Oxidation of Good’s buffers by hydrogen peroxide

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• 作者：Guanghua Zhao and N. Dennis Chasteen
• 关键词：Buffers ; Hydrogen peroxide ; Good’ ; s buffers ; Ferritin ; Oxidation
• 刊名：Analytical Biochemistry
• 出版年：2006
• 出版时间：15 February 2006
• 年：2006
• 卷：349
• 期：2
• 页码：262-267
• 全文大小：323 K

文摘

Good’s zwitterionic buffers are widely used in biological and biochemical research in which hydrogen peroxide is a solution component. This study was undertaken to determine whether Good’s buffers exhibit reactivity toward H₂O₂. It is found that H₂O₂ oxidizes both morpholine ring-containing buffers (e.g., Mops, Mes) and piperazine ring-containing zwitterionic buffers (e.g., Pipes, Hepes, and Epps) to produce their corresponding N-oxide forms. The percentage of oxidized buffer increases as the concentration of H₂O₂ increases. However, the rate of oxidation is relatively slow. For example, no oxidized Mops was detected 2 h after adding 0.1 M H₂O₂ to 0.1 M Mops (pH 7.0), and only 5.7 % was oxidized after 24 h exposure to H₂O₂. Thus, although all of these buffers can be oxidized by H₂O₂, their slow reaction does not significantly perturb levels of H₂O₂ in the time frame and at the concentrations of most biochemical studies. Therefore, the previously reported rapid loss of H₂O₂ produced from the ferroxidase reaction of ferritin is unlikely due to reaction of H₂O₂ with buffer, a conclusion supported by the fact that H₂O₂ is also lost rapidly when the solution pH of the ferroxidase reaction is controlled by a pH stat apparatus in the absence of buffer.