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SPECTROSCOPY OF CATALASE
1Courtauld Institute of Biochemistry, Middlesex Hospital Medical School, London, England, and the Laboratory of Physiological Chemistry, Yale University, New Haven).
The Journal of General Physiology
|October 30, 2009
Summary
Catalase, an enzyme containing a hemin group, demonstrates remarkable stability against oxidizing and reducing agents due to its protein component. This stability, distinct from methemoglobin, highlights the unique hematin-protein linkage in catalase.
Area of Science:
- Biochemistry
- Enzymology
Background:
- Catalase is an enzyme crucial for cellular defense against reactive oxygen species.
- Understanding the chemical properties and stability of catalase is vital for its biotechnological and medical applications.
Purpose of the Study:
- To investigate the chemical stability and properties of the catalase enzyme, particularly its hemin group.
- To elucidate the factors contributing to the unique resistance of catalase to reducing agents compared to other heme proteins.
Main Methods:
- Chemical treatments with oxidizing and reducing agents (ferricyanide, hydrogen, hydrosulfite, cysteine).
- Complexation studies with various ligands (cyanide, fluoride, carbon monoxide, hydrazine, pyridine).
- Spectroscopic analysis, including absorption band measurements (Soret's band at 409 mμ).
Main Results:
- Catalase is resistant to a wide range of oxidizing and reducing agents.
- The hemin group of catalase binds to specific ligands but not carbon monoxide.
- The stability of the ferric iron in catalase is attributed to the protein component, not the protoporphyrin structure.
- Hydrazine and pyridine convert catalase into hemochromogens with ferrous iron, where hematin detaches from the protein.
Conclusions:
- The protein component of catalase confers exceptional stability to its ferric iron center.
- Catalase exhibits distinct chemical properties compared to methemoglobin, suggesting a unique hematin-protein linkage.
- Spectroscopic data supports the hemin nature of the catalase enzyme.
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