93-35-6Relevant academic research and scientific papers
Fluorescence detection of hydroxyl radical generated from oxygen reduction on Fe/N/C catalyst
Chen, Li-Na,Yu, Wen-Song,Wang, Tao,Yang, Xiao-Dong,Yang, Hui-Juan,Chen, Zhi-Xin,Wang, Tan,Tian, Na,Zhou, Zhi-You,Sun, Shi-Gang
, p. 198 - 202 (2020)
Pyrolyzed Fe/N/C catalyst has been considered as the most promising candidate to replace Pt for oxygen reduction reaction (ORR) in fuel cells. However, poor stability of Fe/N/C catalyst, mainly attributed to the oxidation corrosion by aggressive ?OH radical, severely hampers its applications. However, the exact mechanism for generation of ?OH is unclear yet. Herein, we developed a fluorescent method to effectively detect ?OH generated from ORR on Fe/N/C catalyst by using coumarin as a fluorescent probe. A great difference in potential dependence between ?OH and H2O2 generated from the ORR was observed, which suggests that ?OH is not generated from the decomposition of H2O2 as traditional viewpoint.
Hydrothermal synthesis of Mn-doped CdS hollow sphere nanocomposites as efficient visible-light driven photocatalysts
Zhang, Chunyan,Lai, Jiasheng,Hu, Juncheng
, p. 15110 - 15117 (2015)
A series of Mn-doped CdS hollow sphere photocatalysts has been directly synthesized by a simple and facile hydrothermal route for the first time. It was demonstrated that GSH acts as the S source and a gas bubble-template in this process. The products were characterized by XRD, SEM, TEM, HRTEM, XPS, and UV-vis spectroscopy. The as-prepared CdS and Mn-doped CdS hollow spheres all showed much higher activity than P25 under visible light (λ > 420 nm) irradiation. Among them, the 2.0 mol% Mn-doped CdS sample exhibited the highest photoactivity for the removal of organic pollutant RhB, and about 99.2% MO was decomposed after 50 min of visible light irradiation. Moreover, this catalyst also showed good stability, and after four cycles, the degradation efficiency still remained at 85%. The excellent photoactivity of the as-prepared Mn-doped CdS hollow spheres could be attributed to the synergistic effects of its appropriate band-gap structure and the special porous spherical morphology. The unique hollow sphere structure may favor the harvesting of excited light due to its special multiple scattering effect within the interior space, and the doping of Mn2+ may facilitate the generation of photoinduced electrons and hole pairs, and inhibit their recombination rate by acting as temporary trapping sites. This material may have great application potentials in environmental remediation and energy harvesting.
Functional characterization of allelic variants of polymorphic human cytochrome P450 2A6 (CYP2A6*5, *7, *8, *18, *19, and *35)
Han, Songhee,Choi, Seunghye,Chun, Young-Jin,Yun, Chul-Ho,Lee, Chang Hoon,Shin, Hee Jung,Na, Han Sung,Chung, Myeon Woo,Kim, Donghak
, p. 394 - 399 (2012)
Cytochrome P450 2A6 (CYP2A6) catalyzes important metabolic reactions of many xenobiotic compounds, including coumarin, nicotine, cotinine, and clinical drugs. Genetic polymorphisms of CYP2A6 can influence its metabolic activities. This study analyzed the functional activities of six CYP2A6 allelic variants (CYP2A6*5,*7,*8,*18,*19, and *35) containing nonsynonymous single-nucleotide polymorphisms. Recombinant variant enzymes of CYP2A6*7,*8,*18,*19, and *35 were successfully expressed in Escherichia coli and purified. However, a P450 holoenzyme spectrum was not detected for the CYP2A6*5 allelic variant (G479V). Structural analysis shows that the G479V mutation may alter the interaction between the A helix and the F-G helices. Enzyme kinetic analyses indicated that the effects of mutations in CYP2A6 allelic variants on drug metabolism are dependent on the substrates. In the case of coumarin 7-hydroxylation, CYP2A6*8 and *35 displayed increased Km values whereas CYP2A6*18 and *19 showed decreased kcat values, which resulted in lower catalytic efficiencies (kcat/Km). In the case of nicotine 5-oxidation, the CYP2A6*19 variant exhibited an increased Km value, whereas CYP2A6*18 and *35 showed much greater decreases in kcatvalues. These results suggest that individuals carrying these allelic variants are likely to have different metabolisms for different CYP2A6 substrates. Functional characterization of these allelic variants of CYP2A6 can help determine the importance of CYP2A6 polymorphisms in the metabolism of many clinical drugs.
A sensitive and selective fluorescence probe for the detection of superoxide radical anion in vivo based on a protection-deprotection process
Chen, Liyan,Lu, Xin,Wu, Di,Xiao, Fengping
, (2021)
Superoxide radical anion (O2·?) plays vital roles in numerous physiological and pathological processes. Thus, it is in great demand to develop an efficient fluorescence probe for the measurement of O2·?. In the investigation, a new fluorescence probe NAP-SCM was developed for detection of O2·? on the basis of a protection-deprotection process. This probe, which utilizes coumarin as the fluorescent platform and 1,8-naphthalimidesulfonyl as the masking moiety, could monitor O2·? with good specificity, rapid response and low detection limit. More importantly, probe NAP-SCM displayed negligible cytotoxicity, good bio-compatibility and excellent capability of tracking the endogenous superoxide radical anion in live cells and live animals. The favorable observations illustrated that this probe has the promising potential to provide a valuable support for exploring the role(s) played by O2·? in the biologically functional processes.
Synthesis of 7-hydroxycoumarins catalysed by solid acid catalysts
Hoefnagel,Gunnewegh,Downing,Van Bekkum
, p. 225 - 226 (1995)
Syntheses of substituted 7-hydroxycoumarins via reactions of 1,3-dihydroxybenzene with ethyl acetoacetate (Pechmann reaction) and with propenoic acid and propynoic acids are reported, in which the production of environmentally harmful waste streams is minimized by the use of solid acid catalysts.
Sn-Doped defect pyrochlore oxide KNbWO6·H2O microcrystals and their photocatalytic reduction of CO2
Zeng, Xu,Chen, Yan,Jiao, Shihui,Fang, Zhenxing,Wang, Boran,Pang, Guangsheng,Feng, Shouhua
, p. 5753 - 5758 (2018)
It is highly desirable to develop new semiconductors for the photocatalytic reduction of CO2 to CH4 and CO to solve greenhouse effect and energy issues. Defect pyrochlore oxides have a flexible composition and the electron/hole mobility can be manipulated by introducing foreign cations into the structure. Through Sn doping into the defect pyrochlore oxide KNbWO6·H2O, we successfully obtained a 2-times higher photocatalytic activity for converting CO2 to CO, CH4 and O2 compared to the original KNbWO6·H2O. According to the data from UV-vis, photoluminescence, and hydroxyl radical amount-related fluorescence spectra, and CO2 adsorption, the improved photocatalytic activity can be attributed to the extended visible light response, the enhanced charge separation and the improved CO2 adsorption due to Sn doping. Our results provide a new strategy for developing high-performance photocatalysts.
Surface-Binding Peptide Facilitates Electricity-Driven NADPH-Free Cytochrome P450 Catalysis
Zernia, Sarah,Frank, Ronny,Wei?e, Renato H.-J.,Jahnke, Heinz-Georg,Bellmann-Sickert, Kathrin,Prager, Andrea,Abel, Bernd,Str?ter, Norbert,Robitzki, Andrea,Beck-Sickinger, Annette G.
, p. 525 - 530 (2018)
Industrial biotechnology aims to exploit cytochrome P450 enzymes to access their sophisticated catalytic activity for challenging chemical reactions on inert C?H bonds. Limited by the need for NADPH, approaches to bind P450 enzymes to electrode surfaces for an artificial electron supply are promising. Here, we demonstrate that a recombinant fusion of an indium tin oxide binding peptide and the multi-domain class VIII cytochrome P450 BM3 can be used in electrically driven catalysis. Bioelectrocatalytic activity is analyzed by direct product quantification resulting in superior activity of the specifically immobilized P450 BM3 in contrast to unspecifically adsorbed enzyme. Spacer and anchor point studies imply that enzyme flexibility and alignment are crucial factors to achieve high activity on the electrode. Furthermore, we demonstrate that our approach is also feasible for pharmaceutical application using naringenin as substrate.
LICRED: A versatile drop-in vector for rapid generation of redox-self-sufficient cytochrome P450s
Sabbadin, Federico,Hyde, Ralph,Robin, Aelig,Hilgarth, Eva-Maria,Delenne, Marie,Flitsch, Sabine,Turner, Nicholas,Grogan, Gideon,Bruce, Neil C.
, p. 987 - 994 (2010)
Cytochromes P450 (P450s) are a family of haem-containing oxidases with considerable potential as tools for industrial biocatalysis. Organismal genomes are revealing thousands of gene sequences that encode P450s of as yet unknown function, the exploitation of which will require high-throughput tools for their isolation and characterisation. In this report, a ligation-independent cloning vector "LICRED" is described that enables the high-throughput generation of libraries of redox-self-sufficient P450s by fusing a range of P450 haem domains to the reductase of P450RhF (RhF-Red) in a robust and generically applicable way. Cloning and expression of fusions of RhF-Red with the haem domains of P450cam and P450-XplA resulted in soluble, active, redox-self-sufficient, chimeric enzymes. In vitro studies also revealed that electron transfer from NADPH to haem was primarily intramolecular. The general applicability of the LICRED platform was then demonstrated through the creation of a library of RhF-Red fusion constructs by using the diverse complement of P450 haem domains identified in the genome of Nocardia farcinica. The resultant fusion-protein library was then screened against a panel of substrates; this revealed chimeric enzymes competent for the hydroxylation of testosterone and methyltestosterone, and the dealkylation of 7-ethoxycoumarin.
New fluorogenic probes for neutral and alkaline ceramidases
Casasampere, Mireia,Bielsa, Núria,Riba, Daniel,Bassas, Laura,Xu, Ruijuan,Mao, Cungui,Fabriàs, Gemma,Abad, José-Luis,Delgado, Antonio,Casas, Josefina
, p. 1174 - 1181 (2019)
New fluorogenic ceramidase substrates derived from the N-acyl modification of our previously reported probes (RBM14) are reported. While none of the new probes were superior to the known RBM14C12 as acid ceramidase substrates, the corresponding nervonic acid amide (RBM14C24:1) is an efficient and selective substrate for the recombinant human neutral ceramidase, both in cell lysates and in intact cells. A second generation of substrates, incorporating the natural 2-(N-acylamino)-1,3-diol-4-ene framework (compounds RBM15) is also reported. Among them, the corresponding fatty acyl amides with an unsaturated N-acyl chain can be used as substrates to determine alkaline ceramidase (ACER)1 and ACER2 activities. In particular, compound RBM15C18:1 has emerged as the best fluorogenic probe reported so far to measure ACER1 and ACER2 activities in a 96-well plate format.
Is surface fluorination of TiO2 effective for water purification? The degradation vs. mineralization of phenolic pollutants
Ryu, Jungho,Kim, Wooyul,Kim, Jaesung,Ju, Jinjung,Kim, Jungwon
, p. 24 - 30 (2017)
The photocatalytic activity of surface fluorinated TiO2 (F-TiO2) for both the degradation and mineralization of bisphenol A (BPA) was compared with that of pure TiO2. The degradation rate of BPA (i.e., the conversion rate of BPA to intermediates) was enhanced, but the mineralization rate (i.e., the conversion rate of BPA to CO2) was reduced by surface fluorination. These behaviors are different from the general trend in photocatalysis, in which the photocatalyst with a higher activity for the degradation also shows a higher activity for the mineralization. The surface fluorination of TiO2 enhanced the production of the hydroxyl radical ([rad]OH), which is primarily responsible for the degradation of BPA, by altering the [rad]OH generation pathway. However, the lower mineralization on F-TiO2, which produced more [rad]OH, implies that the role of [rad]OH in the photocatalytic mineralization process is minor. The production of superoxide/hydroperoxyl radical (O2[rad]?/HO2[rad]), which is suggested as an essential oxidant for the mineralization of phenolic pollutants, by F-TiO2 was lower than that exhibited by pure TiO2. The reduced photocurrent (Iph) generation and the enhanced H2O2 production on F-TiO2 indicate that fluorides on the TiO2 surface reduce the interfacial electron transfer rate (i.e., the production of O2[rad]?/HO2[rad]) and enhance the reduction of O2[rad]?/HO2[rad] to H2O2. The degradation rate increased, but the mineralization efficiency decreased with increasing the surface coverage of fluorides, which depends on the pH and fluoride concentration in the solution. The reduced mineralization efficiency of other phenolic pollutants (4-chlorophenol, phenol, methylene blue, rhodamine B, and acid orange 7) was also observed on F-TiO2. This result indicates that the negative effect of surface fluorination on the mineralization of phenolic pollutants is pervasive and is not restricted to BPA.
