Impact of hydrogen peroxide on structure, stability, and aggregational properties of human γS-crystallin

• Published in: Journal of biosciences Vol. 48; no. 1; p. 5
• Main Author: Vendra, Venkata Pulla Rao
• Format: Journal Article
• Language: English
• Published: New Delhi Springer India 27.02.2023; Springer Nature B.V
• Subjects: Age; Analytical methods; Biomedical and Life Sciences; Biomedicine; Cataract - genetics; Cataracts; Cell Biology; Chromatography; Circular dichroism; Complementary DNA; Crystallin; Crystallins; Dichroism; Fluorescence; Gel filtration; Gels; Humans; Hydrogen peroxide; Hydrogen Peroxide - pharmacology; Hydrophobicity; Ion exchange; Lens, Crystalline; Life Sciences; Microbiology; Microenvironments; Oxidative Stress; Plant Sciences; Protein structure; Risk factors; Secondary structure; Spectroscopy; Stability; Structural stability; Tertiary structure; Thermal stability; Tryptophan; Zoology; Aggregation; cataract; H; crystallins; eye lens; oxidative stress; O
• ISSN: 0973-7138; 0250-5991; 0973-7138
• DOI: 10.1007/s12038-023-00330-w

Cataract is the leading cause of blindness worldwide. Oxidative stress is one of the known risk factors for age-related cataracts. The present study was designed to understand the effect of H 2 O 2 -induced oxidative stress on human γS-crystallin and its relationship to lens opacification and cataract. Human γS-crystallin cDNA was cloned into the pET-20b vector, overexpressed in BL21 Star (DE3) cells, and was purified using ion-exchange and gel filtration chromatography. The structure, stability, and aggregational properties of human γS-crystallin under H 2 O 2 stress were studied using fluorescence and circular dichroism spectroscopy methods. H 2 O 2 treatment did not show any significant effect on the γS-crystallin secondary structure but showed an effect on its tertiary structure, resulting in N′-formylkynurenine formation. The H 2 O 2 -treated sample showed increased surface hydrophobicity, was less stable, and opened its Greek key motifs earlier with a midpoint of thermal unfolding curve (T m ) of 70.2°C compared with untreated γS-crystallin (T m =71.4°C). The sample treated with H 2 O 2 aggregated earlier in response to heating at 65°C. H 2 O 2 -induced oxidative stress alters the tryptophan microenvironment and the surface hydrophobicity of γS-crystallin, and these changes decrease its thermal stability and increase its tendency to aggregate, consistent with its role as a risk factor in age-related cataract.