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Dehydroalanine crosslinks in human lens
Mikhail Linetsky1, J M W Hill, Roy D LeGrand
1Mason Eye Institute, University of Missouri, Columbia, MO 65212, USA. linetskym@health.missouri.edu
Experimental Eye Research
|September 24, 2004
Summary
This study developed a method to detect histidinoalanine, lanthionine, and lysinoalanine crosslinks in human lenses. Elevated levels of histidinoalanine and lanthionine were found in cataractous lenses, indicating their role in cataract formation.
Area of Science:
- Biochemistry
- Ophthalmology
- Analytical Chemistry
Background:
- Lens proteins undergo modifications with age and disease.
- Dehydroalanine crosslinks, such as histidinoalanine and lanthionine, are implicated in protein aggregation and lens opacification.
- Quantifying these crosslinks is crucial for understanding cataractogenesis.
Purpose of the Study:
- To establish a robust methodology for the purification and quantification of histidinoalanine, lanthionine, and lysinoalanine in human lens proteins.
- To investigate the levels of these crosslinks in both normal and cataractous human lenses.
- To correlate the presence and abundance of these crosslinks with cataract development.
Main Methods:
- Hydrolysis and anion-exchange chromatography of human lens proteins (water-soluble and water-insoluble fractions).
- Derivatization of dehydroalanine crosslinks with dansyl chloride.
- Separation and quantification using reversed-phase high-performance liquid chromatography (RP-HPLC).
- Validation of purified compound identity against synthesized standards.
Main Results:
- Histidinoalanine and lanthionine were identified as the predominant dehydroalanine crosslinks in lens proteins.
- Significantly elevated levels of histidinoalanine were observed in both water-soluble and water-insoluble proteins of cataractous lenses compared to normal lenses.
- Lanthionine levels were notably higher in water-insoluble proteins of cataractous lenses and showed a marked accumulation in water-soluble proteins.
- Lysinoalanine was detected at picomolar concentrations, primarily in cataractous lens proteins.
Conclusions:
- The developed RP-HPLC method effectively quantifies histidinoalanine, lanthionine, and lysinoalanine in human lens tissue.
- Increased levels of histidinoalanine and lanthionine are associated with human cataract formation.
- These findings highlight the role of specific dehydroalanine crosslinks in the pathogenesis of cataracts.
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