Chemistry Letters
Online ISSN : 1348-0715
Print ISSN : 0366-7022
ISSN-L : 0366-7022
Volume 46 , Issue 3
Showing 1-38 articles out of 38 articles from the selected issue
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  • Osami Shoji, Yoshihito Watanabe
    2017 Volume 46 Issue 3 Pages 278-288
    Published: March 05, 2017
    Released: March 05, 2017
    JOURNALS RESTRICTED ACCESS

    Cytochrome P450s are a family of heme-containing enzymes that catalyze monooxygenation of inert substrates. Bacterial cytochrome P450s are great candidates as biocatalysts for synthetic applications because of their high hydroxylation activity and their high solubility in water. However, the substrate specificity of bacterial cytochrome P450s is generally high, and their low catalytic activities toward nonnative substrates tends to restrict their application as biocatalysts. We have developed a reaction system that utilizes dummy substrates with structures similar to those of natural substrates, as “decoy molecules”. The decoy molecules induce substrate misrecognition of bacterial P450s, leading to the generation of the active species and ultimately enabling them to catalyze the oxidation of nonnative substrates. The catalytic activity and the enantioselectivity are dependent on the structure of the decoy molecules, suggesting that the reactions can be controlled by variation in the designed structure of the decoy molecules.

    Cytochrome P450s are a family of heme-containing enzymes that catalyze monooxygenation of inert substrates. Bacterial cytochrome P450s are great candidates as biocatalysts for synthetic applications because of their high hydroxylation activity and their high solubility in water. However, the substrate specificity of bacterial cytochrome P450s is generally high, and their low catalytic activities toward nonnative substrates tends to restrict their applicable use as biocatalysts. We have developed a reaction system that utilize dummy substrates whose structures are similar to those of natural substrates, as “decoy molecules”. The decoy molecules induce substrate misrecognition of bacterial P450s, leading to the generation of the active species and ultimately enabling them to catalyze the oxidation of nonnative substrates. The catalytic activity and the enantioselectivity are dependent on the structure of the decoy molecules, suggesting that the reactions can be controlled by variation in the designed structure of the decoy molecules. Fullsize Image
     
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  • Kenji Aramaki, Kotoko Ichikawa, Lok Kumar Shrestha
    2017 Volume 46 Issue 3 Pages 408-410
    Published: March 05, 2017
    Released: March 05, 2017
    JOURNALS RESTRICTED ACCESS

    We report the percolation behavior of nonionic surfactant reverse micelles (RMs) composed of sorbitan laurate (Span20) and poly(oxyethylene) sorbitan monooleate (Tween80) in isopropyl myristate (IPM) in presence of a trace amount of water and electrolyte (KCl). Abrupt increase of conductivity above 20 °C for oil/surfactant = 8/2 and Span20/Tween80 = 3/2 composition is an indication of the typical percolation behavior. The dynamic percolation behavior was suggested based on the scaling analysis of the conductivity change around the percolation temperature. Contrary to the ionic surfactant RMs, conductivity maxima was observed in the present nonionic RM system. Small-angle X-ray scattering (SAXS) data showed sphere-to-rod-type RM microstructure transition with increasing temperature in the lower temperature region. On the other hand, RM shrunk in the high temperature region due to dehydration of poly(oxyethylene) chains. It is anticipated that this characteristic feature of nonionic surfactant led to the depercolation at high temperatures.

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