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Cofactor‐Free, Direct Photoactivation of Enoate Reductases for the Asymmetric Reduction of C=C Bonds
Lee, Sahng Ha,Choi, Da Som,Pesic, Milja,Lee, Yang Woo,Paul, Caroline E.,Hollmann, Frank,Park, Chan Beum VCH Verlagsgesellschaft mbH 2017 Angewandte Chemie Vol.56 No.30
<P><B>Abstract</B></P><P>Enoate reductases from the family of old yellow enzymes (OYEs) can catalyze stereoselective <I>trans</I>‐hydrogenation of activated C=C bonds. Their application is limited by the necessity for a continuous supply of redox equivalents such as nicotinamide cofactors [NAD(P)H]. Visible light‐driven activation of OYEs through NAD(P)H‐free, direct transfer of photoexcited electrons from xanthene dyes to the prosthetic flavin moiety is reported. Spectroscopic and electrochemical analyses verified spontaneous association of rose bengal and its derivatives with OYEs. Illumination of a white light‐emitting‐diode triggered photoreduction of OYEs by xanthene dyes, which facilitated the enantioselective reduction of C=C bonds in the absence of NADH. The photoenzymatic conversion of 2‐methylcyclohexenone resulted in enantiopure (<I>ee</I>>99 %) (<I>R</I>)‐2‐methylcyclohexanone with conversion yields as high as 80–90 %. The turnover frequency was significantly affected by the substitution of halogen atoms in xanthene dyes.</P>
New Platform for Cytochrome P450 Reaction Combining in Situ Immobilization on Biopolymer
Lee, Jae Hyung,Nam, Dong Heon,Lee, Sahng Ha,Park, Jong Hyun,Park, Si Jae,Lee, Seung Hwan,Park, Chan Beum,Jeong, Ki Jun American Chemical Society 2014 Bioconjugate chemistry Vol.25 No.12
<P>We describe an efficienct chemical conversion platform with in situ immobilization of P450-BM3 on poly(3-hydroxybutyrate) granules. Through fusion with phasin, P450-BM3 is easily immobilized on poly(3-hydroxybutyrate) granules in <I>Escherichia coli</I>. In our work, the immobilized P450 exhibited higher stability and catalytic activity compared to free P450 against changes of pH, temperature, and concentrations of urea and ions. Through quick recovery of immobilized enzyme, the P450–P(3HB) complex successfully catalyzed an O-dealkylation reaction several times with maintained activity. Using the robust P450–P(3HB) complex, we performed a P450-catalyzed reaction on a preparative reactor scale (100 mL) and high-level production (12.3 μM) of 7-hydroxycoumarine from 7-ethoxycoumarin could be achieved.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/bcches/2014/bcches.2014.25.issue-12/bc500404j/production/images/medium/bc-2014-00404j_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/bc500404j'>ACS Electronic Supporting Info</A></P>
Cytochrome P450‐catalyzed <i>O</i>‐dealkylation coupled with photochemical NADPH regeneration
Lee, Sahng Ha,Kwon, Yong‐,Chan,Kim, Dong‐,Myung,Park, Chan Beum Wiley Subscription Services, Inc., A Wiley Company 2013 Biotechnology and bioengineering Vol.110 No.2
<P><B>Abstract</B></P><P>Cytochrome P450 monooxygenases are multifunctional enzymes with potential applications in chemoenzymatic synthesis of complex chemicals as well as in studies of metabolism and xenobiotics. Widespread application of cytochrome P450s, however, is encumbered by the critical need for redox equivalents in their catalytic function. To overcome this limitation, we studied visible light‐driven regeneration of NADPH for P450‐catalyzed <I>O</I>‐dealkylation reaction; we used eosin Y as a photosensitizing dye, triethanolamine as an electron donor, and [Cp*Rh(bpy)H<SUB>2</SUB>O] as an electron mediator. We analyzed catalytic activity of cell‐free synthesized P450 BM3 monooxygenase variant (Y51F/F87A, BM3m2) in the presence of key components for NADPH photoregeneration. The P450‐catalyzed <I>O</I>‐dealkylation reaction sustainably maintained its turnover with the continuous supply of photoregenerated NADPH. Visible light‐driven, non‐enzymatic NADPH regeneration provides a new route for efficient, sustainable utilization of P450 monooxygenases. Biotechnol. Bioeng. 2013; 110: 383–390. © 2012 Wiley Periodicals, Inc.</P>
Lee, Sahng Ha,Nam, Dong Heon,Kim, Jae Hong,Baeg, Jin-Ook,Park, Chan Beum WILEY-VCH Verlag 2009 Chembiochem Vol.10 No.10
<P>Dye-sensitized photosynthesis: Eosin Y (EY), a dye photosensitizer, works efficiently as a molecular photoelectrode by catalyzing the visible-light-driven electron-transfer reaction for efficient regeneration of NADH through a photosensitizer–electron relay dyad. Injection of the photosensitized electron resulted in highly accelerated regeneration of NADH, which can be used by glutamate dehydrogenase for the photosynthesis of L-glutamate. <img src='wiley_img/14394227-2009-10-10-CBIC200900156-content.gif' alt='wiley_img/14394227-2009-10-10-CBIC200900156-content'> </P> <B>Graphic Abstract</B> <P>Dye-sensitized photosynthesis: Eosin Y (EY), a dye photosensitizer, works efficiently as a molecular photoelectrode by catalyzing the visible-light-driven electron-transfer reaction for efficient regeneration of NADH through a photosensitizer–electron relay dyad. Injection of the photosensitized electron resulted in highly accelerated regeneration of NADH, which can be used by glutamate dehydrogenase for the photosynthesis of L-glutamate. <img src='wiley_img/14394227-2009-10-10-CBIC200900156-content.gif' alt='wiley_img/14394227-2009-10-10-CBIC200900156-content'> </P>
Colloidal Nanoparticles as a Wireless Booster for Electroenzymatic Reactions
Lee, Sahng Ha,Won, Keehoon,Song, Hyun-Kon,Park, Chan Beum WILEY-VCH Verlag 2009 Small Vol.5 No.19
<B>Graphic Abstract</B> <P>Nanoparticles in a wireless form are employed to overcome the extremely low efficiency of electroenzymatic synthesis reactions. The nanoparticle-mediated electrochemical regeneration of cofactor (NADH) is used in the enzymatic conversion of α-ketoglutarate to L-glutamate (see picture). The use of colloidal nanoparticles in electrolyte provides a new strategy for electroenzymatic catalysis. <img src='wiley_img/16136810-2009-5-19-SMLL200900595-content.gif' alt='wiley_img/16136810-2009-5-19-SMLL200900595-content'> </P>
Lee, Sahng Ha,Nam, Dong Heon,Park, Chan Beum WILEY-VCH Verlag 2009 Advanced Synthesis & Catalysis Vol.351 No.16
<P>Regeneration of the nicotinamide cofactor is a critical issue in biocatalysis. Herein we have screened xanthene dyes for a highly efficient, visible light-driven photochemical regeneration of cofactors and enzymatic synthesis. Superior catalytic performance was observed with several xanthene dyes such as phloxine B, erythrosine B, eosin Y, and rose bengal. We found that the photo- and electrochemical properties of the xanthene dyes were affected by the halogen atom substitution, which is a key factor in the efficient light-induced electron transfer from the donor molecule to the catalytic mediator.</P> <B>Graphic Abstract</B> <P> <img src='wiley_img/16154150-2009-351-16-ADSC200900547-content.gif' alt='wiley_img/16154150-2009-351-16-ADSC200900547-content'> </P>
Silicon Nanowire Photocathodes for Light-Driven Electroenzymatic Synthesis
Lee, Sahng Ha,Ryu, Gyeong Min,Nam, Dong Heon,Kim, Jae Hong,Park, Chan Beum Wiley (John WileySons) 2014 ChemSusChem Vol.7 No.11
<P>The photoelectroenzymatic synthesis of chemical compounds employing platinum nanoparticle-decorated silicon nanowires (Pt-SiNWs) is presented. The Pt-SiNWs proved to be an efficient material for photoelectrochemical cofactor regeneration because the silicon nanowires absorbs a wide range of the solar spectrum while the platinum nanoparticle serve as an excellent catalyst for electron and proton transfer. By integrating the platform with redox enzymatic reaction, visible-light-driven electroenzymatic synthesis of L-glutamate was achieved. Compared to electrochemical and photochemical methods, this approach is free from side reactions caused by sacrificial electron donors and has the advantage of applying low potential to realize energy-efficient and sustainable synthesis of chemicals by a photoelectroenzymatic system.</P>
Lee, Sahng Ha,Ryu, Jungki,Nam, Dong Heon,Park, Chan Beum Royal Society of Chemistry 2011 Chemical communications Vol.47 No.16
<P>Sustainable photochemical NADH regeneration and redox-enzymatic synthesis are accomplished by using CdS nanocrystals grown on the surface of SiO<SUB>2</SUB> beads. CdS nanocrystals grown on SiO<SUB>2</SUB> beads worked efficiently as a visible-light absorbing photocatalyst for <I>in situ</I> NADH regeneration with high catalytic activity and minimal loss of activity despite repeated uses.</P> <P>Graphic Abstract</P><P>Sustainable photochemical NADH regeneration and redox-enzymatic synthesis of <SMALL>L</SMALL>-glutamate are accomplished by using CdS nanocrystals grown on the surface of SiO<SUB>2</SUB> beads. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0cc05246a'> </P>