Search Results (9)

The study compares how acetyl donor molecules tetraacetylethylenediamine (TAED) and pentaacetate glucose (PAG) improve the antibacterial efficacy of solutions activated with a low-temperature atmospheric-pressure argon plasma jet. Plasma activation of solubilised TAED and PAG produce solutions with different chemical compositions and oxidative potentials. Both acetyl donor molecules enhance the hydrogen peroxide (H₂O₂) concentration in solution with TAED being more effective compared to PAG. However, PAG is more effective at forming peracetic acid (PAA) from reaction of its acetyl donor groups with plasma generated H₂O₂. The enhanced oxidative potential of plasma activated TAED and PAG solutions were shown to significantly improve bactericidal activity against common wound pathogens Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus compared to plasma activated water produced without acetyl donors. Furthermore, the oxidative capacity of plasma activated PAG was least affected by the bacterial oxidative defence enzyme catalase, attributed to the high concentration of PAA produced in this formulation. Overall, the above data show that acetyl donors may help improve next generation of antimicrobial formulations produced by plasma, which might help combat increasing problems of antimicrobial resistance. Full article

Acyl glucoses are a group of specialized metabolites produced by Solanaceae. Solanum pennellii, a wild-type tomato plant, produces acyl glucoses in its hair-like epidermal structures known as trichomes. These compounds have been found to be herbicides, microbial growth inhibitors, or allelopathic compounds. However, there are a few reports regarding isolation and investigation of biological activities of acyl glucoses in its pure form due to the difficulty of isolation. Here, we report a new acyl glucose, pennelliiside D, isolated and identified from S. pennellii. Its structure was determined by 1D NMR and 2D NMR, together with FD-MS analysis. To clarify the absolute configuration of the acyl moiety of 2-methylbutyryl in the natural compound, two possible isomers were synthesized starting from β-D-glucose pentaacetate. By comparing the spectroscopic data of natural and synthesized compounds of isomers, the structure of pennelliiside D was confirmed to be 3,4-O-diisobutyryl-2-O-((S)-2-methylbutyryl)-D-glucose. Pennelliiside D and its constituent fatty acid moiety, (S)-2-methylbutanoic acid, did not show root growth-inhibitory activity. Additionally, in this study, chemical synthesis pathways toward pennelliisides A and B were adapted to give 1,6-O-dibenzylpennelliisides A and B. Full article

Acetyl xylan esterases (AXEs) are enzymes capable of hydrolysing the acetyl bonds in acetylated xylan, allowing for enhanced activity of backbone-depolymerizing enzymes. Bioprospecting novel AXE is essential in designing enzyme cocktails with desired characteristics targeting the complete breakdown of lignocellulose. In this article, we report the characterisation of a novel AXE identified as Gene_id_40363 in the metagenomic library analysed from the gut microbiota of the common black slug. The conserved domain description was identified with an NCBI BLASTp search using the translated nucleotide sequence as a query. The activity of the recombinant enzyme was tested on various synthetic substrates and acetylated substrates. The protein sequence matched the conserved domain described as putative hydrolase and aligned closely to an uncharacterized esterase from Buttiauxella agrestis, hence the designation as BaAXE. BaAXE showed low sequence similarity among characterized CE family proteins with an available 3D structure. BaAXE was active on 4-nitrophenyl acetate, reporting a specific activity of 78.12 U/mg and a Km value of 0.43 mM. The enzyme showed optimal activity at 40 °C and pH 8 and showed high thermal stability, retaining over 40% activity after 2 h of incubation from 40 °C to 100 °C. BaAXE hydrolysed acetyl bonds, releasing acetic acid from acetylated xylan and β-D-glucose pentaacetate. BaAXE has great potential for biotechnological applications harnessing its unique characteristics. In addition, this proves the possibility of bioprospecting novel enzymes from understudied environments. Full article

The SGNH family esterases are highly effective biocatalysts due to their strong catalytic efficiencies, great stabilities, relatively small sizes, and ease of immobilization. Here, a novel SGNH family esterase (LaSGNH1) from Lactobacillus acidophilus NCFM, which has homologues in many Lactobacillus species, was identified, characterized, and immobilized. LaSGNH1 is highly active towards acetate- or butyrate-containing compounds, such as p-nitrophenyl acetate or 1-naphthyl acetate. Enzymatic properties of LaSGNH1, including thermal stability, optimum pH, chemical stability, and urea stability, were investigated. Interestingly, LaSGNH1 displayed a wide range of substrate specificity that included glyceryl tributyrate, tert-butyl acetate, and glucose pentaacetate. Furthermore, immobilization of LaSGNH1 by crosslinked enzyme aggregates (CLEAs) showed enhanced thermal stability and efficient recycling property. In summary, this work paves the way for molecular understandings and industrial applications of a novel SGNH family esterase (LaSGNH1) from Lactobacillus acidophilus. Full article

Molecular information about family VIII esterases, which have similarities with class C β-lactamases and penicillin-binding proteins, remains largely unknown. In this study, a novel family VIII esterase with β-lactamase activity (PsEstA) from Paenibacillus sp. was characterized using several biochemical and biophysical methods. PsEstA was effective on a broad range of substrates including tertiary butyl acetate, glyceryl tributyrate, glucose pentaacetate, olive oil, and p-nitrophenyl esters. Additionally, PsEstA hydrolyzed nitrocefin, cefotaxime, and 7-aminocephalosporanic acid. Interestingly, two forms of immobilized PsEstA (CLEAs-PsEstA and mCLEAs-PsEstA) showed high recycling property and enhanced stability, but hybrid nanoflowers (hNFs) of PsEstA require improvement. This study provides a molecular understanding of substrate specificities, catalytic regulation, and immobilization of PsEstA, which can be efficiently used in biotechnological applications. Full article

Hydrogels are used for a variety of technical and medical applications capitalizing on their three-dimensional (3D) cross-linked polymeric structures and ability to act as a reservoir for encapsulated species (potentially encapsulating or releasing them in response to environmental stimuli). In this study, carbohydrate-based organogels were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization of a β-D-glucose pentaacetate containing methacrylate monomer (Ac-glu-HEMA) in the presence of a di-vinyl cross-linker; these organogels could be converted to hydrogels by treatment with sodium methoxide (NaOMe). These materials were studied using solid state ¹³C cross-polarization/magic-angle spinning (CP/MAS) NMR, Fourier transform infrared (FTIR) spectroscopy, and field emission scanning electron microscopy (FE-SEM). The swelling of the gels in both organic solvents and water were studied, as was their ability to absorb model bioactive molecules (the cationic dyes methylene blue (MB) and rhodamine B (RhB)) and absorb/release silver nitrate, demonstrating such gels have potential for environmental and biomedical applications. Full article

Carbohydrate-active enzymes (CAZymes) regulate the synthesis, degradation, and modification of the poly—and oligosaccharides in all three kingdoms of life. A novel carbohydrate acetylesterase from Sinorhizobium meliloti, designated SmAcE1, was identified, characterized, and crystallized. This SmAcE1 is classified into the carbohydrate esterase family 3 (CE3) based on the sequence alignments with other currently known carbohydrate esterase (CE) family enzymes. The SmAcE1 was crystallized as a hexamer in a space group P2₁2₁2₁ with the unit cell parameters: a = 99.12 Å, b = 148.88 Å, c = 149.84 Å, and α = β = γ = 90.00°. The diffraction data set was collected up to a 2.05 Å resolution. Hydrolysis activity of SmAcE1 towards glucose pentaacetate and cellulose acetate was further confirmed using acetic acid release assay. Further crystallographic and functional analyses studies on SmAcE1 would be followed to fully understand the reaction mechanisms of CEs. Full article

Cellulose acetate (CA)-based materials, like cigarette filters, contribute to landscape pollution challenging municipal authorities and manufacturers. This study investigates the potential of enzymes to degrade CA and to be potentially incorporated into the respective materials, enhancing biodegradation. Deacetylation studies based on Liquid Chromatography-Mass Spectrometry-Time of Flight (LC-MS-TOF), High Performance Liquid Chromatography (HPLC), and spectrophotometric analysis showed that the tested esterases were able to deacetylate the plasticizer triacetin (glycerol triacetate) and glucose pentaacetate (cellulose acetate model compound). The most effective esterases for deacetylation belong to the enzyme family 2 (AXE55, AXE 53, GAE), they deacetylated CA with a degree of acetylation of up to 1.8. A combination of esterases and cellulases showed synergistic effects, the absolute glucose recovery for CA 1.8 was increased from 15% to 28% when an enzymatic deacetylation was performed. Lytic polysaccharide monooxygenase (LPMO), and cellobiohydrolase were able to cleave cellulose acetates with a degree of acetylation of up to 1.4, whereas chitinase showed no activity. In general, the degree of substitution, chain length, and acetyl group distribution were found to affect CA degradation. This study shows that, for a successful enzyme-based deacetylation system, a cocktail of enzymes, which will randomly cleave and generate shorter CA fragments, is the most suitable. Full article

The deacylation of glucose, galactose and mannose pentaacetates, galactose and mannose penta(3-bromo)benzoates, as well as the dealkylation of 2,3,4,6-tetra-O-acetyl and 2,3,4,6-tetra-O-(3-bromo)benzoyl methyl α-D-glucopyranosides have been studied. In addition, a computational study on the deacylation of β-D-glucose pentaacetate has been carried out with density functional theory (B3LYP/6-31G*). The anomeric effect during deacetylation and dealkylation has been clearly demonstrated in both experimental and computational results. Full article