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Published on: August 6, 2018
The reduction potential of lactoperoxidase
Acta Chemica Scandinavica. Series B: Organic Chemistry and Biochemistry
|January 1, 1983
Summary
The reduction potential of iron(III)/iron(II) lactoperoxidase was determined using multiple methods. The standard potential (Em,7.0) was found to be approximately -180 to -190 mV, providing key data for enzyme studies.
Area of Science:
- Biochemistry
- Enzymology
- Redox Chemistry
Background:
- Lactoperoxidase is an important enzyme involved in various biological processes.
- Understanding the redox properties of lactoperoxidase, specifically the Fe(III)/Fe(II) couple, is crucial for elucidating its catalytic mechanisms.
- Accurate determination of reduction potentials is essential for biochemical and biophysical studies of metalloenzymes.
Purpose of the Study:
- To accurately determine the reduction potential of the Fe(III)/Fe(II) couple in lactoperoxidase.
- To compare results obtained from different electrochemical and optical methods.
- To investigate the influence of surfactants on the reduction potential.
Main Methods:
- Optical determinations using 2-methyl-3-hydroxy-1,4-naphthoquinone and 9,10-anthraquinone-2-sulfonate as indicator and reducing agent, respectively.
- Potentiometric determinations employing 9,10-anthraquinone-2-sulfonate as a mediator.
- Measurements in the presence of N-cetyl-N,N,N-trimethyl-ammonium bromide (a surfactant) with dithionite as the reducing agent and anthraquinone derivatives as mediators.
Main Results:
- Optical methods yielded an Em,7.0 of -191 ± 2 mV.
- Potentiometric methods provided an Em,7.0 of -188 ± 1 mV.
- In the presence of surfactant, Em,7.0 values ranged from -179 mV to -183 mV depending on the anthraquinone mediator used.
Conclusions:
- The reduction potential of the Fe(III)/Fe(II) lactoperoxidase couple is consistently determined to be within the range of -179 mV to -191 mV under various conditions.
- The results highlight the reliability of both optical and potentiometric techniques for assessing enzyme redox states.
- The addition of a cationic surfactant slightly alters the reduction potential, suggesting potential interactions with the enzyme's active site or redox environment.
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