Origin of supercharging in electrospray ionization of noncovalent complexes from aqueous solution.
Origin of supercharging in electrospray ionization of noncovalent complexes from aqueous solution.
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DOI：
10.1016/j.jasms.2009.06.012
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发表时间：
2009-10
影响因子：
3.2
通讯作者：
Williams ER
中科院分区：
文献类型：
--
作者：
Sterling HJ;Williams ER
研究了间硝基苄基醇（m-NBA）对水溶液电喷雾电离形成的非共价络合物的增强作用。添加高达1%的m-NBA可导致复合物的平均电荷显著增加，范围从NtrC4-RC的同型七聚体的~13% （317 kDa，最大电荷态从42+增加到44+）到肌红蛋白的~49% （17.6 kDa，最大电荷态从9+增加到16+）。未加入m-NBA的加热溶液中得到的较大配合物的电荷态分布与含有少量m-NBA的溶液非常相似。在添加较高浓度的m-NBA和加热时，观察到配合物通过相同的通道解离。这些结果表明，在电喷雾水溶液中加入m-NBA后，由于m-NBA的高沸点导致液滴加热，从而导致配合物的高阶结构改变和/或解离。对于单体蛋白质和小复合物，加热水溶液的充电增强比含有m-NBA的溶液要低，因为不含m-NBA的加热溶液中的蛋白质在电喷雾液滴形成并蒸发冷却后会发生快速折叠。
The use of m-nitrobenzyl alcohol (m-NBA) to enhance charging of noncovalent complexes formed by electrospray ionization from aqueous solutions was investigated. Addition of up to 1% m-NBA can result in a significant increase in the average charging of complexes, ranging from ~13% for the homo-heptamer of NtrC4-RC (317 kDa; maximum charge state increases from 42+ to 44+) to ~49% for myoglobin (17.6 kDa; maximum charge state increases from 9+ to 16+). Charge state distributions of larger complexes obtained from heated solutions to which no m-NBA was added are remarkably similar to those containing small amounts of m-NBA. Dissociation of the complexes through identical channels both upon addition of higher concentrations of m-NBA and heating is observed. These results indicate that the enhanced charging upon addition of m-NBA to aqueous electrospray solutions is a result of droplet heating owing to the high boiling point of m-NBA, which results in a change in the higher-order structure and/or dissociation of the complexes. For monomeric proteins and small complexes, the enhancement of charging is lower for heated aqueous solutions than from solutions with m-NBA because rapid folding of proteins from heated solutions that do not contain m-NBA can occur after the electrospray droplet is formed and is evaporatively cooled.