5 research outputs found
Antimicrobial Peptides Designed against the Ω-Loop of Class A β-Lactamases to Potentiate the Efficacy of β-Lactam Antibiotics
Class A serine β-lactamases (SBLs) have a conserved non-active site structural domain called the omega loop (Ω-loop), in which a glutamic acid residue is believed to be directly involved in the hydrolysis of β-lactam antibiotics by providing a water molecule during catalysis. We aimed to design and characterise potential pentapeptides to mask the function of the Ω-loop of β-lactamases and reduce their efficacy, along with potentiating the β-lactam antibiotics and eventually decreasing β-lactam resistance. Considering the Ω-loop sequence as a template, a group of pentapeptide models were designed, validated through docking, and synthesised using solid-phase peptide synthesis (SPPS). To check whether the β-lactamases (BLAs) were inhibited, we expressed specific BLAs (TEM-1 and SHV-14) and evaluated the trans-expression through a broth dilution method and an agar dilution method (HT-SPOTi). To further support our claim, we conducted a kinetic analysis of BLAs with the peptides and employed molecular dynamics (MD) simulations of peptides. The individual presence of six histidine-based peptides (TSHLH, ETHIH, ESRLH, ESHIH, ESRIH, and TYHLH) reduced β-lactam resistance in the strains harbouring BLAs. Subsequently, we found that the combinational effect of these peptides and β-lactams sensitised the bacteria towards the β-lactam drugs. We hypothesize that the antimicrobial peptides obtained might be considered among the novel inhibitors that can be used specifically against the Ω-loop of the β-lactamases
Antimicrobial Peptides Designed against the Ω-Loop of Class A β-Lactamases to Potentiate the Efficacy of β-Lactam Antibiotics
Class A serine β-lactamases (SBLs) have a conserved non-active site structural domain called the omega loop (Ω-loop), in which a glutamic acid residue is believed to be directly involved in the hydrolysis of β-lactam antibiotics by providing a water molecule during catalysis. We aimed to design and characterise potential pentapeptides to mask the function of the Ω-loop of β-lactamases and reduce their efficacy, along with potentiating the β-lactam antibiotics and eventually decreasing β-lactam resistance. Considering the Ω-loop sequence as a template, a group of pentapeptide models were designed, validated through docking, and synthesised using solid-phase peptide synthesis (SPPS). To check whether the β-lactamases (BLAs) were inhibited, we expressed specific BLAs (TEM-1 and SHV-14) and evaluated the trans-expression through a broth dilution method and an agar dilution method (HT-SPOTi). To further support our claim, we conducted a kinetic analysis of BLAs with the peptides and employed molecular dynamics (MD) simulations of peptides. The individual presence of six histidine-based peptides (TSHLH, ETHIH, ESRLH, ESHIH, ESRIH, and TYHLH) reduced β-lactam resistance in the strains harbouring BLAs. Subsequently, we found that the combinational effect of these peptides and β-lactams sensitised the bacteria towards the β-lactam drugs. We hypothesize that the antimicrobial peptides obtained might be considered among the novel inhibitors that can be used specifically against the Ω-loop of the β-lactamases
Interfacial Solid-State Mediator-Based Z‑Scheme Heterojunction TiO<sub>2</sub>@Ti<sub>3</sub>C<sub>2</sub>/MgIn<sub>2</sub>S<sub>4</sub> Microflower for Efficient Photocatalytic Pharmaceutical Micropollutant Degradation and Hydrogen Generation: Stability, Kinetics, and Mechanistic Insights
Interface engineering is a vital concern to achieve high
efficiency
in heterojunction photocatalysts. The judicious design of efficient
interfacial electron mediators to accelerate the charge transfer efficiency
in Z-scheme heterojunctions with interfacial contact for enhancing
the performance of photocatalysts is essential and has been considered
an immense challenge. Inspired by nature, multivariate all-solid-state
Z-scheme TiO2@Ti3C2/MIS heterojunction
composites were fabricated via a simple two-step oxidation strategy
for highly promoted multiple photocatalytic applications. The morphological
analysis of TiO2@Ti3C2/MIS composites
demonstrated that MgIn2S4 (MIS) microflowers
were accumulated on the surface of Ti3C2@TiO2 nanosheets, providing dense active sites to the MIS microflowers
for efficient photocatalytic applications. The HRTEM and XPS characterization
distinctly clarified the close interfacial interaction between MIS
with Ti3C2 and TiO2. The optimized
TiO2@Ti3C2/MIS-15 photocatalysts
exhibited the highest photocatalytic ciprofloxacin degradation (92%)
and hydrogen evolution (520.3 μmol h–1) as
compared to those of their pristine counterparts. From the mechanistic
insights, the charge migration pathway was observed between MIS and
TiO2, where Ti3C2 nanosheets served
as an electron bridge in constructing the Z-scheme and thus extended
the lifetime of the charge carriers photoinduced by MIS and TiO2. The significant participation of •O2– and •OH radicals during
photocatalytic CIP degradation was verified by active species trapping
experiments, EPR, and liquid chromatography–mass spectrometry
(LC-MS) analysis. The current study provides a strategy to design
mediator-based Z-scheme heterojunction interfaces for improving the
catalytic activity of MXene-derived photocatalysts
MXene Schottky Functionalized Z‑scheme Ternary Heterostructure for Enhanced Photocatalytic H<sub>2</sub>O<sub>2</sub> Production and H<sub>2</sub> Evolution
The design and development of a multiheterostructure
interface
signifies a promising route to overcome the drawbacks of single-component
and traditional heterostructured photocatalysts. Herein, a one-dimensional
(1D)/two-dimensional (2D)/2D heterostructure, α-MnO2@B/O-g-C3N4/d-Ti3C2,
is constructed by a facile two-step synthesis method to ensure charge
separation and is utilized for photocatalytic H2O2 production and H2 evolution. The formation of the individual
materials and nanohybrids as well as the 1D/2D/2D interfacial interaction
is ascertained by X-ray diffraction, Raman, and electron microscopy
studies, respectively. 5-MX/MBOCN shows optimum photocatalytic H2O2 production (2846.4 μmol h–1 g–1) with 10% ethanol and H2 evolution
(897.2 μmol h–1), which is, respectively,
2.5 and 1.6 times higher than that of the binary MBOCN counterpart.
The greater cathodic current density from linear sweep voltammetry,
hindered charge recombination from electrochemical impedance spectroscopy
and photoluminescence measurement, and better photodurability all
systematically demonstrated the improved photocatalytic performance.
The mechanistic investigation shows that in the ternary hybrid, electrons
flow from MnO2 to boron-doped g-C3N4 through a Z-scheme charge dynamics and then electrons flow to the
d-MXene surface, which acts as a cocatalyst. The charge transfer dynamics
is corroborated by time-resolved photoluminescence, cyclic voltametric
analysis, trapping experiment, and ESR analysis. This work instigates
the design and development of a high-efficiency cocatalyst-integrated
Z-scheme photocatalyst with strong interfacial interaction and high
redox ability for solar to chemical energy conversion