Search for: histidine
0.006 seconds

    Dft study on gas-phase interaction between histidine and alkali metal ions (li+, na+, k+); and influence of these ions on histidine acidity

    , Article Journal of Theoretical and Computational Chemistry ; Volume 8, Issue 3 , 2009 , Pages 475-490 ; 02196336 (ISSN) Tavasoli, E ; Fattahi, A. R ; Sharif University of Technology
    The gas-phase metal affinities of histidine Li+, Na+ and K+ ions have been determined theoretically employing the hybrid B3LYP exchangecorrelation functional and using 6-311++G** basis sets. All computations indicate that the metal ion affinity decreases on going from Li+ to Na+ and K+ for the considered amino acid. Different types of M+ coordinations on several histidine conformers/tautomers were considered in detail. The optimized structures indicate that Li+ and Na+ prefer a tri-dentate coordination, bonding with a nitrogen atom of imidazole ring (N τ), NH2, and an oxygen atom of a carbonyl, while in the K+-histidine lowest-energy conformer, the cation appears to be bi-coordinated to both... 

    Dft study of bond energies and attachment sites of sample divalent cations (mg2+, ca2+, zn2+) to histidine in the gas phase

    , Article Journal of Theoretical and Computational Chemistry ; Volume 8, Issue 3 , 2009 , Pages 347-371 ; 02196336 (ISSN) Tavasoli, E ; Fattahi, A ; Sharif University of Technology
    In view of better understanding interactions of amino acids and peptides with metallic cations in the isolated state, the model system histidineM 2+ (M2+ = Mg2+, Ca2+, Zn 2+) has been studied theoretically. The computations have been performed with the help of the density functional theory (DFT) and the B3LYP functional. The extended basis set was the standard 6-311++G**. All the molecular complexes obtained by the interaction between several energetically low-lying tautomers/conformers/zwitterions of histidine and the cations on different binding sites were considered. Our study shows that complexes of histidine with Mg2+, Ca2+, Zn2+ are rather similar. In the isolated state, the most... 

    Conformational behavior and potential energy profile of gaseous histidine

    , Article Journal of Molecular Structure: THEOCHEM ; Volume 960, Issue 1-3 , November , 2010 , Pages 73-85 ; 01661280 (ISSN) Aliakbar Tehrani, Z ; Tavasoli, E ; Fattahi, A ; Sharif University of Technology
    Histidine as a natural amino acid is found to be biologically important and is known to function as a nucleophile or enzyme co-factor, or in proton transfer process. The properties of gaseous aromatic amino acid histidine depend on the structural forms it may take in gas-phase. Ab initio method has been used to characterize the gas-phase conformer/tautomers of histidine. Wide range of possible structures for histidine was surveyed at the MM level, and then the geometries of the unique conformers were refined at the B3LYP/6-311++G (d,p) levels. At this theoretical level, 25 conformers were located for both tautomers of histidine i.e., His [NπH] and His [NτH]. The MM level provides a poor... 

    Conformational Substates of Wild Type and Mutant (V68N) Myoglobin-CO

    , M.Sc. Thesis Sharif University of Technology Shams, Hengameh (Author) ; Ejtehadi, Mohammad Reza (Supervisor)
    Folded protein experience several conformational substates. Each substate reperesents a minimum in the free energy surface of the system. Since Myoglobin is the smallest protein that can reversibly bind to gas molecules and, it can be used as prototype for more complex systems.IR pecrtum of CO inside of myolgobin shows that distinct conformational substates can occur. It was shown that Histidine residue inside heme pocket plays an essential rolle in structural properties of substates. In this study, we used molecular dynamice simulation together with umbrella sampling method to obtain free energy profile of MbCO system. The configuration of distal Histidine (His64), CO and Heme is studied... 

    Theoretical Investigation of Hydrogen Bonding Effects on Interaction of Metal Nanoclusters with Histidine, Oxidation of Olefins by MnO4– & Acidity Enhancement of Alcohols

    , Ph.D. Dissertation Sharif University of Technology Jebeli Javan, Marjan (Author) ; Fattahi, Alireza (Supervisor) ; Mahmoodi Hashemi, Mohammad (Supervisor) ; Jamshidi, Zahra (Supervisor)
    This thesis is divided into three parts: In part I, interactions of neutral and anionic forms of histidine with coinage metal nano clusters M3 (M = Au, Ag and Cu) are investigated. Results demonstrate that nonconventional M…H-O hydrogen bonds and M-X bonds (X = N, O) play stabilization roles in interactions of histidine and metal nano clusters. Presence of negative charge in ligand leads to increase of binding energy of complexes. In the next step, the effects of coinage metal nano clusters on the gas-phase acidity of weak organic acid (histidine) have been explored. The acidity of isolated histidine is compared with the acidity of its Au3–, Ag3– and Cu3–complexed species. Moreover, pKa... 

    Using Vitamin B1 as a Catalyst in Performing Multi-Component Reactions and Synthesis of Affinity Column ChromatograpHy for Purification of Recombinant Proteins

    , M.Sc. Thesis Sharif University of Technology Lohi Khosroshahi, Ameneh (Author) ; Kalhor, Hamid Reza (Supervisor)
    Due to the importance of using pure proteins in the industry and basic research in order to study them in the structural contexts and interactions of proteins in recent years, purification methods have been extensively developed. The purification steps usually depend on the size of the protein, its physical and chemical properties, the binding affinity and the biological activity of the protein in question, In the purification process, the protein portion is separated from the non-protein portion. The biggest challenge is when we want to separate different proteins. Different chromatographic methods are used, depending on the properties of the impure proteins. One of these chromatographic... 

    Interactions of coinage metal clusters with histidine and their effects on histidine acidity; Theoretical investigation

    , Article Organic and Biomolecular Chemistry ; Volume 10, Issue 47 , Oct , 2012 , Pages 9373-9382 ; 14770520 (ISSN) Javan, M. J ; Jamshidi, Z ; Tehrani, Z. A ; Fattahi, A ; Sharif University of Technology
    Understanding the nature of interaction between metal nanoparticles and biomolecules such as amino acids is important in the development and design of biosensors. In this paper, binding of M3 clusters (M = Au, Ag and Cu) with neutral and anionic forms of histidine amino acid was studied using density functional theory (DFT-B3LYP). It was found that the interaction of histidine with M3 clusters is governed by two major bonding factors: (a) the anchoring N-M and O-M bonds and (b) the nonconventional N-H⋯M and O-H⋯M hydrogen bonds. The nature of these chemical bonds has been investigated based on quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. In the next... 

    A theoretical study of repeating sequence in HRP II: A combination of molecular dynamics simulations and 17O quadrupole coupling tensors

    , Article Biophysical Chemistry ; Volume 137, Issue 2-3 , 2008 , Pages 76-80 ; 03014622 (ISSN) Behzadi, H ; Esrafili, M. D ; van der spoel, D ; Hadipour, N. L ; Parsafar, G ; Sharif University of Technology
    Histidine rich protein II derived peptide (HRP II 169-182) was investigated by molecular dynamics, MD, simulation and 17O electric field gradient, EFG, tensor calculations. MD simulation was performed in water at 300 K with α-helix initial structure. It was found that peptide loses its initial α-helix structure rapidly and is converted to random coil and bent secondary structures. To understand how peptide structure affects EFG tensors, initial structure and final conformations resulting from MD simulations were used to calculate 17O EFG tensors of backbone carbonyl oxygens. Calculations were performed using B3LYP method and 6-31 + G* basis set. Calculated 17O EFG tensors were used to... 

    Homozygous mutations in C14orf39/SIX6OS1 cause non-obstructive azoospermia and premature ovarian insufficiency in humans

    , Article American Journal of Human Genetics ; Volume 108, Issue 2 , 2021 , Pages 324-336 ; 00029297 (ISSN) Fan, S ; Jiao, Y ; Khan, R ; Jiang, X ; Javed, A. R ; Ali, A ; Zhang, H ; Zhou, J ; Naeem, M ; Murtaza, G ; Li, Y ; Yang, G ; Zaman, Q ; Zubair, M ; Guan, H ; Zhang, X ; Ma, H ; Jiang, H ; Ali, H ; Dil, S ; Shah, W ; Ahmad, N ; Zhang, Y ; Shi, Q ; Sharif University of Technology
    Cell Press  2021
    Human infertility is a multifactorial disease that affects 8%–12% of reproductive-aged couples worldwide. However, the genetic causes of human infertility are still poorly understood. Synaptonemal complex (SC) is a conserved tripartite structure that holds homologous chromosomes together and plays an indispensable role in the meiotic progression. Here, we identified three homozygous mutations in the SC coding gene C14orf39/SIX6OS1 in infertile individuals from different ethnic populations by whole-exome sequencing (WES). These mutations include a frameshift mutation (c.204_205del [p.His68Glnfs∗2]) from a consanguineous Pakistani family with two males suffering from non-obstructive... 

    The metabolome profiling of obese and non-obese individuals: Metabolically healthy obese and unhealthy non-obese paradox

    , Article Iranian Journal of Basic Medical Sciences ; Volume 23, Issue 2 , 2020 , Pages 186-194 Chashmniam, S ; Madani, N. H ; Ghoochani, B. F. N. M ; Safari Alighiarloo, N ; Khamseh, M. E ; Sharif University of Technology
    Mashhad University of Medical Sciences  2020
    Objective(s): The molecular basis of “metabolically healthy obese” and “metabolically unhealthy non-obese” phenotypes is not fully understood. Our objective was to identify metabolite patterns differing in obese (metabolically healthy vs unhealthy (MHO vs MUHO)) and non-obese (metabolically healthy vs unhealthy (MHNO vs MUHNO)) individuals. Materials and Methods: This case-control study was performed on 86 subjects stratified into four groups using anthropometric and clinical measurements: MHO (21), MUHO (21), MHNO (22), and MUHNO (22). Serum metabolites were profiled using nuclear magnetic resonance (NMR). Multivariate analysis was applied to uncover discriminant metabolites, and enrichment...