• Title/Summary/Keyword: Molecular modeling

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Molecular Modeling and its Experimental Verification for the Catalytic Mechanism of Candida antarctica Lipase B

  • Kwon, Cheong-Hoon;Shin, Dae-Young;Lee, Jong-Ho;Kim, Seung-Wook;Kang, Jeong-Won
    • Journal of Microbiology and Biotechnology
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    • v.17 no.7
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    • pp.1098-1105
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    • 2007
  • Quantum mechanical and molecular dynamics simulation analysis has been performed on the model system for CALB (Candida antarctica lipase B) with esters to study the reaction mechanism and conformational preference of catalytic hydrolysis and the esterification reaction. Using quantum mechanical analysis, the ping-pong bi-bi mechanism was applied and energies and 3-dimensional binding configurations of the whole reaction pathways were calculated. Further molecular dynamics simulation analysis was performed on the basis of the transition state obtained from quantum mechanical study to observe the effect of structures of the substrates. Calculation results using substrates of different chain length and chiral configurations were compared for conformational preference. The calculated results showed very small influence on chain length, whereas chiral conformation showed big differences. Calculated results from molecular modeling studies have been compared qualitatively with the experimental data using racemic mixtures of (${\pm}$)-cis-4-acetamido-cyclopent-2-ene-1-ethyl acetate as substrates.

Molecular Modeling of Enantio-discrimination of α-Methoxy-α-trifluoromethylphenylacetic Acid (MTPA) by Cyclomaltoheptaose (β-Cyclodextrin) and 6-Amino-6-deoxy-cyclomaltoheptaose

  • Jung, Eun-Kyoung;Jeong, Karp-Joo;Lee, Sang-San;Kim, Jee-In;Jung, Seun-Ho
    • Bulletin of the Korean Chemical Society
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    • v.24 no.11
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    • pp.1627-1631
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    • 2003
  • Molecular modeling was performed to comprehend the chiral recognition of ${\alpha}$-methoxy-${\alpha}$-trifluoromethylphenylacetic acid (MTPA) enantiomers by cyclomaltoheptaose (${\beta}$-cyclodextrin,${\beta}$-CD) and 6-amino-6-deoxy-cyclomaltoheptaose (am-${\beta}$-CD). Monte Carlo (MC) docking coupled to constant temperature molecular dynamics (MD) simulations was applied to the investigation for the ${\alpha}$-methoxy-${\alpha}$-trifluoromethylphenylacetic acid complexation with two different CDs in terms of the relative distribution of the interaction energies. The calculated results are finely correlated with the experimental observations in chiral recognition thermodynamics. Am-${\beta}$-CD as a host showed the superior enantio-discrimination ability to the native ${\beta}$-CD where the amino group of am-${\beta}$-CD was critically involved in enhancing the ability of chiral discrimination via the Coulombic interaction with MTPA.

The Study of Physical Properties for the Organic Compounds and their Binary Mixture according to Molecular Connectivity Method (Molecular Connectivity法을 이용한 有機化合物과 二成分 混合物에 對한 物理化學的 性質에 關한 硏究 (Ⅱ))

  • Ui-Rak Kim;Kyung-Sub Min;Myung-Jae Lee;Sang-Hae Kim;Bong-Jin Jeong
    • Journal of the Korean Chemical Society
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    • v.36 no.4
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    • pp.485-495
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    • 1992
  • The viscosities of organic compounds (alcohols, acetates, alkanes, acids, substituted $NH_2$) in liquid states, gas states and the binary mixtures of n-alkane / 1-chloroalkane were calculated by molecular modeling techniques. The molecular descriptors of molecular modeling technique are Molecular connectivity indices, Wiener indices and ad hoc descriptors, which can encode the information of compound properties about the effect of size, branching, cyclization, unsaturation, heteroatom content, polarizability, and so on. The successful results among method have been Molecular connectivity indices, binary mixtures of n-alkane / 1-chloroalkane, Wiener indices for gas state and ad hoc descriptor for liquid states. Also we obtained the regression equations for viscosities using molecular modeling indices for gas, liquid states and binary mixtures of n-alkane / 1-chloroalkane. The calculated viscosity values for organic compounds are in good agreement with experimental results.

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