Search results for "RADIS"
showing 10 items of 95 documents
Horseradish peroxidase-catalyzed oxidation of chlorophyll a with hydrogen peroxide
2010
Horseradish peroxidase was verified to catalyze, without any phenol, the hydrogen peroxide oxidation of chlorophyll a (Chl a), solubilized with Triton X-100. The 13(2)(S) and 13(2)(R) diastereomers of 13(2)-hydroxyChl a were characterized as major oxidation products (ca. 60%) by TLC on sucrose, UV-vis, (1)H, and (13)C NMR spectra, as well as fast-atom bombardment MS. A minor amount of the 15(2)-methyl, 17(3)-phytyl ester of Mg-unstable chlorin was identified on the basis of its UV-vis spectrum and reactivity with diazomethane, which converted it to the 13(1),15(2)-dimethyl, 17(3)-phytyl ester of Mg-purpurin 7. The side products (ca. 10%) were suggested to include the 17(3)-phytyl ester of M…
Conformational relaxation of a low-temperature protein as probed by photochemical hole burning. Horseradish peroxidase
1991
For the first time, conformational relaxation processes have been measured in a small protein, mesoporphyrin-horseradish peroxidase via their influence on spectral diffusion broadening of holes burnt in the fluorescence excitation spectrum of free base mesoporphyrin. Holes were burnt in three 0----0 bands of different tautomeric forms of the chromophore at 1.5 and 4 K, and the spectral diffusion broadening was measured in temperature cycling experiments between 4 and 30 K. The inhomogeneous linewidth for the tautomeric 0----0 bands was estimated to be 60-70 cm-1; the hole width was found narrow, being in the order of 350 MHz (10(-2) cm-1) at 1.5 K what allowed for an extremely sensitive det…
Oxidative Copolymerisation ofpara-Functionalized Phenols Catalyzed by Horseradish peroxidase and Thermocrosslinking via Diels-Alder and (1+3) Cycload…
2001
The horseradish peroxidase- (HRP-) catalyzed polyrecombination of N-(4-hydroxyphenyl)-2-furamide (2) and 4-hydroxyphenylmaleimide (1) is described. The resulting copolymer was used to build crosslinked materials via Diels-Alder and cycloaddition reactions. We followed the enzymatic copolymerization process of an equimolar mixture of 1 and 2 using high pressure liquid chromatography (HPLC), size-exclusion chromatography (SEC) and by matrix assisted laser desorption/ionization-time of flight mass spectroscopy (MALDI-TOF MS) analysis and found that the polymerization of 2, which has a significant higher highest occupied molecular orbital (HOMO) energy, proceeds much faster. The HOMO energies o…
Grapefruit essential oils inhibit quorum sensing of Pseudomonas aeruginosa.
2019
Citrus essential oils are used in food to confer flavor and aromas. The citrus essential oils have been granted as GRAS and could be used as antimicrobial additives to control bacterial quorum sensing from potential food bacterial pathogens. The chemical composition and inhibitory activity of Citrus paradisi (grapefruit) essential oils obtained by cold-pressed method (EOP) and cold-pressed method followed by steam distillation, against Pseudomonas aeruginosa were determined . The GC-MS analyses of the oil indicated the amount of the essential oil components was highest with D-limonene in both cases. However, the extraction method modified the chemical composition. EOP had higher amount of …
Mechanisms of interference of p-diphenols with the Trinder reaction
2020
p-Diphenols, such as homogentisic acid, gentisic acid, etamsylate, and calcium dobesilate, interfere with diagnostic tests utilizing the Trinder reaction but the mechanisms of these effects are not fully understood. We observed substantial differences both in oxidation of p-diphenols by horseradish peroxidase and their influence on oxidation of 4-aminoantipyrine and various phenolic substrates. Homogentisic acid was rapidly oxidized by the enzyme and completely blocked chromophore formation. Enzymatic oxidation of the remaining p-diphenols was slow and they only moderately inhibited chromophore formation. However, in the presence of standard substrates all tested p-diphenols were rapidly co…
Protective, antioxidant and antiproliferative activity of grapefruit integropectin on sh-sy5y cells
2021
Tested in vitro on SH-SY5Y neuroblastoma cells, grapefruit IntegroPectin is a powerful protective, antioxidant and antiproliferative agent. The strong antioxidant properties of this new citrus pectin, and its ability to preserve mitochondrial membrane potential and morphology, severely impaired in neurodegenerative disorders, make it an attractive therapeutic and preventive agent for the treatment of oxidative stress-associated brain disorders. Similarly, the ability of this pectic polymer rich in RG-I regions, as well as in naringin, linalool, linalool oxide and limonene adsorbed at the outer surface, to inhibit cell proliferation or even kill, at high doses, neoplastic cells may have open…
Towards sarcosine determination in urine for prostatic carcinoma detection
2019
Abstract Sarcosine, a potential biomarker for prostate cancer, can be detected in a solid state enzyme based biosensor using sarcosine oxidase, with particle immobilised reagents. A novel fusion protein of the fluorescent protein, mCherry, sarcosine oxidase (SOx), and the polypeptide R5 (R52-mCherry-SOx-R5-6 H), was explored, which allowed self-immobilization on silica microparticles and long-term (90 days +) retention of activity, even at room temperature. In contrast, commercial wildtype SOx lost activity in a few days. A silica-R52-mCherry-SOx-R5-6H microparticle sensor for determination of sarcosine in urine, linked the SOx coproduct, H2O2, to a measurement catalysed by horseradish pero…
L'elemento acqua nella tradizione islamica
2014
Questo intervento tocca l'argomento elemento acqua così come viene mostrato dalle principali fonti della tradizione islamica: il Corano e la sunna del profeta Muhammad. Dall'acqua passa l'abluzione, sia quella denominata maggiore sia la minore, anche se bisogna considerare che ogni vera purità passa dalla purificazione del cuore. Anche la Sunna cita ripetutamente l'acqua nelle narrazioni relative ad episodi della vita di Muhammad e nei suoi detti. Si constata anche come l'acqua sia oggetto di avvenimenti prodigiosi, mentre nello stesso tempo, varie raccomandazioni ed avvertimenti ruotano nel suo utilizzo.
A thin layer-based amperometric enzyme immunoassay for the rapid and sensitive diagnosis of respiratory syncytial virus infections
2012
Abstract A simple electrochemical sandwich immunoassay involving a polystyrene microarray slide coated with monoclonal capture antibodies and carbon screen-printed sensors (SPS) was designed for the rapid diagnosis of respiratory syncytial virus (RSV). The detection of the antibody-antigen complex formation relied on the use of a horseradish peroxidase conjugate. Its chronoamperometric measurement detection was performed by confining a droplet of H 2 O 2 /3,3',5,5'-tetramethylbenzidine enzyme substrate/mediator solution within a thin layer between one spot of the microarray and the surface of one screen-printed electrochemical cell. The accumulation of the enzyme product in the thin film of…
Patterns of variation in tail ornament size in birds
1988
In recent years several different kinds of sexual selection models have been developed, and tail ornaments in birds have frequently been used as an example of a sexually selected character where the models might apply. However, very little is known about intra- and interpopulation variation in ornament size. We have studied the elongated tail ornaments in four species of whydahs Vidua, the forktailed flycatcher Tyrannus savana and the Asian paradise flycatcher Terpsiphone paradisi. Ornaments were relatively longer in males with the longest tarsi (‘heterogony’ with positive allometry). Also, tail lengths were remarkably variable within each geographical area, the coefficient of variation (av…