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An engineered heme-copper center in myoglobin: CO migration and binding
Karin Nienhaus1, John S Olson, G Ulrich Nienhaus
1Institute of Applied Physics and Center for Functional Nanostructures, Karlsruhe Institute of Technology, Karlsruhe, Germany.
Biochimica Et Biophysica Acta
|March 6, 2013
Summary
Copper binding in myoglobin mutants (CuBMb) alters carbon monoxide (CO) migration and binding. The copper ion traps CO, enhancing ligand rebinding and mimicking heme-copper oxidase activity.
Area of Science:
- Biochemistry
- Biophysics
- Protein Science
Background:
- Myoglobin (Mb) is crucial for oxygen transport.
- Heme-copper oxidases are vital respiratory enzymes.
- Copper-binding myoglobin mutants (CuBMb) aim to mimic these enzymes.
Purpose of the Study:
- Investigate carbon monoxide (CO) migration and binding in CuBMb.
- Understand the role of copper in ligand binding dynamics.
- Compare CuBMb to wild-type Mb.
Main Methods:
- Fourier transform infrared spectroscopy.
- Flash photolysis over a wide temperature range.
- Utilized a double mutant (L29H-F43H) of myoglobin.
Main Results:
- Copper ion in CuBMb significantly affects ligand binding to the heme iron.
- In CuBMb, CO coordinates to the copper ion instead of secondary docking sites.
- Copper binding enhances CO trapping and restricts His64 side chain motion.
- Observed enhanced geminate and slow bimolecular CO rebinding.
Conclusions:
- Copper ion acts as an efficient CO trapping site in CuBMb.
- CuBMb's behavior supports mechanistic models of ligand binding in hemoglobins.
- The study elucidates the role of the CuB site in heme-copper oxidase function.
Keywords:
Cu(B)MbFTIRFourier transform infraredFourier transform infrared spectroscopyHCOHeme proteinLigand bindingLigand migrationMbPhotolysis difference spectroscopyTDSTemperature derivative spectroscopycopper-binding Mb mutant L29H–F43Hheme–copper oxidasemyoglobintemperature derivative spectroscopyMore Related Videos
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