Cho DH

References (4)

Title : Transition metal cation inhibition of Mycobacterium tuberculosis esterase RV0045C - Bowles_2021_Protein.Sci__
Author(s) : Bowles IE , Pool EH , Lancaster BS , Lawson EK , Savas CP , Kartje ZJ , Severinac L , Cho DH , Macbeth MR , Johnson RJ , Hoops GC
Ref : Protein Science , : , 2021
Abstract : Mycobacterium tuberculosis virulence is highly metal-dependent with metal availability modulating the shift from the dormant to active states of M. tuberculosis infection. Rv0045c from M. tuberculosis is a proposed metabolic serine hydrolase whose folded stability is dependent on divalent metal concentration. Herein, we measured the divalent metal inhibition profile of the enzymatic activity of Rv0045c and found specific divalent transition metal cations (Cu(2+) <= Zn(2+) > Ni(2+) > Co(2+) ) strongly inhibited its enzymatic activity. The metal cations bind allosterically, largely affecting values for k(cat) rather than K(M) . Removal of the artificial N-terminal 6xHis-tag did not change the metal-dependent inhibition, indicating that the allosteric inhibition site is native to Rv0045c. To isolate the site of this allosteric regulation in Rv0045c, the structures of Rv0045c were determined at 1.8 A and 2.0 A resolution in the presence and absence of Zn(2+) with each structure containing a previously unresolved dynamic loop spanning the binding pocket. Through the combination of structural analysis with and without zinc and targeted mutagenesis, this metal-dependent inhibition was traced to multiple chelating residues (H202A/E204A) on a flexible loop, suggesting dynamic allosteric regulation of Rv0045c by divalent metals. Although serine hydrolases like Rv0045c are a large and diverse enzyme superfamily, this is the first structural confirmation of allosteric regulation of their enzymatic activity by divalent metals. This article is protected by copyright. All rights reserved.
ESTHER : Bowles_2021_Protein.Sci__
PubMedSearch : Bowles_2021_Protein.Sci__
PubMedID: 33914998
Gene_locus related to this paper: myctu-RV0045C

Title : Functional expression of polyethylene terephthalate-degrading enzyme (PETase) in green microalgae - Kim_2020_Microb.Cell.Fact_19_97
Author(s) : Kim JW , Park SB , Tran QG , Cho DH , Choi DY , Lee YJ , Kim HS
Ref : Microb Cell Fact , 19 :97 , 2020
Abstract : BACKGROUND: For decades, plastic has been a valuable global product due to its convenience and low price. For example, polyethylene terephthalate (PET) was one of the most popular materials for disposable bottles due to its beneficial properties, namely impact resistance, high clarity, and light weight. Increasing demand of plastic resulted in indiscriminate disposal by consumers, causing severe accumulation of plastic wastes. Because of this, scientists have made great efforts to find a way to biologically treat plastic wastes. As a result, a novel plastic degradation enzyme, PETase, which can hydrolyze PET, was discovered in Ideonella sakaiensis 201-F6 in 2016. RESULTS: A green algae, Chlamydomonas reinhardtii, which produces PETase, was developed for this study. Two representative strains (C. reinhardtii CC-124 and CC-503) were examined, and we found that CC-124 could express PETase well. To verify the catalytic activity of PETase produced by C. reinhardtii, cell lysate of the transformant and PET samples were co-incubated at 30 degC for up to 4 weeks. After incubation, terephthalic acid (TPA), i.e. the fully-degraded form of PET, was detected by high performance liquid chromatography analysis. Additionally, morphological changes, such as holes and dents on the surface of PET film, were observed using scanning electron microscopy. CONCLUSIONS: A PET hydrolyzing enzyme, PETase, was successfully expressed in C. reinhardtii, and its catalytic activity was demonstrated. To the best of our knowledge, this is the first case of PETase expression in green algae.
ESTHER : Kim_2020_Microb.Cell.Fact_19_97
PubMedSearch : Kim_2020_Microb.Cell.Fact_19_97
PubMedID: 32345276

Title : Lipase-catalyzed enantioselective synthesis of (R,R)-lactide from alkyl lactate to produce PDLA (poly D-lactic acid) and stereocomplex PLA (poly lactic acid) - Jeon_2013_J.Biotechnol_168_201
Author(s) : Jeon BW , Lee J , Kim HS , Cho DH , Lee H , Chang R , Kim YH
Ref : J Biotechnol , 168 :201 , 2013
Abstract : R-lactide, a pivotal monomer for the production of poly (D-lactic acid) (PDLA) or stereocomplex poly (lactic acid) (PLA) was synthesized from alkyl (R)-lactate through a lipase-catalyzed reaction without racemization. From among several types of lipase, only lipase B from Candida antarctica (Novozym 435; CAL-B) was effective in the reaction that synthesized (R,R)-lactide. Enantiopure (R,R)-lactide, which consisted of over 99% enantiomeric excess, was synthesized from methyl (R)-lactate through CAL-B catalysis. Removal of the methanol by-product was critical to obtain a high level of lactide conversion. The (R,R)-lactide yield was 56% in a reaction containing 100 mg of Novozym 435, 10 mM methyl (R)-lactate and 1500 mg of molecular sieve 5A in methyl tert-butyl ether (MTBE). The important monomer (R,R)-lactide that is required for the production of the widely recognized bio-plastic PDLA and the PLA stereocomplex can be obtained using this novel synthetic method.
ESTHER : Jeon_2013_J.Biotechnol_168_201
PubMedSearch : Jeon_2013_J.Biotechnol_168_201
PubMedID: 23845270
Gene_locus related to this paper: canar-LipB

Title : Enzymatic coproduction of biodiesel and glycerol carbonate from soybean oil and dimethyl carbonate - Seong_2011_Enzyme.Microb.Technol_48_505
Author(s) : Seong PJ , Jeon BW , Lee M , Cho DH , Kim DK , Jung KS , Kim SW , Han SO , Kim YH , Park C
Ref : Enzyme Microb Technol , 48 :505 , 2011
Abstract : The enzymatic coproduction of biodiesel and glycerol carbonate by the transesterification of soybean oil was studied using lipase as catalyst in organic solvent. To produce biodiesel and glycerol carbonate simultaneously, experiments were designed sequentially. Enzyme screening, the molar ratio of dimethyl carbonate (DMC) to soybean oil, reaction temperature and solvent effects were investigated. The results of enzyme screening, at 100 g/L Novozym 435 (immobilized Candida antarctica lipase B), biodiesel and glycerol carbonate showed conversions of 58.7% and 50.7%, respectively. The optimal conditions were 60 degreeC, 100 g/L Novozym 435, 6.0:1 molar ratio with tert-butanol as solvent: 84.9% biodiesel and 92.0% glycerol carbonate production was achieved.
ESTHER : Seong_2011_Enzyme.Microb.Technol_48_505
PubMedSearch : Seong_2011_Enzyme.Microb.Technol_48_505
PubMedID: 22113023
Gene_locus related to this paper: canar-LipB