US EPA

5018104 

Journal Article 

New insight on 8-anilino-1-naphthalene sulfonic acid interaction with TgFNR for hydrophobic exposure analysis 

Singh, K; Hussain, I; Mishra, V; Akhtar, MS 

2019 

Yes 

International Journal of Biological Macromolecules
ISSN: 0141-8130
EISSN: 1879-0003 

122 

636-643 

English 

30391427 

10.1016/j.ijbiomac.2018.10.208 

WOS:000456226700072 

http://://WOS:000456226700072
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The exposed hydrophobic patches of protein are widely detected through the binding by the fluorescent probes such as 1-anilino-8-naphthalene sulfonate (ANS), Nile Red (NR) and 1-(N-phenylamino) naphthalene, N-(1-Naphthyl) aniline (1NPN). Interestingly, at pH4, where the Toxoplasma gondii Ferredoxin-NADP(+) reductase (TgFNR) is stable, an exclusive binding and fluorescence emission was observed for ANS. To understand the underlying difference in the binding of ANS, NR and 1NPN; their effect on the protein structure was studied in detail. ANS was found to interact with TgFNR via electrostatic as well as hydrophobic interactions at pH4. NR and 1NPN did not show any such binding to TgFNR in the similar conditions, however showed strong hydrophobic interaction in the presence of NaCl or DSS (2, 2-dimethyl-2-silapentane-5-sulfonate). The subsequent structural studies suggest that ANS, NaCl and DSS induced partial unfolding of TgFNR by modulating ionic interactions of the enzyme, leading to the exposure of buried hydrophobic patches amicable for the binding by NR and 1NPN. The induced unfolding of TgFNR by ANS is unique and thus cautions to use the fluorescent dye as simple indicator to probe the exposed hydrophobic patches of the protein or its folding intermediates. 

article; CGH buffer; 1-anilino-8-naphthalene sulfonate (ANS); Nile Red; Protein stability; Folding intermediates; Toxoplasma gondii; aniline; electrostatic interactions; enzymes; exposure assessment; fluorescence; fluorescent dyes; hydrophobic bonding; hydrophobicity; naphthalene; protein structure; sodium chloride; sulfonic acid