Arnold F H
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena 91125.
Protein Eng. 1988 Apr;2(1):21-5. doi: 10.1093/protein/2.1.21.
Improving protein stability in unnatural and suboptimal environments is a promising application of protein engineering technology. Carefully designed amino acid alterations may lead to dramatic positive effects on the stability of proteins under highly perturbing conditions, such as in non-aqueous solvents. Applications of biocatalysts and proteins with specific binding capabilities in the chemical industry have been severely limited by constraints placed on the solvent environment. With the advent of convenient methods for altering the amino acid composition and even synthesizing entirely new protein molecules, it is worthwhile to consider engineering proteins for stability in non-aqueous solvents. In order to identify the features that a protein would need for stability in organic media, we have been studying the structure and properties of the hydrophobic protein crambin. Crambin is unique in that it is soluble and stable in very high concentrations of polar organic solvents. Crambin and its water-soluble homologs offer a powerful demonstration of protein engineering for non-aqueous solvents. This paper describes the structural features that contribute to crambin's special properties. Based on these observations and consideration of how non-aqueous solvents affect the interactions important in protein folding, a set of rules for designing non-aqueous solvent-stable proteins is proposed.
在非天然和次优环境中提高蛋白质稳定性是蛋白质工程技术一个很有前景的应用方向。精心设计的氨基酸改变可能会对蛋白质在高度干扰条件下（如在非水溶剂中）的稳定性产生显著的积极影响。生物催化剂和具有特定结合能力的蛋白质在化学工业中的应用一直受到溶剂环境限制的严重制约。随着改变氨基酸组成甚至合成全新蛋白质分子的便捷方法的出现，考虑对蛋白质进行工程改造以使其在非水溶剂中保持稳定是很有价值的。为了确定蛋白质在有机介质中保持稳定所需的特性，我们一直在研究疏水蛋白克拉宾的结构和性质。克拉宾的独特之处在于它在非常高浓度的极性有机溶剂中可溶且稳定。克拉宾及其水溶性同源物为非水溶剂中的蛋白质工程提供了有力的例证。本文描述了有助于克拉宾具有特殊性质的结构特征。基于这些观察结果以及对非水溶剂如何影响蛋白质折叠中重要相互作用的思考，提出了一套设计非水溶剂稳定型蛋白质的规则。
