Combined engineering of substrate specificity and thermostability of Bacteroides phosphatase to promote in vitro biotransformation of d-allulose by multienzyme cascades.

Recently, in vitro multienzyme cascade biotransformation based on phosphorylation-isomerization-dephosphorylation has been extensively utilized in the industrial production of rare sugars. It exhibited distinct advantages in conversion and yield compared with the direct isomerization catalyzed by single isomerase, due to phosphorylation activating glycosyl molecules to reduce the energy barrier of isomerization. However, as a critical enzyme catalyzing the dephosphorylation to drive the equilibrium forward, phosphatases that satisfy the ideal catalytic model of 'one enzyme-one substrate' generally require high substrate specificity and catalytic activity.

High-valued hexoses bioproduction from natural sugar resources: Status, trends, challenges and perspectives.

The high-valued conversion of natural sugar resources is one of the priorities for global resource utilization and human health development. These conversions can not only greatly improve the efficiency of carbon resource utilization, but its diversified products are also potential candidates for alleviating the increasingly serious human health problems such as obesity and diabetes. As a novel sugar food additive, the industrial-scale production of high-valued hexoses have emerged as a critical focus in food science and biotechnology.

Multiple strategies were adopted to optimize the enzymatic characteristics and improve the expression of bovine chymosin BtChy in for cheese production.

Chymosin (EC3.4.23.

Current state and sustainable management of waste polyethylene terephthalate bio-disposal: enzymatic degradation to upcycling.

Poly (ethylene terephthalate) (PET) is a widely used plastic that leads to significant environmental pollution due to its durability. Enzymatic degradation of PET presents an eco-friendly disposal approach, with potential scalability for industrial applications. This review examines key crucial factors influencing PET enzymatic degradation, including the catalytic efficiency of PET hydrolase, production scalability of PET hydrolase, and recyclability of degraded PET.

One-step sensitive detection of UDG activity based on nicking enzyme-assisted signal amplification coupled with APE1 and triggered reporter.

Background: UDG (Uracil-DNA glycosylase) is a pivotal enzyme in the base excision repair (BER) mechanism, and it is widely distributed across most organisms. Its primary function is to identify and excise uracil bases from DNA, thereby facilitating the repair of DNA and the creation of apurinic/apyrimidinic (AP) sites. Furthermore, abnormal expression or dysregulation of UDG activity has been closely associated with ageing, cancer, and other diseases such as immunodeficiency and lymphoma.

Enhancement of the yield of poly (ethylene terephthalate) hydrolase production using cell membrane protection strategy.

Biodegradation, particularly via enzymatic degradation, has emerged as an efficient and eco-friendly solution for Poly (ethylene terephthalate) (PET) pollution. The production of PET hydrolases plays a role in the large-scale enzymatic degradation. However, an effective variant, 4Mz, derived from Thermobifida fusca cutinase (Tfu_0883), was previously associated with a significant reduction in yield when compared to the wild-type enzyme.

Molecular Mechanism of Double-Displacement Retaining β-Kdo Glycosyltransferase WbbB.

Glycosyltransferases (GTs) are pivotal enzymes involved in glycosidic bond synthesis, which can lead to either retention or inversion of the glycosyl moiety's anomeric configuration. However, the catalytic mechanism for retaining GTs remains a subject of controversy. In this study, we employ MD and QM/MM metadynamics to investigate the double-displacement catalytic mechanism of the retaining β-Kdo transferase WbbB.

Enhancing the heterologous expression of latex clearing protein from Streptomyces sp. strain K30 in Escherichia coli through fermentation condition optimization and molecular modification.

Latex clearing protein from Streptomyces sp. strain K30 (Lcp) is a natural oxidoreductase that can catalyse the cleavage of rubber through dioxygenation. It has significant potential applications in polymer degradation.

Conformational Switch of the 250s Loop Enables the Efficient Transglycosylation in GH Family 77.

Amylomaltases (AMs) play important roles in glycogen and maltose metabolism. However, the molecular mechanism is elusive. Here, we investigated the conformational dynamics of the 250s loop and catalytic mechanism of AM using path-metadynamics and QM/MM MD simulations.

Mechanistic Insights into How the Protonation State of D234 Dictates the Reactivity in β--Acetylhexosaminidase.

β--Acetylhexosaminidases (HEXs) play important roles in human diseases and the biosynthesis of human milk oligosaccharides. Despite extensive research, the catalytic mechanism of these enzymes remains largely unexplored. In this study, we employed quantum mechanics/molecular mechanics metadynamics to investigate the molecular mechanism of HEX (HEX), which has shed light on the transition state structures and conformational pathways of this enzyme.

Enhancing 2-O-α-D-glucopyranosyl-L-ascorbic acid synthesis by weakening the acceptor specificity of CGTase toward glucose and maltose.

2-O-α-D-glucopyranosyl-L-ascorbic acid (AA-2G) is a stable derivative of L-ascorbic acid (L-AA), which has been widely used in food and cosmetics industries. Sugar molecules, such as glucose and maltose produced by cyclodextrin glycosyltransferase (CGTase) during AA-2G synthesis may compete with L-AA as the acceptors, resulting in low AA-2G yield. Multiple sequence alignment combined with structural simulation analysis indicated that residues at positions 191 and 255 of CGTase may be responsible for the difference in substrate specificity.

Multiple approaches of loop region modification for thermostability improvement of 4,6-α-glucanotransferase from Limosilactobacillus fermentum NCC 3057.

4,6-α-glucanotransferase (4,6-α-GT), as a member of the glycoside hydrolase 70 (GH70) family, converts starch/maltooligosaccharides into α,1-6 bond-containing α-glucan and possesses potential applications in food, medical and related industries but does not satisfy the high-temperature requirement due to its poor thermostability. In this study, a 4,6-α-GT (ΔGtfB) from Limosilactobacillus fermentum NCC 3057 was used as a model enzyme to improve its thermostability. The loops of ΔGtfB as the target region were optimized using directed evolution, sequence alignment, and computer-aided design.

Trehalose promotes high-level heterologous expression of 4,6-α-glucanotransferase GtfR2 in Escherichia coli and mechanistic analysis.

4,6-α-Glucanotransferases (4,6-α-GTs) hold great potential for applications in the food and medical industries because of their efficient transglycosylation ability. However, it is relatively difficult to achieve high soluble expression because of their high molecular weight and multidomain nature. In this study, 4,6-α-GT of Burkholderia sp.

Directional-path modification strategy enhances PET hydrolase catalysis of plastic degradation.

Poly (ethylene terephthalate) (PET) is a widely used type of general plastic that produces a significant amount of waste due to its non-degradable properties. We propose a novel directional-path modification (DPM) strategy, involving positive charge amino acid introduction and binding groove remodeling, and apply it to Thermobifida fusca cutinase to enhance PET degradation. The highest value of PET degradation (90%) was achieved in variant 4Mz (H184S/Q92G/F209I/I213K), exhibiting values almost 30-fold that of the wild-type.

Diverse prebiotic effects of isomaltodextrins with different glycosidic linkages and molecular weights on human gut bacteria in vitro.

Isomaltodextrin (IMD) is a novel dietary fiber enzymatically produced by reconstructing the molecular chain structure of starch using glycosyltransferases. In this study, the specific prebiotic effects of α-1,6 linear and α-1,2 or α-1,3 branched IMDs with different molecular weights (Mw) on human intestinal bacteria were investigated by pure culture of single strains and mixed fermentation of human fecal microflora in vitro. The results showed that α-1,6 linear IMDs markedly promoted beneficial Bifidobacterium and Lactobacillus in both pure culture and mixed fermentation.

Effect of point defects on acetylene hydrogenation reaction over Ni(111) surface: a density functional theory study.

Density functional theory (DFT) calculations are carried out to investigate the effect of point defects on acetylene hydrogenation reaction over Ni(111) surface with three different defect concentrations (DC = 0.0500, 0.0625, and 0.

Efficient bioproduction of 5-aminolevulinic acid, a promising biostimulant and nutrient, from renewable bioresources by engineered .

Background: 5-Aminolevulinic acid (5-ALA) is a promising biostimulant, feed nutrient, and photodynamic drug with wide applications in modern agriculture and therapy. Considering the complexity and low yield of chemical synthesis methods, bioproduction of 5-ALA has drawn intensive attention recently. However, the present bioproduction processes use refined glucose as the main carbon source and the production level still needs further enhancement.

Metabolic engineering of Corynebacterium glutamicum by synthetic small regulatory RNAs.

Corynebacterium glutamicum is an important platform strain that is wildly used in industrial production of amino acids and various other biochemicals. However, due to good genomic stability, C. glutamicum is more difficult to engineer than genetically tractable hosts.

Theoretical study on the reaction mechanism and selectivity of acetylene semi-hydrogenation on Ni-Sn intermetallic catalysts.

Recently, Ni-Sn intermetallic compounds (IMCs) with unique geometric structures have been proved to be selective catalysts for acetylene hydrogenation to ethylene, but the origin of the selectivity remains unclear. In this work, a density functional theory (DFT) study has been carried out to investigate the mechanism of acetylene hydrogenation on six surfaces of Ni-Sn IMCs, and the geometric effects towards ethylene selectivity were revealed. Two key parameters (adsorption energy and the hydrogenation barrier of ethylene), which determine the ethylene selectivity, were studied quantitatively.

Enhancing thermostability and removing hemin inhibition of Rhodopseudomonas palustris 5-aminolevulinic acid synthase by computer-aided rational design.

Objective: To enhance the thermostability and deregulate the hemin inhibition of 5-aminolevulinic acid (ALA) synthase from Rhodopseudomonas palustris (RP-ALAS) by a computer-aided rational design strategy.

Results: Eighteen RP-ALAS single variants were rationally designed and screened by measuring their residual activities upon heating. Among them, H29R and H15K exhibited a 2.

Simultaneously improving the activity and thermostability of a new proline 4-hydroxylase by loop grafting and site-directed mutagenesis.

trans-Proline 4-hydroxylases (trans-P4Hs) hydroxylate free L-proline to trans-4-hydroxy-L-proline (trans-4-Hyp) is a valuable chiral synthon for important pharmaceuticals such as carbapenem antibiotics. However, merely few microbial trans-P4Hs have been identified, and trans-4-Hyp fermentations using engineered Escherichia coli strains expressing trans-P4Hs are usually performed at temperatures below 37 °C, which is likely due to poor stability and low activities. In the present study, a new trans-P4H from uncultured bacterium esnapd13 (UbP4H) with potential in the fermentative production of trans-4-Hyp at 37 °C was reported.

Insights into Interfacial Synergistic Catalysis over Ni@TiO Catalyst toward Water-Gas Shift Reaction.

The mechanism on interfacial synergistic catalysis for supported metal catalysts has long been explored and investigated in several important heterogeneous catalytic processes (e.g., water-gas shift (WGS) reaction).

The reaction mechanism and selectivity of acetylene hydrogenation over Ni-Ga intermetallic compound catalysts: a density functional theory study.

Intermetallic compounds (IMCs) have shown excellent catalytic performance toward the selective hydrogenation of acetylene, but the theoretical understanding on this reaction over Ni-based IMCs is rather limited. In this work, the adsorptions of the C species, Bader charge, projected density of states (PDOS) and the reaction pathways were calculated by the density functional theory (DFT) method to investigate the mechanism and selectivity for the acetylene hydrogenation on the (111) surface of NiGa (n = 1, 3) IMCs, with a comparative study on the pristine Ni(111) surface. The results indicate that the adsorption energy of acetylene increased along with the Ni/Ga ratio, therefore a feasible acetylene adsorption on the Ga-rich surface guaranteed a low effective barrier, leading to the best activity for the NiGa(111) surface among three surfaces.

Hierarchical CoNi-Sulfide Nanosheet Arrays Derived from Layered Double Hydroxides toward Efficient Hydrazine Electrooxidation.

A hierarchical CoNi-sulfide nanosheet array is fabricated via an in situ reduction of CoNi-layered double hydroxide (LDH) nanosheets, then a vulcanization process. The material inherits the morphology of the LDH precursor, consisting of well-distributed CoNi-alloy@CoNi-sulfide nanoparticles with a core-shell structure, and demonstrates promising performance toward hydrazine electrooxidation.