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Belgaum, India

Shah C.,Max Delbruck Center for Molecular Medicine | Shah C.,Free University of Berlin | Hegde B.G.,Rani Channamma University | Moren B.,Umea University | And 10 more authors.
Structure | Year: 2014

The dynamin-related Eps15-homology domain-containing protein 2 (EHD2) is a membrane-remodeling ATPase that regulates the dynamics of caveolae. Here, we established an electron paramagnetic resonance (EPR) approach to characterize structural features of membrane-bound EHD2. We show that residues at the tip of the helical domain can insert into the membrane and may create membrane curvature by a wedging mechanism. Using EPR and X-ray crystallography, we found that the N terminus is folded into a hydrophobic pocket of the GTPase domain in solution and can be released into the membrane. Cryoelectron microscopy demonstrated that the N terminus is not essential for oligomerization of EHD2 into a membrane-anchored scaffold. Instead, we found a function of the N terminus in regulating targeting and stable association of EHD2 to caveolae. Our data uncover an unexpected, membrane-induced regulatory switch in EHD2 and demonstrate the versatility of EPR to study structure and function of dynamin superfamily proteins. © 2014 Elsevier Ltd.

Yallappa S.,Kuvempu University | Manjanna J.,Rani Channamma University | Dhananjaya B.L.,Jain University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2015

A green chemistry approach for the synthesis of Au, Ag and Au-Ag alloy nanoparticles (NPs) using the corresponding metal precursors and Jasminum sambac leaves extract as both reducing and capping media, under microwave irradiation, is reported. During the formation, as expected, the reaction mixture shows marginal decrease in pH and an increase in solution potential. The formation of NPs is evident from their surface plasmon resonance (SPR) peak observed at ∼555 nm for Au, ∼435 nm for Ag and ∼510 nm for Au-Ag alloy. The XRD pattern shows fcc structure while the FTIR spectra indicate the presence of plant residues adsorbed on these NPs. Such a bio-capping of NPs is characterized by their weight loss, ∼35% due to thermal degradation of biomass, as observed in TG analysis. The colloidal dispersion of NPs is stable for about 6 weeks. The near spherical shape of NPs (20-50 nm) is observed by FE-SEM/TEM images and EDAX gives the expected elemental composition. Furthermore, these NPs showed enhanced antimicrobial activity (∼1-4-fold increase in zone of inhibition) in combination with antimicrobials against test strains. Thus, the phytosynthesized NPs could be used as effective growth inhibitors for various microorganisms. © 2014 Elsevier B.V. All rights reserved.

Nayaka G.P.,Kuvempu University | Manjanna J.,Rani Channamma University | Pai K.V.,Kuvempu University | Vadavi R.,Bk College | And 2 more authors.
Hydrometallurgy | Year: 2015

A well characterized cathode material (LiCoO2) recovered from spent lithium-ion battery is dissolved in aqueous mixture of citric acid (chelating agent) and ascorbic acid (reductant) at 80 °C. The dissolution proceeds with a reductive-complexing mechanism, and complete dissolution occurs in about 6 h when stoichiometric amount of C/A is used. The dissolution rate constants (k) are 3.1 × 10- 3 min- 1 for Li and 0.8 × 10- 3 min- 1 for Co ions as determined by 'cubic rate law' plots. The formation of Co(III)- to Co(II)-citrate during the dissolution is confirmed from the UV-Vis spectra. The dissolved solution was subjected for selective precipitation of cobalt as Co-oxalate and lithium as LiF using oxalic acid and NH4F, respectively. The present study has a merit when compared to literature reports as we make use of mild organic acids as alternatives to mineral acids. © 2014 Elsevier B.V.

Nayaka G.P.,Kuvempu University | Pai K.V.,Kuvempu University | Santhosh G.,Nmam Institute Of Technology | Manjanna J.,Rani Channamma University
Hydrometallurgy | Year: 2016

Environmentally benign hydrometallurgical dissolution process is investigated for the recovery of cobalt from the cathode active materials of spent lithium-ion batteries (LIBs). A mixture of tartaric acid and ascorbic acid is used to dissolve the LiCoO2 collected from spent LIBs. The reductive-complexing mechanism led to > 95% dissolution with 0.4 M tartaric acid and 0.02 M ascorbic acid in about 5 h at 80 °C. The dissolved Co was separated as cobalt oxalate from the mixture. © 2016 Elsevier B.V. All rights reserved.

Rani G.N.,H+ Technology | Ayachit N.H.,Rani Channamma University
Canadian Journal of Physics | Year: 2015

MgAl2O4 spinel was synthesized by a novel route method of sol-gel technique. Spinel powders were sintered at various temperatures to investigate the phase contents and crystallinity. The characterization of the samples was carried out by using various techniques. The formation of the spinel phase was inferred by differential thermal analyzer, while crystalline and structural properties were studied by X-ray diffraction, Fourier transform infrared spectroscopy and magic angle spinning nuclear magnetic resonance (MAS-NMR). These studies infer the formation of spinel phase at much lower temperature (around 375 °C) and order-disorder transition in the spinel around 700 °C. The studies also indicate the formation of the spinel with better crystallinity. The inversion parameter was also calculated using MAS-NMR and its value is found to be approximately 0.30 for a sample sintered around 1000 °C. © 2015 Published by NRC Research Press.

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