Mechanistic insights into the urea-induced denaturation of human sphingosine kinase 1

Faez Iqbal Khan, Preeti Gupta, Sonam Roy, Naved Azum, Khalid A. Alamry, Abdullah M. Asiri, Dakun Lai*, Md Imtaiyaz Hassan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


Sphingosine kinase 1 (SphK1) plays a significant role in various cellular processes, including cell proliferation, apoptosis, and angiogenesis. SphK1 is considered as an attractive target for drug development owing to its connection with several diseases, including cancer. In the current work, the urea-induced unfolding of SphK1 was performed at pH 8.0 and 25 °C using CD and fluorescence spectroscopy. SphK1 follows a biphasic unfolding transition (N ⇌ I ⇌ D) with an intermediate (I) state populated around 4.0 M urea concentration. The circular dichroism ([θ]222) and fluorescence emission spectra (λmax) of SphK1 with increasing concentrations of urea were analyzed to calculate Gibbs free energy (ΔG0) for both the transitions (N ⇌ I and I ⇌ D). A significant overlap of both the transitions obtained by two spectroscopic properties ([θ]222 and λmax) was observed, indicating that both N ⇌ I and I ⇌ D transition follow two-step equilibrium unfolding pattern. Also, we performed 100 ns molecular dynamics (MD) simulations to get atomistic insights into the structural changes in SphK1 with increasing urea concentrations. Our results showed a consistent pattern of the SphK1 unfolding with increasing urea concentrations. Together, spectroscopic and MD simulation findings provide deep insights into the unfolding mechanism and conformational features of SphK1.

Original languageEnglish
Pages (from-to)1496-1505
Number of pages10
JournalInternational Journal of Biological Macromolecules
Publication statusPublished - 15 Oct 2020
Externally publishedYes


  • Gibbs free energy
  • Molecular dynamics simulation
  • Protein folding and denaturation
  • Protein stability
  • Sphingosine kinase 1


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