Browsing by Author "Sharma, D"

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    Mechanism underlying N-(3-oxo-dodecanoyl)-L-homoserine lactone mediated intracellular calcium mobilization in human platelets
    (Academic Press, 2019) Yadav, V.K; Singh, P.K; Sharma, D; Singh, Sunil Kumar; Agarwal,V.
    Acyl-homoserine lactones (AHLs), are the key autoinducer molecules that mediate Pseudomonas aeruginosa associated quorum sensing. P. aeruginosa produces two types of AHLs; N-(3-oxododecanoyl)-L-homoserine lactone (3-oxo-C12 HSL) and N-butyryl-L-homoserine lactone (C4 HSL). AHLs are not only regulating the virulence gene of bacteria but also influence the host cell functions by interkingdom signaling. In this study, we explored the mechanism of AHLs induced calcium mobilization in human platelets. We found that 3-oxo-C12 HSL but not C4 HSL induces intracellular calcium release. 3-oxo-C12 HSL induced calcium mobilization was majorly contributed from the dense tubular system (DTS). Furthermore, 3-oxo-C12 HSL also stimulates the store-operated Ca2+ entry (SOCE) in platelet. Intracellular calcium rise was significantly lowered in rotenone, and bafilomycin pre-treated platelets suggesting partial involvement of mitochondria and acidic vacuoles. The significant effect of 3-oxo-C12 HSL on calcium mobilization can alter the platelet functions that might results in thrombotic disorders in individuals infected with P. aeruginosa. © 2019
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    Structural, kinetic and thermodynamic characterizations of SDS-induced molten globule state of a highly negatively charged cytochrome c
    (Oxford University Press, 2019) Jain, R; Sharma, D; Kumar, Rakesh; Kumar, Rajesh
    This study presents the structural, kinetic and thermodynamic characterizations of previously unknown submicellar concentrations of SDS-induced molten globule (MGSDS) state of a highly negatively charged basedenatured ferricytochrome c (U B -state) at pH ∼12.8 (±0.2). The far-UV CD, near-UV CD, ANS-fluorescence data of UB-state in the presence of different concentrations of SDS indicate that the submicellar concentrations of SDS (≤0.4mM) transform the UBstate to MG SDS -state. The MG SDS -state has nativelike α-helical secondary structure but lacks tertiary structure. The free energy change (ΔG° D) for U B → MG SDS transition determined by far-UV CD (∼2.7 kcal mol -1 ) is slightly higher than those determined by fluorescence (∼2.0 kcal mol -1 ) at 25°C. At very low SDS and NaCl concentrations, the MG SDS -state undergoes cold denaturation. As SDS concentration is increased, the thermal denaturation temperature increases and the cold denaturation temperature decrease. Kinetic experiments involving the measurement of the CO-association rate to the base-denatured ferrocytochrome c at pH ≈12.8 (±0.2), 25°C indicate that the submicellar concentrations of SDS restrict the internal dynamics of base-denatured protein. © The Author(s) 2018. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.