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Soluble ascorbate free radical reductase in the human lens
1Department of Ophthalmology, Tokai University School of Medicine, Kanagawa, Japan.
Japanese Journal of Ophthalmology
|January 1, 1994
Summary
Researchers isolated two ascorbate free radical (AFR) reductases from human eye lenses. The major enzyme, a key antioxidant, was purified and characterized, showing distinct properties from similar enzymes in other organisms.
Area of Science:
- Biochemistry
- Ophthalmology
- Enzymology
Background:
- The human lens relies on antioxidant systems to prevent oxidative damage.
- Ascorbate free radical (AFR) reductase plays a crucial role in maintaining the antioxidant capacity of the lens.
Purpose of the Study:
- To isolate and characterize AFR reductases from the human lens.
- To differentiate lens AFR reductases from those found in other biological systems.
Main Methods:
- DEAE-cellulose ion-exchange chromatography for initial separation.
- 5'AMP-Sepharose 4B affinity chromatography for partial purification.
- Native polyacrylamide disc gel electrophoresis and gel filtration for characterization.
Main Results:
- Two AFR reductases (major and minor) were identified in the human lens soluble fraction.
- The major AFR reductase exhibited diaphorase activity and was partially purified.
- Its molecular weight was determined to be 32 kDa, with an apparent Km for AFR of approximately 15 µM.
- This enzyme showed distinct biochemical properties compared to AFR reductases from other sources and related enzymes.
Conclusions:
- The human lens possesses distinct AFR reductase activity.
- The characterized major AFR reductase is a unique enzyme with potential implications for lens health and oxidative stress research.