利用EXAFS研究酿酒酵母与Zn(Ⅱ)的相互作用机制

为深入探讨酿酒酵母与重金属离子Zn(Ⅱ)的相互作用机制,利用扩展X射线吸收精细结构谱(EXAFS)研究了在不同实验条件下,酿酒酵母吸附重金属离子Zn(Ⅱ)的局域结构.结果表明, Zn以四配位体和六配位体混合构型与酵母细胞表面结合,且以四配位体构型为主. Zn的第一配位层Zn--O原子间距和配位数分别在0.197～0.203 nm和3.2～4.3范围内. Zn(Ⅱ)初始浓度升高、初始pH值升高导致Zn--O配位数下降,活酵母细胞Zn--O配位数低于死酵母细胞, Zn--O原子间距下降.

Interaction mechanism between Zn(II) and Saccharomyces cerevisiae using EXAFS

The extended X-ray absorption fine structure spectroscopy (EXAFS) was used to investigate the mechanisms of interaction between Zn(II) and Saccharomyces cerevisiae. The nature of the zinc center in the yeast cells exposed to different Zn(II) concentrations and initial pH was determined by Zn K-edge X-ray absorption spectroscopy. The experimental results suggested that the adsorbed zinc ion on the yeast was the mixture of tetrahedron and octahedron structure, and Zn-O bond length changed within 0.197-0.203 nm and coordination number varied between 4.3 and 3.2 under different conditions. Increase of the initial concentration of Zn(II) and initial pH value decreased the coordination number of Zn-O. Zn-O bond length and coordination number of the live cells of the yeast was lower than that of dead cells.