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Cooperative unfolding of apolipoprotein A-1 induced by chemical denaturation
- Source :
- Biophysical chemistry. 240
- Publication Year :
- 2018
-
Abstract
- Apolipoprotein A-1 (Apo A-1) plays an important role in lipid transfer and obesity. Chemical unfolding of α-helical Apo A-1 is induced with guanidineHCl and monitored with differential scanning calorimetry (DSC) and CD spectroscopy. The unfolding enthalpy and the midpoint temperature of unfolding decrease linearly with increasing guanidineHCl concentration, caused by the weak binding of denaturant. At room temperature, binding of 50–60 molecules guanidineHCl leads to a complete Apo A-1 unfolding. The entropy of unfolding decreases to a lesser extent than the unfolding enthalpy. Apo A-1 chemical unfolding is a dynamic multi-state equilibrium that is analysed with the Zimm-Bragg theory modified for chemical unfolding. The chemical Zimm-Bragg theory predicts the denaturant binding constant KD and the protein cooperativity σ. Chemical unfolding of Apo A-1 is two orders of magnitude less cooperative than thermal unfolding. The free energy of thermal unfolding is ~0.2 kcal/mol per amino acid residue and ~1.0 kcal/mol for chemical unfolding at room temperature. The Zimm-Bragg theory calculates conformational probabilities and the chemical Zimm-Bragg theory predicts stretches of α-helical segments in dynamic equilibrium, unfolding and refolding independently and fast.
- Subjects :
- 0301 basic medicine
Circular dichroism
Protein Denaturation
Protein Folding
Entropy
Enthalpy
Biophysics
Thermodynamics
Cooperativity
Biochemistry
03 medical and health sciences
Differential scanning calorimetry
Molecule
Humans
Dynamic equilibrium
Guanidine
030102 biochemistry & molecular biology
Apolipoprotein A-I
Calorimetry, Differential Scanning
Chemistry
Circular Dichroism
Organic Chemistry
Binding constant
Recombinant Proteins
Kinetics
030104 developmental biology
biological sciences
Entropy (order and disorder)
Subjects
Details
- ISSN :
- 18734200
- Volume :
- 240
- Database :
- OpenAIRE
- Journal :
- Biophysical chemistry
- Accession number :
- edsair.doi.dedup.....df2469439d89f3997d0efa3ec2d23f48