MECHANISM OF ACID-INDUCED FOLDING OF PROTEINS
MECHANISM OF ACID-INDUCED FOLDING OF PROTEINS
复制标题
DOI：
10.1021/bi00466a009
复制
发表时间：
1990-04-10
期刊：
影响因子：
2.9
通讯作者：
FINK, AL
中科院分区：
文献类型：
--
作者：
GOTO, Y;TAKAHASHI, N;FINK, AL
我们之前已经展示了[后藤，Y.，卡尔恰诺湖J.，和Fink，A. L.等人（1990）Proc. Acad. Sci. U.S.A. 87，573-577]，β-内酰胺酶、细胞色素c和脱辅基肌红蛋白在低离子强度的条件下在pH 2下最大程度地解折叠，但是通过增加HCl的浓度进一步降低pH，使蛋白质重折叠到具有与熔融球状态的性质类似的性质的A状态。为了了解酸诱导蛋白质结构重折叠的机制，我们研究了各种强酸及其中性盐对铁细胞色素c和脱辅基肌红蛋白酸解折叠状态的影响。在20 ℃下监测细胞色素c的构象转变。C通过使用在远紫外CD和Soret吸收在394 nm处的变化，并通过在远紫外CD的变化监测的脱辅基肌红蛋白。各种强酸（即，硫酸、高氯酸、硝酸、三氯乙酸和三氟乙酸）将酸解折叠的细胞色素c和脱辅基肌红蛋白重折叠到A状态，与HCl的情况一样。对于这两种蛋白质，这些酸的中性盐引起了类似的构象转变，确认阴离子是负责带来的过渡。阴离子的有效性顺序为铁氰化物>亚铁氰化物>硫酸盐>三氯乙酸盐>硫氰酸盐>高氯酸盐>碘离子>硝酸盐>三氟乙酸盐>溴离子>氯离子。该系列类似于阴离子对阴离子交换树脂的电选择性系列[Gregor，H. P.，贝儿，J.，和Marcus，R. A.等（1955）J. Am. 77，2713-2719; Gjerde，D. T.，Schmuchler，G.，和Fritz，J.S.（1980）J. Chromatogr. 187，35-45]，表明阴离子与A态的优先结合导致构象转变。
We have previously shown [Goto, Y., Calciano, L. J., and Fink, A. L. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 573-577] that .beta.-lactamase, cytochrome c, and apomyoglobin are maximally unfolded at pH 2 under conditions of low ionic strength, but a further decrease in pH, by increasing the concentration of HCl, refolds the proteins to the A state with properties similar to those of a molten globule state. To understand the mechanism of acid-induced refolding of protein structure, we studied the effects of various strong acids and their neutral salts on the acid-unfolded states of ferricytochrome c and apomyoglobin. The conformational transition of cytochrome c was monitored at 20.degree. C by using changes in the far-UV CD and in the Soret absorption at 394 nm, and that of apomyoglobin was monitored by changes in the far-UV CD. Various strong acids (i.e., sulfuric acid, perchloric acid, nitric acid, trichloroacetic acid, and trifluoroacetic acid) refolded the acid-unfolded cytochrome c and apomyoglobin to the A states as was the case with HCl. For both proteins neutral salts of these acids caused similar conformational transitions, confirming that the anions are responsible for bringing about the transition. The order of effectiveness of anions was shown to be ferricyanide > ferrocyanide > sulfate > trichloroacetate > thiocyanate > perchlorate > iodide > nitrate > trifluoroacetate > bromide > chloride. This series is similar to the electroselectivity series of anions toward the anion-exchange resins [Gregor, H. P., Belle, J., and Marcus, R. A. (1955) J. Am. Chem. Soc. 77, 2713-2719; Gjerde, D. T., Schmuchler, G., and Fritz, J.S. (1980) J. Chromatogr. 187, 35-45], showing that preferential binding of anions to the A states causes the conformational transitions.