• Nitin Chattopadhyay

      Articles written in Journal of Chemical Sciences

    • Fluorescence resonance energy transfer from tryptophan in human serum albumin to a bioactive indoloquinolizine system

      Paramita Das Arabinda Mallick Basudeb Haldar Alok Chakrabarty Nitin Chattopadhyay

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      The interaction between a bioactive molecule, 3-acetyl-4-oxo-6,7-dihydro-12H indolo-[2,3-a] quinolizine (AODIQ), with human serum albumin (HSA) has been studied using steady-state absorption and fluorescence techniques. A 1 : 1 complex formation has been established and the binding constant (𝐾) and free energy change for the process have been reported. The AODIQ-HSA complex results in fluorescence resonance energy transfer (FRET) from the tryptophan moiety of HSA to the probe. The critical energy-transfer distance ($R_0$) for FRET and the Stern-Volmer constant ($K_{sv}$) for the fluorescence quenching of the donor in the presence of the acceptor have been determined. Importantly, $K_{SV}$ has been shown to be equal to the binding constant itself, implying that the fluorescence quenching arises only from the FRET process. The study suggests that the donor and the acceptor are bound to the same protein at different locations but within the quenching distance.

    • Interaction of cyclodextrins with human and bovine serum albumins: A combined spectroscopic and computational investigation

      Saptarshi Ghosh Bijan Kumar Paul Nitin Chattopadhyay

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      Interaction of cyclodextrins (CDs) with the two most abundant proteins, namely human serum albumin (HSA) and bovine serum albumin (BSA), has been investigated using steady-state and time-resolved fluorometric techniques, circular dichroism measurements and molecular docking simulation. The study reveals that the three CDs interact differently on the fluorescence and fluorescence lifetimes of the serum albumins. However, fluorescence anisotropy and circular dichroism are not affected. Depending on their size, different CDs bind to the serum albumins in different positions, resulting in changes in the spectral behaviour of the proteins. Docking study suggests the probable binding sites of the three CDs with the proteins. Combined experimental and computational studies imply that sufficiently high concentration of CDs causes loosening of the rigid structures of these transport proteins, although their secondary structures remain intact. Thus, CDs are found to be safe for the serum proteins from the structural point of view.

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