Metal-Ion-Specific Screening of Charge Effects in Protein Amide H/D Exchange and the Hofmeister Series
Metal-Ion-Specific Screening of Charge Effects in Protein Amide H/D Exchange and the Hofmeister Series
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DOI：
10.1021/ac502714v
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发表时间：
2014-10-21
影响因子：
7.4
通讯作者：
Shaw, Bryan F.
中科院分区：
文献类型：
--
作者：
Abdolvahabi, Alireza;Gober, Jennifer L.;Shaw, Bryan F.
在这项研究中，蛋白质电荷阶梯和质谱被用来量化Hofmeister系列中的金属阳离子（Na+, K+, Li+， Mg2+和Ca2+）如何排列赖氨酸乙酰化对代表性蛋白质（肌红蛋白，Mb）中酰胺H/D交换速率的影响。18 Lys-epsilon-NH3的连续的乙酰化作用导致Mb(+)组的线性减少全球利率酰胺H / D交换(以质谱),尽管也减少Mb的耐热性> 10度c的能力一个金属阳离子在H / D屏幕动能静电影响交流和废除乙酰化作用的保护作用与H / D交易所发现取决于他认为系列阳离子的位置。Na+和K+阳离子不能完全平衡电荷阶梯各“梯级”之间的H/D交换速率，而Mg2+和Ca2+在不消除蛋白质疏水核心（即不展开Mb）的情况下平衡了速率；Li+表现出中间效应。Mg2+和Ca2+完全屏蔽与Mb电荷异构体H/D交换相关的静电效应的能力表明，Mg2+或Ca2+（但不包括Na+或K+）可以用来量化静电电荷对观察到的蛋白质酰胺H/D交换率的贡献程度。
In this study, protein charge ladders and mass spectrometry were used to quantify how metal cations in the Hofmeister series (Na+, K+, Li+, Mg2+, and Ca2+) permute the effects of lysine acetylation on the rate of amide H/D exchange in a representative protein (myoglobin, Mb). The successive acetylation of up to 18 Lys-epsilon-NH3(+) groups in Mb caused a linear decrease in its global rate of amide H/D exchange (as measured by mass spectrometry), despite also decreasing the thermostability of Mb by >10 degrees C. The ability of a metal cation to screen kinetic electrostatic effects during H/D exchange-and to abolish the protective effect of acetylation against H/D exchange-was found to depend on the position of the cation in the Hofmeister series. Na+ and K+ cations did not fully equalize the rates of H/D exchange among each "rung" of the charge ladder, whereas Mg2+ and Ca2+ did equalize rates without eliminating the hydrophobic core of the protein (i.e., without unfolding Mb); Li+ exhibited intermediate effects. The ability of Mg2+ and Ca2+ to completely screen electrostatic effects associated with the H/D exchange of charge isomers of Mb suggests that Mg2+ or Ca2+ (but not Na+ or K+) can be used to quantify the magnitude by which electrostatic charge contributes to the observed rates of amide H/D exchange in proteins.