Search results for "Concentration."
showing 10 items of 1849 documents
Vomilenine Reductase — a novel Enzyme catalyzing a crucial Step in the Biosynthesis of the Therapeutically applied Antiarrhythmic Alkaloid Ajmaline
2002
Delineation of the biochemical pathway leading to the antiarrhythmic Rauvolfia alkaloid ajmaline has been an important target in biosynthetic research for many years. The biosynthetic sequence starting with tryptamine and the monoterpene secologanin consists of about 10 different steps. Most of the participating enzymes have been detected and characterized previously, except those catalyzing the reduction of the intermediate vomilenine. A novel NADPH-dependent enzyme that reduces the intermediate has been isolated from Rauvolfia serpentina cell suspension cultures. Vomilenine reductase (M(r )43 kDa, temp opt 30 degrees C, pH opt 5.7-6.2), saturates the indolenine double bond of vomilenine w…
Acidic Environment Leads to ROS-Induced MAPK Signaling in Cancer Cells
2011
Tumor micromilieu often shows pronounced acidosis forcing cells to adapt their phenotype towards enhanced tumorigenesis induced by altered cellular signalling and transcriptional regulation. In the presents study mechanisms and potential consequences of the crosstalk between extra- and intracellular pH (pH(e), pH(i)) and mitogen-activated-protein-kinases (ERK1/2, p38) was analyzed. Data were obtained mainly in AT1 R-3327 prostate carcinoma cells, but the principle importance was confirmed in 5 other cell types. Extracellular acidosis leads to a rapid and sustained decrease of pH(i) in parallel to p38 phosphorylation in all cell types and to ERK1/2 phosphorylation in 3 of 6 cell types. Furth…
Purification and spectroscopic studies on catechol oxidases from Lycopus europaeus and Populus nigra: evidence for a dinuclear copper center of type …
1999
We purified two catechol oxidases from Lycopus europaeus and Populus nigra which only catalyze the oxidation of catechols to quinones without hydroxylating tyrosine. The molecular mass of the Lycopus enzyme was determined to 39,800 Da and the mass of the Populus enzyme was determined to 56,050 Da. Both catechol oxidases are inhibited by thiourea, N-phenylthiourea, dithiocarbamate, and cyanide, but show different pH behavior using catechol as substrate. Atomic absorption spectrosopic analysis found 1.5 copper atoms per protein molecule. Using EPR spectroscopy we determined 1.8 Cu per molecule catechol oxidase. Furthermore, EPR spectroscopy demonstrated that catechol oxidase is a copper enzym…
Behaviour of the plasma concentration of gelatinases and their tissue inhibitors in subjects with venous leg ulcers.
2015
Venous leg ulcers are common in subjects with chronic venous insufficiency. The increased intraluminal pressure causes alteration of the skin microcirculation, leukocyte activation and release of proteolytic enzymes leading to ulceration. An impaired expression and activity of matrix metalloproteases (MMPs) and their tissue inhibitors (TIMPs) might influence extracellular matrix degradation and deposition in chronic venous ulcers with the failure of the healing process. Our aim was to evaluate plasma concentration of gelatinases (MMP-2 and MMP-9) and their inhibitors (TIMP-1 and TIMP-2) in subjects with venous leg ulcers before and after the compression therapy. We enrolled 36 subjects (12 …
Occurrence of priority pollutants in WWTP effluents and Mediterranean coastal waters of Spain
2011
A comprehensive study aimed at evaluating the occurrence, significance of concentrations and spatial distribution of priority pollutants (PPs) along the Comunidad Valenciana coastal waters (Spain) was carried out in order to fulfil the European Water Framework Directive (WFD). Additionally, PP concentrations were also analysed in the effluent of 28 WWTPs distributed along the studied area. In coastal waters 36 organic pollutants of the 71 analysed, including 26 PPs were detected although many of them with low frequency of occurrence. Only 13 compounds, which belong to four different classes (VOCs, organochlorinated pesticides, phthalates and tributyltin compounds (TBT)) showed a frequency o…
SARS-CoV-2 RNA in wastewater anticipated COVID-19 occurrence in a low prevalence area
2020
Preprint disponible en http://hdl.handle.net/10261/209125
Occurrence of selected antibiotics and antiretroviral drugs in Nairobi River Basin, Kenya.
2015
In this paper, we investigated the occurrence of three antibiotics (sulfamethoxazole, trimethoprim and ciprofloxacin) and three antiretroviral (lamivudine, nevirapine and zidovudine) drugs in the Nairobi River Basin, Kenya. The analytical procedure involved extraction using solid phase extraction followed by liquid chromatography-electrospray ionization tandem mass spectrometry (SPE-LC-ESI-MS/MS). In this study, 40 sites were selected for sampling, including 38 sites along the rivers and 2 wastewater treatment effluent sites. All the studied compounds were detected with sulfamethoxazole having the highest detection frequency of 97.5% and ciprofloxacin had the lowest at 60%. The results show…
Enzymes involved in vinyl acetate decomposition by Pseudomonas fluorescens PCM 2123 strain
2014
Esterases are widely used in food processing industry, but there is little information concerning enzymes involved in decompositions of esters contributing to pollution of environment. Vinyl acetate (an ester of vinyl alcohol and acetic acid) is a representative of volatile organic compounds (VOCs) in decomposition, of which hydrolyses and oxidoreductases are mainly involved. Their activities under periodically changing conditions of environment are essential for the removal of dangerous VOCs. Esterase and alcohol/aldehyde dehydrogenase activities were determined in crude cell extract from Pseudomonas fluorescens PMC 2123 after vinyl acetate induction. All examined enzymes exhibit their hig…
Inhibition of Folic Acid Uptake by Catechins and Tea Extracts in Caco-2 Cells
2006
In this present study it was aimed to determine whether the catechins contained in green tea and the whole extracts of Camellia sinensis (Theaceae) inhibit the uptake of folic acid by Caco-2 cell monolayers. Our results indicate that (-)-epigallocatechin 3-gallate (EGCG) and (-)-epicatechin 3-gallate (ECG) inhibit cellular folic acid uptake with IC50 values of 34.8 micromol/L and 30.8 micromol/L, respectively. Furthermore, green and black tea extracts were also found to inhibit folic acid uptake with IC50 values of approximately 7.5 and 3.6 mg/mL, respectively. According to these results, simultaneous intake of tea and folic acid may inhibit intestinal folic acid absorption. The consequence…
Metabolic Clearance of the Antioxidant Ascorbic Acid in Surgical Patients1
2005
Background A reduction of plasma ascorbic acid concentration in the post-operative period has been well documented and is associated with an increase in post-operative complications. The underlying reason for the decreased concentration of ascorbic acid in the plasma is not clear. However, only an increased post-operative requirement for ascorbic acid would justify a substitution. Therefore, we investigated the pre-operative and post-operative metabolic clearance of ascorbic acid. Materials and Methods We calculated the metabolic clearance subsequent to intravenous bolus injection of 6 mg ascorbic acid/kg body weight in 15 patients before and after they underwent major maxillofacial surgery…