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1.
Colloids Surf B Biointerfaces ; 238: 113917, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38615391

RESUMO

In this study, the encapsulation and structural characteristics of the self-assembled liposome formed by epigallocatechin gallate (EGCG) and alcohol dehydrogenase (ADH) were studied. According to the results, EGCG significantly increased the catalytic activity of ADH with a 33.33 % activation rate and the liposomes were able to entrap EGCG-ADH with an effectiveness of 88.94 %. The self-assembled monolayers had nanometer-sized particles, and the excellent self-assembled system was demonstrated by the low PDI value and high surface absolute potential. The scanning electron microscope showed that the self-assembled liposome was honeycomb, groove-shaped, and rough. The spectroscopic results showed that EGCG-ADH complex was formed through hydrogen bond, which changed the secondary structure of the liposome, and verified EGCG-ADH liposome system was successfully prepared. In vitro digestion experiments showed that the gastrointestinal tolerance and antioxidant activity of EGCG-ADH liposomes were significantly higher than those of free EGCG-ADH.


Assuntos
Álcool Desidrogenase , Catequina , Lipossomos , Lipossomos/química , Catequina/química , Catequina/análogos & derivados , Álcool Desidrogenase/química , Álcool Desidrogenase/metabolismo , Antioxidantes/química , Antioxidantes/farmacologia , Tamanho da Partícula , Ligação de Hidrogênio
2.
Chem Biol Interact ; 394: 110992, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38579923

RESUMO

Histidine residues 44 and 48 in yeast alcohol dehydrogenase (ADH) bind to the coenzymes NAD(H) and contribute to catalysis. The individual H44R and H48Q substitutions alter the kinetics and pH dependencies, and now the roles of other ionizable groups in the enzyme were studied in the doubly substituted H44R/H48Q ADH. The substitutions make the enzyme more resistant to inactivation by diethyl pyrocarbonate, modestly improve affinity for coenzymes, and substantially decrease catalytic efficiencies for ethanol oxidation and acetaldehyde reduction. The pH dependencies for several kinetic parameters are shifted from pK values for wild-type ADH of 7.3-8.1 to values for H44R/H48Q ADH of 8.0-9.6, and are assigned to the water or alcohol bound to the catalytic zinc. It appears that the rate of binding of NAD+ is electrostatically favored with zinc-hydroxide whereas binding of NADH is faster with neutral zinc-water. The pH dependencies of catalytic efficiencies (V/EtKm) for ethanol oxidation and acetaldehyde reduction are similarly controlled by deprotonation and protonation, respectively. The substitutions make an enzyme that resembles the homologous horse liver H51Q ADH, which has Arg-47 and Gln-51 and exhibits similar pK values. In the wild-type ADHs, it appears that His-48 (or His-51) in the proton relay systems linked to the catalytic zinc ligands modulate catalytic efficiencies.


Assuntos
Álcool Desidrogenase , Domínio Catalítico , Histidina , Saccharomyces cerevisiae , Álcool Desidrogenase/metabolismo , Álcool Desidrogenase/genética , Álcool Desidrogenase/química , Concentração de Íons de Hidrogênio , Histidina/metabolismo , Histidina/química , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/enzimologia , Cinética , Etanol/metabolismo , Acetaldeído/metabolismo , Acetaldeído/química , Oxirredução , Substituição de Aminoácidos , Dietil Pirocarbonato/metabolismo , Dietil Pirocarbonato/química , NAD/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Zinco/metabolismo , Zinco/química
3.
J Chem Inf Model ; 64(8): 3400-3410, 2024 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-38537611

RESUMO

Lactobacillus kefir alcohol dehydrogenase (LkADH) and ketoreductase from Chryseobacterium sp. CA49 (ChKRED12) exhibit different chemoselectivity and stereoselectivity toward a substrate with both keto and aldehyde carbonyl groups. LkADH selectively reduces the keto carbonyl group while retaining the aldehyde carbonyl group, producing optically pure R-alcohols. In contrast, ChKRED12 selectively reduces the aldehyde group and exhibits low reactivity toward ketone carbonyls. This study investigated the structural basis for these differences and the role of specific residues in the active site. Molecular dynamics (MD) simulations and quantum chemical calculations were used to investigate the interactions between the substrate and the enzymes and the essential cause of this phenomenon. The present study has revealed that LkADH and ChKRED12 exhibit significant differences in the structure of their respective active pockets, which is a crucial determinant of their distinct chemoselectivity toward the same substrate. Moreover, residues N89, N113, and E144 within LkADH as well as Q151 and D190 within ChKRED12 have been identified as key contributors to substrate stabilization within the active pocket through electrostatic interactions and van der Waals forces, followed by hydride transfer utilizing the coenzyme NADPH. Furthermore, the enantioselectivity mechanism of LkADH has been elucidated using quantum chemical methods. Overall, these findings not only provide fundamental insights into the underlying reasons for the observed differences in selectivity but also offer a detailed mechanistic understanding of the catalytic reaction.


Assuntos
Aldeídos , Cetonas , Simulação de Dinâmica Molecular , Cetonas/química , Cetonas/metabolismo , Aldeídos/química , Aldeídos/metabolismo , Especificidade por Substrato , Teoria Quântica , Lactobacillus/enzimologia , Lactobacillus/metabolismo , Domínio Catalítico , Álcool Desidrogenase/metabolismo , Álcool Desidrogenase/química
4.
Protein Sci ; 33(4): e4933, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38501647

RESUMO

Alcohol dehydrogenases (ADHs) are synthetically important biocatalysts for the asymmetric synthesis of chiral alcohols. The catalytic performance of ADHs in the presence of organic solvents is often important since most prochiral ketones are highly hydrophobic. Here, the organic solvent tolerance of KpADH from Kluyveromyces polyspora was semi-rationally evolved. Using tolerant variants obtained, meticulous experiments and computational studies were conducted to explore properties including stability, activity and kinetics in the presence of various organic solvents. Compared with WT, variant V231D exhibited 1.9-fold improvement in ethanol tolerance, while S237G showed a 6-fold increase in catalytic efficiency, a higher T 50 15 $$ {\mathrm{T}}_{50}^{15} $$ , as well as 15% higher tolerance in 7.5% (v/v) ethanol. Based on 3 × 100 ns MD simulations, the increased tolerance of V231D and S237G against ethanol may be ascribed to their enhanced ability in retaining water molecules and repelling ethanol molecules. Moreover, 6.3-fold decreased KM value of V231D toward hydrophilic ketone substrate confirmed its capability of retaining hydration shell. Our results suggest that retaining hydration shell surrounding KpADH is critical for its tolerance to organic solvents, as well as catalytic performance. This study provides useful guidance for engineering organic solvent tolerance of KpADH and other ADHs.


Assuntos
Álcool Desidrogenase , Etanol , Álcool Desidrogenase/genética , Álcool Desidrogenase/química , Solventes/química , Água , Catálise , Cetonas
5.
Plant J ; 118(4): 1054-1070, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38308388

RESUMO

Alcohol dehydrogenases (ADHs) are a group of zinc-binding enzymes belonging to the medium-length dehydrogenase/reductase (MDR) protein superfamily. In plants, these enzymes fulfill important functions involving the reduction of toxic aldehydes to the corresponding alcohols (as well as catalyzing the reverse reaction, i.e., alcohol oxidation; ADH1) and the reduction of nitrosoglutathione (GSNO; ADH2/GSNOR). We investigated and compared the structural and biochemical properties of ADH1 and GSNOR from Arabidopsis thaliana. We expressed and purified ADH1 and GSNOR and determined two new structures, NADH-ADH1 and apo-GSNOR, thus completing the structural landscape of Arabidopsis ADHs in both apo- and holo-forms. A structural comparison of these Arabidopsis ADHs revealed a high sequence conservation (59% identity) and a similar fold. In contrast, a striking dissimilarity was observed in the catalytic cavity supporting substrate specificity and accommodation. Consistently, ADH1 and GSNOR showed strict specificity for their substrates (ethanol and GSNO, respectively), although both enzymes had the ability to oxidize long-chain alcohols, with ADH1 performing better than GSNOR. Both enzymes contain a high number of cysteines (12 and 15 out of 379 residues for ADH1 and GSNOR, respectively) and showed a significant and similar responsivity to thiol-oxidizing agents, indicating that redox modifications may constitute a mechanism for controlling enzyme activity under both optimal growth and stress conditions.


Assuntos
Álcool Desidrogenase , Proteínas de Arabidopsis , Arabidopsis , Oxirredução , Arabidopsis/enzimologia , Arabidopsis/genética , Álcool Desidrogenase/metabolismo , Álcool Desidrogenase/genética , Álcool Desidrogenase/química , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/química , Especificidade por Substrato , S-Nitrosoglutationa/metabolismo , Sequência de Aminoácidos , Etanol/metabolismo
6.
Biochem Biophys Res Commun ; 691: 149298, 2024 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-38011820

RESUMO

Alcohol dehydrogenases (ADHs) are popular catalysts for synthesizing chiral synthons a vital step for active pharmaceutical intermediate (API) production. They are grouped into three superfamilies namely, medium-chain (MDRs), short-chain dehydrogenase/reductases (SDRs), and iron-containing alcohol dehydrogenases. The former two are used extensively for producing various chiral synthons. Many studies screen multiple enzymes or engineer a specific enzyme for catalyzing a substrate of interest. These processes are resource-intensive and intricate. The current study attempts to decipher the ability to match different ADHs with their ideal substrates using machine learning algorithms. We explore the catalysis of 284 antibacterial ketone intermediates, against MDRs and SDRs to demonstrate a unique pattern of activity. To facilitate machine learning we curated a dataset comprising 33 features, encompassing 4 descriptors for each compound. Subsequently, an ensemble of machine learning techniques viz. Partial Least Squares (PLS) regression, k-Nearest Neighbors (kNN) regression, and Support Vector Machine (SVM) regression, was harnessed. Moreover, the assimilation of Principal Component Analysis (PCA) augmented precision and accuracy, thereby refining and demarcating diverse compound classes. As such, this classification is useful for discerning substrates amenable to diverse alcohol dehydrogenases, thereby mitigating the reliance on high-throughput screening or engineering in identifying the optimal enzyme for specific substrate.


Assuntos
Álcool Desidrogenase , Algoritmos , Álcool Desidrogenase/química , Catálise , Aprendizado de Máquina , Máquina de Vetores de Suporte
7.
Phys Chem Chem Phys ; 25(45): 31292-31300, 2023 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-37955422

RESUMO

Alcohol dehydrogenases (ADH) are a family of enzymes that catalyse the interconversion between ketones/aldehydes and alcohols in the presence of NADPH cofactor. It is challenging to desymmetrise the substituted cyclopentane-1,3-dione by engineering an ADH, while the reaction mechanism of the metal independent ADH remains elusive. Here we measured the conversion of a model substrate 2-benzyl-2-methylcyclopentane-1,3-dione by LbADH and found it predominately gave the (2R,3R) product. Binding mode analysis of the substrate in LbADH from molecular dynamics simulations disclosed the origin of the enantioselectivity of the enzyme; the opening and closing of the loop 191-205 above the substrate are responsible for shaping the binding pocket to orientate the substrate, so as to give different stereoisomer products. Using QM/MM calculations, we elucidated the reaction mechanism of LbADH. Furthermore, we demonstrated the reaction profile corresponding to the production of different stereoisomers, which is in accordance with our experimental observations. This research here will shed a light on the rational engineering of ADH to achieve stereodivergent stereoisomer products.


Assuntos
Álcool Desidrogenase , Álcoois , Álcool Desidrogenase/química , Aldeídos , Catálise , Cetonas/química , Especificidade por Substrato
8.
Protein Eng Des Sel ; 362023 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-37306945

RESUMO

Gene fusion or co-immobilization are key tools to optimize enzymatic reaction cascades by modulating catalytic features, stability and applicability. Achieving a defined spatial organization between biocatalysts by site-specific applications is complicated by the involvement of oligomeric enzymes. It can lead to activity losses due to disturbances of the quaternary structures and difficulties in stoichiometric control. Thus, a toolkit of active and robust monomeric enzymes is desirable for such applications. In this study, we engineered one of the rare examples of monomeric alcohol dehydrogenases for improved catalytic characteristics by site-directed mutagenesis. The enzyme from the hyperthermophilic archaeon Thermococcus kodakarensis naturally exhibits high thermostability and a broad substrate spectrum, but only low activity at moderate temperatures. The best enzyme variants showed an ~5-fold (2-heptanol) and 9-fold (3-heptanol) higher activity while preserving enantioselectivity and good thermodynamic stability. These variants also exhibited modified kinetic characteristics regarding regioselectivity, pH dependence and activation by NaCl.


Assuntos
Álcool Desidrogenase , Álcool Desidrogenase/genética , Álcool Desidrogenase/química , Álcool Desidrogenase/metabolismo , Heptanol , Mutagênese Sítio-Dirigida , Temperatura , Termodinâmica , Estabilidade Enzimática , Cinética
9.
Bioorg Med Chem ; 83: 117255, 2023 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-36966660

RESUMO

Barriers to the ready adoption of biocatalysis into asymmetric synthesis for early stage medicinal chemistry are addressed, using ketone reduction by alcohol dehydrogenase as a model reaction. An efficient substrate screening approach is used to show the wide substrate scope of commercial alcohol dehydrogenase enzymes, with a high tolerance to chemical groups employed in drug discovery (heterocycle, trifluoromethyl and nitrile/nitro groups) observed. We use our screening data to build a preliminary predictive pharmacophore-based screening tool using Forge software, with a precision of 0.67/1, demonstrating the potential for developing substrate screening tools for commercially available enzymes without publicly available structures. We hope that this work will facilitate a culture shift towards adopting biocatalysis alongside traditional chemical catalytic methods in early stage drug discovery.


Assuntos
Álcool Desidrogenase , Farmacóforo , Álcool Desidrogenase/química , Álcool Desidrogenase/metabolismo , Biocatálise , Catálise , Cetonas/química
10.
Chembiochem ; 24(8): e202200794, 2023 04 17.
Artigo em Inglês | MEDLINE | ID: mdl-36748930

RESUMO

Baeyer-Villiger monooxygenases (BVMOs) are attractive for selectively oxidizing various ketones using oxygen into valuable esters and lactones. However, the application of BVMOs is restrained by cofactor dependency and enzyme instability combined with water-related downsides such as low substrate loading, low oxygen capacity, and water-induced side reactions. Herein, we described a redox-neutral linear cascade with in-situ cofactor regeneration catalyzed by fused alcohol dehydrogenase and cyclohexanone monooxygenase in aqueous and microaqueous organic media. The cascade conditions have been optimized regarding substrate concentrations as well as the amounts of enzymes and cofactors with the Design of Experiments (DoE). The carrier-free immobilization technique, crosslinked enzyme aggregates (CLEAs), was applied to fusion enzymes. The resultant fusion CLEAs were proven to function in microaqueous organic systems, in which the enzyme ratios, water contents (0.5-5 vol. %), and stability have been systematically studied. The fusion CLEAs showed promising operational (up to 5 cycles) and storage stability.


Assuntos
Álcool Desidrogenase , Oxigenases de Função Mista , Oxigenases de Função Mista/metabolismo , Oxirredução , Álcool Desidrogenase/química , Cetonas/química , Água , Estabilidade Enzimática
11.
Biotechnol Appl Biochem ; 70(2): 537-552, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35751426

RESUMO

There are three prominent alcohol dehydrogenases superfamilies: short-chain, medium-chain, and iron-containing alcohol dehydrogenases (FeADHs). Many members are valuable catalysts for producing industrially relevant products such as active pharmaceutical intermediates, chiral synthons, biopolymers, biofuels, and secondary metabolites. However, FeADHs are the least explored enzymes among the superfamilies for commercial tenacities. They portray a conserved structure having a "tunnel-like" cofactor and substrate binding site with particular functions, despite representing high sequence diversity. Interestingly, phylogenetic analysis demarcates enzymes catalyzing distinct native substrates where closely related clades convert similar molecules. Further, homologs from various mesophilic and thermophilic microbes have been explored for designing a solvent and temperature-resistant enzyme for industrial purposes. The review explores different iron-containing alcohol dehydrogenases potential engineering of the enzymes and substrates helpful in manufacturing commercial products.


Assuntos
Álcool Desidrogenase , Ferro , Álcool Desidrogenase/genética , Álcool Desidrogenase/química , Álcool Desidrogenase/metabolismo , Filogenia , Sequência de Aminoácidos , Sítios de Ligação
12.
Acta Crystallogr D Struct Biol ; 78(Pt 10): 1221-1234, 2022 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-36189742

RESUMO

Enzymes catalyze reactions by binding and orienting substrates with dynamic interactions. Horse liver alcohol dehydrogenase catalyzes hydrogen transfer with quantum-mechanical tunneling that involves fast motions in the active site. The structures and B factors of ternary complexes of the enzyme with NAD+ and 2,3,4,5,6-pentafluorobenzyl alcohol or NAD+ and 2,2,2-trifluoroethanol were determined to 1.1-1.3 Šresolution below the `glassy transition' in order to extract information about the temperature-dependent harmonic motions, which are reflected in the crystallographic B factors. The refinement statistics and structures are essentially the same for each structure at all temperatures. The B factors were corrected for a small amount of radiation decay. The overall B factors for the complexes are similar (13-16 Å2) over the range 25-100 K, but increase somewhat at 150 K. Applying TLS refinement to remove the contribution of pseudo-rigid-body displacements of coenzyme binding and catalytic domains provided residual B factors of 7-10 Å2 for the overall complexes and of 5-10 Å2 for C4N of NAD+ and the methylene carbon of the alcohols. These residual B factors have a very small dependence on temperature and include local harmonic motions and apparently contributions from other sources. Structures at 100 K show complexes that are poised for hydrogen transfer, which involves atomic displacements of ∼0.3 Šand is compatible with the motions estimated from the residual B factors and molecular-dynamics simulations. At 298 K local conformational changes are also involved in catalysis, as enzymes with substitutions of amino acids in the substrate-binding site have similar positions of NAD+ and pentafluorobenzyl alcohol and similar residual B factors, but differ by tenfold in the rate constants for hydride transfer.


Assuntos
Álcool Desidrogenase , NAD , Álcool Desidrogenase/química , Álcool Desidrogenase/metabolismo , Aminoácidos/química , Animais , Álcoois Benzílicos/química , Álcoois Benzílicos/metabolismo , Sítios de Ligação , Carbono , Cristalografia por Raios X , Fluorbenzenos , Fluorocarbonos , Cavalos , Hidrogênio/química , Cinética , Fígado , NAD/química , Conformação Proteica , Temperatura , Trifluoretanol/química , Trifluoretanol/metabolismo
13.
Appl Biochem Biotechnol ; 194(11): 5537-5555, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35793060

RESUMO

Two iron-containing alcohol dehydrogenases (ADHs) are encoded in the genome of the hyperthermophilic euryarchaeon Thermococcus barophilus Ch5 (Tba ADH641 and Tba ADH547). In our previous publication, we reported biochemical characteristics and catalytic mechanism of Tba ADH547. Herein, we present evidence that Tba ADH641 possesses two activities for ethanol oxidization and acetaldehyde reduction at high temperature, capable of using NAD(H) and NADP(H) as coenzyme. Biochemical data show that Tba ADH641 possesses optimal reaction temperature, thermostability, divalent ion requirement, and substrate specificity distinct from Tba ADH547 and other iron-containing ADH homologues. However, Tba ADH641 and Tba ADH547 display same optimal reaction pH. Kinetic analyses demonstrate that Tba ADH641 displays higher catalytic efficiency for acetaldehyde reduction than that for ethanol oxidation, which is consistent with Tba ADH547. Mutational data demonstrate that residues D115, K118, E159, D190, and E215 in Tba ADH641, which has not been described to date, are necessary for enzyme activity, thus augmenting our understanding on catalytic mechanism of iron-containing ADH. Overall, our work demonstrates that Tba ADH641 is an iron-containing ADH with novel features, which is distinct from Tba ADH547, thus providing a potential biocatalyst for biotransformation reaction.


Assuntos
Thermococcus , Thermococcus/genética , Thermococcus/metabolismo , Álcool Desidrogenase/química , Ferro , NADP/metabolismo , NAD/metabolismo , Sequência de Aminoácidos , Cinética , Etanol , Acetaldeído
14.
Nanotechnology ; 33(43)2022 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-35835080

RESUMO

Ceramic materials with high surface area, large and open porosity are considered excellent supports for enzyme immobilization owing to their stability and reusability. The present study reports the electrospinning of aluminum silicate nanofiber supports from sol-gel precursors, the impact of different fabrication parameters on the microstructure of the nanofibers and their performance in enzyme immobilization. A change in nanofiber diameter and pore size of the aluminum silicate nanofibers was observed upon varying specific processing parameters, such as the sol-composition (precursor and polymer concentration), the electrospinning parameters and the subsequent heat treatment (calcination temperature). The enzyme, alcohol dehydrogenase (ADH), was immobilized on the aluminum silicate nanofibers by physical adsorption and covalent bonding. Activity retention of 17% and 42% was obtained after 12 d of storage and repeated reaction cycles for physically adsorbed and covalently bonded ADH, respectively. Overall, the immobilization of ADH on aluminum silicate nanofibers resulted in high enzyme loading and activity retention. However, as compared to covalent immobilization, a marked decrease in the enzyme activity during storage for physically adsorbed enzymes was observed, which was ascribed to leakage of the enzymes from the nanofibers. Such fibers can improve enzyme stability and promote a higher residual activity of the immobilized enzyme as compared to the free enzyme. The results shown in this study thus suggest that aluminum silicate nanofibers, with their high surface area, are promising support materials for the immobilization of enzymes.


Assuntos
Nanofibras , Álcool Desidrogenase/química , Alumínio , Silicatos de Alumínio , Enzimas Imobilizadas/química , Nanofibras/química
15.
Biosens Bioelectron ; 213: 114453, 2022 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-35728364

RESUMO

Non-invasive measurement of volatile organic compounds (VOCs) emitted from living organisms is a powerful technique for diagnosing health conditions or diseases in humans. Bio-based gas sensors are suitable for the sensitive and selective measurement of a target VOC from a complex mixture of VOCs. Conventional bio-based sensors are normally prepared as wet-type probes to maintain proteins such as enzymes in a stable state, resulting in limitations in the commercialization of sensors, their operating environment, and performance. In this study, we present an enzyme-based fluorometric electrospun fiber sensor (eFES) mesh as a gas-phase biosensor in dry form. The eFES mesh targeting ethanol was fabricated by simple one-step electrospinning of polyvinyl alcohol with an alcohol dehydrogenase and an oxidized form of nicotinamide adenine dinucleotide. The enzyme embedded in the eFES mesh worked actively in a dry state without pretreatment. Substrate specificity was also maintained, and the sensor responded well to ethanol with a sufficient dynamic range. Adjustment of the pH and coenzyme quantity in the eFES mesh also affected enzyme activity. The dry-form biosensor-eFES mesh-will open a new direction for gas-phase biosensors because of its remarkable performance and simple fabrication, which is advantageous for commercialization.


Assuntos
Técnicas Biossensoriais , Compostos Orgânicos Voláteis , Álcool Desidrogenase/química , Técnicas Biossensoriais/métodos , Testes Respiratórios/métodos , Etanol/metabolismo , Gases , Humanos , Polímeros
16.
Chembiochem ; 23(15): e202200149, 2022 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-35557486

RESUMO

The asymmetric reduction of ketones to chiral hydroxyl compounds by alcohol dehydrogenases (ADHs) is an established strategy for the provision of valuable precursors for fine chemicals and pharmaceutics. However, most ADHs favor linear aliphatic and aromatic carbonyl compounds, and suitable biocatalysts with preference for cyclic ketones and diketones are still scarce. Among the few candidates, the alcohol dehydrogenase from Thauera aromatica (ThaADH) stands out with a high activity for the reduction of the cyclic α-diketone 1,2-cyclohexanedione to the corresponding α-hydroxy ketone. This study elucidates catalytic and structural features of the enzyme. ThaADH showed a remarkable thermal and pH stability as well as stability in the presence of polar solvents. A thorough description of the substrate scope combined with the resolution and description of the crystal structure, demonstrated a strong preference of ThaADH for cyclic α-substituted cyclohexanones, and indicated structural determinants responsible for the unique substrate acceptance.


Assuntos
Álcool Desidrogenase , Thauera , Álcool Desidrogenase/química , Catálise , Cetonas/química , Especificidade por Substrato , Thauera/metabolismo , Zinco
17.
Biosens Bioelectron ; 211: 114376, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-35598555

RESUMO

Given the significance of dihydronicotinamide adenine dinucleotide (NADH) and nicotinamide adenine dinucleotide (NAD+) in numerous biochemical fields such as clinical diagnostics and fermentation monitoring, a synergistic strategy was proposed based on the co-catalysis of NAD+-dependent dehydrogenases and nanoporous gold (NPG) towards the oxidation of substrates and NADH, respectively. An NAD+-dependent dehydrogenase/NPG/SPE biosensing platform was developed by modifying screen-printed electrode (SPE) with NPG and NAD+-dependent dehydrogenase for the electrochemical detections of NADH, ethanol, and glucose. Owing to the exceptional oxidation activity of NPG towards NADH, the amperometric detection of NADH exhibited good linearity from 50 µM to 2.0 mM with a low detection limit (LOD) of 15.18-16.39 µM and a satisfactory sensitivity of 1.58-1.72 µA mM-1 within a wide pH range. With alcohol dehydrogenase (ADH) and glucose dehydrogenase (GDH) as model enzymes, ADH/NPG/SPE and GDH/NPG/SPE exhibited excellent analytic characteristics (sensitivity of 0.66 µA mM-1 and 2.04 µA mM-1, LOD of 40.72 µM and 14.83 µM) of ethanol and glucose detection in buffer solution as well as in human serum and fermentation broth. The sensitive micro-sample detections of ethanol and glucose in both real samples were achieved using the proposed biosensors with comparable accuracy (deviation rates of 0.85-7.92%) as automatic analyzers. The proposed biosensing platform elicited many advantageous properties in practical applications, including micro-sample analysis, cost-efficient, easy fabrication, and flexible adaptability, which made it a promising candidate for the clinical blood test, urinalysis, and fermentation monitoring.


Assuntos
Técnicas Biossensoriais , Nanoporos , Álcool Desidrogenase/química , Catálise , Eletrodos , Etanol/análise , Glucose , Glucose 1-Desidrogenase , Ouro/química , Humanos , NAD/química
18.
Sheng Wu Gong Cheng Xue Bao ; 38(4): 1518-1526, 2022 Apr 25.
Artigo em Chinês | MEDLINE | ID: mdl-35470623

RESUMO

Covalently anchoring of a ligand/metal via polar amino acid side chain(s) is often observed in metalloenzyme, while the substitutability of metal-binding sites remains elusive. In this study, we utilized a zinc-dependent alcohol dehydrogenase from Thermoanaerobacter brockii (TbSADH) as a model enzyme, analyzed the sequence conservation of the three residues Cys37, His59, and Asp150 that bind the zinc ion, and constructed the mutant library. After experimental validation, three out of 224 clones, which showed comparative conversion and ee values as the wild-type enzyme in the asymmetric reduction of the model substrate tetrahydrofuran-3-one, were screened out. The results reveal that the metal-binding sites in TbSADH are substitutable without tradeoff in activity and stereoselectivity, which lay a foundation for designing ADH-catalyzed new reactions via metal ion replacement.


Assuntos
Álcool Desidrogenase , Zinco , Álcool Desidrogenase/química , Álcool Desidrogenase/genética , Álcool Desidrogenase/metabolismo , Domínio Catalítico , Ligantes , Domínios Proteicos , Zinco/metabolismo
19.
Proteins ; 90(8): 1570-1583, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35357038

RESUMO

Three-dimensional structures of I86A and C295A mutant secondary alcohol dehydrogenase (SADH) from Thermoanaerobacter pseudoethanolicus were determined by x-ray crystallography. The tetrameric structure of C295A-SADH soaked with NADP+ and dimethyl sulfoxide (DMSO) was determined to 1.85 Å with an Rfree of 0.225. DMSO is bound to the tetrahedral zinc in each subunit, with ligands from SG of Cys-37, NE2 of His-59, and OD2 of Asp-150. The nicotinamide ring of NADP is hydrogen-bonded to the N of Ala-295 and the O of Val-265 and Gly-293. The O of DMSO is connected to a network of hydrogen bonds with OG of Ser-39, the 3'-OH of NADP, and ND1 of His-42. The structure of I86A-SADH soaked with 2-pentanol and NADP+ contains (R)-2-pentanol bound in each subunit, ligated to the tetrahedral zinc, and connected to the proton relay network. The structure of I86A-SADH soaked with 3-methylcyclohexanol and NADP+ has alcohol bound in three subunits. Two of the sites have the alcohol ligated to the zinc in an axial position, with OE2 of Glu-60 in the other axial position of a trigonal bipyramidal complex. One site has 3-methylcyclohexanol bound noncovalently, with the zinc in an inverted tetrahedral geometry with Glu-60. The fourth site also has the zinc in a trigonal bipyramidal complex with axial Glu-60 and water ligands. These structures demonstrate that ligand exchange of SADH involves pentacoordinate and inverted zinc complexes with Glu-60. Furthermore, we see a network of hydrogen bonds connecting the substrate oxygen to the external solvent that is likely to play a role in the mechanism of SADH.


Assuntos
Prótons , Thermoanaerobacter , Álcool Desidrogenase/química , Oxirredutases do Álcool , Sítios de Ligação , Cristalografia por Raios X , Dimetil Sulfóxido , Ligantes , NADP/metabolismo , Pentanóis , Thermoanaerobacter/metabolismo , Zinco
20.
Faraday Discuss ; 234(0): 315-335, 2022 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-35156975

RESUMO

Artificial metalloenzymes (ArMs) confer non-biological reactivities to biomolecules, whilst taking advantage of the biomolecular architecture in terms of their selectivity and renewable origin. In particular, the design of ArMs by the supramolecular anchoring of metal catalysts to protein hosts provides flexible and easy to optimise systems. The use of cofactor dependent enzymes as hosts gives the advantage of both a (hydrophobic) binding site for the substrate and a cofactor pocket to accommodate the catalyst. Here, we present a computationally driven design approach of ArMs for the transfer hydrogenation reaction of cyclic imines, starting from the NADP+-dependent alcohol dehydrogenase from Thermoanaerobacter brockii (TbADH). We tested and developed a molecular docking workflow to define and optimize iridium catalysts with high affinity for the cofactor binding site of TbADH. The workflow uses high throughput docking of compound libraries to identify key structural motifs for high affinity, followed by higher accuracy docking methods on smaller, focused ligand and catalyst libraries. Iridium sulfonamide catalysts were selected and synthesised, containing either a triol, a furane, or a carboxylic acid to provide the interaction with the cofactor binding pocket. IC50 values of the resulting complexes during TbADH-catalysed alcohol oxidation were determined by competition experiments and were between 4.410 mM and 0.052 mM, demonstrating the affinity of the iridium complexes for either the substrate or the cofactor binding pocket of TbADH. The catalytic activity of the free iridium complexes in solution showed a maximal turnover number (TON) of 90 for the reduction of salsolidine by the triol-functionalised iridium catalyst, whilst in the presence of TbADH, only the iridium catalyst with the triol anchoring functionality showed activity for the same reaction (TON of 36 after 24 h). The observation that the artificial metalloenzymes developed here lacked stereoselectivity demonstrates the need for the further investigation and optimisation of the ArM. Our results serve as a starting point for the design of robust artificial metalloenzymes, exploiting supramolecular anchoring to natural NAD(P)H binding pockets.


Assuntos
Álcool Desidrogenase , Metaloproteínas , Álcool Desidrogenase/química , Álcool Desidrogenase/metabolismo , Catálise , Irídio , Simulação de Acoplamento Molecular
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