Characterization of pre-molten globule state of yeast iso-1-cytochrome c and its deletants at pH 6.0 and 25°C

Md Anzarul Haque, Shah Ubaid-ullah, Sobia Zaidi, Md Imtaiyaz Hassan, Asimul Islam, Janendra K. Batra, Faizan Ahmad

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

To understand the role of five extra N-terminal residues, we prepared wild type (WT) yeast iso-1-cytochrome c (y-cyt-c) and its deletants by subsequently deleting these residues. Denaturation of all these proteins induced by LiCl was followed by observing changes in molar absorption coefficient at 405nm (δε405), the mean residue ellipticity at 222nm ([θ]222), and the difference mean residue ellipticity at 409nm (δ[θ]409) near physiological pH and temperature (pH 6.0 and 25°C). It was observed that in each case LiCl induces biphasic transition, N (native) state↔X (intermediate) state↔D (denatured) state. The intermediate (X) was characterized by the far-UV, near-UV and Soret circular dichroism, ANS (8-anilino-1-naphthalenesulfonic acid) binding and dynamic light scattering measurements. These measurements led us to conclude that X state of each protein has structural characteristics of PMG (pre-molten globule) state. Thermodynamic stability of all proteins was also determined. It was observed that the N-terminal extension stabilizes the native WT protein but it has no effect on the stability of PMG state. Another state was observed for each protein, in the presence of 0.33M Na2SO4 at pH 2.1, which when characterized showed all structural characteristics of MG (molten globule) state.

Original languageEnglish (US)
Pages (from-to)1406-1418
Number of pages13
JournalInternational Journal of Biological Macromolecules
Volume72
DOIs
StatePublished - Jan 1 2015
Externally publishedYes

Keywords

  • Molten globule
  • Pre-molten globule
  • Protein folding
  • Protein stability
  • Yeast iso-1-cytochrome c

ASJC Scopus subject areas

  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Economics and Econometrics
  • Energy(all)

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