1
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Kim JH, Cheon H, Jo HJ, Kim JW, Kim GY, Seo HR, Seo PW, Kim JS, Park JB. Engineering of two thiamine diphosphate-dependent enzymes for the regioselective condensation of C1-formaldehyde into C4-erythrulose. Int J Biol Macromol 2023; 253:127674. [PMID: 37890751 DOI: 10.1016/j.ijbiomac.2023.127674] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 10/17/2023] [Accepted: 10/24/2023] [Indexed: 10/29/2023]
Abstract
A number of carboligases, which catalyze condensation of C1- and/or C2-aldehydes into multi-carbon products, have been reported. However, their catalytic activities and/or regioselectivities remained rather low. Thereby, this study has focused on engineering of C1 and C2 carboligases for the regioselective condensation of C1-formaldehyde into C4-erythrulose via C2-glycolaldehyde. The crystal structure of the glyoxylate carboligase from Escherichia coli (EcGCL) was elucidated in complex with glycolaldehyde. A structure-guided rationale generated several mutants, one of whose catalytic activity reached 15.6 M-1·s-1, almost 10 times greater than the wild-type enzyme. Another variant (i.e., EcGCL_R484M/N283Q/L478M/M488L/R284K) has shown significantly increased stability to the glycolaldehyde toxicity, enabling production of glycolaldehyde to 31 mM from 75 mM formaldehyde (conversion: 83 %). Besides, the E1 subunit of α-ketoglutarate dehydrogenase complex from Vibrio vulnificus (VvSucA) was engineered as a regiospecific C2 carboligase for condensation of glycolaldehyde into erythrulose. The combination of EcGCL_R484M/N283Q/L478M/M488L/R284K and VvSucA_K228L led to the cascade production of erythrulose to 8 mM from 90 mM formaldehyde via glycolaldehyde without byproduct formation. This study will contribute to valorization of C1 gases into industrially relevant multi-carbon products in an environment-friendly way.
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Affiliation(s)
- Jun-Hong Kim
- Department of Chemistry, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Huijin Cheon
- Department of Food Science and Engineering, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Hye-Jin Jo
- Department of Food Science and Engineering, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Ji-Won Kim
- Department of Chemistry, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Ga Young Kim
- Department of Food Science and Engineering, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Hye-Rim Seo
- Department of Food Science and Engineering, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Pil-Won Seo
- Department of Chemistry, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Jeong-Sun Kim
- Department of Chemistry, Chonnam National University, Gwangju 61186, Republic of Korea.
| | - Jin-Byung Park
- Department of Food Science and Engineering, Ewha Womans University, Seoul 03760, Republic of Korea.
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2
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Mrowicka M, Mrowicki J, Dragan G, Majsterek I. The importance of thiamine (vitamin B1) in humans. Biosci Rep 2023; 43:BSR20230374. [PMID: 37389565 PMCID: PMC10568373 DOI: 10.1042/bsr20230374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 06/11/2023] [Accepted: 06/14/2023] [Indexed: 07/01/2023] Open
Abstract
Thiamine (thiamin, B1) is a vitamin necessary for proper cell function. It exists in a free form as a thiamine, or as a mono-, di- or triphosphate. Thiamine plays a special role in the body as a coenzyme necessary for the metabolism of carbohydrates, fats and proteins. In addition, it participates in the cellular respiration and oxidation of fatty acids: in malnourished people, high doses of glucose result in acute thiamine deficiency. It also participates in energy production in the mitochondria and protein synthesis. In addition, it is also needed to ensure the proper functioning of the central and peripheral nervous system, where it is involved in neurotransmitter synthesis. Its deficiency leads to mitochondrial dysfunction, lactate and pyruvate accumulation, and consequently to focal thalamic degeneration, manifested as Wernicke's encephalopathy or Wernicke-Korsakoff syndrome. It can also lead to severe or even fatal neurologic and cardiovascular complications, including heart failure, neuropathy leading to ataxia and paralysis, confusion, or delirium. The most common risk factor for thiamine deficiency is alcohol abuse. This paper presents current knowledge of the biological functions of thiamine, its antioxidant properties, and the effects of its deficiency in the body.
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Affiliation(s)
- Małgorzata Mrowicka
- Małgorzata Mrowicka, Jerzy Mrowicki, Grzegorz Dragan, Ireneusz Majsterek, Department of Clinical Chemistry and Biochemistry, Medical University of Lodz, Mazowiecka 5, 92-215 Lodz, Poland
| | - Jerzy Mrowicki
- Małgorzata Mrowicka, Jerzy Mrowicki, Grzegorz Dragan, Ireneusz Majsterek, Department of Clinical Chemistry and Biochemistry, Medical University of Lodz, Mazowiecka 5, 92-215 Lodz, Poland
| | - Grzegorz Dragan
- Małgorzata Mrowicka, Jerzy Mrowicki, Grzegorz Dragan, Ireneusz Majsterek, Department of Clinical Chemistry and Biochemistry, Medical University of Lodz, Mazowiecka 5, 92-215 Lodz, Poland
| | - Ireneusz Majsterek
- Małgorzata Mrowicka, Jerzy Mrowicki, Grzegorz Dragan, Ireneusz Majsterek, Department of Clinical Chemistry and Biochemistry, Medical University of Lodz, Mazowiecka 5, 92-215 Lodz, Poland
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3
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Planas F, McLeish MJ, Himo F. Enzymatic Stetter Reaction: Computational Study of the Reaction Mechanism of MenD. ACS Catal 2021. [DOI: 10.1021/acscatal.1c02292] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Ferran Planas
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm SE-10691, Sweden
| | - Michael J. McLeish
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
| | - Fahmi Himo
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm SE-10691, Sweden
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4
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Human 2-Oxoglutarate Dehydrogenase and 2-Oxoadipate Dehydrogenase Both Generate Superoxide/H 2O 2 in a Side Reaction and Each Could Contribute to Oxidative Stress in Mitochondria. Neurochem Res 2019; 44:2325-2335. [PMID: 30847859 DOI: 10.1007/s11064-019-02765-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 02/25/2019] [Accepted: 02/26/2019] [Indexed: 12/30/2022]
Abstract
According to recent findings, the human 2-oxoglutarate dehydrogenase complex (hOGDHc) could be an important source of the reactive oxygen species in the mitochondria and could contribute to mitochondrial abnormalities associated with multiple neurodegenerative diseases, including Alzheimer's disease, Huntington disease, and Parkinson's disease. The human 2-oxoadipate dehydrogenase (hE1a) is a novel protein, which is encoded by the DHTKD1 gene. Both missence and nonsense mutations were identified in the DHTKD1 that lead to alpha-aminoadipic and alpha-oxoadipic aciduria, a metabolic disorder with a wide variety of the neurological abnormalities, and Charcot-Marie-Tooth disease type 2Q, an inherited neurological disorder affecting the peripheral nervous system. Recently, the rare pathogenic mutations in DHTKD1 and an increased H2O2 production were linked to the genetic ethiology of Eosinophilic Esophagitis (EoE), a chronic allergic inflammatory esophageal disorder. In view of the importance of hOGDHc in the tricarboxylic acid cycle (TCA cycle) and hE1a on the L-lysine, L-hydroxylysine and L-tryptophan degradation pathway in mitochondria, and to enhance our current understanding of the mechanism of superoxide/H2O2 generation by hOGDHc, and by human 2-oxoadipate dehydrogenase complex (hOADHc), this review focuses on several novel and unanticipated recent findings in vitro that emerged from the Jordan group's research. Most significantly, the hE1o and hE1a now join the hE3 as being able to generate the superoxide/H2O2 in mitochondria.
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5
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Hsu N, Wang Y, Lin K, Chang C, Ke S, Lyu S, Hsu L, Li Y, Chen S, Wang K, Li T. Evidence of Diradicals Involved in the Yeast Transketolase Catalyzed Keto-Transferring Reactions. Chembiochem 2018; 19:2395-2402. [PMID: 30155962 PMCID: PMC6282555 DOI: 10.1002/cbic.201800378] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Indexed: 11/12/2022]
Abstract
Transketolase (TK) catalyzes a reversible transfer of a two-carbon (C2 ) unit between phosphoketose donors and phosphoaldose acceptors, for which the group-transfer reaction that follows a one- or two-electron mechanism and the force that breaks the C2"-C3" bond of the ketose donors remain unresolved. Herein, we report ultrahigh-resolution crystal structures of a TK (TKps) from Pichia stipitis in previously undiscovered intermediate states and support a diradical mechanism for a reversible group-transfer reaction. In conjunction with MS, NMR spectroscopy, EPR and computational analyses, it is concluded that the enzyme-catalyzed non-Kekulé diradical cofactor brings about the C2"-C3" bond cleavage/formation for the C2 -unit transfer reaction, for which suppression of activation energy and activation and destabilization of enzymatic intermediates are facilitated.
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Affiliation(s)
- Ning‐Shian Hsu
- Genomics Research CenterAcademia SinicaTaipei115Taiwan
- Institute of Biochemistry and Molecular BiologyNational Yang-Ming UniversityTaipei112Taiwan
| | - Yung‐Lin Wang
- Genomics Research CenterAcademia SinicaTaipei115Taiwan
| | - Kuan‐Hung Lin
- Genomics Research CenterAcademia SinicaTaipei115Taiwan
- Institute of Biochemistry and Molecular BiologyNational Yang-Ming UniversityTaipei112Taiwan
| | - Chi‐Fon Chang
- Genomics Research CenterAcademia SinicaTaipei115Taiwan
| | - Shyue‐Chu Ke
- Department of PhysicsNational Dong Hwa UniversityHualien974Taiwan
| | - Syue‐Yi Lyu
- Genomics Research CenterAcademia SinicaTaipei115Taiwan
| | - Li‐Jen Hsu
- Genomics Research CenterAcademia SinicaTaipei115Taiwan
| | - Yi‐Shan Li
- Genomics Research CenterAcademia SinicaTaipei115Taiwan
| | | | | | - Tsung‐Lin Li
- Genomics Research CenterAcademia SinicaTaipei115Taiwan
- Biotechnology CenterNational Chung Hsing UniversityTaichung City402Taiwan
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6
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Zhang J, Liu Y. Theoretical study of the catalytic mechanism of glyoxylate carboligase and its mutant V51E. Theor Chem Acc 2017. [DOI: 10.1007/s00214-017-2079-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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7
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Jirgis ENM, Bashiri G, Bulloch EMM, Johnston JM, Baker EN. Structural Views along the Mycobacterium tuberculosis MenD Reaction Pathway Illuminate Key Aspects of Thiamin Diphosphate-Dependent Enzyme Mechanisms. Structure 2016; 24:1167-77. [PMID: 27291649 DOI: 10.1016/j.str.2016.04.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 04/19/2016] [Accepted: 04/27/2016] [Indexed: 01/19/2023]
Abstract
Menaquinone (MQ) is an essential component of the respiratory chains of many pathogenic organisms, including Mycobacterium tuberculosis (Mtb). The first committed step in MQ biosynthesis is catalyzed by 2-succinyl-5-enolpyruvyl-6-hydroxy-3-cyclohexadiene-1-carboxylate synthase (MenD), a thiamin diphosphate (ThDP)-dependent enzyme. Catalysis proceeds through two covalent intermediates as the substrates 2-oxoglutarate and isochorismate are successively added to the cofactor before final cleavage of the product. We have determined a series of crystal structures of Mtb-MenD that map the binding of both substrates, visualizing each step in the MenD catalytic cycle, including both intermediates. ThDP binding induces a marked asymmetry between the coupled active sites of each dimer, and possible mechanisms of communication can be identified. The crystal structures also reveal conformational features of the two intermediates that facilitate reaction but prevent premature product release. These data fully map chemical space to inform early-stage drug discovery targeting MenD.
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Affiliation(s)
- Ehab N M Jirgis
- Maurice Wilkins Centre for Molecular Biodiscovery, School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1010, New Zealand
| | - Ghader Bashiri
- Maurice Wilkins Centre for Molecular Biodiscovery, School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1010, New Zealand
| | - Esther M M Bulloch
- Maurice Wilkins Centre for Molecular Biodiscovery, School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1010, New Zealand
| | - Jodie M Johnston
- Maurice Wilkins Centre for Molecular Biodiscovery, School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1010, New Zealand.
| | - Edward N Baker
- Maurice Wilkins Centre for Molecular Biodiscovery, School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1010, New Zealand.
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8
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Si HM, Zhang F, Wu AN, Han RZ, Xu GC, Ni Y. DNA microarray of global transcription factor mutant reveals membrane-related proteins involved in n-butanol tolerance in Escherichia coli. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:114. [PMID: 27252779 PMCID: PMC4888631 DOI: 10.1186/s13068-016-0527-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 05/11/2016] [Indexed: 05/07/2023]
Abstract
BACKGROUND Escherichia coli has been explored as a platform host strain for biofuels production such as butanol. However, the severe toxicity of butanol is considered to be one major limitation for butanol production from E. coli. The goal of this study is therefore to construct butanol-tolerant E. coli strains and clarify the tolerance mechanisms. RESULTS A recombinant E. coli strain harboring σ(70) mutation capable of tolerating 2 % (v/v) butanol was isolated by the global transcription machinery engineering (gTME) approach. DNA microarrays were employed to assess the transcriptome profile of butanol-tolerant strain B8. Compared with the wild-type strain, 329 differentially expressed genes (197 up-regulated and 132 down-regulated) (p < 0.05; FC ≥ 2) were identified. These genes are involved in carbohydrate metabolism, energy metabolism, two-component signal transduction system, oxidative stress response, lipid and cell envelope biogenesis and efflux pump. CONCLUSIONS Several membrane-related proteins were proved to be involved in butanol tolerance of E. coli. Two down-regulated genes, yibT and yghW, were identified to be capable of affecting butanol tolerance by regulating membrane fatty acid composition. Another down-regulated gene ybjC encodes a predicted inner membrane protein. In addition, a number of up-regulated genes, such as gcl and glcF, contribute to supplement metabolic intermediates for glyoxylate and TCA cycles to enhance energy supply. Our results could serve as a practical strategy for the construction of platform E. coli strains as biofuel producer.
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Affiliation(s)
- Hai-Ming Si
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122 Jiangsu China
| | - Fa Zhang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122 Jiangsu China
| | - An-Ning Wu
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122 Jiangsu China
| | - Rui-Zhi Han
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122 Jiangsu China
| | - Guo-Chao Xu
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122 Jiangsu China
| | - Ye Ni
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122 Jiangsu China
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9
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Tereshina EV, Laskavy VN, Ivanenko SI. Four components of the conjugated redox system in organisms: Carbon, nitrogen, sulfur, oxygen. BIOCHEMISTRY (MOSCOW) 2015; 80:1186-200. [DOI: 10.1134/s0006297915090096] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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10
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Jordan F, Nemeria NS. Progress in the experimental observation of thiamin diphosphate-bound intermediates on enzymes and mechanistic information derived from these observations. Bioorg Chem 2014; 57:251-262. [PMID: 25228115 DOI: 10.1016/j.bioorg.2014.08.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 08/11/2014] [Indexed: 11/26/2022]
Abstract
Thiamin diphosphate (ThDP), the vitamin B1 coenzyme is an excellent representative of coenzymes, which carry out electrophilic catalysis by forming a covalent complex with their substrates. The function of ThDP is to greatly increase the acidity of two carbon acids by stabilizing their conjugate bases, the ylide/carbene/C2-carbanion of the thiazolium ring and the C2α-carbanion/enamine, once the substrate binds to ThDP. In recent years, several ThDP-bound intermediates on such pathways have been characterized by both solution and solid-state methods. Prominent among these advances are X-ray crystallographic results identifying both oxidative and non-oxidative intermediates, rapid chemical quench followed by NMR detection of several intermediates which are stable under acidic conditions, solid-state NMR and circular dichroism detection of the states of ionization and tautomerization of the 4'-aminopyrimidine moiety of ThDP in some of the intermediates. These methods also enabled in some cases determination of the rate-limiting step in the complex series of steps. This review is an update of a review with the same title published by the authors in 2005 in this Journal. Much progress has been made in the intervening decade in the identification of the intermediates and their application to gain additional mechanistic insight.
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Affiliation(s)
- Frank Jordan
- Department of Chemistry, Rutgers University, Newark, NJ 07102, USA.
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11
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Patel H, Nemeria NS, Andrews FH, McLeish MJ, Jordan F. Identification of charge transfer transitions related to thiamin-bound intermediates on enzymes provides a plethora of signatures useful in mechanistic studies. Biochemistry 2014; 53:2145-52. [PMID: 24628377 PMCID: PMC3985856 DOI: 10.1021/bi4015743] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Identification
of enzyme-bound intermediates via their spectroscopic
signatures, which then allows direct monitoring of the kinetic fate
of these intermediates, poses a continuing challenge. As an electrophilic
covalent catalyst, the thiamin diphosphate (ThDP) coenzyme forms a
number of noncovalent and covalent intermediates along its reaction
pathways, and multiple UV–vis and circular dichroism (CD) bands
have been identified at Rutgers pertinent to several among them. These
electronic transitions fall into two classes: those for which the
conjugated system provides a reasonable guide to the observed λmax and others in which there is no corresponding conjugated
system and the observed CD bands are best ascribed to charge transfer
(CT) transitions. Herein is reported the reaction of four ThDP enzymes
with alternate substrates: (a) acetyl pyruvate, its methyl ester,
and fluoropyruvate, these providing the shortest side chains attached
at the thiazolium C2 atom and leading to CT bands with λmax values of >390 nm, not pertinent to any on-pathway conjugated
systems (estimated λmax values of <330 nm), and
(b) (E)-4-(4-chlorophenyl)-2-oxo-3-butenoic acid
displaying both a conjugated enamine (430 nm) and a CT transition
(480 nm). We suggest that the CT transitions result from an interaction
of the π bond on the ThDP C2 side chain as a donor, and the
positively charged thiazolium ring as an acceptor, and correspond
to covalent ThDP-bound intermediates. Time resolution of these bands
allows the rate constants for individual steps to be determined. These
CD methods can be applied to the entire ThDP superfamily of enzymes
and should find applications with other enzymes.
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Affiliation(s)
- Hetalben Patel
- Department of Chemistry, Rutgers, the State University of New Jersey , Newark, New Jersey 07102, United States
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12
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Andrews FH, McLeish MJ. Using site-saturation mutagenesis to explore mechanism and substrate specificity in thiamin diphosphate-dependent enzymes. FEBS J 2013; 280:6395-411. [DOI: 10.1111/febs.12459] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 07/23/2013] [Accepted: 07/26/2013] [Indexed: 12/25/2022]
Affiliation(s)
- Forest H. Andrews
- Department of Chemistry and Chemical Biology; Indiana University-Purdue University Indianapolis; IN USA
| | - Michael J. McLeish
- Department of Chemistry and Chemical Biology; Indiana University-Purdue University Indianapolis; IN USA
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Jordan F, Patel H. Catalysis in Enzymatic Decarboxylations: Comparison of Selected Cofactor-dependent and Cofactor-independent Examples. ACS Catal 2013; 3:1601-1617. [PMID: 23914308 DOI: 10.1021/cs400272x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
This review is focused on three types of enzymes decarboxylating very different substrates: (1) Thiamin diphosphate (ThDP)-dependent enzymes reacting with 2-oxo acids; (2) Pyridoxal phosphate (PLP)-dependent enzymes reacting with α-amino acids; and (3) An enzyme with no known co-factors, orotidine 5'-monophosphate decarboxylase (OMPDC). While the first two classes have been much studied for many years, during the past decade studies of both classes have revealed novel mechanistic insight challenging accepted understanding. The enzyme OMPDC has posed a challenge to the enzymologist attempting to explain a 1017-fold rate acceleration in the absence of cofactors or even metal ions. A comparison of the available evidence on the three types of decarboxylases underlines some common features and more differences. The field of decarboxylases remains an interesting and challenging one for the mechanistic enzymologist notwithstanding the large amount of information already available.
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Affiliation(s)
- Frank Jordan
- Department of Chemistry, Rutgers, The State University of New Jersey, 73 Warren Street, Newark,
New Jersey 07102, United States
| | - Hetalben Patel
- Department of Chemistry, Rutgers, The State University of New Jersey, 73 Warren Street, Newark,
New Jersey 07102, United States
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14
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Jordan F, Nemeria NS. Experimental observation of thiamin diphosphate-bound intermediates on enzymes and mechanistic information derived from these observations. Bioorg Chem 2005; 33:190-215. [PMID: 15888311 PMCID: PMC4189838 DOI: 10.1016/j.bioorg.2005.02.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2004] [Revised: 02/08/2005] [Accepted: 02/10/2005] [Indexed: 11/27/2022]
Abstract
Thiamin diphosphate (ThDP), the vitamin B1 coenzyme, is an excellent representative of coenzymes, which carry out electrophilic catalysis by forming a covalent complex with their substrates. The function of ThDP is to greatly increase the acidity of two carbon acids by stabilizing their conjugate bases, the ylide/C2-carbanion of the thiazolium ring and the C2alpha-carbanion (or enamine) once the substrate binds to ThDP. In recent years, several ThDP-bound intermediates on such pathways have been characterized by both solution and solid-state (X-ray) methods. Prominent among these advances are X-ray crystallographic results identifying both oxidative and non-oxidative intermediates, rapid chemical quench followed by NMR detection of a several intermediates which are stable under acidic conditions, and circular dichroism detection of the 1',4'-imino tautomer of ThDP in some of the intermediates. Some of these methods also enable the investigator to determine the rate-limiting step in the complex series of steps.
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Affiliation(s)
- Frank Jordan
- Department of Chemistry, Rutgers University, Newark, NJ 07102, USA
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