Effect of sequential deletion of extra N-terminal residues on the structure and stability of yeast iso-1-cytochrome-c

Shah Ubaid-Ullah, Md Anzarul Haque, Sobia Zaidi, Md Imtaiyaz Hassan, Asimul Islam, Janendra K. Batra, Tej P. Singh, Faizan Ahmad

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


A sequence alignment of yeast cytochrome-c (y-cyt-c) with mammalian cyts-c shows that the yeast protein has a five residue long N-terminal extension. A question arises: Does this N-terminal extension play any roles in the stability, structure, and folding of the yeast protein? To answer this question, in silico and in vitro studies were carried out on the wild type (WT) protein and its five deletants (Δ(-5/-5), Δ(-5/-4), Δ(-5/-3), Δ(-5/-2), and Δ(-5/-1) where Δ denotes the deletion and the numbers refer to the residues deleted, e.g. Δ(-5/-1) denotes the deletion of residues numbered from -5 to -1 (TEFKA), while Δ(-5/-2) denotes the deletion of resides numbered from -5 to -2 (TEFK) and so on). The main conclusion of the in silico study is that the order of stability of deletants and WT protein is Δ(-5/-4) > WT > Δ(-5/-3) > Δ(-5/-5) > Δ(-5/-1) ~ Δ(-5/-2). In vitro studies involved (i) measurements of thermodynamic stability of all proteins by differential scanning calorimetry and from sigmoidal curves of two different structural properties ([θ] 222, a probe for detecting change in secondary structure, and Δε405, a probe for detecting alteration in the heme environment), and (ii) characterization of all proteins by various spectral properties. The main conclusions of the in vitro studies are as follows: (i) The order of thermodynamic stability of all proteins is in excellent agreement with that predicted by in silico studies, and (ii) A sequential deletion of the N-terminal extension has no effects on protein structure and folding.

Original languageEnglish (US)
Pages (from-to)2005-2016
Number of pages12
JournalJournal of Biomolecular Structure and Dynamics
Issue number12
StatePublished - Dec 2 2014
Externally publishedYes


  • differential scanning calorimetry
  • protein stability
  • two-state denaturation
  • yeast iso-1-cytochrome-c

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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