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Basic Research on Structure-Fluctuation-Function Relation of Food Proteins

食品蛋白质结构-波动-功能关系的基础研究

基本信息

批准号：
01560142
负责人：
GEKKO Kunihiko
金额：
$ 1.28万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01560142/
关键词：
Food proteins Fluctuation Structure Function Compressibility

项目摘要

To elucidate the fluctuation-structure-function relationships of food proteins, the adiabatic compressibility, beta, of various egg and milk proteins was determined by means of sound velocity and density measurements in aqueous solutions. All the protein showed positive beta values, indicating the large internal flexibility characteristic of the protein molecules. On the basis of statistical analyses of beta, the flexibility-structureーfunction relationship was discussed in terms of the internal cavity and hydration, focusing on the hydrophobicity of proteins. It was found that beta increases with increasing partial specific volume and hydrophobicity of proteins. The helix element also seemed to be a dynamic domein to increase beta. Four amino acid residues (Leu, Glu, Phe, and His) greatly increased beta, and another four (Asn, Gly, Ser, and Thr) decreased it. Some empirical equations were derived for the estimation of the beta values of unknown proteins on the basis of their amino acid compositions. The volume fluctuations of proteins revealed by the compressibility data were in the range of 30-200 ml/mol, which corresponded to about 0.3 % of the total protein volume. Most proteases and protease inhibitors were less compressible compared with nutrient (storage) proteins such as egg and milk proteins while an extreemely high flexibility was observed for the transport proteins. Protease susceptibility, foaming capacity, and free energy of unfolding of proteins were positively correlated to beta. The conformational fluctuation seemed to enhance the thermal stability of proteins. These results indicate that the flexibility of the structure plays an essential role in the conformational stability and functional properties of food proteins.

为了阐明食品蛋白质的涨落-结构-功能关系，通过测量水溶液中的声速和密度，测定了各种蛋和奶蛋白质的绝热压缩系数β。所有蛋白质均显示正β值，表明蛋白质分子具有较大的内部柔性特征。在对β统计分析的基础上，从蛋白质的内部空腔和水化作用两个方面讨论了蛋白质的柔性-结构-功能关系，重点讨论了蛋白质的疏水性。发现β随蛋白质的偏比容和疏水性的增加而增加。螺旋元件似乎也是一个动态的圆顶，以增加β。有4个氨基酸残基（Leu、Glu、Phe和His）使β值显著增加，而另外4个氨基酸残基（Asn、Gly、Ser和Thr）使β值减小，并根据未知蛋白质的氨基酸组成推导出了估算其β值的经验公式。由可压缩性数据揭示的蛋白质的体积波动在30-200 ml/mol的范围内，其对应于总蛋白质体积的约0.3%。大多数蛋白酶和蛋白酶抑制剂与营养（储存）蛋白质如蛋和奶蛋白相比可压缩性较差，而运输蛋白质则观察到极高的灵活性。蛋白酶敏感性、起泡能力和蛋白质展开自由能与β-淀粉酶活性呈正相关。构象波动似乎增强了蛋白质的热稳定性。这些结果表明，结构的灵活性在食品蛋白质的构象稳定性和功能特性中起着至关重要的作用。