Competitive Binding of Protons, Calcium, Cadmium, and Zinc to Isolated Cell Walls of a Gram-Positive Soil Bacterium

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• 作者：Alexandra C. C. Plette ; Marc F. Benedetti ; and Willem H. van Riemsdijk
• 刊名：Environmental Science & Technology
• 出版年：1996
• 出版时间：June 1996
• 年：1996
• 卷：30
• 期：6
• 页码：1902 - 1910
• 全文大小：353K
• 年卷期：v.30,no.6(June 1996)
• ISSN：1520-5851

文摘

Metal ion binding to the bacterial cell wall is thefirst step in the interactions of a metal with abacterium.Cadmium and zinc ion binding to isolated cell wallsof Rhodococcus erythropolis A177 has beenstudiedfor a wide range of proton and calcium concentrations. The release of calcium ions and protons duringmetal ion binding is an indication of the competitivenature of the binding. Calculations, based on themetal binding data and the pH-dependent chargingbehavior, reveal that the cell wall becomes positivelycharged at high coverage with bivalent ions. Acooperative effect of the presence of calcium onmetal ion binding was observed. Apparently, the cellwall structure is altered in the presence of bivalentions. Since calcium is a dominant bivalent cation inmost natural systems, one may regard the calciumas a "structure determining ion". On the basis ofaqualitative interpretation of the data, the NICA modelwas selected for a quantitative description of the data.