1-Anilino-8-naphthalene sulfonate (ANS) binding to proteins revisited: Investigation of dye binding to molten globule states by electrospray ionization mass spectrometry

Ray, Soumya S and Balaram, Padmanabhan (1999) 1-Anilino-8-naphthalene sulfonate (ANS) binding to proteins revisited: Investigation of dye binding to molten globule states by electrospray ionization mass spectrometry. In: Journal of physical Chemistry B, 103 (34). pp. 7068-7072.

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Abstract

The binding of 1-anilino-8-naphthalene-sulfonic acid to globular proteins at acidic pH has been investigated by electrospray ionization mass spectrometry (ESIMS). Mass spectra of apomyoglobin recorded in the pH range 2−7 establish that maximal ANS binding is observed at pH 4.0. As many as seven distinct species may be observed in the gas phase which correspond to protein molecules containing one to six molecules of bound ANS. At neutral pH only a single molecule of ANS is bound. In the case of cytochrome c, maximal binding is observed at pH 4.0, with five molecules being bound. Binding is suppressed at neutral pH. In both cases ESIMS demonstrates maximal ANS binding at pH values where the proteins have been reported to exist in molten globule states. ANS binding is not observed for lysozyme, which has a tightly folded structure over the entire pH range. Reduction of disulfide bonds in lysozyme leads to the detection of ANS-bound species at neutral pH. Binding is suppressed at low pH due to complete unfolding of the reduced protein. The results suggest that ESIMS may provide a convenient method of probing the stoichiometry and distribution of dye complexes with molten protein globules

Item Type:	Journal Article
Publication:	Journal of physical Chemistry B
Publisher:	American Chemical Society
Additional Information:	Copyright of this article belongs to American Chemical Society.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	14 Dec 2010 07:05
Last Modified:	14 Dec 2010 07:05
URI:	http://eprints.iisc.ac.in/id/eprint/33877

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