In vitro UV-B effect on lens protein solutions

Area of Science:

• Ophthalmology
• Biochemistry
• Photochemistry

Background:

• The eye lens is susceptible to UV-B radiation damage.
• Lens proteins undergo structural and functional changes upon UV-B exposure.
• Understanding differential sensitivity of lens parts to UV-B is crucial for eye health.

Purpose of the Study:

• To investigate UV-B induced damage in different rabbit lens protein fractions.
• To compare the susceptibility of various lens parts (equator, anterior cortex, nucleus, posterior cortex) to UV-B.
• To evaluate the protective effect of glutathione (GSH) against UV-B damage.

Main Methods:

• Rabbit lenses were dissected into four parts: equator (Eq), anterior cortex (Ac), nucleus (Nu), and posterior cortex (Pc).
• Water-soluble proteins were isolated, homogenized, and irradiated with UV-B (0–0.225 J/cm²).
• Assays included protein sulfhydryl (SH) content, carbonyl groups, light scattering, and SDS-PAGE, with and without added GSH.

Main Results:

• UV-B irradiation progressively reduced protein sulfhydryl groups.
• Nonprotein thiol (GSH) was depleted faster than protein SH groups.
• High molecular weight protein aggregates formed via disulfide bonds.
• Carbonyl groups and light scattering increased, indicating oxidative stress and aggregation.
• Lens nucleus proteins showed the highest sensitivity to UV-B, while equatorial proteins were least affected (Eq < Ac ≤ Pc < Nu).

Conclusions:

• Rabbit lens proteins exhibit varying sensitivity to UV-B damage across different regions.
• The nucleus is the most vulnerable part of the lens to UV-B radiation.
• Glutathione (GSH) offers partial protection but is rapidly consumed during UV-B exposure.