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Human corneal aldehyde dehydrogenase: purification, kinetic characterisation and phenotypic variation
1School of Science, Griffith University, Nathan, Brisbane, Australia.
Biochemistry and Molecular Biology International
|September 1, 1993
Summary
Human corneal aldehyde dehydrogenase (ALDH3) efficiently oxidizes harmful aldehydes and absorbs UV radiation. This enzyme is crucial for mammalian cornea health, with variants found in Australian populations.
Area of Science:
- Biochemistry
- Ophthalmology
- Enzymology
Background:
- The mammalian cornea contains aldehyde dehydrogenase (ALDH3) as a major soluble protein.
- ALDH3's role in protecting the cornea from UV radiation and oxidative stress is under investigation.
Purpose of the Study:
- To purify and characterize human corneal aldehyde dehydrogenase (ALDH3).
- To investigate the substrate specificity and inhibition patterns of ALDH3.
- To explore the dual role of ALDH3 in UV absorption and aldehyde oxidation in the cornea.
Main Methods:
- Purification of human corneal ALDH3 to homogeneity.
- Enzyme characterization including substrate specificity and inhibition assays using thiol reagents.
- Analysis of corneal and surrounding tissue proteins in human and cow.
Main Results:
- ALDH3 efficiently catalyzes the oxidation of medium-chain peroxidic aldehydes.
- p-hydroxymercuribenzoate rapidly inactivated ALDH3, while disulfiram showed no inhibition.
- Changes in soluble protein profiles were observed in cornea and surrounding tissues of humans and cows.
- Phenotype variants of ALDH3 were identified in an Australian population.
Conclusions:
- ALDH3 plays a significant dual role in UV absorption and peroxidic aldehyde oxidation in the mammalian cornea.
- ALDH3 is sensitive to specific thiol reagents, indicating the importance of cysteine residues in its function.
- Protein composition of the cornea is dynamic and can vary between species and populations, with ALDH3 exhibiting genetic variation.