Title
Urea-induced denaturation of human calcium/calmodulin-dependent protein kinase IV: a combined spectroscopic and MD simulation studies
Author
Huma Naz, Mohd. Shahbaaz, Md. Anzarul Haque, Krishna Bisetty, Asimul Islam, Faizan Ahmad, Md. Imtaiyaz Hassan
Year
2016
Journal
Journal of Biomolecular Structure and Dynamics
Abstract
Calcium/calmodulin-dependent protein kinase IV (CaMKIV) is a multifunctional enzyme which belongs to the Ser/Thr kinase family. CaMKIV plays important role in varieties of biological processes such as gene expression regulation, memory consolidation, bone growth, T-cell maturation, sperm motility, regulation of microtubule dynamics, cell-cycle progression, and apoptosis. To measure stability parameters, urea-induced denaturation of CaMKIV was carried out at pH 7.4 and 25°C, using three different probes, namely far-UV CD, near-UV absorption, and tryptophan fluorescence. A coincidence of normalized denaturation curves of these optical properties suggests that urea-induced denaturation is a two-state process. Analysis of these denaturation curves gave values of 4.20 ± 0.12 kcal mol−1, 2.95 ± 0.15 M, and 1.42 ± 0.06 kcal mol−1 M−1 for (Gibbs free energy change (ΔGD) in the absence of urea), Cm (molar urea concentration ([urea]) at the midpoint of the denaturation curve), and m (=∂ΔGD/∂[urea]), respectively. All these experimental observations have been fully supported by 30 ns molecular dynamics simulation studies.
Instrument
J-1500
Keywords
Circular dichroism, Protein denaturation, Protein folding, Thermodynamics, Secondary structure, Biochemistry