Trimethylamine-N-oxide switches from stabilizing nature: A mechanistic outlook through experimental techniques and molecular dynamics simulation.

Anjeeta Rani,Abhilash Jayaraj,Venkatesu Pannuru,B. Jayaram

doi:10.1038/srep23656

Anjeeta Rani, Abhilash Jayaraj + Show 2 more

Open Access

https://doi.org/10.1038/srep23656

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Abstract

In adaptation biology of the discovery of the intracellular osmolytes, the osmolytes are found to play a central role in cellular homeostasis and stress response. A number of models using these molecules are now poised to address a wide range of problems in biology. Here, a combination of biophysical measurements and molecular dynamics (MD) simulation method is used to examine the effect of trimethylamine-N-oxide (TMAO) on stem bromelain (BM) structure, stability and function. From the analysis of our results, we found that TMAO destabilizes BM hydrophobic pockets and active site as a result of concerted polar and non-polar interactions which is strongly evidenced by MD simulation carried out for 250 ns. This destabilization is enthalpically favourable at higher concentrations of TMAO while entropically unfavourable. However, to the best of our knowledge, the results constitute first detailed unambiguous proof of destabilizing effect of most commonly addressed TMAO on the interactions governing stability of BM and present plausible mechanism of protein unfolding by TMAO.

Highlights

Recent studies unveil the fact that TMAO can behave as a denaturant which is intriguing general interest of the researchers[9,13,14,15,16]
Granata et al reported that TMAO decreased thermal stability of prion protein (PrP) at low pH but behaved as a denaturant at room temperature[15]
Circular dichroism (CD), UV-visible and Fourier transform infrared (FTIR) spectroscopy to explore these critical issues and to gain insight into the microscopic understanding of molecular mechanism of the protecting action of TMAO on BM. We combine these experiments with molecular dynamics (MD) simulation which is an effective tool to obtain atomistic level framework for the understanding/delineating the interactions involved in the system of protein, TMAO and water

Summary

Introduction

Recent studies unveil the fact that TMAO can behave as a denaturant which is intriguing general interest of the researchers[9,13,14,15,16]. Granata et al reported that TMAO decreased thermal stability of prion protein (PrP) at low pH but behaved as a denaturant at room temperature[15]. Nandi and his co-workers observed the formation of the misfolded prion protein oligomers and their polymerization to amyloids in TMAO16. In addition to this puzzled area of research, the molecular mechanism of destabilization of protein in TMAO is a more complex problem and still unclear. To the best of our knowledge, this study represents the first detailed experimental and simulation evidence about the mechanism of destabilization of protein by TMAO

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