Yu X, Wojciechowski M, Fenselau C
Department of Chemistry and Biochemistry, University of Maryland Baltimore County 21228.
Anal Chem. 1993 May 15;65(10):1355-9. doi: 10.1021/ac00058a010.
A method has been developed that combines electrospray ionization mass spectrometry with pH control to provide analysis of metals in native or reconstituted metallothioneins. These metalloproteins cooperatively bind seven divalent metal ions, most commonly Zn2+ and Cd2+. Since the protein is denatured and metal ions are lost below pH3, the pH of the electrospray solution is critical to successful results. The metal-free apoprotein was detected with its most abundant ions in a charge state of 6+, while the folded metallothionein-metal complexes were observed with lower charge states. The retention of seven metals in the molecular ions detected is consistent with the hypothesis that metallothionein retains its conformation in the gas phase. This mass spectrometric technique can be used to determine rapidly and accurately how many and what cations are incorporated per molecule of protein. Information about molar distributions and estimates of relative abundances of various complexes in the sample can be acquired in a single measurement.
已开发出一种将电喷雾电离质谱与pH控制相结合的方法，用于分析天然或重组金属硫蛋白中的金属。这些金属蛋白协同结合七个二价金属离子，最常见的是Zn2+和Cd2+。由于蛋白质在pH值低于3时会变性且金属离子会流失，因此电喷雾溶液的pH值对于获得成功结果至关重要。检测到无金属的脱辅基蛋白，其最丰富的离子带6+电荷，而折叠的金属硫蛋白-金属络合物则以较低的电荷态被观察到。在检测到的分子离子中保留七个金属，这与金属硫蛋白在气相中保持其构象的假设一致。这种质谱技术可用于快速准确地确定每个蛋白质分子结合了多少以及何种阳离子。关于样品中各种络合物的摩尔分布和相对丰度估计的信息可以通过一次测量获得。
