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Stereo-Selectivity of Human Serum Albumin to Enantiomeric and Isoelectronic Pollutants Dissected by Spectroscopy, Calorimetry and Bioinformatics.

Authors :
Ahmad, Ejaz
Rabbani, Gulam
Zaidi, Nida
Singh, Saurabh
Rehan, Mohd
Khan, Mohd Moin
Rahman, Shah Kamranur
Quadri, Zainuddin
Shadab, Mohd.
Ashraf, Mohd Tashfeen
Subbarao, Naidu
Bhat, Rajiv
Khan, Rizwan Hasan
Source :
PLoS ONE; 2011, Vol. 6 Issue 11, p1-18, 18p
Publication Year :
2011

Abstract

1-naphthol (1N), 2-naphthol (2N) and 8-quinolinol (8H) are general water pollutants. 1N and 2N are the configurational enantiomers and 8H is isoelectronic to 1N and 2N. These pollutants when ingested are transported in the blood by proteins like human serum albumin (HSA). Binding of these pollutants to HSA has been explored to elucidate the specific selectivity of molecular recognition by this multiligand binding protein. The association constants (K<subscript>b</subscript>) of these pollutants to HSA were moderate (10<superscript>4</superscript>-10<superscript>5</superscript> M<superscript>-1</superscript>). The proximity of the ligands to HSA is also revealed by their average binding distance, r, which is estimated to be in the range of 4.39-5.37 nm. The binding free energy (ΔG) in each case remains effectively the same for each site because of enthalpy-entropy compensation (EEC). The difference observed between ΔC<subscript>p</subscript> <superscript>exp</superscript> and ΔC<subscript>p</subscript> <superscript>calc</superscript> are suggested to be caused by binding-induced flexibility changes in the HSA. Efforts are also made to elaborate the differences observed in binding isotherms obtained through multiple approaches of calorimetry, spectroscopy and bioinformatics. We suggest that difference in dissociation constants of pollutants by calorimetry, spectroscopic and computational approaches could correspond to occurrence of different set of populations of pollutants having different molecular characteristics in ground state and excited state. Furthermore, our observation of enhanced binding of pollutants (2N and 8H) in the presence of hemin signifies that ligands like hemin may enhance the storage period of these pollutants in blood that may even facilitate the ill effects of these pollutants. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
19326203
Volume :
6
Issue :
11
Database :
Complementary Index
Journal :
PLoS ONE
Publication Type :
Academic Journal
Accession number :
73903839
Full Text :
https://doi.org/10.1371/journal.pone.0026186