Molecular Interpretation of Kinetic-Ionic Strength Effects

Document Type

Article

Language

eng

Format of Original

13 p.

Publication Date

1981

Publisher

Elsevier

Source Publication

Journal of Inorganic Biochemistry

Source ISSN

0162-0134

Abstract

A recent and important approach to investigating electron transfer mechanisms of redox proteins has been through kinetic-ionic strength studies. There is, however, significant controversy as to whether such studies (1) yield information regarding the charge (or location) of the electron transfer site or (2) more simply reflect the influence of net or overall protein charge on the electrostatic interactions. A critical analysis using different theoretical approaches is made of our recent work and of the bulk of the published non-physiological small molecule-protein and protein-protein kinetic ionic strength studies; it is concluded that (1) the approximated Bronsted-Debye-Huckel equation can not be used at all for protein redox reactions, (2) irrespective of the theoretical approaches discussed, such studies do not provide information regarding the charge of the electron transfer site, (3) it is the net charge of the reactants that control the electrostatic interactions, (4) both the equation derived by Wherland and Gray and the full Bronsted-Debye-Huckel equation provide reasonably good approximations of net protein charge, (5) pH changes quantitatively modulate net protein charge, and (6) thus, protein redox rates need to be electrostatically corrected if relevant interpretations of kinetic-ionic strength experiments are to be made.

Comments

Journal of Inorganic Biochemistry, Vol. 15, No. 3 (1981): 187-199. DOI.

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