Quantifying Additive Interactions of the Osmolyte Proline with Individual Functional Groups of Proteins: Comparisons with Urea and Glycine Betaine, Interpretation of m-Values
Quantifying Additive Interactions of the Osmolyte Proline with Individual Functional Groups of Proteins: Comparisons with Urea and Glycine Betaine, Interpretation of m-Values
复制标题
DOI：
10.1021/bi400683y
复制
发表时间：
2013-09-03
期刊：
影响因子：
2.9
通讯作者：
Record, M. Thomas, Jr.
中科院分区：
文献类型：
--
作者：
Diehl, Roger C.;Guinn, Emily J.;Record, M. Thomas, Jr.
为了量化渗透液l -脯氨酸与蛋白质官能团的相互作用，并预测它们对蛋白质过程的影响，我们使用蒸汽压渗透法来确定化学势衍生物d mu(2)/dm(3) = mu(23)，量化脯氨酸（组分3）与21种溶质（组分2）的优先相互作用，这些溶质选择了脂肪族或芳香族C、酰胺、羧酸盐、磷酸盐或羟基O，以及酰胺或阳离子N表面的不同组合。溶解度数据得出四种较难溶溶质的mu（23）值。使用基于asa的分析对mu（23）的值进行剖析，以检验可加性假设，并获得这八种表面类型和三种无机离子的α值（脯氨酸相互作用势）。由这些α值预测的mu（23）值与实验结果一致，证明了可加性。利用溶质分配模型对α值进行分子解释，得到分配系数（K-p），用于量化每个官能团水化水中脯氨酸的局部积累或排除。根据α值和ASA信息预测了脯氨酸与天然蛋白质表面的相互作用以及脯氨酸对蛋白质展开的影响，并与实验数据、甘氨酸、甜菜碱和尿素的结果以及传递自由能分析的预测进行了比较。我们得出结论，脯氨酸稳定蛋白质是因为它与酰胺氧和脂肪烃表面的不利相互作用（排除在外），脯氨酸是一种有效的体内渗透剂，因为它与细胞质蛋白质和核酸表面的阴离子（羧酸盐和磷酸盐）、酰胺氧和脂肪烃基团的不利相互作用导致渗透压增加。
To quantify interactions of the osmolyte L-proline with protein functional groups and predict their effects on protein processes, we use vapor pressure osmometry to determine chemical potential derivatives d mu(2)/dm(3) = mu(23), quantifying the preferential interactions of proline (component 3) with 21 solutes (component 2) selected to display different combinations of aliphatic or aromatic C, amide, carboxylate, phosphate or hydroxyl O, and amide or cationic N surface. Solubility data yield mu(23) values for four less-soluble solutes. Values of mu(23) are dissected using an ASA-based analysis to test the hypothesis of additivity and obtain alpha-values (proline interaction potentials) for these eight surface types and three inorganic ions. Values of mu(23) predicted from these alpha-values agree with the experiment, demonstrating additivity. Molecular interpretation of alpha-values using the solute partitioning model yields partition coefficients (K-p) quantifying the local accumulation or exclusion of proline in the hydration water of each functional group. Interactions of proline with native protein surfaces and effects of proline on protein unfolding are predicted from alpha-values and ASA information and compared with experimental data, with results for glycine betaine and urea, and with predictions from transfer free energy analysis. We conclude that proline stabilizes proteins because of its unfavorable interactions with (exclusion from) amide oxygens and aliphatic hydrocarbon surfaces exposed in unfolding and that proline is an effective in vivo osmolyte because of the osmolality increase resulting from its unfavorable interactions with anionic (carboxylate and phosphate) and amide oxygens and aliphatic hydrocarbon groups on the surface of cytoplasmic proteins and nucleic acids.