Catalytic Proficiency Research Articles

Developing Catalysts for the Hydrolysis of Glycosidic Bonds in Oligosaccharides Using a Spectrophotometric Screening Assay.

In a proof-of-concept study, a method for the empirical design of polyacrylate gel catalysts with the ability to cleave 1→4 α-glycosidic bonds in di- and trisaccharides was elaborated. The study included the synthesis of a 300-gel member library based on two different cross-linkers and 10 acrylate monomers, identification of monomodal gels by dynamic light scattering, and a 96-well plate spectrophotometric screening assay to monitor the hydrolysis of chromophore-free maltose into glucose units. The composition of the matrix of the most efficient catalysts in the library was found to enable CH-π, hydrophobic, and H-bond accepting interactions during the hydrolysis as typically seen in glycosylases. The same gel catalysts allowed the hydrolysis of the trisaccharide maltotriose with a catalytic proficiency of 2 × 106 indicating transition state stabilization during the hydrolysis of 5 × 10-7. The results place the developed gels among the most efficient catalysts developed for the hydrolysis of natural saccharides. The elaborated strategy may lead to catalysts that can transform polysaccharides into valuable synthons in the near future.

Computational Screening of Putative Catalyst Transition Metal Complexes as Guests in a Ga4L612- Nanocage.

Metal-organic cages form well-defined microenvironments that can enhance the catalytic proficiency of encapsulated transition metal complexes (TMCs). We introduce a screening protocol to efficiently identify TMCs that are promising candidates for encapsulation in the Ga4L612- nanocage. We obtain TMCs from the Cambridge Structural Database with geometric and electronic characteristics amenable to encapsulation and mine the text of associated manuscripts to curate TMCs with documented catalytic functionality. By docking candidate TMCs inside the nanocage cavity and carrying out electronic structure calculations, we identify a subset of successfully optimized candidates (TMC-34) and observe that encapsulated guests occupy an average of 60% of the cavity volume, in line with previous observations. Notably, some guests occupy as much as 72% of the cavity as a result of linker rotation. Encapsulation has a universal effect on the electrostatic potential (ESP), systematically decreasing the ESP at the metal center of each TMC in the TMC-34 data set, while minimally altering TMC metal partial charges. Collectively these observations support geometry-based screening of potential guests and suggest that encapsulation in Ga4L612- cages could electrostatically stabilize diverse cationic or electropositive intermediates. We highlight candidate guests with associated known reactivity and solubility most amenable for encapsulation in experimental follow-up studies.

Sustainable Co(III)/Co(II) cycles triggered by Co-Zn bimetallic MOF encapsulating Fe nanoparticles for high-efficiency peracetic acid activation to degrade sulfamethoxazole: Enhanced performance and synergistic mechanism

Herein, a dual-metal-organic framework (MOF) assisted strategy to construct a core-shell structure magnetic Fe3O4@ZIFs composites was proposed for peracetic acid (PAA) activation. Results showed that the Fe3O4@ZIFs displayed superior activity relative to analogous counterparts, achieving 99.3 % degradation of SMX within 30 min. Both the radical pathways of CH3C(O)OO· and non-radical 1O2 were recognized as the primary mechanisms in SMX oxidation, while the radicals such as ·OH, CH3C(O)O·, and ·O2– along with high-valent metal species (CoIVO2+ and FeIVO2+) demonstrated a limited contribution. During the process, the Co sites on the surface of ZIFs, serving as the primary active sites, activated the PAA through the redox cycle of Co(II)/Co(III) to generate reactive oxygen species (ROS). The encapsulated Fe3O4 nanoparticles were subjected to precise electron transmission, benefiting Co(II) recovery for enhanced Co(II)/Co(III) cycling. Besides, the strong interaction between Zn and Co in outer bimetallic ZIFs effectively mitigated Co leaching, highlighting the synergy effect of the catalytic system with multiple active sites. The Fe3O4@ZIFs composites retained excellent catalytic proficiency after four successive cycles. This study provides a strategy to accelerate Co(II)/Co(III) circulation in heterogeneous systems and highlights the significant potential of MOFs in the construction of high-efficiency Co-based catalysts for PAA activation in environmental remediation.

Engineered Methionine Adenosyltransferase Cascades for Metabolic Labeling of Individual DNA Methylomes in Live Cells.

Methylation, a widely occurring natural modification serving diverse regulatory and structural functions, is carried out by a myriad of S-adenosyl-l-methionine (AdoMet)-dependent methyltransferases (MTases). The AdoMet cofactor is produced from l-methionine (Met) and ATP by a family of multimeric methionine adenosyltransferases (MAT). To advance mechanistic and functional studies, strategies for repurposing the MAT and MTase reactions to accept extended versions of the transferable group from the corresponding precursors have been exploited. Here, we used structure-guided engineering of mouse MAT2A to enable biocatalytic production of an extended AdoMet analogue, Ado-6-azide, from a synthetic methionine analogue, S-(6-azidohex-2-ynyl)-l-homocysteine (N3-Met). Three engineered MAT2A variants showed catalytic proficiency with the extended analogues and supported DNA derivatization in cascade reactions with M.TaqI and an engineered variant of mouse DNMT1 both in the absence and presence of competing Met. We then installed two of the engineered variants as MAT2A-DNMT1 cascades in mouse embryonic stem cells by using CRISPR-Cas genome editing. The resulting cell lines maintained normal viability and DNA methylation levels and showed Dnmt1-dependent DNA modification with extended azide tags upon exposure to N3-Met in the presence of physiological levels of Met. This for the first time demonstrates a genetically stable system for biosynthetic production of an extended AdoMet analogue, which enables mild metabolic labeling of a DNMT-specific methylome in live mammalian cells.

Synergistic catalytic performance of g-C3N4/UiO-66 based mesoporous carbons: Synthesis, characterization, and applications in oxidation reactions

Todays, the heteroatom-doped mesoporous carbon resulting from Metal-Organic Framework (MOF) has attracted the substantial consideration in various filed especially in the heterogeneous catalytic protocols due to their adaptable features. These materials have a high Specific Surface Area (SSA), which offers copious activated sites for the catalytic activity. The mesoporous nature also simplifies the effectual mass transfer, thereby amplifying the overall catalytic procedure. In this study, a highly effective Zr@NC-T samples were synthesized via pyrolyzing a composite of g-C3N4 and UiO-66. The mesoporous structure of Zr@NC-T, revealed a desired SSA varying from 591.38 to 404.26 m2.g−1 due to its surface defect and disorder. Among the synthesized catalysts, Zr@NC-700 (pyrolyzed at 700 °C) exposed preferred catalytic proficiency in the selective oxidation of BnOHs to BnCHO due to its higher surface defect which is caused the higher SSA and structure defect. Furthermore, the Zr@NC-700 catalyst as well proved the acceptable chemical stability due to its reusability.

Selenium-doped porous-C3N4 decorated with Cu NPs, as an operative heterogenous catalyst for the nitroarenes reduction reaction

In this project, the insitu selenium-doped porous graphitic carbon nitride, named as Se-p-C3N4 was synthezied using melamine, ammonium chloride, and selenium dioxide as the low-cost precursor materials via a facil thermal condensation protocol and applied as an superlative support with high specific surface area (125.3 m2/g). Cu NPs were coorporated on the surface of Se-p-C3N4 over the co-reduction protocol with Hydrazine Hydrate as a reducing agant to prepare the Se-p-C3N4/Cu nanocatalyst. Several chemophysical analysis confirmed the structure of Se-p-C3N4/Cu. The Se-p-C3N4/Cu was showen the exceptional catalytic proficiency in the hydrogenation of nitroaromatic compounds utilizing a green redactant in an environmentally friendly aqueous media, and the related anilines were produced as sole products. The supreme catalytic effeciency and durability of the Se-p-C3N4/Cu can be attributed to the synergetic collaboration between the highly distributed Cu NPs and the support.

Discovery, Structure, and Engineering of a cis‐Geranylfarnesyl Diphosphate Synthase

Abstractcis‐Prenyltransferases (cis‐PTs) catalyze the sequential head‐to‐tail condensation of isopentenyl diphosphate (IPP) to allylic diphosphates, producing mixed E–Z prenyl diphosphates of varying lengths; however, the specific enzymes synthesizing cis‐C25 prenyl diphosphates have not been identified. Herein, we present the discovery and characterization of a cis‐geranylfarnesyl diphosphate synthase (ScGFPPS) from Streptomyces clavuligerus. This enzyme demonstrates high catalytic proficiency in generating six distinct cis‐polyisoprenoids, including three C25 and three C20 variants. We determined the crystal structure of ScGFPPS. Additionally, we unveil the crystal structure of nerylneryl diphosphate synthase (NNPS), known for synthesizing an all‐cis‐C20 polyisoprenoid. Comparative structural analysis of ScGFPPS and NNPS has identified key differences that influence product specificity. Through site‐directed mutagenesis, we have identified eight single mutations that significantly refine the selectivity of ScGFPPS for cis‐polyisoprenoids. Our findings not only expand the functional spectrum of cis‐PTs but also provide a structural comparison strategy in cis‐PTs engineering.

Discovery, Structure, and Engineering of a cis-Geranylfarnesyl Diphosphate Synthase.

cis-Prenyltransferases (cis-PTs) catalyze the sequential head-to-tail condensation of isopentenyl diphosphate (IPP) to allylic diphosphates, producing mixed E-Z prenyl diphosphates of varying lengths; however, the specific enzymes synthesizing cis-C25 prenyl diphosphates have not been identified. Herein, we present the discovery and characterization of a cis-geranylfarnesyl diphosphate synthase (ScGFPPS) from Streptomyces clavuligerus. This enzyme demonstrates high catalytic proficiency in generating six distinct cis-polyisoprenoids, including three C25 and three C20 variants. We determined the crystal structure of ScGFPPS. Additionally, we unveil the crystal structure of nerylneryl diphosphate synthase (NNPS), known for synthesizing an all-cis-C20 polyisoprenoid. Comparative structural analysis of ScGFPPS and NNPS has identified key differences that influence product specificity. Through site-directed mutagenesis, we have identified eight single mutations that significantly refine the selectivity of ScGFPPS for cis-polyisoprenoids. Our findings not only expand the functional spectrum of cis-PTs but also provide a structural comparison strategy in cis-PTs engineering.

Selection of a promiscuous minimalist cAMP phosphodiesterase from a library of de novo designed proteins

The ability of unevolved amino acid sequences to become biological catalysts was key to the emergence of life on Earth. However, billions of years of evolution separate complex modern enzymes from their simpler early ancestors. To probe how unevolved sequences can develop new functions, we use ultrahigh-throughput droplet microfluidics to screen for phosphoesterase activity amidst a library of more than one million sequences based on a de novo designed 4-helix bundle. Characterization of hits revealed that acquisition of function involved a large jump in sequence space enriching for truncations that removed >40% of the protein chain. Biophysical characterization of a catalytically active truncated protein revealed that it dimerizes into an α-helical structure, with the gain of function accompanied by increased structural dynamics. The identified phosphodiesterase is a manganese-dependent metalloenzyme that hydrolyses a range of phosphodiesters. It is most active towards cyclic AMP, with a rate acceleration of ~109 and a catalytic proficiency of >1014 M−1, comparable to larger enzymes shaped by billions of years of evolution.

Impact of N-Glycosylation on Protein Structure and Dynamics Linked to Enzymatic C-H Activation in the M. oryzae Lipoxygenase.

Lipoxygenases (LOXs) from pathogenic fungi are potential therapeutic targets for defense against plant and select human diseases. In contrast to the canonical LOXs in plants and animals, fungal LOXs are unique in having appended N-linked glycans. Such important post-translational modifications (PTMs) endow proteins with altered structure, stability, and/or function. In this study, we present the structural and functional outcomes of removing or altering these surface carbohydrates on the LOX from the devastating rice blast fungus, M. oryzae, MoLOX. Alteration of the PTMs did notinfluence the active site enzyme-substrate ground state structures as visualized by electron-nuclear double resonance (ENDOR) spectroscopy. However, removal of the eight N-linked glycans by asparagine-to-glutamine mutagenesis nonetheless led to a change in substrate selectivity and an elevated activation energy for the reaction with substrate linoleic acid, as determined by kinetic measurements. Comparative hydrogen-deuterium exchange mass spectrometry (HDX-MS) analysis of wild-type and Asn-to-Gln MoLOX variants revealed a regionally defined impact on the dynamics of the arched helix that covers the active site. Guided by these HDX results, a single glycan sequon knockout was generated at position 72, and its comparative substrate selectivity from kinetics nearly matched that of the Asn-to-Gln variant. The cumulative data from model glyco-enzyme MoLOX showcase how the presence, alteration, or removal of even a single N-linked glycan can influence the structural integrity and dynamics of the protein that are linked to an enzyme's catalytic proficiency, while indicating that extensive glycosylation protects the enzyme during pathogenesis by protecting it from protease degradation.

Review—Recent Advancements in Molybdenum Carbides for Efficient Hydrogen Evolution Reaction

The quest for economical and sustainable electrocatalysts to facilitate the hydrogen evolution reaction (HER) is paramount in addressing the pressing challenges associated with carbon dioxide emissions. Molybdenum carbide-based nanomaterials have emerged as highly promising electrocatalysts for HER due to their Pt-like catalytic proficiency, exceptional stability, and the versatility of their crystal phases. Within this comprehensive review, we explore the diverse methodologies for synthesizing molybdenum carbides, including solid-gas, solid-solid, and solid-liquid phase reactions. In addition, a thorough elucidation of the hydrogen generation process through water electrolysis is provided. Furthermore, a spectrum of innovative strategies aimed at augmenting the performance of molybdenum carbides in the HER milieu is introduced, encompassing cutting-edge techniques such as phase-transition engineering, the construction of heterostructures, hetero-atom doping, the integration of hybrid structures with carbon materials, defect engineering, and meticulous surface modification. The review culminates by underscoring the current challenges and the promising prospects in the advancement of electrocatalysts for hydrogen production, with a dedicated focus on molybdenum carbide-based catalysts.

Enhanced production of naphtha-range compounds from arundo donax via catalytic fast pyrolysis using SAPO-11

Arundo donax, acknowledged for its elevated energy content, substantial biomass yield and rapid growth, stands as an alluring candidate for biofuel production. In this investigation, a molecular sieve-based catalyst was utilized to scrutinize the catalytic fast pyrolysis (CFP) of Arundo donax, aiming for the production of naphtha-range compounds. The study also encompassed the evaluation of pyrolysis product yields within a fixed-bed reactor. The systematic exploration included an assessment of the impacts arising from catalyst type, temperature, weight hourly space velocity (WHSV), and N2 flow rate. The results demonstrated that at 500 °C, WHSV of 1 h−1 and N2 flow rate of 300 ml/min, SAPO-11 exhibited a selectivity of 64.55% to naphtha-range compounds and 64.55% to isomerous naphtha-range compounds. This was in stark contrast to the control group, which contained no catalyst (with a selectivity of 41.40% and 3.19%, respectively), SAPO-41 (with a selectivity of 11.02% and 9.55%, respectively) and HZSM-5 (with a selectivity of 59.89% and 53.51%, respectively). Additionally, SAPO-11 yielded the highest bio-oil compared to other catalysts (SAPO-11 of 28.52 wt% > none of 19.48 wt% > HZSM-5 of 18.90 wt% > SAPO-41 of 13.11 wt%). The conclusions drawn from these findings imply that the synthesized SAPO-11 catalyst exhibited superior catalytic activity and isomerization proficiency in contrast to other catalysts (SAPO-41 and HZSM-5). Remarkably, under the specified conditions of SAPO-11 catalyst, temperature = 500 °C, WHSV = 1 h−1 and N2 flow rate = 200 ml/min, the CFP process yielded a remarkable maximum absolute yield of the naphtha-range compound at 25.82 wt%, with an isomerized naphtha-range compound absolute yield of 25.35 wt%.

New Cu(II) Schiff-base complex modified on magnetic nanoparticles: Oxidation and DFT investigation

A copper magnetic nanocatalyst was facilely synthesized by surface modification of silica magnetic nanoparticles (Fe3O4@SiO2) via reaction with 3-aminopropyltrimethoxysilane (Fe3O4@SiO2@APTMS), followed by a subsequent reaction with thiophene-2-carbaldehyde to form a Schiff base (Fe3O4@SiO2@SB). Sequentially, reaction with Cu(CH3COO)2·H2O in ethanol yielded Fe3O4@SiO2@[SB@Cu] (CH3COO)2. This nanomagnetic catalyst was comprehensively characterized using Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Thermogravimetric Analysis (TGA), and Vibrating Sample Magnetometry (VSM) techniques. The catalytic proficiency of these nanoparticles was evaluated through alkene and alcohol oxidation reactions. Under optimized conditions, the nanocatalyst exhibited significant efficacy in oxidizing styrene, cyclohexene, and benzyl alcohol, with notable selectivity values of 88 %, 100 %, and 100 % for the respective formation of styrene epoxide, 2-cyclohexene-1-one, and benzoic acid. The heterogeneous copper nanocatalyst offers advantages, including high conversion rates, facile separation, and exceptional selectivity in alkene and alcohol oxidation. Additionally, this study investigated density functional theory (DFT) methods, encompassing geometric optimization, natural charge analysis, molecular electrostatic potential maps, and vibrational normal modes of the chelating ligands.

Theoretical Improvements in Enzyme Efficiency Associated with Noisy Rate Constants and Increased Dissipation.

Previous studies have revealed the extraordinarily large catalytic efficiency of some enzymes. High catalytic proficiency is an essential accomplishment of biological evolution. Natural selection led to the increased turnover number, kcat, and enzyme efficiency, kcat/KM, of uni-uni enzymes, which convert a single substrate into a single product. We added or multiplied random noise with chosen rate constants to explore the correlation between dissipation and catalytic efficiency for ten enzymes: beta-galactosidase, glucose isomerase, β-lactamases from three bacterial strains, ketosteroid isomerase, triosephosphate isomerase, and carbonic anhydrase I, II, and T200H. Our results highlight the role of biological evolution in accelerating thermodynamic evolution. The catalytic performance of these enzymes is proportional to overall entropy production-the main parameter from irreversible thermodynamics. That parameter is also proportional to the evolutionary distance of β-lactamases PC1, RTEM, and Lac-1 when natural or artificial evolution produces the optimal or maximal possible catalytic efficiency. De novo enzyme design and attempts to speed up the rate-limiting catalytic steps may profit from the described connection between kinetics and thermodynamics.

UV-assisted photochemical transformation of a tetranuclear copper(II) complex: a DFT supported study on β-lactamase inhibitory activity towards antibiotic resistance.

Herein, we present a dark-green crystalline tetranuclear Cu(II) Schiff base complex {C1 = [Cu4L4](ClO4)4(DMF)4(H2O)} using a N,N,O donor ligand (HL), namely 2-(((2-hydroxypropyl)imino)methyl)-6-methoxyphenol. Spectro-photometrical investigation on the β-lactamase-like activity of this coordinately saturated system revealed its catalytic inefficiency towards hydrolysis of nitrocefin as a model substrate. This complex has attracted significant interest as a promising photo-catalyst owing to its narrow band gap (2.40 eV) as predicted from DFT calculations and its higher responsivity towards UV light. Therefore, C1 is effectively involved in the photocatalytic reduction of perchlorate to Cl- in the presence of a hole scavenger (H2O-MeOH) under prolonged UV irradiation and itself becomes photo-cleaved to yield a new dark-brown colored chlorobridged dinuclear crystalline complex C2 {[CuL(H2O)2Cl3]H2O}. Furthermore, C2 was deployed as a functional β-lactamase model and was found to show a remarkable catalytic proficiency towards the hydrolysis of nitrocefin in 70 : 30 (V/V) MeOH-H2O medium. This pro-catalyst C2 has been speculated to generate an aqua bridged active catalyst that plays a crucial factor in hydrolysis. This phenomenon was again experimentally established by potentiometric pH titration where C2 displays only one pKa value (7.11) in the basic pH range, indicating the deprotonation of the bridged water molecule. Based on several other kinetic studies, it may be postulated that the hydrolysis of nitrocefin is initiated by the nucleophilic attack of a bridging hydroxide, followed by very fast protonation of the intermediate to furnish the hydrolyzed product. It is noteworthy that the rate of nitrocefin hydrolysis is greatly inhibited in the presence of external chloride concentration. To the best of our knowledge, this is the first report on the photochemical behavior of such a tetranuclear copper(II) Schiff base complex. Our current interest is focused on inventing a potent β-lactamase inhibitory therapeutic as well as elucidating its mechanism through comprehensive chemical analysis.

The synergistic benefits of hydrate CoMoO4 and carbon nanotubes culminate in the creation of highly efficient electrocatalysts for hydrogen evolution

The electrochemical hydrogen evolution reaction (HER) stands as a burgeoning clean energy prospect. This work synthesized composite materials (CMOxCNT), exhibiting exceptional electrocatalytic prowess, emerged from the fusion of cobalt molybdate (CMO) and carbon nanotubes (CNT). The outcomes of characterization established the CMO as a hydrated cobalt molybdate mineral, the theoretical molecular formula CoMoO4·nH2O. The CMO particles demonstrated a distinctive rod-shaped morphology. Notably, under the optimal mass ratio (CMO/CNT=7/3), carbon nanotubes exhibited partial coverage of the CMO particle surface. Electrochemical hydrogen evolution experiments decisively illuminated the catalytic potency of the CMO-CNT composites, which effectively improved the HER efficiency. The CMO3CNT, distinguished by elevated electrochemically active surface area, yielded a lower HER overpotential of 171.5 mV (at 10 mA·cm−2) and Tafel slope of 69.9 mV dec−1. Importantly, the material demonstrated commendable catalytic stability across a 30-hour span of i-t tests and 3000 CV cycles. Density Functional Theory (DFT) analyses unveiled at the adept electron transfer capabilities in CNT and favorable catalytic ability exhibited in CMO contributed substantively to the composite's overall efficacy. The remarkable catalytic proficiency of CMO stemmed from the synergistic interplay between cobalt and molybdenum atoms. The amalgamation of both inherent advantages engendered the composite's pronounced electrocatalytic performance.

Continuous Fatty Acid Decarboxylation using an Immobilized Photodecarboxylase in a Membrane Reactor.

The realm of photobiocatalytic alkane biofuel synthesis has burgeoned recently; however, the current dearth of well-established and scalable production methodologies in this domain remains conspicuous. In this investigation, we engineered a modified form of membrane-associated fatty acid photodecarboxylase sourced from Micractinium conductrix (McFAP). This endeavour resulted in creating an innovative assembled photoenzyme-membrane (protein load 5 mg cm-2 ), subsequently integrated into an illuminated flow apparatus to achieve uninterrupted generation of alkane biofuels. Through batch experiments, the photoenzyme-membrane exhibited its prowess in converting fatty acids spanning varying chain lengths (C6-C18). Following this, the membrane-flow mesoscale reactor attained a maximum space-time yield of 1.2 mmol L-1 h-1 (C8) and demonstrated commendable catalytic proficiency across eight consecutive cycles, culminating in a cumulative runtime of eight hours. These findings collectively underscored the photoenzyme-membrane's capability to facilitate the biotransformation of diverse fatty acids, furnishing valuable benchmarks for the conversion of biomass via photobiocatalysis.

Retracing the Rapid Evolution of an Herbicide-Degrading Enzyme by Protein Engineering.

The mechanisms underlying the rapid evolution of novel enzymatic activities from promiscuous side activities are poorly understood. Recently emerged enzymes catalyzing the catabolic degradation of xenobiotic substances that have been spread out into the environment during the last decades provide an exquisite opportunity to study these mechanisms. A prominent example is the herbicide atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine), which is degraded through a number of enzymatic reactions constituting the Atz pathway. Here, we analyzed the evolution of the hydroxyatrazine ethylaminohydrolase AtzB, a Zn(II)-dependent metalloenzyme that adopts the amidohydrolase fold and catalyzes the second step of the Atz pathway. We searched for promiscuous side activities of AtzB, which might point to the identity of its progenitor. These investigations revealed that AtzB has low promiscuous guanine deaminase activity. Furthermore, we found that the two closest AtzB homologues, which have not been functionally annotated up to now, are guanine deaminases with modest promiscuous hydroxyatrazine hydrolase activity. Based on sequence comparisons with the closest AtzB homologues, the guanine deaminase activity of AtzB could be increased by three orders of magnitude through the introduction of only four active site mutations. Interestingly, introducing the inverse four mutations into the AtzB homologues significantly enhanced their hydroxyatrazine hydrolase activity, and in one case is even equivalent to that of wild-type AtzB. Molecular dynamics simulations elucidated the structural and molecular basis for the mutation-induced activity changes. The example of AtzB highlights how novel enzymes with high catalytic proficiency can evolve from low promiscuous side activities by only few mutational events within a short period of time.

Assisted assembling of Bi2WO6/rGO composites: A 3D/2D Hierarchical nanostructures for enhanced photocatalytic water remediation and photo-(electro)catalytic water splitting proficiency

The current study explores the possibility of effectively improving Bi2WO6 (BWO) nanostructures in photocatalytic clean H2 generation and treating water from pharmaceutical wastes. BWO nanoparticles (NPs) hybridized with carbon-derived materials proved to be an efficient candidate in the field of photocatalysis. In this work, BWO nanostructures have been synthesized via the facile co-precipitation technique. The reduced graphene oxide (r-GO) was used as the carbon derivative for the hybridization process. Furthermore, different weight percentages of rGO were loaded with BWO NPs through the wet impregnation technique. The structural, and morphological analysis confirmed the formation of BWO/x% rGO composites. UV-DRS analysis showcased the reduction in bandgap in annexure with increased light absorbance region upon rGO inclusion. Time-resolved photoluminescence (TRPL) proved a prolonged lifetime for BWO/15% rGO composite. In addition, their photocatalytic abilities were put to the test, and BWO/15% rGO nano-hybrid demonstrated a superior degradation of pharmaceutical wastes like tetracycline hydrochloride (TCH) and levofloxacin (LVX) from water in 15 min. Furthermore, photo-electrochemical measurements showed the lowest onset potential and better charge transfer for efficient splitting of water. The photocatalytic water splitting was performed in the presence of sacrificial agents and in the absence of sacrificial agents, where BWO/15% rGO exhibited maximum H2 evolution.

Synthesis, Characterization, and Environmental Applications of Cu-Ni-Doped Bismuth Molybdate

Bismuthoxide-based catalysts gained attention for photocatalytic remediation of environmental pollutants owing to their low cost, feasibility, stability, small, and tunable band gap. In the present work, bismuth molybdate was modified via transition metal doping to achieve maximum catalytic efficiency. This aim was accomplished by synthesizing novel Cu2+ and Ni2+ codoped bismuth molybdate (CuNi/Bi2MoO6, Cu/Bi2MoO6, and Ni/Bi2MoO6) which were utilized for heavy metal reduction and dyes degradation. Pure bismuth molybdate was also fabricated for comparative studies. All the prepared samples were characterized by XRD, Raman spectroscopy, SEM, and EDX. Optical studies for band gap calculations were carried out by UV-Visible spectrophotometry and decrease in band gap was observed in doped materials. Pseudo-first-order kinetic studies were performed to find the rate constants and regression values for Cr(VI) reduction and degradation of rhodamine B and malachite green using CuNi/Bi2MoO6. Codoped bismuth molybdate exhibited more than 95% photocatalytic performance for Cr(VI) reduction and degradation of rhodamine B and malachite green dyes. Reusability of catalyst was confirmed up to six cycles. Considering its catalytic proficiency, CuNi/Bi2MoO6 is anticipated to be utilized for more environment friendly applications in future.