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排序方式: 共有113条查询结果,搜索用时 93 毫秒
71.
Iulia Gabriela David Mihai-Alexandru Florea Oana Georgiana Cracea Dana Elena Popa Mihaela Buleandra Emilia Elena Iorgulescu Vasile David Irinel Adriana Badea Anton Alexandru Ciucu 《Chemical Papers》2015,69(7):901-910
Due to the importance of B1 and B6 vitamins for human health it is useful to develop new cheap and rapid methods for their determination. Voltammetric behavior of these vitamins on a pencil graphite electrode was investigated using cyclic voltammetry in different media. Direct quantitative determination of the two vitamins, one in the presence of the other, was done by differential pulse voltammetry. Vitamin B1 was electroactive only in a NaOH solution generating two irreversible oxidation peaks; the first peak obtained at 250 mV is well-defined and was used in quantitative determinations. In case of vitamin B6, a well-defined oxidation peak was observed in all investigated supporting electrolytes except for HCl. The linear concentration ranges were 10?5–10?3 M for vitamin B1 in a NaOH solution and 5 × 10?6–10?3 M for vitamin B6 in an acetate buffer solution. The obtained detection limits were 5.34 × 10?6 M and 2.81 × 10?6 M for vitamin B1 and vitamin B6, respectively. The developed method is simple and rapid and it was successfully applied in the determination of the two vitamins in pharmaceuticals. 相似文献
72.
73.
Sahoo H Hennig A Florea M Roth D Enderle T Nau WM 《Journal of the American Chemical Society》2007,129(51):15927-15934
The collision-induced fluorescence quenching of a 2,3-diazabicyclo[2.2.2]oct-2-ene-labeled asparagine (Dbo) by hydrogen atom abstraction from the tyrosine residue in peptide substrates was introduced as a single-labeling strategy to assay the activity of tyrosine kinases and phosphatases. The assays were tested for 12 different combinations of Dbo-labeled substrates and with the enzymes p60c-Src Src kinase, EGFR kinase, YOP protein tyrosine phosphatase, as well as acid and alkaline phosphatases, thereby demonstrating a broad application potential. The steady-state fluorescence changed by a factor of up to 7 in the course of the enzymatic reaction, which allowed for a sufficient sensitivity of continuous monitoring in steady-state experiments. The fluorescence lifetimes (and intensities) were found to be rather constant for the phosphotyrosine peptides (ca. 300 ns in aerated water), while those of the unphosphorylated peptides were as short as 40 ns (at pH 7) and 7 ns (at pH 13) as a result of intramolecular quenching. Owing to the exceptionally long fluorescence lifetime of Dbo, the assays were alternatively performed by using nanosecond time-resolved fluorescence (Nano-TRF) detection, which leads to an improved discrimination of background fluorescence and an increased sensitivity. The potential for inhibitor screening was demonstrated through the inhibition of acid and alkaline phosphatases by molybdate. 相似文献
74.
Verdoes M Florea BI van der Linden WA Renou D van den Nieuwendijk AM van der Marel GA Overkleeft HS 《Organic & biomolecular chemistry》2007,5(9):1416-1426
The synthesis and evaluation of hybrid proteasome inhibitors that contain structural elements of the known inhibitors bortezomib, epoxomicin and peptide vinyl sulfones is described. From the panel of 15 inhibitors some structure activity relationships can be deduced with regard to inhibitory activity in relation to peptide recognition element, inhibitor size and nature of the electrophilic trap. Further, the panel contains one of the most potent peptide-based pan-proteasome inhibitors reported to date. 相似文献
75.
Sara Christina Stolze Edgar Deu Farnusch Kaschani Nan Li Bogdan I. Florea Kerstin H. Richau Tom Colby Renier A.L. van der Hoorn Hermen S. Overkleeft Matthew Bogyo Markus Kaiser 《Chemistry & biology》2012,19(12):1546-1555
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76.
Dr. Mara Florea Dr. Srikanth Kudithipudi Dr. Ana Rei María José González‐Álvarez Prof. Dr. Albert Jeltsch Prof. Dr. Werner M. Nau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(12):3521-3528
The demand for practical and convenient enzyme assays for histone lysine methyltransferases (HKMTs) emerges along with the rapid development of this young class of enzymes. A supramolecular reporter pair composed of p‐sulfonatocalix[4]arene (CX4) and the fluorescent dye lucigenin (LCG) has been used to monitor enzymatic trimethylation of lysine residues in peptide substrates. The assay affords a switch‐ON fluorescence response and operates in a continuous, real‐time, and label‐free fashion. The underlying working principle relies on the higher affinity of the macrocycle towards the trimethylated product of the enzymatic reaction as compared to the substrate, which allows the assay to be carried out in the product‐selective mode. The final product incorporates a trimethylammonium moiety, a known high‐affinity binding motif for CX4. Two substrates corresponding to the H3 N‐terminal tail, namely, S2 (RTKQTA RKSTG GKAP) and S6 (QTA RKSTG GS), were selected as model compounds for methylation with the Neurospora crassa Dim‐5 enzyme and investigated by the newly developed supramolecular tandem HKMTs assay. Only the longer substrate S2 underwent methylation in solution. The potential of the assay for inhibitor screening was demonstrated by means of inhibition studies with 1,10‐phenanthroline to afford an inhibition constant of (70±20) μM . 相似文献
77.
Speranta Avram Ana Maria Udrea Diana Camelia Nuta Carmen Limban Adrian Cosmin Balea Miron Teodor Caproiu Florea Dumitrascu Ctlin Buiu Alexandra Teodora Bordei 《Molecules (Basel, Switzerland)》2021,26(14)
(1) Background: The research aims to find new treatments for neurodegenerative diseases, in particular, Alzheimer’s disease. (2) Methods: This article presents a bioinformatics and pathology study of new Schiff bases, (EZ)-N′-benzylidene-(2RS)-2-(6-chloro-9H-carbazol-2-yl)propanehydrazide derivatives, and aims to evaluate the drug-like, pharmacokinetic, pharmacodynamic and pharmacogenomic properties, as well as to predict the binding to therapeutic targets by applying bioinformatics, cheminformatics and computational pharmacological methods. (3) Results: We obtained these Schiff bases by condensing (2RS)-2-(6-chloro-9H-carbazol-2-yl)propanehydrazide with aromatic aldehydes, using the advantages of microwave irradiation. The newly synthesized compounds were characterized spectrally, using FT-IR and NMR spectroscopy, which confirmed their structure. Using bioinformatics tools, we noticed that all new compounds are drug-likeness features and may be proposed as potentially neuropsychiatric drugs (4) Conclusions: Using bioinformatics tools, we determined that the new compound 1e had a high potential to be used as a good candidate in neurodegenerative disorders treatment. 相似文献
78.
Florea M Kudithipudi S Rei A González-Álvarez MJ Jeltsch A Nau WM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(12):3521-3528
The demand for practical and convenient enzyme assays for histone lysine methyltransferases (HKMTs) emerges along with the rapid development of this young class of enzymes. A supramolecular reporter pair composed of p-sulfonatocalix[4]arene (CX4) and the fluorescent dye lucigenin (LCG) has been used to monitor enzymatic trimethylation of lysine residues in peptide substrates. The assay affords a switch-ON fluorescence response and operates in a continuous, real-time, and label-free fashion. The underlying working principle relies on the higher affinity of the macrocycle towards the trimethylated product of the enzymatic reaction as compared to the substrate, which allows the assay to be carried out in the product-selective mode. The final product incorporates a trimethylammonium moiety, a known high-affinity binding motif for CX4. Two substrates corresponding to the H3 N-terminal tail, namely, S2 (RTKQTARKSTGGKAP) and S6 (QTARKSTGGS), were selected as model compounds for methylation with the Neurospora crassa Dim-5 enzyme and investigated by the newly developed supramolecular tandem HKMTs assay. Only the longer substrate S2 underwent methylation in solution. The potential of the assay for inhibitor screening was demonstrated by means of inhibition studies with 1,10-phenanthroline to afford an inhibition constant of (70±20)?μM. 相似文献
79.
2-Oxoglutarate oxygenases (2-OGs) are a large enzyme family involved in numerous processes in health and disease. Rotili et?al. (2011) describe in this issue of Chemistry & Biology an activity-based protein profiling-based strategy with which the activity of individual members of the 2-OG family can be addressed in the context of complex biological systems. 相似文献
80.
Mihaela Miu Irina Kleps Florea Craciunoiu Monica Simion Adina Bragaru Teodora Ignat 《Solid State Sciences》2010,12(11):1917-1922
The scope of this paper is development of a new laboratory-on-a-chip (LOC) device for biomedical studies consisting of a microfluidic system coupled to microelectronic/optical transducers with nanometric features, commonly called biosensors. The proposed device is a hybrid system with sensing element on silicon (Si) chip and microfluidic system on polydimethylsiloxane (PDMS) substrates, taking into accounts their particular advantages. Different types of nanoelectrode arrays, positioned in the reactor, have been investigated as sensitive elements for electrical detection and the recording of neuron extracellular electric activity has been monitorized in parallel with whole-cell patch-clamp membrane current. Moreover, using an additional porosification process the sensing element became efficient for optical detection also. The preliminary test results demonstrate the functionality of the proposed design and also the fabrication technology, the devices bringing advantages in terms enhancement of sensitivity in both optoelectronic detection schemes. 相似文献