Oxidation of deoxy myoglobin by [Fe(CN) 6] 3

• Published in: Journal of inorganic biochemistry Vol. 75; no. 4; pp. 241 - 244
• Main Authors: Dunn, Cory Joyce, Rohlfs, Ronald J., Fee, James A., Saltman, Paul
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.07.1999
• Subjects: [Fe(CN) 6] 3; Amino Acid Substitution; Animals; Distal histidine (H64); Electron transport; Ferricyanides - chemistry; Ferricyanides - metabolism; Histidine; Myoglobin; Myoglobin - analogs & derivatives; Myoglobin - chemistry; Myoglobin - genetics; Myoglobin - metabolism; Oxidation-Reduction; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Redox mechanisms; Spectrophotometry - methods; Whales; Myoglobin; [Fe(CN) 6] 3; Electron transport; Distal histidine (H64); Redox mechanisms
• ISSN: 0162-0134; 1873-3344
• DOI: 10.1016/S0162-0134(99)00093-8

The ability of myoglobin (Mb) to reversibly bind O 2 and other ligands has been well characterized. Mb also participates with a variety of redox metals to form metmyoglobin ( metMb). By using an anaerobic stopped-flow device we have measured outer-sphere oxidation by [Fe(CN) 6] 3− of native sperm whale myoglobin, recombinant wild-type Mb, and a series of mutant Mb proteins in which the distal His-64 was changed to Gly, Phe, Leu or Val. Second-order rate constants for oxidation of mutant proteins are 10–15 times greater than for recombinant or native ( k ox ~ 10 6 M − s −). We attribute the reduced rate of oxidation of wild-type protein to a higher reorganization energy imposed by the presence of the unique water/His-64/heme interaction, which is absent in the mutant proteins.