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Effect of Sorbitol on Alpha-Crystallin Structure and Function

Ch. Uday Kumar1,a, Udaykanth Suryavanshi1,b, Vishwaraj Sontake1,c, P. Yadagiri Reddy1,d, Rajeshwer S. Sankhala2,e, Musti J. Swamy2,f, and G. Bhanuprakash Reddy1,g*

1Biochemistry Division, National Institute of Nutrition, Hyderabad 500007, India

2School of Chemistry, University of Hyderabad, Hyderabad 500046, India

* To whom correspondence should be addressed.

Received September 21, 2021; Revised January 13, 2022; Accepted January 29, 2022
Loss of eye lens transparency due to cataract is the leading cause of blindness all over the world. While aggregation of lens crystallins is the most common endpoint in various types of cataracts, chaperone-like activity (CLA) of α-crystallin preventing protein aggregation is considered to be important for maintaining the eye lens transparency. Osmotic stress due to increased accumulation of sorbitol under hyperglycemic conditions is believed to be one of the mechanisms for diabetic cataract. In addition, compromised CLA of α-crystallin in diabetic cataract has been reported. However, the effect of sorbitol on the structure and function of α-crystallin has not been elucidated yet. Hence, in the present exploratory study, we described the effect of varying concentrations of sorbitol on the structure and function of α-crystallin. Alpha-crystallin purified from the rat lens was incubated with varying concentrations of sorbitol in the dark under sterile conditions for up to 5 days. At the end of incubation, structural properties and CLA were evaluated by spectroscopic methods. Interestingly, different concentrations of sorbitol showed contrasting results: at lower concentrations (5 and 50 mM) there was a decrease in CLA and subtle alterations in secondary and tertiary structure but not at higher concentrations (500 mM). Though, these results shed a light on the effect of sorbitol on α-crystallin structure–function, further studies are required to understand the mechanism of the observed effects and their implication to cataractogenesis.
KEY WORDS: alpha-crystallin, cataract, chaperone-like activity, sorbitol, structure

DOI: 10.1134/S0006297922020055