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Updated: Aug 5, 2026
13:56
Characterization of Molecular Mechanisms of In vivo UVR Induced Cataract
Published on: November 28, 2012
Structural and functional changes in catalase induced by near-UV radiation
S Zigman1, J Reddan, J B Schultz
1Department of Ophthalmology, University of Rochester School of Medicine and Dentistry, NY 14642, USA. zigmanB@ophth.rochester.edu
Photochemistry and Photobiology
|June 1, 1996
Summary
Near-UV light damages catalase, an important enzyme, by altering its structure and reducing its activity. Antioxidants like alpha-tocopherol and deferoxamine offer some protection against this UVA-induced damage in lens cells.
Area of Science:
- Biochemistry
- Photochemistry
- Ophthalmology
Background:
- Catalase is a crucial enzyme protecting cells from oxidative stress by breaking down hydrogen peroxide.
- Near-ultraviolet (UVA) radiation exposure is a potential environmental stressor for biological tissues, including the eye lens.
- Understanding UVA's impact on catalase is vital for assessing potential ocular damage.
Purpose of the Study:
- To investigate the effects of UVA radiation on purified beef liver catalase and catalase within cultured rabbit and squirrel lens epithelial cells.
- To evaluate the protective potential of antioxidants alpha-tocopherol and deferoxamine against UVA-induced catalase damage.
Main Methods:
- Purified catalase and cultured lens epithelial cells were exposed to UVA radiation (99% UVA, 1% UVB).
- Changes in catalase chemistry and enzymatic activity were assessed.
- Antioxidants were used to test for protective effects before UVA exposure.
- Catalase activity assays were performed on cell homogenates.
Main Results:
- UVA exposure altered purified catalase's spectral absorbance, caused aggregation, lowered its isoelectric point, and significantly reduced enzymatic activity.
- UVA radiation strongly inhibited catalase activity in both rabbit and squirrel lens epithelial cells.
- Antioxidants alpha-tocopherol and deferoxamine lessened catalase inactivation in lens cells.
- Photochemical changes were exacerbated by phosphate buffer or medium containing riboflavin and tryptophan.
Conclusions:
- UVA radiation directly damages catalase, impairing its enzymatic function.
- Antioxidants demonstrate a protective role against UVA-induced catalase damage in lens epithelial cells.
- Singlet oxygen and hydroxyl radical formation are implicated in near-UV damage to lens catalase.
- Inhibition of catalase by UVA may increase hydrogen peroxide toxicity and contribute to lens damage.
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