Browsing by Subject "Biocatalysis"

Now showing 1 - 5 of 5
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    Dual-Enzyme-Loaded Multifunctional Hybrid Nanogel System for Pathological Responsive Ultrasound Imaging and T2-Weighted Magnetic Resonance Imaging.
    (ACS nano, 2015-06) Wang, Xia; Niu, Dechao; Li, Pei; Wu, Qing; Bo, Xiaowan; Liu, Boji; Bao, Song; Su, Teng; Xu, Huixiong; Wang, Qigang
    A dual-enzyme-loaded multifunctional hybrid nanogel probe (SPIO@GCS/acryl/biotin-CAT/SOD-gel, or SGC) has been developed for dual-modality pathological responsive ultrasound (US) imaging and enhanced T2-weighted magnetic resonance (MR) imaging. This probe is composed of functionalized superparamagnetic iron oxide particles, a dual enzyme species (catalase and superoxide dismutase), and a polysaccharide cationic polymer glycol chitosan gel. The dual-modality US/MR imaging capabilities of the hybrid nanogel for responsive US imaging and enhanced T2-weighted MR imaging have been evaluated both in vitro and in vivo. These results show that the hybrid nanogel SGC can exhibit efficient dual-enzyme biocatalysis with pathological species for responsive US imaging. SGC also demonstrates increased accumulation in acidic environments for enhanced T2-weighted MR imaging. Further research on these nanogel systems may lead to the development of more efficient US/MR contrast agents.
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    Emi2-mediated inhibition of E2-substrate ubiquitin transfer by the anaphase-promoting complex/cyclosome through a D-box-independent mechanism.
    (Mol Biol Cell, 2010-08-01) Tang, Wanli; Wu, Judy Qiju; Chen, Chen; Yang, Chih-Sheng; Guo, Jessie Yanxiang; Freel, Christopher D; Kornbluth, Sally
    Vertebrate eggs are arrested at Metaphase II by Emi2, the meiotic anaphase-promoting complex/cyclosome (APC/C) inhibitor. Although the importance of Emi2 during oocyte maturation has been widely recognized and its regulation extensively studied, its mechanism of action remained elusive. Many APC/C inhibitors have been reported to act as pseudosubstrates, inhibiting the APC/C by preventing substrate binding. Here we show that a previously identified zinc-binding region is critical for the function of Emi2, whereas the D-box is largely dispensable. We further demonstrate that instead of acting through a "pseudosubstrate" mechanism as previously hypothesized, Emi2 can inhibit Cdc20-dependent activation of the APC/C substoichiometrically, blocking ubiquitin transfer from the ubiquitin-charged E2 to the substrate. These findings provide a novel mechanism of APC/C inhibition wherein the final step of ubiquitin transfer is targeted and raise the interesting possibility that APC/C is inhibited by Emi2 in a catalytic manner.
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    HRP-mediated polymerization forms tough nanocomposite hydrogels with high biocatalytic performance.
    (Chemical communications (Cambridge, England), 2013-09) Su, Teng; Zhang, Da; Tang, Zhou; Wu, Qing; Wang, Qigang
    This communication describes the mild and quick construction of tough nanocomposite hydrogels via a horseradish peroxidase-mediated radical polymerization for effectively immobilizing enzymes to attain high catalytic performance in various solvents.
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    In vivo architecture of the telomerase RNA catalytic core in Trypanosoma brucei.
    (Nucleic acids research, 2021-12) Dey, Abhishek; Monroy-Eklund, Anais; Klotz, Kaitlin; Saha, Arpita; Davis, Justin; Li, Bibo; Laederach, Alain; Chakrabarti, Kausik
    Telomerase is a unique ribonucleoprotein (RNP) reverse transcriptase that utilizes its cognate RNA molecule as a template for telomere DNA repeat synthesis. Telomerase contains the reverse transcriptase protein, TERT and the template RNA, TR, as its core components. The 5'-half of TR forms a highly conserved catalytic core comprising of the template region and adjacent domains necessary for telomere synthesis. However, how telomerase RNA folding takes place in vivo has not been fully understood due to low abundance of the native RNP. Here, using unicellular pathogen Trypanosoma brucei as a model, we reveal important regional folding information of the native telomerase RNA core domains, i.e. TR template, template boundary element, template proximal helix and Helix IV (eCR4-CR5) domain. For this purpose, we uniquely combined in-cell probing with targeted high-throughput RNA sequencing and mutational mapping under three conditions: in vivo (in WT and TERT-/- cells), in an immunopurified catalytically active telomerase RNP complex and ex vivo (deproteinized). We discover that TR forms at least two different conformers with distinct folding topologies in the insect and mammalian developmental stages of T. brucei. Also, TERT does not significantly affect the RNA folding in vivo, suggesting that the telomerase RNA in T. brucei exists in a conformationally preorganized stable structure. Our observed differences in RNA (TR) folding at two distinct developmental stages of T. brucei suggest that important conformational changes are a key component of T. brucei development.
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    Thermal responsive microgels as recyclable carriers to immobilize active proteins with enhanced nonaqueous biocatalytic performance.
    (Chemical communications (Cambridge, England), 2013-12) Wu, Qing; Su, Teng; Mao, Yanjie; Wang, Qigang
    We describe the preparation of a thermoresponsive microgel, which can non-covalently immobilize active proteins with enhanced biocatalytic performance in organic solvents and easy reusability due to the porous microstructure and temperature responsive property.