title: Characterization of pre-molten globule state of yeast iso-1-cytochrome c and its deletants at pH 6.0 and 25 °C.
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 405 nm (Δɛ405), the mean residue ellipticity at 222 nm ([θ]222), and the difference mean residue ellipticity at 409 nm (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 0.33 M Na2SO4 at pH 2.1, which when characterized showed all structural characteristics of MG (molten globule) state.
authors.affiliation: Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, 110025, India.
authors.forename: Md Anzarul
authors.initials: MA
authors.lastname: Haque
authors.affiliation: Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, 110025, India; Immunochemistry Lab, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors.forename: Shah
authors.initials: S
authors.lastname: Ubaid-Ullah
authors.affiliation: Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, 110025, India.
authors.forename: Sobia
authors.initials: S
authors.lastname: Zaidi
authors.affiliation: Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, 110025, India.
authors.forename: Md Imtaiyaz
authors.initials: MI
authors.lastname: Hassan
authors.affiliation: Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, 110025, India.
authors.forename: Asimul
authors.initials: A
authors.lastname: Islam
authors.affiliation: Immunochemistry Lab, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors.forename: Janendra K
authors.initials: JK
authors.lastname: Batra
authors.affiliation: Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, 110025, India. Electronic address: fahmad@jmi.ac.in.
authors.forename: Faizan
authors.initials: F
authors.lastname: Ahmad
mesh_terms: D002942:Circular Dichroism; D045304:Cytochromes c / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D018021:Lithium Chloride / Q000494:pharmacology; D011489:Protein Denaturation / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*; D017384:Sequence Deletion; D013050:Spectrometry, Fluorescence; D013329:Structure-Activity Relationship; D013696:Temperature
chemical_list: C014059:CYC1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D045304:Cytochromes c; D018021:Lithium Chloride
keywords: Molten globule; Pre-molten globule; Protein folding; Protein stability; Yeast iso-1-cytochrome c