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Jang, Seyoung,Gang, Haemin,Kim, Byung-Gee,Choi, Kwon-Young IPC Science and Technology Press 2018 Enzyme and microbial technology Vol.112 No.-
<P>In this study, we engineered E. coif cells to express L-tyrosine converting enzymes, including tyrosine ammonialyase (TAL), p-coumarate 3-hydroxylase (C3H), feruloyl-CoA synthetase (FCS), and enoyl-CoA hydratase/aldolase (ECH). A catabolic circuit, which consisted of the protocatechualdehyde and p-hydroxybenzaldehyde production pathways, was reconstituted through combinatorial production of discrete enzymes. First, cells expressing FCS and ECH could convert each 5 mM of caffeic acid and ferulic acid into protocatechualdehyde (70.5%) and vanillin (96.5%), respectively. Second, TAL and C3H were co-expressed with FCS and ECH. This strain converted L-tyrosine into caffeic acid, which was then converted into protocatechualdehyde. Ascorbic acid was used as an inhibitor of catechol aldehyde-based melanin formation, and the production yields of protocatechualdehyde and p-hydroxybenzaldehyde were 31.0 +/- 5.6 and 24.0 +/- 4.2 mg/L, respectively. Finally, caffeic acid-based melanin formation was observed with higher production rate of 40.9 +/- 6.2 mg/L/h by co-expressing FCS and ECH in the presence of caffeic acid.</P>
Carbonic anhydrase assisted calcium carbonate crystalline composites as a biocatalyst
Hwang, Ee Taek,Gang, Haemin,Chung, Jinyang,Gu, Man Bock The Royal Society of Chemistry 2012 GREEN CHEMISTRY Vol.14 No.8
<P>In the present study, we report on the carbonic anhydrase (CA)-assisted formation of biomineralized calcium carbonate crystalline composites (CCCCs). Ellipsoidal CCCCs, such as calcite polymorphism, in a micro-size range catalyzed by CA were successfully synthesized with polyethylene glycol and magnetic nanoparticles in the constant CO<SUB>2</SUB> pressure controlled chamber, for the first time. CA-assisted CCCCs characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and dynamic light scattering, showed their crystalline phase with mesoporous property according to Fourier transform infrared and Brunauer–Emmett–Teller area. These CCCCs retained about 43% of free CA esterase activity. Furthermore, the magnet-based separation was also successful for the reuse of the CCCCs. As a result, the CCCCs produced preserved their catalytic activity even after its ten repeated usages, and were stable for more than 50 days under room temperature. The reported method paves the way for novel biomineralization <I>via</I> CA for the formation of functional CA containing nanocomposites and biocatalyst technology applications.</P> <P>Graphic Abstract</P><P>Carbonic anhydrase-assisted calcium carbonate crystalline composites as a reusable biocatalyst. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2gc35444f'> </P>