Pulse Radiolysis Reduction of Myoglobin. Hydrated Electrons Diffusion Inside the Protein Matrix
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- 作者：Vé ; ronique Le Tilly ; Serge Pin ; Bernard Hickel ; and Bernard Alpert
- 刊名：Journal of the American Chemical Society
- 出版年：1997
- 出版时间：November 5, 1997
- 年：1997
- 卷：119
- 期：44
- 页码：10810 - 10814
- 全文大小：137K
- 年卷期：v.119,no.44(November 5, 1997)
- ISSN：1520-5126
文摘
Pulse radiolysis studies have demonstrated that the kinetics ofmyoglobin reduction changes with the pHof the solution. The reduction rate constant of the proteindecreases with increasing pH. The net charge of themacromolecule was longtime considered to be responsible for thisdependence. However, for every protein moleculebearing many reduction sites, the reduction rate of the protein wouldbe the summation of the individual reactionsof hydrated electrons on each particular reducible site. The twoschemes of protein reduction were checked by theinvestigation of the behavior of the experimental reduction constantvalues (i) versus the protein charge (Brönstedapproach) and (ii) versus the reducible imidazolium groups number ofthe protein. Although the two plots are linearand seem to assert that the two approaches are equivalent, a criticalanalysis shows that the Brönsted formulationcannot be applied to proteins. This scheme gives also erroneousdifferent radii for the same protein. Thus, thiswork rationalizes the pH-dependent rate of reduction by an interactionof the hydrated electron with protonatedhistidine residues of the protein.