Fourier transform infrared studies of proteins using nonaqueous solvents. Effects of methanol and ethylene glycol on albumin and immunoglobulin G.
Fourier transform infrared studies of proteins using nonaqueous solvents. Effects of methanol and ethylene glycol on albumin and immunoglobulin G.
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使用非水溶剂对蛋白质进行傅里叶变换红外研究。
DOI：
10.1021/bi00379a038
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发表时间：
1987
期刊：
影响因子：
2.9
通讯作者：
Jakobsen,RJ
中科院分区：
文献类型：
--
作者：
Wasacz,FM;Olinger,JM;Jakobsen,RJ
Battelle’s Columbus Laboratories, Columbus, Ohio 43201 1986 年 6 月 5 日收到；修订稿于 1986 年 10 月 21 日收到摘要：红外/衰减全反射 (ATR) 技术已用于研究非水溶剂引起的蛋白质结构变化，而无需将蛋白质溶解在非水溶剂中。对于所研究的两种蛋白质，甲醇和乙二醇引起白蛋白的类似变化，即螺旋二级结构的增加。然而，这两种溶剂对免疫球蛋白 G (IgG) 的影响不同。 IgG 水溶液 pH 值的变化产生了第三种效应。通过将一些 IgG 溶解在乙二醇中，然后将该溶液中的 IgG 吸附到 ATR 晶体上，可以研究吸附过程的时间行为，并提出结构变化的机制。蛋白质在非水溶剂中的行为既可用于研究不同溶剂引起的蛋白质结构变化，也可用于比较在非水和水溶液中的行为，以阐明水在蛋白质折叠、展开和稳定中的作用（Singer，1962）。然而，由于蛋白质在非水溶剂中缺乏溶解度，大多数这些研究要么是理论上的，要么使用溶剂和水的混合物。这导致对非水溶剂中蛋白质的红外研究非常少（Purcell & Susi，1984）。衰减全反射红外光谱的优点是不需要将蛋白质溶解在非水溶剂中。在本文中，我们将蛋白质薄膜沉积在水溶液中的红外衰减全反射（ATR）晶体上。然后我们可以使用任何所需的溶剂替换蛋白质水溶液，从而可以将蛋白质膜暴露于非水溶剂。通过这种方式，我们研究了白蛋白和球蛋白 (IgG) 暴露于甲醇或乙二醇的行为，此外，还研究了 IgG 从非常稀的乙二醇溶液中吸附到 ATR 晶体上的情况。我们将非水溶液的光谱结果与水溶液的光谱结果进行了比较，将光谱变化与蛋白质二级结构的变化联系起来，并假设了这些变化如何发生的机制。
Battelle’s Columbus Laboratories, Columbus, Ohio 43201 Received June 5, 1986; Revised Manuscript Received October 21, 1986 abstract: An infrared/attenuated total reflection (ATR) technique has been utilized to study the structural changes in proteins induced bynonaqueous solvents, without the need of dissolving the protein in the nonaqueous solvent. For the two proteins studied, methanol and ethylene glycol caused similar changes in albumin, ie, an increase in helix secondary structure. However, the two solvents had dissimilar effects on immunoglobulin G (IgG). Changes in the pH of aqueous solutions of IgG produced a third effect. By dissolving some IgG in ethylene glycol and then adsorbing IgG from this solution onto an ATR crystal, the time behavior of the adsorption process could be studied and a mechanism for the structural changes proposed. e behavior of proteins in nonaqueous solvents has been used both to study structural changes in proteins induced by different solvents and to compare behavior in nonaqueous and aqueous solutions in order to elucidate the role of water in protein folding, unfolding, and stabilization (Singer, 1962). However, due to the lack of solubility of proteins in nonaqueous solvents, most of these studies either have been theoretical or have used a mixture of solvent and water. This has led to very few infrared studies (Purcell & Susi, 1984) of proteins in nonaqueous solvents. Attenuated total reflectance infrared spectroscopy offers the advantage of not requiring the protein to be dissolved in the nonaqueous solvents. In this paper, we have deposited protein films on an infrared-attenuated total reflection (ATR) crystal from aqueous solution. We could then replace the aqueous protein solution by using any desired solvent and thus could expose the protein film to nonaqueous solvents. In this manner, we have studied the behavior of albumin and-globulin (IgG) exposed either to methanol or to ethylene glycol and, in addition, have studied the adsorption of IgG onto the ATR crystal from a very dilute ethylene glycol solution. We have compared the spectral results in nonaqueous solutions to the spectra of aqueous solutions, related the spectral changes to changes in the secondary structure of the protein, and postulated a mechanism for how these changes occur.