Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Debasish Das Mahanta is active.

Publication


Featured researches published by Debasish Das Mahanta.


Langmuir | 2016

Effect of Short Chain Poly(ethylene glycol)s on the Hydration Structure and Dynamics around Human Serum Albumin.

Nirnay Samanta; Trung Quan Luong; Debasish Das Mahanta; Rajib Kumar Mitra; Martina Havenith

We report the changes in the hydration dynamics around a globular protein, human serum albumin (HSA), in the presence of two short chain crowding agents, namely poly(ethylene glycol)s (PEG 200 and 400). The change in the network water structure is investigated using FTIR spectroscopy in the far-infrared (FIR) frequency range. Site specific changes are obtained by time-resolved fluorescence spectroscopic technique using the intrinsic fluorophore tryptophan (Trp214) of HSA. The collective hydration dynamics of HSA in the presence of PEG molecules are obtained using terahertz (THz) time domain spectroscopy (TTDS) and high intensity p-Ge THz measurements. Our study affirms a considerable perturbation of HSA hydration beyond a critical concentration of PEG.


Journal of Chemical Physics | 2016

Non-monotonic dynamics of water in its binary mixture with 1,2-dimethoxy ethane: A combined THz spectroscopic and MD simulation study

Debasish Das Mahanta; Animesh Patra; Nirnay Samanta; Trung Quan Luong; Biswaroop Mukherjee; Rajib Kumar Mitra

A combined experimental (mid- and far-infrared FTIR spectroscopy and THz time domain spectroscopy (TTDS) (0.3-1.6 THz)) and molecular dynamics (MD) simulation technique are used to understand the evolution of the structure and dynamics of water in its binary mixture with 1,2-dimethoxy ethane (DME) over the entire concentration range. The cooperative hydrogen bond dynamics of water obtained from Debye relaxation of TTDS data reveals a non-monotonous behaviour in which the collective dynamics is much faster in the low Xw region (where Xw is the mole fraction of water in the mixture), whereas in Xw ∼ 0.8 region, the dynamics gets slower than that of pure water. The concentration dependence of the reorientation times of water, calculated from the MD simulations, also captures this non-monotonous character. The MD simulation trajectories reveal presence of large amplitude angular jumps, which dominate the orientational relaxation. We rationalize the non-monotonous, concentration dependent orientational dynamics by identifying two different physical mechanisms which operate at high and low water concentration regimes.


ChemPhysChem | 2017

Nonmonotonic Hydration Behavior of Bovine Serum Albumin in Alcohol/Water Binary Mixtures: A Terahertz Spectroscopic Investigation

Dipak Kumar Das; Debasish Das Mahanta; Rajib Kumar Mitra

We report the experimental observation of nonmonotonic changes in the collective hydration of bovine serum albumin (BSA) in the presence of alcohols of varying carbon-chain lengths, that is, ethanol, 2-propanol, and tert-butyl alcohol (TBA), by using terahertz (THz) time domain spectroscopy. We measured the THz absorption coefficient (α) of the protein solutions, and it was observed that α fluctuated periodically as a function of alcohol concentration at a fixed protein concentration. For a fixed alcohol concentration, an increase in the protein concentration resulted in nonmonotonic changes in α; thus, it first decreased rapidly and then increased, which was followed by a shallow decrease. An alcohol-induced α helix to random coil transition of the protein secondary structure was revealed by circular dichroism spectroscopy measurements, and the effect was most prominent in TBA. The anomalous change in the hydration was found to be a delicate balance between the various interactions present in the three-component system.


Journal of Chemical Physics | 2017

Collective hydration dynamics in some amino acid solutions: A combined GHz-THz spectroscopic study

Nirnay Samanta; Debasish Das Mahanta; Samiran Choudhury; Anjan Barman; Rajib Kumar Mitra

A detailed understanding of hydration of amino acids, the building units of protein, is a key step to realize the overall solvation processes in proteins. In the present contribution, we have made a combined GHz (0.2-50) to THz (0.3-2.0) experimental spectroscopic study to investigate the dynamics of water at room temperature in the presence of different amino acids (glycine, L-serine, L-lysine, L-tryptophan, L-arginine, and L-aspartic acid). The THz absorption coefficient, α(ν), of amino acids follows a trend defined by their solvent accessible surface area. The imaginary and real dielectric constants obtained in GHz and THz regions are fitted into multiple Debye model to obtain various relaxation times. The ∼100 ps time scale obtained in the GHz frequency region is attributed to the rotational motion of the amino acids. In the THz region, we obtain ∼8 ps and ∼200 fs time scales which are related to the cooperative dynamics of H-bond network and partial rotation or sudden jump of the under-coordinated water molecules. These time scales are found to be dependent on the amino acid type and the cooperative motion is found to be dependent on both the hydrophobic as well as the hydrophilic residue of amino acids.


International Journal of Biological Macromolecules | 2018

Soft interaction and excluded volume effect compete as polyethylene glycols modulate enzyme activity

Nirnay Samanta; Debasish Das Mahanta; Animesh Patra; Rajib Kumar Mitra

Polyethylene glycols (PEGs) can either preferentially bind to biomolecules or exert excluded volume effect depending upon their chain length and concentration. We have studied the effect of ethylene glycol (EG) and PEGs of different chain lengths (Mn 400 and 4000) on the enzyme efficiency of hen-egg-white lysozyme (HEWL) on Micrococcus lysodeikticus (M. Lys.) cell. The activity shows a bell-like profile as the turnover number increases from ~1.3 × 105 s-1 M-1 in water to ~1.7 × 105 s-1 M-1 in presence of 2% PEG-400 beyond which it decreases to ~0.7 × 105 s-1 M-1 at 20% PEG-400. Solvent polarity, excluded volume effect, soft nonspecific interactions and structural flexibility are found to be the competing factors which govern the overall enzyme activity as evidenced from circular dichroism (CD) and fluorescence measurements. Thermal unfolding temperature (Tm) of HEWL also shows a bell-shaped profile with PEG concentration which establishes possible correlation with its activity. We also observe a minimum in the activation energy barrier for the catalysis at low osmolyte concentrations. The maximum in the enzyme efficiency has been explained on the basis of an optimization between excluded volume effect and soft interaction among the protein and the cosolutes.


Chemistry-an Asian Journal | 2014

Does urea alter the collective hydrogen-bond dynamics in water? A dielectric relaxation study in the terahertz-frequency region.

Nirnay Samanta; Debasish Das Mahanta; Rajib Kumar Mitra


Physical Chemistry Chemical Physics | 2014

Collective hydration dynamics of guanidinium chloride solutions and its possible role in protein denaturation: a terahertz spectroscopic study†

Nirnay Samanta; Debasish Das Mahanta; Rajib Kumar Mitra


Journal of Molecular Liquids | 2016

The effect of monovalent cations on the collective dynamics of water and on a model protein

Debasish Das Mahanta; Nirnay Samanta; Rajib Kumar Mitra


Journal of Physical Chemistry B | 2017

Decisive Role of Hydrophobicity on the Effect of Alkylammonium Chlorides on Protein Stability: A Terahertz Spectroscopic Finding

Debasish Das Mahanta; Nirnay Samanta; Rajib Kumar Mitra


international conference on infrared, millimeter, and terahertz waves | 2015

Urea and guanidinium chloride act as ‘water structure breakers’: The debate revisited by dielectric relaxation study in THz range

Nirnay Samanta; Debasish Das Mahanta; Rajib Kumar Mitra

Collaboration


Dive into the Debasish Das Mahanta's collaboration.

Top Co-Authors

Avatar

Rajib Kumar Mitra

S.N. Bose National Centre for Basic Sciences

View shared research outputs
Top Co-Authors

Avatar

Nirnay Samanta

S.N. Bose National Centre for Basic Sciences

View shared research outputs
Top Co-Authors

Avatar

Animesh Patra

S.N. Bose National Centre for Basic Sciences

View shared research outputs
Top Co-Authors

Avatar

Biswaroop Mukherjee

S.N. Bose National Centre for Basic Sciences

View shared research outputs
Top Co-Authors

Avatar

Dipak Kumar Das

S.N. Bose National Centre for Basic Sciences

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Amitabha Chattopadhyay

Centre for Cellular and Molecular Biology

View shared research outputs
Top Co-Authors

Avatar

Anjan Barman

S.N. Bose National Centre for Basic Sciences

View shared research outputs
Top Co-Authors

Avatar

Debkumar Rana

S.N. Bose National Centre for Basic Sciences

View shared research outputs
Top Co-Authors

Avatar

Samiran Choudhury

S.N. Bose National Centre for Basic Sciences

View shared research outputs
Researchain Logo
Decentralizing Knowledge