High Specific Activity Research Articles

Microencapsulation of trypsin from the intestine of yellowfin tuna (Thunnus Albacares)

Fish viscera is one of the waste products from fisheries that have not been widely used it tends to be disposed of more. Whereas in fish innards there are some enzymes including the trypsin found in the intestines. To increase the added value of fish viscera, a study on the extraction and microencapsulation of trypsin from fish intestines was carried out. This study aimed to analyze the activity of the trypsin from tuna intestine microencapsulated using maltodextrin. The concentrations of maltodextrin used were 0%, 1%, 2%, and 3% w/v. The microencapsulated enzymes were then dried using a spray dryer. The results showed that the crude extract of the trypsin had a specific activity value of 0.250 U/mg with a Vmax value of 0.0379 mmol/s and Km 0.2299 mM. Trypsin microencapsulated with 1% (w/v) maltodextrin was the best treatment because it has the highest specific activity (0.235±0.013 U/mg) with Vmax values of 0,0208 mmol/s and Km of 0,8581 mM. After going through the drying process with a spray dryer, the enzyme activity decreased by 10±1%.

Time-dependent oxidation of graphite and cobalt oxide nanoparticles as electrocatalysts for the oxygen evolution reaction

• Co 3 O 4 /G OX was synthesized via a facile hydrothermal method for the OER. • Co 3 O 4 /G OX-10 catalyst showed the lowest overpotential of 250 mV at 10 mA cm −2 . • The optimal catalyst exhibited higher specific activity and turnover frequency. • Demonstrated improved electrical conductivity and small charge transfer resistance. • The optimal catalyst Exhibited excellent stability and durability. Water splitting is a promising way of producing hydrogen, but a highly efficient and durable electrocatalyst to accelerate the oxygen evolution reaction (OER) is required. In this study, we report cobalt oxide (Co 3 O 4 ) and oxidized graphite (G OX ) synthesized by a simple hydrothermal method to prepare a catalyst (Co 3 O 4 /G OX ) for the OER. Time-dependent oxidation of graphite (G) and Co 3 O 4 nanoparticles was observed by physical and electrochemical studies. The optimal catalyst (Co 3 O 4 /G OX-10 ) demonstrated the best catalytic OER performance with the lowest overpotential of 250 mV to reach 10 mA cm −2 and a small Tafel slope of 67 mV dec -1 , which is substantially smaller than that of pristine Co 3 O 4 and Co 3 O 4 /G. An efficient synergistic effect between Co 3 O 4 and G OX in the composite catalyst was observed compared to the individual catalysts. The optimal catalyst exhibited high specific activity (1.543 mA cm −2 ) and turnover frequency (0.474 s −1 ) compared to the other catalysts in this study. The high catalytic performance of the catalyst is attributed to the presence of oxygen functional groups, which induced a high electrochemical surface area, additional active site exposure, fast electron transfer, and enhanced dispersion of the catalyst. Thus, the synthesized Co 3 O 4 /G OX-10 catalyst can replace noble metals as an efficient OER electrocatalyst.

Enhanced performance of an in-situ synthesized Pd/N-TiO2/Ti cathode for electrocatalytic hydrodechlorination

The generation capacity of adsorbed reactively atomic hydrogen (Hads*) and the electrocatalytic hydrodechlorination (ECHD) activity can be improved by adjusting the electronic structure of Pd during the metal-support interaction. In addition, the durability and conductivity of the cathode significantly affect the ECHD efficiency. In this study, nitrogen-doped titanium dioxide (N-TiO2) is synthesized in situ using Ti sheet as matrix. Pd is loaded on N-TiO2/Ti electrode by hydrothermal synthesis self-assembly. The in-situ synthesized Pd/N-TiO2/Ti electrode can improve the atomic utilization rate of Pd and omit the insulating polymer binder during preparation. Moreover, it has unique advantages, such as large electrochemically active area, high stability and electrical conductivity. Under the condition of Pd loading of 0.75 mg, 84.09 % removal of 2,4-DCP (0.61 mM) is achieved on the electrode within 4 h at a potential of − 1.24 V (vs Hg/Hg2SO4). Finally, the Pd/N-TiO2/Ti cathode with good durability and high specific catalytic activity has a promising application prospect in electrocatalytic dehalogenation.

Encapsulation of 67Cu therapeutic radiometal in luminescent lanthanide phosphate core and core-shell nanoparticles

Copper-67 (67Cu) has physical characteristics useful for both therapy and imaging. However, its applicability has been hindered by the complexity of obtaining large quantities of a product with high specific activity. With the advancement of 67Cu production methods, suitable radioisotope carriers are sought. Lanthanide phosphate nanoparticles have demonstrated their multifunctional characteristics for biomedical applications and, more recently, their potential in radiopharmaceuticals. Thus, we produced luminescent lanthanide phosphate nanoparticles with core and core-shell structures, incorporating 67Cu during their synthesis. The nanoparticles exhibited hexagonal crystalline structure and spherical morphology with sizes below 6 nm. The luminescent colloidal suspensions evidenced the characteristic 5D0-7FJ for Eu3+, providing the red color under UV light. A radiochemical yield of 67Cu >95% was obtained with both core and core-shell LaPO4:Eu. The core-shell nanoparticles reduced the release of 67Cu by a factor of ∼2 over that from the core, which continuously decreased with time. Multifunctional LnPO4 nanoparticles have the potential to be used as a carrier of single or multiple radioisotopes to enhance image-guided targeted nano-radiopharmaceutical therapy.

Surface Functionalized Magnetic Nanoparticles as a Selective Sorbent for Affinity Fishing of PPAR-γ Ligands from Choerospondias axillaris.

Coronary heart disease (CHD), which has developed into one of the major diseases, was reported to be treated by the target of peroxisome proliferators-activate receptor γ (PPAR-γ). As a natural medicine long used in the treatment of CHD, there are few studies on how to screen the target active compounds with high specific activity from Choerospondias axillaris. To advance the pace of research on target-specific active compounds in natural medicines, we have combined magnetic ligand fishing and functionalized nano-microspheres to investigate the active ingredients of PPAR-γ targets in Choerospondias axillaris. The PPAR-γ functionalized magnetic nano-microspheres have been successfully synthesized and characterized by vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The specificity, reusability, and reproducibility of the nano-microspheres were investigated with the help of the specific binding of rosiglitazone to PPAR-γ. In addition, the incubation temperature and the pH of the buffer solution in the magnetic ligand fishing were optimized to improve the specific adsorption efficiency of the analytes. Finally, with the aid of ultraperformance liquid chromatography plus Q-Exactive Orbitrap tandem mass spectrometry (UHPLC-Q-Exactive Orbitrap-MS/MS), the 16 active ligands including 9 organic acids, 5 flavonoids, and 2 phenols were found in the ethanolic extracts of Choerospondias axillaris. Therefore, the study can provide a successful precedent for realizing the designated extraction and rapid isolation of target-specific active ingredient groups in the complex mixtures.

Effective Biotransformation of Variety of Guaiacyl Lignin Monomers Into Vanillin by Bacillus pumilus.

Biotransformation has gained increasing attention due to its being an eco-friendly way for the production of value-added chemicals. The present study aimed to assess the potential of Bacillus pumilus ZB1 on guaiacyl lignin monomers biotransformation for the production of vanillin. Consequently, isoeugenol, eugenol, and vanillyl alcohol could be transformed into vanillin by B. pumilus ZB1. Based on the structural alteration of masson pine and the increase of total phenol content in the supernatant, B. pumilus ZB1 exhibited potential in lignin depolymerization and valorization using masson pine as the substrate. As the precursors of vanillin, 61.1% of isoeugenol and eugenol in pyrolyzed bio-oil derived from masson pine could be transformed into vanillin by B. pumilus ZB1. Four monooxygenases with high specific activity were identified that were involved in the transformation process. Thus, B. pumilus ZB1 could emerge as a candidate in the biosynthesis of vanillin by using wide guaiacyl precursors as the substrates.

Hypocretin-1 measurements in cerebrospinal fluid using radioimmunoassay: within and between assay reliability and limit of quantification.

Study ObjectivesThe most sensitive and specific investigative method for the diagnosis of narcolepsy type 1 (NT1) is the determination of hypocretin-1 (orexin-A) deficiency (≤110 pg/mL) in cerebrospinal fluid using a radioimmunoassay (RIA). We aimed to assess the reliability of the Phoenix Pharmaceuticals hypocretin-1 RIA, by determining the lower limit of quantification (LLOQ), the variability around the cutoff of 110 pg/mL, and the inter- and intra-assay variability.MethodsRaw data of 80 consecutive hypocretin-1 RIAs were used to estimate the intra- and inter-assay coefficient of variation (CV). The LLOQ was established and defined as the lowest converted concentration with a CV <25%; the conversion is performed using a harmonization sample which is internationally used to minimize variation between RIAs.ResultsThe mean intra-assay CV was 4.7%, while the unconverted inter-assay CV was 28.3% (18.5% excluding 2 outliers) and 7.5% when converted to international values. The LLOQ was determined as 27.9 pg/mL. The intra-assay CV of RIAs with lower specific radioactive activity showed a median of 5.6% (n = 41, range 1.6%–17.0%), which was significantly higher than in RIAs with higher specific activity (n = 36; median 3.2%, range 0.4%–11.6%, p = .013). The CV around the 110 pg/mL cutoff was <7%.ConclusionsHypocretin-1 RIAs should always be harmonized using standard reference material. The specific activity of an RIA has a significant impact on its reliability, because of the decay of 125I radioactivity. Values around the hypocretin-1 cut-off can reliably be measured. Hypocretin-1 concentrations below 28 pg/mL should be reported as “undetectable” when measured with the Phoenix Pharmaceuticals RIA.Clinical Trial InformationThis study is not registered in a clinical trial register, as it has a retrospective database design

Evaluation of MxOy/fucoidan hybrid system and their application in lipase immobilization process

In this work, new MxOy/fucoidan hybrid systems were fabricated and applied in lipase immobilization. Magnesium (MgO) and zirconium (ZrO2) oxides were used as MxOy inorganic matrices. In the first step, the proposed oxides were functionalized with fucoidan from Fucus vesiculosus (Fuc). The obtained MgO/Fuc and ZrO2/Fuc hybrids were characterized by means of spectroscopic analyses, including Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and nuclear magnetic resonance. Additionally, thermogravimetric analysis was performed to determine the thermal stability of the hybrids. Based on the results, the mechanism of interaction between the oxide supports and fucoidan was also determined. Furthermore, the fabricated MxOy/fucoidan hybrid materials were used as supports for the immobilization of lipase from Aspergillus niger, and a model reaction (transformation of p-nitrophenyl palmitate to p-nitrophenol) was performed to determine the catalytic activity of the proposed biocatalytic system. In that reaction, the immobilized lipase exhibited high apparent and specific activity (145.5 U/gcatalyst and 1.58 U/mgenzyme for lipase immobilized on MgO/Fuc; 144.0 U/gcatalyst and 2.03 U/mgenzyme for lipase immobilized on ZrO2/Fuc). The immobilization efficiency was also confirmed using spectroscopic analyses (FTIR and XPS) and confocal microscopy.

O-27 - Using high-specific activity Samarium-153 for the development of [153Sm] Sm DOTA-TATE for targeted radionuclide therapy of neuroendocrine tumors

O-27 - Using high-specific activity Samarium-153 for the development of [153Sm] Sm DOTA-TATE for targeted radionuclide therapy of neuroendocrine tumors

Trace nitrogen-incorporation stimulates dual active sites of nickel catalysts for efficient hydrogen oxidation electrocatalysis

The insufficient activity of Ni-based catalysts toward hydrogen oxidation reaction (HOR) severely hinders their deployment in alkaline polymer electrolyte fuel cells. Here, we demonstrate that trace nitrogen-incorporation can greatly activate monometallic Ni catalysts by constructing synergetic dual active sites across micro-heterogeneous interfaces, resulting in impressive HOR electrocatalytic performance that rivals that of state-of-the-art Pt/C catalysts in alkaline media. The obtained catalyst achieves a high specific activity of 0.074 mA cm−2, a high mass activity of 60.9 A g−1, and outperforms both Ni3N and Ni analogues, uncovering an unexpected nitrogen-incorporation criterion for Ni electrocatalysts. Moreover, it also exhibits a remarkable CO tolerance capacity that Pt/C lacks. Mechanistic studies reveal that self-regulated d-band centers of Ni (downshift) in Ni-N bonding and Ni (upshift) in Ni-Ni bonding derived from apparent charge redistribution can weaken hydrogen binding energy and increase hydroxyl binding energy simultaneously, resulting in the HOR enhancement.

Evaluation of 186WS2 target material for production of high specific activity 186Re via proton irradiation: separation, radiolabeling and recovery/recycling

Abstract Enriched tungsten disulfide (186WS2) was evaluated at increasing proton beam currents (20–50 μA) and times (up to 4 h) on a GE PETtrace cyclotron for production of high specific activity (HSA) 186Re. The HSA 186Re was separated from the irradiated target as [186Re][ReO4]– by a liquid–liquid extraction method and radiolabeled with a new N2S2 ligand (222-MAMA-N-ethylpropionate). The enriched 186W was recovered from the extraction process, analyzed for purity and enrichment, and converted back to the disulfide (186WS2). The results demonstrate that the 186WS2 is an easily pressed target material that can withstand relatively high currents and can be readily recovered and recycled. The 186Re produced was isolated in high specific activity and readily formed the radiotracers [186Re][ReO(222-MAMA-N-ethylpropionate)] and [186Re][Re(CO)3(OH2)3] +.

Hollow-Structure Pt-Ni Nanoparticle Electrocatalysts for Oxygen Reduction Reaction

An electrocatalyst with high oxygen reduction reaction (ORR) activity and high stability during start–stop operation is necessary. In this paper, hollow-structure Pt-Ni electrocatalysts are investigated as ORR catalysts. After synthesis via sacrificial SiO2 template method, the electrocatalyst exhibits much higher specific activity (1.88 mA/cm2) than a commercial Pt/C catalyst. The mass activity (0.49 A/mg) is 7 times higher than the commercial Pt/C catalyst. The kinetics of the ORR is evaluated using Tafel and K-L plots. It also exhibits a higher durability than commercial Pt/C catalyst during accelerated durability test (ADT). Moreover, the electrocatalyst shows good resistance against accelerated durability test for start–stop, the specific activity and mass activity drops 34.6% and 40.8%, respectively, far better than the commercial catalyst.

Characterization and Molecular Mechanism of a Novel Cytochrome b5 Reductase with NAD(P)H Specificity from Mortierella alpina.

The electron-transfer capabilities of cytochrome b5 reductase (Cyt b5R) and NADPH supply have been shown to be critical factors in microbial fatty acid synthesis. Unfortunately, Cyt b5R substrate specificity is limited to the coenzyme NADH. In this study, we discovered that a novel Cyt b5R from Mortierella alpina (MaCytb5RII) displays affinity for NADPH and NADH. The enzymatic characteristics of high-purity MaCytb5RII were determined with the Km,NADPH and Km,NADH being 0.42 and 0.07 mM, respectively. MaCytb5RII shows high specific activity at 4 °C and pH 9.0. We anchored the residues that interacted with the coenzymes using the homology models of MaCytb5Rs docking NAD(P)H and FAD. The enzyme activity analysis of the purified mutants MaCytb5RII[S230N], MaCytb5RII[Y242F], and MaCytb5RII[S272A] revealed that Ser230 is essential for MaCytb5RII to have dual NAD(P)H dependence, whereas Tyr242 influences MaCytb5RII's NADPH affinity and Ala272 greatly decreases MaCytb5RII's NADH affinity.

Identification of a novel d‐amino acid aminotransferase involved in d‐glutamate biosynthetic pathways in the hyperthermophile Thermotoga maritima

The hyperthermophilic bacterium Thermotoga maritima has an atypical peptidoglycan that contains d-lysine alongside the usual d-alanine and d-glutamate. We previously identified a lysine racemase involved in d-lysine biosynthesis, and this enzyme also possesses alanine racemase activity. However, T. maritima has neither alanine racemase nor glutamate racemase enzymes; hence, the precise biosynthetic pathways of d-alanine and d-glutamate remain unclear in T. maritima. In the present study, we identified and characterized a novel d-amino acid aminotransferase (TM0831) in T. maritima. TM0831 exhibited aminotransferase activity towards 23 d-amino acids, but did not display activity towards l-amino acids. It displayed high specific activities towards d-homoserine and d-glutamine as amino donors. The most preferred acceptor was 2-oxoglutarate, followed by glyoxylate. Additionally, TM0831 displayed racemase activity towards four amino acids including aspartate and glutamate. Catalytic efficiency (kcat /Km ) for aminotransferase activity was higher than for racemase activity, and pH profiles were distinct between these two activities. To evaluate the functions of TM0831, we constructed a TTHA1643 (encoding glutamate racemase)-deficient Thermus thermophilus strain (∆TTHA1643) and integrated the TM0831 gene into the genome of ∆TTHA1643. The growth of this TM0831-integrated strain was promoted compared with ∆TTHA1643 and was restored to almost the same level as that of the wild-type strain. These results suggest that TM0831 is involved in d-glutamate production. TM0831 is a novel d-amino acid aminotransferase with racemase activity that is involved in the production of d-amino acids in T. maritima.

Ultrafine RuO2 nanoparticles/MWCNTs cathodes for rechargeable Na-CO2 batteries with accelerated kinetics of Na2CO3 decomposition

Na-CO2 batteries have attracted extensive attention due to their high theoretical energy density (1125 Wh/kg), efficient utilization of CO2, and abundant sodium resources. However, they are trapped by the sluggish decomposition kinetic of discharge products (mainly Na2CO3) on cathode side during the charging process. Here we prepared a series of nano-composites composed of RuO2 nanoparticles in situ loaded on activated multi-walled carbon nanotubes (RuO2@a-MWCNTs) through hydrolyzing reaction followed by calcination method and used them as cathode catalysts to accelerate the decomposition of Na2CO3. Among all catalysts, the RuO2@a-MWCNTs with appropriate ratio of RuO2 (49.7 wt%) demonstrated best stability and rate performance in Na-CO2 batteries, benefiting from both high specific surface area (160.3 m2/g) and highly dispersed RuO2 with ultrafine nanostructures (∼2 nm). At a limited capacity of 500 mAh/g, Na-CO2 batteries could afford the operation of over 120 cycles at 100 mA/g, and even at the current density to 500 mA/g, the charge voltage was still lower than 4.0 V after 40 cycles. Further theoretical calculations proved that RuO2 was the catalytically active center and contributed to the decomposition of Na2CO3 by weakening the C=O bond. The synergetic functions of high specific surface (CNTs) and high catalytic activity (RuO2) will inspire more progress on metal-CO2 batteries.

Asn57 N-glycosylation promotes the degradation of hemicellulose by β-1,3-1,4-glucanase from Rhizopus homothallicus.

N-glycosylation alters the properties of different enzymes in different ways. Rhizopus homothallicus was first described as an environmental isolate from desert soil in Guatemala. A new gene encoding glucanase RhGlu16B was identified in R. homothallicus. It had high specific activity (9673 U/mg) when barley glucan was used as asubstrate, and β-glucan is hemicellulose that isabundant in nature. RhGlu16B has only one N-glycosylation site in its Ala55-Gly64 loop. It was found that N-glycosylation increased its Tm value and catalytic efficiency by 5.1°C and 59%, respectively. Adding N-glycosylation to the same region of GH16 family glucanases TlGlu16A (from Talaromyces leycettanus) increased its thermostability and catalytic efficiency by 6.4°C and 38%, respectively. In a verification experiment using GH16 family glucanases BisGlu16B (from Bisporus) in which N-glycosylation was removed, N-glycosylation also appeared to promote thermostability and catalytic efficiency. N-glycosylation reduced the overall root mean square deviation of the enzyme structure, creating rigidity and increasing overall thermostability. This study provided a reference for the molecular modification of GH16 family glucanases and guided the utilization of β-glucan in hemicellulose.

Anti-malarial activity in a Chinese herbal supplement containing Inonotus obliquus and Panax notoginseng.

Plasmodium falciparum, the most virulent human malaria parasite, causes serious diseases among the infected patients in the world and is particularly important in African regions. Although artemisinin combination therapy is recommended by the WHO for treatment of P. falciparum-malaria, the emergence of artemisinin-resistant parasites has become a serious issue which underscores the importance of sustained efforts to obtain novel chemotherapeutic agents against malaria. As a part of such efforts, thirty-nine herbal extracts from traditional Chinese medicine (TCM) were assayed for their anti-malarial activity using 3D7 strain of P. falciparum. Three herbal supplements appeared to possess higher specific anti-malarial activity than the others. One of them (D3) was separated by two sequential fractionations with reverse-phase (the first step) and normal-phase (the second step) liquid chromatography, in which some fractions resulted in higher specific activities than those of D3 or the previous fractions. Cell toxicity assay was performed with the fractions of the first fractionation and demonstrated no obvious cell toxicity. These results suggest that structure determination of the major compound for the anti-malarial activity in D3 may help the development of more potent chemicals in the future.

Activation and Stabilization of Lipase B from Candida antarctica by Immobilization on Polymer Brushes with Optimized Surface Structure

A reusable support system for the immobilization of lipases is developed using hybrid polymer-inorganic core shell nanoparticles. The biocatalyst core consists of a silica nanoparticle. PMMA is grafted from the nanoparticle as polymer brush via ARGET ATRP (activator regenerated by electron transfer atom transfer radical polymerization), which allows defining the surface properties by chemical synthesis conditions. Lipase B from Candida antarctica is immobilized on the hybrid particles. The activity and stability of the biocatalyst are analyzed by spectroscopic activity analysis. It is shown that the hydrophobic PMMA brushes provide an activating surface for the lipase giving a higher specific activity than the enzyme in solution. Varying the surface structure from disordered to ordered polymer brushes reveals that the reusability of the biocatalyst is more effectively optimized by the surface structure than by the introduction of crosslinking with glutaraldehyde (GDA). The developed immobilization system is highly suitable for biocatalysis in non-native media which is shown by a transesterification assay in isopropyl alcohol and an esterification reaction in n-heptane.

Biohydrogen and biomethane production from food waste using a two-stage dynamic membrane bioreactor (DMBR) system

This study examined a two-stage dynamic membrane bioreactor (DMBR) system for biohydrogen and biomethane production from food waste (FW) in mesophilic condition. The two-stage DMBR system enabled high-rate H2 and CH4 production from particulate feedstock by enhanced microorganism retention. Chemical energy in FW was recovered up to 79% as renewable energy. The highest average hydrogen production rate of 7.09 ± 0.42 L/L-d was observed at a hydraulic retention time (HRT) of 8 h in the H2-DMBR, while the highest CH4 average production rate of 0.99 ± 0.02 L/L-d was observed at an HRT of 6 d in the CH4-DMBR. The high specific methanogenic activity of 71.7 mL CH4/g VSS-d was maintained at the short HRT, which also contributed to the high MPR. The genus Clostridium was dominant in the H2-DMBR, while bacterial and archaeal populations in the CH4-DMBR were dominated by the class Clostridia and genera Methanobacterium and Methanosaeta, respectively.

Enrichment of Ca. Jettenia in sequencing batch reactors operated with low nitrogen loading rate and high influent nitrogen concentration

To apply the anammox processes into the mainstream of domestic wastewater treatment plants, two laboratory-scale sequence batch reactors have been developed and used with two different activated sludges seeded in each sequence batch reactors with gradually increases influent total nitrogen concentrations under low nitrogen loading rates. During 320 days of operation, both sequence batch reactors showed high specific anammox activity (0.68 – 0.75 kgN kg−1VSS d−1) and a nitrogen removal efficiency of 97.50%. To monitor changes in microbial community dynamics during enrichment, high-throughput sequencing analysis was performed. Members taxonomically affiliated with Candidatus Jettenia were markedly enriched and predominant in both sequence batch reactors in response to the increasing influent total nitrogen concentrations. These results suggest that Candidatus Jettenia might be a prominent anammox genus under low nitrogen loading rate with high total nitrogen concentration conditions and could be suitably applied to the mainstream process of domestic wastewater treatment systems.