20th-banner-rev.png

Albany 2019: 20th Conversation - Abstracts

category image Albany 2019
Conversation 20
June 11-15 2019
Adenine Press (2019)

Effect of crown ether, 15-crown-5, on lysozyme amyloid fibrillation

Amyloid fibrils are highly organized protein or peptide aggregates with cross β-sheet rich secondary structure responsible for various pathological disorders such as type 2 diabetes, Alzheimer’s, Huntington’s, and Parkinson’s diseases. Amyloid fibrils can also be formed by several nonpathogenic proteins like serum albumins and hen egg-white lysozyme under suitable conditions in vitro. This suggests aggregation to be an inherent property of proteins. Although amyloid fibrillation causes many fatal diseases, effective therapeutic treatments are still obscure. Various crown ethers have been shown to retard fibrillation effectively (Tian et al., 2014; Banik et al. 2016). Here, we have studied the effect of crown ether, viz. 15-crown-5, on amyloid fibrillation in lysozyme in order to design effective anti-amyloidogenic agents that can target native proteins and offer advantageous prospect to develop therapeutics. Lysozyme is an antimicrobial enzyme present in various tissues as well as protective secretions which can form amyloid fibrils readily and hence serves an excellent model system for studying protein amyloidogenesis. In this work hen egg-white lysozyme was taken as the model protein system since it shares ~60% sequence homology with human lysozyme that is linked with many hereditary non-neuropathic systemic amyloidosis. Various assays were undertaken to ascertain the inhibitory influence of the crown ether on lysozyme fibrillation. The results of Thioflavin T fluorescence assay indicated that the crown ether can attenuate fibrillation effectively. This observation was further reiterated by a complementary Congo Red Assay in absorbance. The kinetics of fibrillation was also studied using the Thioflavin T fluorescence assay. Far-UV circular dichroism studies indicated that the lysozyme samples undergo α-to-β transition, upon amyloid fibrillation. From the far-UV circular dichroism studies it was also inferred that the β-sheet content of the protein was reduced in the presence of crown ether which suggested that amyloid fibrillation was inhibited. Fluorescence microscopy, Nile red fluorescence assay, 8-anilino-1-naphthalenesulfonicacid binding assay, intrinsic (tryptophan) fluorescence studies along with steady-state fluorescence anisotropy also testified that the crown ether had significant fibril attenuating ability. Atomic force microscopy (AFM) imaging studies unequivocally established that fibril formation was reduced in the presence of the crown ether. Thus, the inhibitory effect of the crown ether, 15-crown-5, on amyloidosis may be exploited for designing better therapeutics for the treatment of amyloidogenesis related diseases.

Acknowledgements: Financial assistance from the Department of Science & Technology and Biotechnology, Govt. of West Bengal (File No.: ST/P/S&T/15G-13/2018) is gratefully acknowledged. The author is grateful to Prof. Ranjan Chakrabarti, Hon’ble Vice-Chancellor, Vidyasagar University for his patronage.

References

    1. Tian, Y., Zhang, X., Li, Y., Shoup, T. M., Teng, X., Elmaleh, D. R., Moore, A., & Ran, C. (2014) Crown Ethers Attenuate Aggregation of Amyloid Beta of Alzheimer’s Disease. Chem. Commun. (Cambridge, U.K.) 50, 15792-15795.

    2. Banik, D.; Dutta, R.; Banerjee, P.; Kundu, S.; & Sarkar N. (2016) Inhibition of Fibrillar Assemblies of L‑Phenylalanine by Crown Ethers: A Potential Approach toward Phenylketonuria. J. Phys. Chem. B 120, 7662−7670.

Anirban Basu

anirban-photo.gif

Anirban Basu obtained his PhD in Chemistry from the Jadavpur University, India in 2013. During 2014–2018 he worked as Research Associate/post-doctoral fellow at various research Institutions in India, and is currently an Assistant Professor of chemistry at Vidyasagar University, Midnapore, India. He will provide a short oral from the platform.

Department of Chemistry and Chemical Technology
Vidyasagar University
Midnapore 721 102, India

Email: basu.ani.anirban@gmail.com