Mapping the Active Site of the Bacterial Enzyme LpxC Using Novel Carbohydrate‐Based Hydroxamic Acid Inhibitors*

LpxC (UDP‐3‐O‐(R‐3‐hydroxymyristoyl)‐GlcNAc deacetylase), an enzyme involved in the biosynthesis of lipid A, is crucial for the growth of Gram‐negative bacteria. This enzyme has accordingly been identified as a potential target for the development of novel antibiotics against Gram‐negative bacteria. The carbohydrate‐derived hydroxamic acid 1 (1,5‐anhydro‐2‐C‐(carboxymethyl N‐hydroxyamide)‐2‐deoxy‐3‐O‐myristoyl‐ D‐glucitol) was previously shown to exhibit a wide spectrum of inhibitory activity against LpxC enzymes. Here we describe the preparation of seven analogs of 1 and their enzymatic evaluation. Two of the hydroxyl groups (OH‐3 and 6) of the GlcNAc residue were found to be involved in the binding interaction, and there is an important hydrophobic interaction in the vicinity O‐3 position with the enzyme that recognizes aromatic as well as aliphatic substituents.     

New method of identifying morphine in urine samples using nanoparticle-dendrimer-enzyme hybrid system

The incorporation of morphine (MOR) into the nanoparticle structure is a viable alternative to traditional enzyme usage. It has good biological potential to separate MOR from real urine samples. In this study, a new method of MOR identification in real urine samples was synthesized using the β-glucuronidase-dendrimer poly amidoamine (PAMAM) enzyme hybrid system. Replacing MOR in dendrimer cavities significantly reduces enzyme consumption. The replacement technique is done in dendrimer cavities in two stages as an alternative to β-glucuronidase enzyme and even MOR. In this paper, firstly, PAMAM dendrimer G2 was synthesized based on silica. The β-glucuronidase enzyme was replaced inside its dendrimer cavities and the compound was released into a real urine sample containing MOR. The enzyme was extracted from dendrimer cavities. The MOR- β-glucuronidase enzyme bond broke. In the next stage of the process, free MOR entered the PAMAM dendrimer G2 cavities. MOR was detected in real urine samples.     

Bioassay-guided isolation of human carboxylesterase 2 inhibitory and antioxidant constituents from Laportea bulbifera: Inhibition interactions and molecular mechanism

Laportea bulbifera (Sieb. et. Zucc.) Wedd has long been utilized in Traditional Chinese Medicines (TCM) for the treatment of rheumatoid arthritis. However, the study of systematic anti-inflammatory chemical constituents in L. bulbifera has never been reported. Thus, bioassay-guided isolation for its roots part led to 46 compounds, including 38 phenolic derivatives. Their structures were determined on the basis of ¹H and ¹³C NMR and MS spectra. All compounds were isolated from L. bulbifera for the first time except for 13 compounds. Most of the compounds showed good COX-2 inhibitory activity (IC₅₀: 0.13–3.94 μM) and DPPH radical-scavenging activity (IC₅₀: 1.57–9.55 μM). Four compounds (4, 17, 35, and 43) with different skeletons showed preferential COX-2 over COX-1 inhibition with selective indices ranging from 12 to 171. High content active compounds are important for elucidating the basis of the active substance of TCM. Compound 4 (COX-2, IC₅₀ 0.24 μM), a high content compound, represented one of the best selective COX-2 inhibitors. Another high content active compound (35) with a different skeleton might have different mechanism. Further study for the inhibition kinetics against COX-2 indicated compounds 4 and 35 were noncompetitive and competitive COX-2 inhibitors, respectively. Moreover, molecular docking and molecular dynamics simulation data further indicated that compound 4 could bind in the cavity of COX-2 and interacted with key residues VAL-538, PHE-142, and GLY-225 of COX-2 through hydrogen bonds. The results indicated that L. bulbifera roots could be applied as antioxidant and anti-inflammatory agents due to their potent selective COX-2 inhibitory and antioxidant activity of phenolic compounds.     

Bimetallic CuCo Derived from Prussian Blue Analogue for Nonenzymatic Glucose Sensing

Bimetallic CuCo composites are prepared by calcinating copper hexacyanocobaltate precursor in N₂ atmosphere. The CuCo modified electrodes are fabricated for nonenzymatic glucose sensing in the alkaline electrolyte. The glucose can be directly electro-oxidized on the surface of the electrode catalyst mediated by the redox couples of Cu and Co. The optimal glucose sensor exhibits a high sensitivity (567 μA ⋅ mM⁻¹ ⋅ cm⁻²) in the range up to 825 μM with a detection limit of 3 μM and acceptable selectivity. The sensor can also be applied in serum samples. This work provides a facile and easily-scalable synthesis method of electrocatalysts for nonenzymatic glucose sensors.     

Small luminescent molecular probe for developing as assay for alkaline phosphatase

Alkaline phosphatase (ALP) is an important biomarker in clinical diagnostics, and the abnormal level of ALP enzyme in serum is closely related to various diseases such as bone metastases, bone or liver cancer, and extrahepatic biliary obstruction. Recognizing the location and expression level of ALP in live cells has a substantial importance in early-stage cancer diagnosis, as well as an important parameter for studying the recovery of the patients after liver transplantation. With the advent of the newer and advanced fluorescence imaging techniques, small-molecule fluorescent probes have become a very powerful tool for mapping the subtle changes in the enzyme expression level in living cells and tissues in real-time. In this account, we provide an overview of recent advances in small-molecule ALP fluorescent probes, mainly during the last few years, including the design strategies and applications for biological applications.     

在体酶生物燃料电池的研究进展

酶生物燃料电池(Enzymatic biofuel cells,EBFCs)具有高专一性和催化性能,可催化与氧化还原反应有关的燃料并获得电能.可用的生物燃料,如葡萄糖、乳酸和丙酮酸盐,可以从汗液、泪液和血液中提取,因而以体液为燃料的EBFCs在可植入式或可穿戴式设备中具有良好的应用前景.采用生物电催化机理对酶生物燃料电池在体液发电中的应用进行了研究,以及对可植入式或可穿戴式生物燃料电池的主要挑战和未来的前景进行了展望.     

Pathway from N-Alkylglycine to Alkylisonitrile Catalyzed by Iron(II) and 2-Oxoglutarate-Dependent Oxygenases

N-alkylisonitrile, a precursor to isonitrile-containing lipopeptides, is biosynthesized by decarboxylation-assisted -N≡C group (isonitrile) formation by using N-alkylglycine as the substrate. This reaction is catalyzed by iron(II) and 2-oxoglutarate (Fe/2OG) dependent enzymes. Distinct from typical oxygenation or halogenation reactions catalyzed by this class of enzymes, installation of the isonitrile group represents a novel reaction type for Fe/2OG enzymes that involves a four-electron oxidative process. Reported here is a plausible mechanism of three Fe/2OG enzymes, Sav607, ScoE and SfaA, which catalyze isonitrile formation. The X-ray structures of iron-loaded ScoE in complex with its substrate and the intermediate, along with biochemical and biophysical data reveal that -N≡C bond formation involves two cycles of Fe/2OG enzyme catalysis. The reaction starts with an Fe^IV-oxo-catalyzed hydroxylation. It is likely followed by decarboxylation-assisted desaturation to complete isonitrile installation.