title: Effect of sequential deletion of extra N-terminal residues on the structure and stability of yeast iso-1-cytochrome-c.
abstract: 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.
authors.affiliation: a Centre for Interdisciplinary Research in Basic Sciences , Jamia Millia Islamia, Jamia Nagar, New Delhi 110025 , India ;
authors.forename: Shah
authors.initials: S
authors.lastname: Ubaid-Ullah
authors.forename: Md Anzarul
authors.initials: MA
authors.lastname: Haque
authors.forename: Sobia
authors.initials: S
authors.lastname: Zaidi
authors.forename: Md Imtaiyaz
authors.initials: MI
authors.lastname: Hassan
authors.forename: Asimul
authors.initials: A
authors.lastname: Islam
authors.forename: Janendra K
authors.initials: JK
authors.lastname: Batra
authors.forename: Tej P
authors.initials: TP
authors.lastname: Singh
authors.forename: Faizan
authors.initials: F
authors.lastname: Ahmad
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003198:Computer Simulation; D003575:Cytochromes c1 / Q000737:chemistry / Q000235:genetics*; D055550:Protein Stability; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*; D017384:Sequence Deletion; D013816:Thermodynamics
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D003575:Cytochromes c1
keywords: differential scanning calorimetry; protein stability; two-state denaturation; yeast iso-1-cytochrome-c