Laburnicolamine: A Rare Penillic Acid Congener from the Nematode Cyst-Associated Fungus Laburnicola nematophila.

A chemical investigation of a methanol extract derived from a solid-state rice culture of the nematode-cyst associated fungus Laburnicola nematophila K01 led to the isolation and characterization of a previously undescribed penillic acid analogue named laburnicolamine (1). The chemical structure was elucidated through comprehensive 1D and 2D NMR spectroscopic analyses in methanol-d4 and DMSO-d6, alongside with HR-ESI-MS spectrometry. The absolute configuration of 1 was concluded through the electronic circular dichroism (ECD) and time-dependent density functional theory-ECD (TDDFT-ECD) computations compared to its acquired spectrum. Biological assays revealed that compound 1 exhibited no significant cytotoxic, antimicrobial, or nematicidal activity.

Selective adsorption and identification of penicillin G sodium in milk by molecularly imprinted polymer doped carbon dot.

A carbon dot (CD) was prepared by o-phenylenediamine and water, which showed bright yellow fluorescence under ultraviolet light irradiation (λ = 580 nm), and verified good fluorescence quenching effect on penicillin G sodium (Png-Na). Using methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a crosslinker, and Png-Na as a template, a kind of composite microsphere combining CD and molecularly imprinted polymer (MIP) was synthesized by surface-initiated atomic transfer radical polymerization (SI-ATRP). For reasons of comparison, we also prepared MIP without CD and non-imprinted polymers (NIPs). Through static and dynamic adsorption experiments, the maximum adsorption capacity was 47.05 mg g-1 and the equilibrium time was 30 min. High-performance liquid chromatography (HPLC) was utilized to determine the content of Png-Na in the spiked milk samples. A sensitive, rapid, and simple method for determination of Png-Na in food samples was developed. The utilized approach enabled the quantification of Png-Na within the concentration range 20-1000 µg L-1 (with a limit of detection of 5 µg L-1). The recoveries achieved were in the range 93.3-98.2%, with a relative standard deviation of 1.2-4.2%. The results demonstrated that CD@MIP possessed the capability of specific adsorption and fluorescence detection of Png-Na, enabling simultaneous detection and enrichment of Png-Na in real samples.

Subcutaneous infusion of high-dose benzathine penicillin G is safe, tolerable, and suitable for less-frequent dosing for rheumatic heart disease secondary prophylaxis: a phase 1 open-label population pharmacokinetic study.

Since 1955, the recommended strategy for rheumatic heart disease (RHD) secondary prophylaxis has been benzathine penicillin G [BPG; 1.2 MU (900 mg)] injections administered intramuscularly every 4 weeks. Due to dosing frequency, pain, and programmatic challenges, adherence is suboptimal. It has previously been demonstrated that BPG delivered subcutaneously at a standard dose is safe and tolerable and has favorable pharmacokinetics, setting the scene for improved regimens with less frequent administration. The safety, tolerability, and pharmacokinetics of subcutaneous infusions of high-dose BPG were assessed in 24 healthy adult volunteers assigned to receive either 3.6, 7.2, or 10.8 MU (three, six, and nine times the standard dose, respectively) as a single subcutaneous infusion. The delivery of the BPG to the subcutaneous tissue was confirmed with ultrasonography. Safety assessments, pain scores, and penicillin concentrations were measured for 16 weeks post-dose. Subcutaneous infusion of penicillin (SCIP) was generally well tolerated with all participants experiencing transient, mild infusion-site reactions. Prolonged elevated penicillin concentrations were described using a combined zero-order (44 days) and first-order (t1/2 = 12 days) absorption pharmacokinetic model. In simulations, time above the conventionally accepted target concentration of 20 ng/mL (0.02 µg/mL) was 57 days for 10.8 MU delivered by subcutaneous infusion every 13 weeks compared with 9 days of every 4-weekly dosing interval for the standard 1.2 MU intramuscular dose (i.e., 63% and 32% of the dosing interval, respectively). High-dose SCIP (BPG) is safe, has acceptable tolerability, and may be suitable for up to 3 monthly dosing intervals for secondary prophylaxis of RHD.

Enlarging the substrate binding pocket of penicillin G acylase from Achromobacter sp. for highly efficient biosynthesis of ß-lactam antibiotics.

Penicillin G acylase (PGA) is a key biocatalyst for the enzymatic production of ß-lactam antibiotics, which can not only catalyze the synthesis of ß-lactam antibiotics but also catalyze the hydrolysis of the products to prepare semi-synthetic antibiotic intermediates. However, the high hydrolysis and low synthesis activities of natural PGAs severely hinder their industrial application. In this study, a combinatorial directed evolution strategy was employed to obtain new PGAs with outstanding performances. The best mutant ßF24G/ßW154G was obtained from the PGA of Achromobacter sp., which exhibited approximately a 129.62-fold and a 52.55-fold increase in specific activity and synthesis/hydrolysis ratio, respectively, compared to the wild-type AsPGA. Thereafter, this mutant was used to synthesize amoxicillin, cefadroxil, and ampicillin; all conversions > 99% were accomplished in 90-135 min with almost no secondary hydrolysis byproducts produced in the reaction. Molecular dynamics simulation and substrate pocket calculation revealed that substitution of the smallest glycine residue at ßF24 and ßW154 expanded the binding pocket, thereby facilitating the entry and release of substrates and products. Therefore, this novel mutant is a promising catalyst for the large-scale production of ß-lactam antibiotics.

Concurrent acute generalized exanthematous pustulosis in siblings.

Acute generalized exanthematous pustulosis (AGEP) is a rare severe cutaneous adverse reaction triggered in most cases by drugs. It is characterized by abrupt onset and rapid evolution of fields of sterile pustules on an erythematous background. The role of genetic predisposition in this reactive disorder is being explored. We report the simultaneous occurrence of AGEP in two siblings after being exposed to the same drug.

Rapid Environmental Impact Assessment of Penicillin G in a Veterinary Product Using an Original Software Method and Monitoring by SPE-Online-UHPLC-MS/MS.

Veterinary antibiotics have become a major concern due to potential environmental effects. This study presents an investigation of the exposure and environmental effects of the veterinary medicinal product in powder form, administered in the drinking water of piglets, chickens and turkeys, containing 250 mg/g penicillin G (benzylpenicillin potassium), performed according to the European Medicines Agency (EMEA) guideline and the results obtained by an analytical method based on online solid-phase extraction, ultra-high performance liquid chromatography coupled to a triple quadrupole mass spectrometer (SPE-online-UHPLC-MS/MS). The study presents the determination of the environmental risk and through an original, interactive, fast software method, created on the basis of a proprietary calculation algorithm that goes through all the prescriptions and recommendations of the EMEA guide. The results demonstrated that the concentration value for penicillin G determined in surface water by SPE-online-UHPLC-MS/MS is much lower than that predicted by calculation (predictable concentration in surface water, PECsurface water = 37.66 µg/L and the concentration SPE-online-UHPLC-MS/MS = 0.032 µg/L). Both results lead to a sub-unit risk quotient (R) indicating that the treatment carried out with the considered veterinary product does not present any risk to the environment.

Congenital Syphilis Infection: A Case Study.

Congenital syphilis (CS) infection occurs by way of vertical transmission of the bacteria Treponema pallidum from mother to fetus. While nearly eliminated by the turn of the twenty-first century, CS has resurged in recent years and currently represents a worldwide public health calamity secondary to insufficient prenatal care and inadequate maternal treatment. Fetal and neonatal consequences include stillbirth, cutaneous and visceral symptoms, asymptomatic infection, and death. Given the rise in cases in both wealthy and resource-poor areas, neonatal clinicians are obligated to maintain acumen specific to risk factors, manifestations, and treatment regimens. However, limited data guide postnatal treatment regimens, particularly in preterm neonates. We present a case report of a preterm female with CS and integrated review of the literature. Our findings indicate that CS is preventable through efficient and judicious perinatal screening, early detection, and adequate treatment of maternal syphilis during pregnancy.

Reactions of cisplatin and oxaliplatin with penicillin G: implications for drug inactivation and biological activity.

Determination of the toxicity of compounds toward cancer cells is a frequent procedure in drug discovery. For metal complexes, which are often reactive prodrugs, care has to be taken to consider reactions with components of the cell culture medium that might change the speciation of the metal complex before it is taken up by the cells. Here, we consider possible reactions between the clinical platinum drugs cisplatin and oxaliplatin with penicillin G, an antibiotic added routinely to cell culture media to prevent bacterial contamination. Platinum has a high affinity for ligands with sulfur donors. Penicillin G is an unstable thioether that degrades in a range of pathways. Nuclear magnetic resonance (NMR) and UV-Vis absorption spectroscopic studies show that reactions with cisplatin can occur within minutes to hours at 310 K, but more slowly with oxaliplatin. The identities of the Pt- adducts were investigated by mass spectrometry. The marked effect on cytotoxicity of co-incubation of cisplatin with penicillin G was demonstrated for the HeLa human cervical cancer cell line. These studies highlight the possibility that reactions with penicillin G might influence the cytotoxic activity of metal complexes determined in culture media.

Synthesis and characterization of g-C3N4-CoFe2O4-ZnO magnetic nanocomposites for enhancing photocatalytic activity with visible light for degradation of penicillin G antibiotic.

Nowadays, antibiotic water pollution is an increasingly dangerous environmental threat. Thus, water treatment is essential for their reduction and removal. In recent decades, photocatalysts have attracted much attention due to their influential role in solving this issue. The photocatalytic process, which is one of the green processes and part of advanced oxidation processes, can be a good choice for treating contaminated water containing non-degradable organic matter. However, the design of high-performance photocatalysts under free sunlight can be challenging. In this study, g-C3N4-Ca, Mg codoped CoFe2O4-ZnO (gCN-CFO-ZnO) nanocomposite photocatalyst was applied in removing penicillin G (PENG) from drug effluents. Also, the effects of contaminant concentration, initial pH, irradiation time, and zinc oxide ratio in the nanocomposites were investigated. The hydrothermal method was carried out to prepare the appropriate composites. Then, the obtained products were characterized by powder X-Ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FT-IR), Raman, field-emission scanning and transmission electron microscope (FE-SEM&TEM), energy dispersive X-Ray (EDX), diffuse reflectance spectroscopy (DRS), vibrating sample magnetometer (VSM) and Photoluminescence (PL) techniques. According to the findings, the degradation of PENG in an acidic environment occurred remarkably; under the same conditions, with decreasing pH from 9 to 5 in the gCN-CFO-ZnO (33.33%) nanocomposite, the degradation efficiency grew from 47% to 74%. Also, the degradation rate of PENG in gCN-CFO-ZnO (16.66%) and gCN-CFO-ZnO (50%) nanocomposites under optimal conditions (pH = 5, PENG the concentration of 10 ppm, and irradiation time of 120 min) was achieved 52% and 60%, respectively. Further, gCN-CFO-ZnO (33.33%) nanocomposite showed higher efficiency in PENG degradation compared to the other two nanocomposites.

Immobilized penicillin G acylase with enhanced activity and stability using glutaraldehyde-modified polydopamine-coated Fe3 O4 nanoparticles.

In this work, Fe3 O4 nanoparticles (NPs) were coated with polydopamine (PDA) to structure Fe3 O4 @PDA NPs by the spontaneous oxygen-mediated self-polymerization of dopamine (DA) in an aqueous solution of pH = 8.5. The fabricated Fe3 O4 @PDA NPs were grafted by glutaraldehyde to realize the immobilization of penicillin G acylase (PGA) under mild conditions. The carriers of each stage were characterized and investigated by transmission electron microscopy, X-ray diffraction, Fourier transform infrared, and vibrating sample magnetometry. To improve the catalytic activity and stability of immobilized PGA, the immobilization conditions were investigated and optimized. Under the optimal immobilization conditions, the enzyme loading capacity, enzyme activity, and enzyme activity recovery of immobilized PGA were 114 mg/g, 26,308 U/g, and 78.5%, respectively. In addition, the immobilized PGA presented better temperature and pH stability compared with free PGA. The reusability study ensured that the immobilized PGA showed an excellent repeating application performance. In particular, the recovery rate of immobilized PGA could reach 94.8% and immobilized PGA could retain 73.0% of its original activity after 12 cycles, indicating that the immobilized PGA exhibited a high operation stability and broad application potential in the biocatalysis field.

The first case of congenital syphilis diagnosed by 16S ribosome-RNA gene sequence analysis.

Syphilis infection during pregnancy causes perinatal complications and mother-to-child transmission if untreated. A newborn was delivered by emergent cesarean section due to non-reassuring fetal status at 34 weeks of gestation. The mother tested negative for rapid plasma reagin (RPR) and Treponema pallidum hemagglutination (TPHA) in early pregnancy. The newborn had a severe inflammatory reaction, thrombocytopenia, and elevated IgM as well as disseminated intravascular coagulation and multiple organ failure. The 16S ribosomal RNA gene sequence analysis of the amniotic fluid detected Treponema pallidum. The newborn tested positive for RPR, TPHA, and IgM fluorescent treponemal antibody-absorption in the blood, and thus, congenital syphilis was diagnosed. This is the first case that 16S ribosomal RNA gene sequencing of the amniotic fluid led to an early diagnosis of congenital syphilis in a newborn. The 16S rRNA gene sequencing may be a useful method for the early detection of the primary causative microbe of congenital infection.

Statistical modeling optimization for antibiotics decomposition by ultrasound/electro-Fenton integrated process: Non-carcinogenic risk assessment of drinking water.

The present work proposes an ultrasound (US) assisted electro-Fenton (EF) process for eliminating penicillin G (PNG) and ciprofloxacin (CIP) from aqueous solutions and the process was further optimized by response surface methodology (RSM)- Box-Behnken design (BBD). The impact of pH, hydrogen peroxide (H2O2) concentration, applied voltage, initial pollutant concentration, and operating time were studied. The capability application of the electro-Fenton (EF) and US processes was compared separately and in combination under the optimum conditions of pH of 4, a voltage of 15 V, the initial antibiotic concentration of 20.7 mg/L, H2O2 concentration of 0.8 mg/L, and the operating time of 75 min. The removal efficiency of PNG and CIP using the sono-electro-Fenton (SEF) process, as the results revealed, was approximately 96% and 98%, respectively. The experiments on two scavengers demonstrated that ⦁OH contributes significantly to the CIP and PNG degradation by SEF, whereas ⦁O-2 corresponds to only a negligible amount. The total organic carbon (TOC) and chemical oxygen demand (COD) analyses were used to assess the mineralization of CIP and PNG. The efficiency of COD and TOC removal was reached at 73.25% and 62.5% for CIP under optimized operating circumstances, and at 61.52% and 72% for PNG, respectively. These findings indicate that a sufficient rate of mineralization was obtained by SEF treatment for the mentioned pollutants. The reaction kinetics of CIP and PNG degradation by the SEF process were found to follow a pseudo-first-order kinetic model. In addition, the human health risk assessment of natural water containing CIP and PNG that was purified by US, EF, and SEF processes was done for the first time. According to the findings, the non-carcinogenic risk (HQ) caused by drinking purified water by all three systems was calculated in the acceptable range. Thus, SEF is a proper system to remove various antibiotics in potable water and reduces their human health risks.

Penicillin G acylase production by Mucor griseocyanus and the partial genetic analysis of its pga gene.

Penicillin acylases (penicillin amidohydrolase, EC 3.5.1.11) are a group of enzymes with many applications within the pharmaceutical industry, and one of them is the production of semi-synthetic beta-lactam antibiotics. This enzyme is mainly produced by bacteria but also by some fungi. In the present study, the filamentous fungus Mucor griseocyanus was used to produce penicillin acylase enzyme (PGA). Its ability to express PGA enzyme in submerged fermentation process was assessed, finding that this fungal strain produces the biocatalyst of interest in an extracellular way at a level of 570 IU/L at 72 h of fermentation; in this case, a saline media using lactose as carbon source and penicillin G as inducer was employed. In addition, a DNA fragment (859 bp) of the pga from a pure Mucor griseocyanus strain was amplified, sequenced, and analyzed in silico. The partial sequence of pga identified in the fungi showed high identity percentage with penicillin G acylase sequences deposited in NCBI through BLAST, especially with the ß subunit of PGA from the Alcaligenes faecalis bacterium¸ which is a region involved in the catalytic function of this protein. Besides, the identification of domains in the penicillin G acylase sequence of Mucor griseocyanus showed three conserved regions of this protein. The bioinformatic results support the identity of the gen as penicillin G acylase. This is the first report that involves sequencing and in silico analysis of Mucor griseocyanus strain gene encoding PGA.

Efficient enzymatic synthesis of cephalexin in suspension aqueous solution system.

An efficient method for the enzymatic synthesis of cephalexin (CEX) from 7-amino-3-deacetoxycephalosporanic acid (7-ADCA) and d-phenylglycine methyl ester (PGME) using immobilized penicillin G acylase (IPGA) as catalyst in a suspension aqueous solution system was developed, where the reactant 7-ADCA and product CEX are mainly present as solid particles. The effects of key factors on the enzymatic synthesis were investigated. Results showed that continuous feeding of PGME was more efficient for the synthesis of CEX than the batch mode. Under the optimized conditions, the maximum 7-ADCA conversion ratio of 99.3% and productivity of 200 mmol/L/H were achieved, both of which are much superior to the homogeneous aqueous solution system. Besides, IPGA still retained 95.4% of its initial activity after 10 cycles of enzymatic synthesis, indicating the excellent stability of this approach. The developed approach shows great potential for the industrial production of CEX via an enzyme-based route.

Investigation of enzymes and solvents in the production process of 6-ammonium penicillanic acid (6-APA) in industry to reduce costs and improve production conditions.

In this study, the optimization of the amount of enzyme consumed in the enzymatic phase of substitution of butanol solvent instead of methanol in the powder washing phase after filtration was investigated. To perform this study, different amounts of the enzyme penicillin G amidase (PGA) were tested in reactions with the same conditions. The highest efficiency was observed in the reaction that the ratio of penicillin powder to the amount of enzyme was 2:1. In this reaction, for every 100 g of penicillin consumed, 50 g of the PGA was used. Replacement of butanol instead of methanol after filtration, the powder obtained from this step was washed with butanol instead of methanol and the powder obtained from this step was examined after drying. The resulting solvent powder was very small and the drying speed of the powder increased compared to the time of methanol usage. Optimizing the amount of enzyme in this process due to the high cost of the enzyme made this reaction more economically viable at the end of this study. In this study, for the first time, butanol was used as a suitable substitute for methanol and the ratio of enzyme use to penicillin powder was optimized. This research deals with the future perspective in the field of research in this regard.

Genetic Encoding and Enzymatic Deprotection of a Latent Thiol Side Chain to Enable New Protein Bioconjugation Applications.

The thiol group of the cysteine side chain is arguably the most versatile chemical handle in proteins. To expand the scope of established and commercially available thiol bioconjugation reagents, we genetically encoded a second such functional moiety in form of a latent thiol group that can be unmasked under mild physiological conditions. Phenylacetamidomethyl (Phacm) protected homocysteine (HcP) was incorporated and its latent thiol group unmasked on purified proteins using penicillin G acylase (PGA). The enzymatic deprotection depends on steric accessibility, but can occur efficiently within minutes on exposed positions in flexible sequences. The freshly liberated thiol group does not require treatment with reducing agents. We demonstrate the potential of this approach for protein modification with conceptually new schemes for regioselective dual labeling, thiol bioconjugation in presence of a preserved disulfide bond and formation of a novel intramolecular thioether crosslink.

Effects of crystalline penicillin G sodium on human T-cells differentiation.

BACKGROUND: Although antibiotics are well-known for their anti-bacterial effects, their inaugurated immunomodulatory roles in chronic inflammatory diseases have not elucidated yet. Anecdotal reports support the beneficial effects of parenteral penicillin in arthritis suggesting an immunomodulatory other than antibacterial effects for penicillin. The present study was designed to address the possible effects of penicillin G sodium (PCN-G) on different T-helper cells differentiation. MATERIALS AND METHODS: In this experimental study, peripheral blood mononuclear cells (PBMCs) of 10 healthy donors were isolated using Ficoll density gradient. The stimulated PBMCs by anti-CD3, anti-CD28, and anti-CD69 were cultured in the presence of 120 µg/ml of PCN-G. Foxp3, T-bet, RORγT, GATA3 as well as interferon-gamma (IFN-γ) and interleukin (IL)-17A mRNA in stimulated cells were measured by the real-time polymerase chain reaction. Mann-Whitney U-test was used for determining differences between the medium of gene expression levels of stimulated cell population and unstimulated cells by PCN. Correlations between the related genes were determined using the Spearman test. RESULTS: Based on the results, T-bet gene expression levels were similar in stimulated cells by PCN G after 24 and 48 h while significant reduction was observed after 72 incubation with PCN G (difference = 3; 0.09-0.34; P = 0.031). Meanwhile, treated cells with PCN G expressed decreased levels of IFN-γ (difference = 8.0; 0.49-1.07; P = 0.001) and IL-17A (difference = 2.2; 0.05-0.75; P ≤ 0.05) genes comparing to unstimulated cell by PCN-G. GATA3 genes expression levels downregulated by PCN G after 72 h of incubation by PBMCs (difference = 1.1; 0.77-0.88; P = 0.035). CONCLUSION: Our results confirmed the immunomodulatory role of PCN G by affecting the expression of different cytokines genes in PBMCs.

Neurosyphilis Treatment Outcomes After Intravenous Penicillin G Versus Intramuscular Procaine Penicillin Plus Oral Probenecid.

BACKGROUND: Data comparing neurosyphilis treatment regimens are limited. METHODS: Participants were enrolled in a study of cerebrospinal fluid (CSF) abnormalities in syphilis that was conducted at the University of Washington between April 2003 to May 2014. They were diagnosed with syphilis and referred by their providers due to concerns for neurosyphilis. We evaluated 150 people with CSF abnormalities who were treated with either intravenous aqueous penicillin G (PenG) or intramuscular aqueous procaine penicillin G plus oral probenecid (APPG-P). An abnormal CSF diagnosis was defined as a white blood cell (WBC) count >20/µL, a CSF protein reading >50 mg/dL, or a reactive CSF-Venereal Disease Research Laboratory test (VDRL). Hazard ratios for normalization of CSF or serum measures were determined using Cox regression. RESULTS: In individuals treated with either PenG or APPG-P, CSF WBCs and CSF-VDRL reactivity normalized within 12 months after treatment, while protein normalized more slowly and less completely. There was no relationship between treatment regimen or human immunodeficiency virus (HIV) status and likelihood of normalization of any measure. Among those living with HIV, CSF WBC counts and CSF-VDRL reactivity were more likely to normalize in those treated with antiretrovirals. Unexpectedly, CSF WBCs were more likely to normalize in those with low CD4+ T cell counts. When neurosyphilis was more stringently defined as a reactive CSF-VDRL, the relationship with the CD4+ T cell count remained unchanged. CONCLUSIONS: In the current antiretroviral treatment era, neurosyphilis treatment outcomes are not different for PenG and APPG-P, regardless of HIV status. The relationship between the normalization of CSF WBC counts and CD4+ T cell counts may indicate continued imprecision in neurosyphilis diagnostic criteria, due to HIV-related CSF pleocytosis.

Penicillin G Induces H+, K+-ATPase via a Nitric Oxide-Dependent Mechanism in the Rat Colonic Crypt.

BACKGROUND/AIMS: The colonic H+, K+ ATPase (HKA2) is a heterodimeric membrane protein that exchanges luminal K+ for intracellular H+ and is involved in maintaining potassium homeostasis. Under homeostatic conditions, the colonic HKA2 remains inactive, since most of the potassium is absorbed by the small intestine. In diarrheal states, potassium is secreted and compensatory potassium absorption becomes necessary. This study proposes a novel mechanism whereby the addition of penicillin G sodium salt (penG) to colonic crypts stimulates potassium uptake in the presence of intracellular nitric oxide (NO), under sodium-free (0-Na+) conditions. METHODS: Sprague Dawley rat colonic crypts were isolated and pHi changes were monitored through the ammonium prepulse technique. Increased proton extrusion in 0-Na+ conditions reflected heightened H+, K+ ATPase activity. Colonic crypts were exposed to penG, L-arginine (a NO precursor), and N-nitro l-arginine methyl ester (L-NAME, a NO synthase inhibitor). RESULTS: Isolated administration of penG significantly increased H+, K+ ATPase activity from baseline, p 0.0067. Co-administration of arginine and penG in 0-Na+ conditions further upregulated H+, K+ ATPase activity, p <0.0001. Crypt perfusion with L-NAME and penG demonstrated a significant reduction in H+, K+ ATPase activity, p 0.0058. CONCLUSION: Overall, acute exposure of colonic crypts to penG activates the H+, K+ ATPase in the presence of NO. This study provides new insights into colonic potassium homeostasis.

Incorporating Lanthanum into Mesoporous Silica Foam Enhances Enzyme Immobilization and the Activity of Penicillin G Acylase Due to Lewis Acid-Base Interactions.

Penicillin G acylase (PGA) has been immobilized on a lanthanum-incorporated mesostructured cellular foam (La-MCF) support by using the interaction between the strong Lewis acid sites on the surface of La-MCF and the free amino groups of lysine residues of PGA. The La-MCF support was successfully synthesized in situ through the addition of a citric acid (CA) complexant. The results of pyridine-IR spectroscopy show the presence of strong Lewis acid sites on the surface of the prepared La-MCF (with CA), attributed to the incorporation of lanthanum species into the framework of MCF. Through interaction with the strong Lewis acid sites, the enzymes can be firmly immobilized on the surface of the support. The results indicate that PGA/La-MCF (with CA) exhibits a high specific activity and greatly enhanced operational stability. For the hydrolysis of penicillin G potassium salt, the initial specific activity of PGA/La-MCF (with CA) reaches 10023 U/g. Even after being recycled 10 times, PGA/La-MCF (with CA) retains 89 % of its initial specific activity, much higher than the 77 % of PGA/Si-MCF.