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Spectrochim Acta A Mol Biomol Spectrosc. 2014;120:151-60. doi: 10.1016/j.saa.2013.09.141. Epub 2013 Oct 9.

Detergent induces the formation of IgG aggregates: a multi-methodological approach.

Author information

1
Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh 202002, India.
2
Department of Chemistry, Faculty of Science, Aligarh Muslim University, Aligarh 202002, India.
3
Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002, India.
4
Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh 202002, India. Electronic address: aabgeenanaim@gmail.com.

Abstract

Role of micellar environment created by Triton X-100 (TX-100) and CHAPSO on protein conformation using IgG as a model system has been studied in this paper. A substantial amount of secondary structure with the reduction in constant tertiary contacts was obtained in both bovine and human IgG in the presence of 0.12 mM TX-100 where as 6 and 8 mM CHAPSO concentration was required for this type of secondary structure. Further addition of either of the detergents result in the induction of α-helix in both the IgGs as evident by helix specific peaks in the amide I region of FTIR and circular dichroism spectra. Tryptophan and 8-anilino-1-naphthalene-sulphonic acid (ANS) fluorescence confirmed changes in protein conformation upon addition of detergents. Maximum ANS binding at 0.12 mM TX-100 in both while 6 and 8 mM CHAPSO in bovine and human IgG respectively, indicate a compact ''molten-globule''-like conformation. An increase addition of these detergents results in the burial of hydrophobic patches of both IgG owing to aggregation. Presence of aggregates at 0.2 and 0.16 mM TX-100 and 8 and 9 mM CHAPSO, for bovine and human IgG respectively, was further confirmed by reduction in ANS fluorescence, dynamic light scattering study, thioflavin T fluorescence and congo red absorbance.

KEYWORDS:

8-anilino-1-naphthalene-sulphonic acid; ANS; Aggregation; BIgG; CD; CHAPSO; CR; DLS; Dynamic light scattering; HIgG; IgG; MG; Molten globule; TX-100; ThT; Thioflavin T; Triton X-100; bovine IgG; circular dichroism; congo red; dynamic light scattering; human IgG; immunoglobulin G; molten globule

PMID:
24184618
DOI:
10.1016/j.saa.2013.09.141
[Indexed for MEDLINE]
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