbumin produced in E coli was found to assume essentially the same conformation as egg white ovalbumin but to lack the post-translational modification. According to the observation that the recombinant protein underwent the alkaline-dependent thermostabilization, the post-translational modification was not involved in the thermostabilization mechanism. An ovalbumin variant R339T was found to be transformed into a thermostabilized form following the cleavage at the P1-P1'site.2. About ovotransferrin : As a structural basis for the structural transition, crystal structure of the apo from of ovotransferrin was determined. Decreased formability of egg white following heat treatments was found to be due to the denaturation of ovotransferrin that can be minimized by addition of some anions.