Glycosylation of Purified Buffalo Heart Galectin-1 Plays Crucial Role in Maintaining Its Structural and Functional Integrity

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G. M. Ashraf^1,2, N. Bilal¹, N. Suhail¹, S. Hasan¹, and N. Banu^1*

¹Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh-202002, Uttar Pradesh, India; E-mail: nbanuamu@gmail.com

²Amity Institute of Biotechnology, Amity University Uttar Pradesh (AUUP), Lucknow Campus-206010, Uttar Pradesh, India; E-mail: ashraf.gm@gmail.com

^* To whom correspondence should be addressed.

Received June 19, 2010; Revision received September 14, 2010

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A buffalo heart galectin-1 purified by gel filtration chromatography revealed the presence of 3.55% carbohydrate content, thus it is the first mammalian heart galectin found to be glycosylated in nature and emphasizes the need to perform deglycosylation studies. Physicochemical comparative analysis between the properties of the native and deglycosylated proteins was carried out to understand the significance of glycosylation. The deglycosylated protein exhibited lesser thermal and pH stability compared to the native galectin. When exposed to thiol blocking reagents, denaturants, and detergents, remarkable differences were observed in the properties of the native and deglycosylated protein. Compared to the native glycosylated protein, the deglycosylated galectin showed enhanced fluorescence quenching when exposed to various agents. CD and FTIR analysis showed that deglycosylation of the purified galectin and its exposure to different chemicals resulted in significant deviations from regular secondary structure of the protein, thus emphasizing the significance of glycosylation for maintaining the active conformation of the protein. The remarkable differences observed in the properties of the native and deglycosylated galectin add an important dimension to the significance of protein glycosylation and its associated biological and clinical relevance.

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KEY WORDS: buffalo heart galectin-1 (B_fHG-1), glycosylation, deglycosylation, deglycosylated B_fHG-1 (dB_fHG-1), oxidation

DOI: 10.1134/S0006297910120059

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