Study of Metal-Binding Metallothionein Characterization in TRIS-Acetate Buffer by Electrospry Ionization Mass Spectrometry
- 化学化工－已发表论文 
金属硫蛋白(metallothionein,MT)是一类对重金属离子(如Zn2+、Cd2+、Hg2+等)有很强亲和力,含丰富半胱氨酸的低分子质量蛋白质。金属结合硫蛋白的电喷雾质谱表征通常是在接近中性条件下采用电喷雾正离子检测模式进行的,然而在该条件下由于MT的离子化效率低而导致检测灵敏度低。选择TRIS-醋酸作为缓冲体系,在中性条件下采用负离子模式实现了对Zn7-MT-2a的灵敏检测。同时考察了可能影响负离子响应的因素,包括溶液的pH值和TRIS-醋酸的浓度。结果表明,在考察范围内采用较低的pH值和较高浓度的TRIS-醋酸均有利于金属结合硫蛋白电喷雾质谱信号强度的增加。Metallothioneins (MTs) are a group of cysteine-rich, low-molecular mass intracellular protein with a high affinity for metals, such as zinc, cadmium and mercury. The identification of metal-binding MT is usually carried out under neutral condition by positive-ion electrospray ionization mass spectrometry (ESI-MS). However, ESI-MS detection under such conditions suffers from the lack of sensitivity because of the low efficiency of protonation during ESI process. A method was developed for the sensitive detection of metal-binding MT by negative-ion ESI-MS detection. The system involved the use of Tris (hydroxymethyl)-aminomethane (TRIS) acetate solutions under near neutral condition. Factors may affect the NI-ESI responses, such as pH and concentration of TRIS acetate. The result shows that lower pH under the pH range evaluated, higher concentration of TRIS acetate would all favor the MS detection.