Probing Conformational Stability and Dynamics of Erythroid and Nonerythroid Spectrin: Effects of Urea and Guanidine Hydrochloride

• DOI: 10.1371/journal.pone.0116991
• Publication Date: 2015-01-24T19:15:54Z
• Authors: Malay Patra; Chaitali Mukhopad...; Abhijit Chakrabarti
• Keywords: Guanidine; Equilibrium unfolding; Protein quaternary structure; Tetramer; Trimer; Hydrochloride; Globular protein

We have studied the conformational stability of two homologous membrane skeletal proteins, erythroid and non-erythroid spectrins, in their dimeric tetrameric forms respectively during unfolding presence urea guanidine hydrochloride (GuHCl). Fluorescence circular dichroism (CD) spectroscopy been used to study changes intrinsic tryptophan fluorescence, anisotropy, far UV-CD extrinsic fluorescence bound 1-anilinonapthalene-8-sulfonic acid (ANS). Chemical both proteins were reversible could be described as a state transition. The folded spectrin directly converted unfolded monomer without formation any intermediate. quenching, ANS binding dynamic light scattering data suggest that low concentrations denaturants (up-to 1M) hydrogen bonding network van der Waals interaction play role inducing quaternary well tertiary structures complete dissociation subunits. This is first report large worm like, multi-domain obeying twofold rule which commonly found small globular proteins. free energy stabilization (ΔGuH20) for has 20 kcal/mol lesser than from.