School Of Basic And Applied Sciences

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Subject: search.filters.subject.Chemical activation

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    Adsorption and Activation of CO2on Small-Sized Cu-Zr Bimetallic Clusters
    (American Chemical Society, 2021-03-17T00:00:00) Megha; Mondal, Krishnakanta; Ghanty, Tapan K.; Banerjee, Arup
    Adsorption and activation of CO2 is a key step in any chemical reaction, which aims to convert it to other useful chemicals. Therefore, it is important to understand the factors that drive the activation process and also search for materials that promote the process. We employ the density functional theory to explore the possibility of using small-sized bimetallic Cu-Zr clusters, Cu4-nZrn, with n = 1-3 for the above-mentioned key step. Our results suggest that after adsorption, a CO2 molecule preferably resides on Zr atoms or at the bridge and triangular faces formed by Zr atoms in bimetallic Cu-Zr clusters accompanied with its high degree of activation. Importantly, maximum activation occurs when CO2 is adsorbed on the CuZr3 cluster. Interestingly, we find that the adsorption energy of CO2 can be tuned by varying the extent of the Zr atom in Cu-Zr clusters. We rationalize the high adsorption of CO2 with the increase in the number of Zr atoms using the d-band center model and the concept of chemical hardness. The strong chemisorption and high activation of CO2 are ascribed to charge migration between Cu-Zr clusters and the CO2 molecule. We find an additional band in the infrared vibrational spectra of CO2 chemisorbed on all of the clusters, which is absent in the case of free CO2. We also observe that the energy barriers for the direct dissociation of the CO2 molecule to CO and O decrease significantly on bimetallic Cu-Zr clusters as compared to that on pure Cu4. In particular, the barrier heights are considerably small for Cu3Zr and CuZr3 clusters. This study demonstrates that Cu3Zr and CuZr3 clusters may serve as good candidates for activation and dissociation of the CO2 molecule. � 2021 American Chemical Society.
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    Gaussian field-based 3D-QSAR and molecular simulation studies to design potent pyrimidine-sulfonamide hybrids as selective BRAFV600E inhibitors
    (Royal Society of Chemistry, 2022-10-21T00:00:00) Singh, Ankit Kumar; Novak, Jurica; Kumar, Adarsh; Singh, Harshwardhan; Thareja, Suresh; Pathak, Prateek; Grishina, Maria; Verma, Amita; Yadav, Jagat Pal; Khalilullah, Habibullah; Pathania, Vikas; Nandanwar, Hemraj; Jaremko, Mariusz; Emwas, Abdul-Hamid; Kumar, Pradeep
    The �RAS-RAF-MEK-ERK� pathway is an important signaling pathway in melanoma. BRAFV600E (70-90%) is the most common mutation in this pathway. BRAF inhibitors have four types of conformers: type I (?C-IN/DFG-IN), type II (?C-IN/DFG-OUT), type I1/2 (?C-OUT/DFG-IN), and type I/II (?C-OUT/DFG-OUT). First- and second-generation BRAF inhibitors show resistance to BRAFV600E and are ineffective against malignancies induced by dimer BRAF mutants causing �paradoxical� activation. In the present study, we performed molecular modeling of pyrimidine-sulfonamide hybrids inhibitors using 3D-QSAR, molecular docking, and molecular dynamics simulations. Previous reports reveal the importance of pyrimidine and sulfonamide moieties in the development of BRAFV600E inhibitors. Analysis of 3D-QSAR models provided novel pyrimidine sulfonamide hybrid BRAFV600E inhibitors. The designed compounds share similarities with several structural moieties present in first- and second-generation BRAF inhibitors. A total library of 88 designed compounds was generated and molecular docking studies were performed with them. Four molecules (T109, T183, T160, and T126) were identified as hits and selected for detailed studies. Molecular dynamics simulations were performed at 900 ns and binding was calculated. Based on molecular docking and simulation studies, it was found that the designed compounds have better interactions with the core active site [the nucleotide (ADP or ATP) binding site, DFG motif, and the phospho-acceptor site (activation segment) of BRAFV600E protein than previous inhibitors. Similar to the FDA-approved BRAFV600E inhibitors the developed compounds have [?C-OUT/DFG-IN] conformation. Compounds T126, T160 and T183 interacted with DIF (Leu505), making them potentially useful against BRAFV600E resistance and malignancies induced by dimer BRAF mutants. The synthesis and biological evaluation of the designed molecules is in progress, which may lead to some potent BRAFV600E selective inhibitors. � 2022 The Royal Society of Chemistry.
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    Nischarin inhibition alters energy metabolism by activating AMP-activated protein kinase
    (American Society for Biochemistry and Molecular Biology Inc., 2017) Dong, Shengli; Baranwal, Somesh; Garcia, Anapatricia; Serrano-Gomez, Silvia; Eastlack, Steven; Iwakuma, Tomoo; Mercante, Donald; Mauvais-Jarvis, Franck; Alahari, Suresh K.; Dong, S.; Baranwal, S.; Garcia, A.; Serrano-Gomez, S.J.; Eastlack, S.; Iwakuma, T.; Mercante, D.; Mauvais-Jarvis, F.; Alahari, S.K.
    Nischarin (Nisch) is a key protein functioning as a molecular scaffold and thereby hosting interactions with several protein partners. To explore the physiological importance of Nisch, here we generated Nisch loss-of-function mutant mice and analyzed their metabolic phenotype. Nisch-mutant embryos exhibited delayed development, characterized by small size and attenuated weight gain. We uncovered the reason for this phenotype by showing that Nisch binds to and inhibits the activity of AMP-activated protein kinase (AMPK), which regulates energy homeostasis by suppressing anabolic and activating catabolic processes. The Nisch mutations enhanced AMPK activation and inhibited mechanistic target of rapamycin signaling in mouse embryonic fibroblasts as well as in muscle and liver tissues of mutant mice. Nisch-mutant mice also exhibited increased rates of glucose oxidation with increased energy expenditure, despite reduced overall food intake. Moreover, the Nisch-mutant mice had reduced expression of liver markers of gluconeogenesis associated with increased glucose tolerance. As a result, these mice displayed decreased growth and body weight. Taken together, our results indicate that Nisch is an important AMPK inhibitor and a critical regulator of energy homeostasis, including lipid and glucose metabolism. ? 2017 by The American Society for Biochemistry and Molecular Biology, Inc.