612 research outputs found
Interaction of prodan with tubulin
No full textThe compound 6-propionyl-2-(N,N-dimethyl)-aminonaphthalene (Prodan), an efficient fluorescent probe for proteins, is shown to bind to tubulin. Detailed experiments on fluorescence enhancement, anisotropy and energy transfer were carried out to unravel the nature of Prodan-tubulin interaction and the Prodan-binding site on tubulin. It was found that Prodan binds to tubulin at a rigid site, with a stoichiometry of 1:1 and a dissociation constant of 20 μM. Competition experiments using 1,8-[3H]anilinonaphthalenesulfonate ([3H]ANS) indicated that the three aminonaphthalenes, ANS, bis(1,8-anilinonaphthalenesulfonate) and Prodan probably bind to a common region on the tubulin molecule
Development of a cold end filament feeder for a hanging 3D printer
No full textHitrost tiskanja 3D tiskalnikov, ki uporabljajo tehnologijo ekstrudiranja polimerne niti (FFF) je v veliki meri odvisna od hitrosti podajalnika polimerne niti. V zaključni nalogi obravnavamo razvoj podajalnika polimerne niti za viseč 3D tiskalnik, ki bo zmogel večjo podajalno hitrost kot obstoječi podajalniki. Predstavljen je postopek od zastavljanja konstrukcijskih zahtev, preko preučevanja delnih funkcij podajalnika, do ocenjevanja prototipov. Na osnovi ocen delnih rešitev smo prišli do končnega prototipa podajalnika.The speed of 3D printers using fused filament fabrication (FFF) technology depends mostly on the speed of the extruder. In this document we discuss the development of a cold end of extruder for a large-scale 3D printer. A presented process starts from the setting of construction requirements, go through the study of the partial functions of the cold end and finish with the evaluation of prototypes. Based on the estimates of partial solutions we create final prototype of cold end of extruder
Profiling of dynamics in protein–lipid–water systems: a time-resolved fluorescence study of a model membrane protein with the label BADAN at specific membrane depths
No full textProfiles of lipid-water bilayer dynamics were determined from picosecond time-resolved fluorescence spectra of membrane-embedded BADAN-labeled M13 coat protein. For this purpose, the protein was labeled at seven key positions. This places the label at well-defined locations from the water phase to the center of the hydrophobic acyl chain region of a phospholipid model membrane, providing us with a nanoscale ruler to map membranes. Analysis of the time-resolved fluorescence spectroscopic data provides the characteristic time constant for the twisting motion of the BADAN label, which is sensitive to the local flexibility of the protein-lipid environment. In addition, we obtain information about the mobility of water molecules at the membrane-water interface. The results provide an unprecedented nanoscale profiling of the dynamics and distribution of water in membrane systems. This information gives clear evidence that the actual barrier of membranes for ions and aqueous solvents is located at the region of carbonyl groups of the acyl chains
A New Interpretation of the Absorption and the Dual Fluorescence of Prodan in Solution
No full textProdan is a fluorescent probe used to monitor biological systems such as lipid membrane,proteins and DNA. Remarkable interest is associated to the interpretation of its fluorescent spectrum.In this paper the sequential hybrid Quantum Mechanics/Molecular Mechanics (S-QM/MM) method was used to establish that the fluorescent emission occurs from two different excited states, resulting in a broad asymmetric emission spectrum with two transitions. The absorption spectra in several solvents were measured and calculated using different theoretical models and they all agree that the first observed band is composed of three electronic excitation very close energetically to each other
PRODAN differentially influences its local environment
No full textEnvironmentally-sensitive membrane dyes have been extensively used to study the different liquid phases, (liquid-ordered (Lo) and liquid-disordered (Ld)) of the heterogenous cellular membrane. However, it is not yet well understood how these dyes affect membrane properties upon and post insertion. Using a combination of molecular dynamics (MD) simulations and fluorescence microscopy, we study the effect of PRODAN insertion upon its local environment. We firstly present the results of the MD simulations of PRODAN interacting with lipid bilayers of various compositions, specifically the resultant hydration and lipid order of the system. Experimentally, the lipid order of Lo and Ld vesicles containing various concentrations of PRODAN are inferred from their Generalised Polarisation (GP) values, calculated using their fluorescence spectra. We then apply the methodology to a more complex biological system, the HeLa cell line. For both systems, the presence of PRODAN influences its local environment differently between the Lo and Ld phases. In the simulated systems, the presence of PRODAN lowers the lipid order in the Ld phase and increases the order in the Lo phase, whilst experimental data demonstrates that even a small increase in PRODAN concentration significantly lowers the order of both phases. We suggest this discrepancy may be ascribed to the differing localisations of the dye molecules within the bilayer, and their effect on the hydration of adjacent lipids
Fluorene Analogues of Prodan with Superior Fluorescence Brightness and Solvatochromism
No full textIn a search for environmentally sensitive (solvatochromic) dyes with superior properties, we extended the electronic conjugation of one of the best solvatochromic dyes, Prodan, by substituting its naphthalene core with fluorene. The newly synthesized fluorene derivatives bearing strong electron-donor (dialkylamino) and -acceptor (carbonyl) groups at the 2 and 7 positions showed red-shifted absorption (close to 400 nm), twice as large of a absorption coefficient (43 000 M<sup>−1</sup> cm<sup>−1</sup>), and a manifold larger two-photon absorption cross section (∼400 GM) compared to Prodan. Studies in solvents revealed much stronger fluorescence solvatochromism of the new dyes, which is connected with their twice as large transition dipole moment (14.0 D). Similarly to Prodan, they exhibit high fluorescence quantum yields, while their photostability is largely improved. Thus, substitution of the naphthalene core in Prodan with fluorene resulted in new fluorophores with superior spectroscopic and solvatochromic properties. We expect them to find a variety of applications as environmentally sensitive probes and labels in biology
Rearrangement and Aromatization of the Ketoenamine Adducts from Dibenzoyl Diazene and Secondary - and -Ketoenamines
No full text
Comparação dos métodos de amostragem área fixa e Prodan em um povoamento de Pinus sp. com 45 anos.
No full textTCC(graduação) - Universidade Federal de Santa Catarina. Campus Curitibanos. Engenharia Florestal.A busca por técnicas que permitam uma melhor avaliação qualitativa e quantitativa dos povoamentos florestais se torna cada vez mais necessária. Atualmente a técnica mais empregada na realização de inventários florestais é a amostragem por parcelas com área fixa. Entretanto, este método apresenta maiores custos e tempo de execução quando comparado com outras alternativas, como é o caso da amostragem por Prodan. Com este estudo objetivou-se comparar a eficiência entre os métodos de amostragem de Área Fixa e Prodan, avaliando a precisão na estimativa dos parâmetros quantitativos (número de árvores, área basal e volume comercial total por hectare). O estudo foi realizado em um povoamento de Pinus sp. com 45 anos de idade localizado no município de Curitibanos, SC, com área de, aproximadamente, 13 hectares. Foram instaladas 13 parcelas para o método de área fixa e 47 parcelas para o método de Prodan. Foram estimadas as variáveis: altura por meio de relações hipsométricas, e obtidos diâmetros ao longo do fuste com equação de afilamento, polinômio de 5° grau, ajustada para o povoamento. As estimativas observadas para o intervalo de confiança de 95% demostraram que o método de área fixa apresentou um volume comercial total de 766,0 m³/ha (± 64,2 m³/ha) e um erro de amostragem de 18%. O método do Prodan resultou um volume comercial total de 606,1 m³/ha (±33,8 m³/ha) e um erro de amostragem de 11%. O método de Área Fixa apresentou uma eficiência relativa 0,87 enquanto o método de Prodan apresentou uma eficiência relativa de 0,70 na estimativa do volume comercial por hectare. Conclui-se que o método de Área Fixa foi mais eficiente, pois apresentou o menor coeficiente de variação entre as parcelas, apesar de dispender maior tempo na execução do inventário, e o método de Prodan foi mais preciso, por ter apresentado os menores erros de amostragem para estimar as variáveis dendrométricas./The search for techniques that allow a better qualitative and quantitative evaluation of the forest stands has become increasingly necessary. Nowadays, the most used technique in the realization of forest inventory is the sampling by plots with a fixed area however, this method presents higher costs and longer time of execution when compared to other alternatives, as it is the case of sampling by the Prodan Method. This study aimed to compare the efficiency of the Fixed Area Sampling Method to the Prodan Method evaluating the precision in the quantitative parameters estimate (number of trees, basal area and total commercial volume per hectare). The study was held in a stand of Pinus sp., 45 years old, located in Curitibanos, SC, with an area of about 13 hectares. For the Fixed Area Method 13 plots were installed and 47 plots were installed for the Prodan Method. The variables were estimated: height by hypsometric relations, and the diameters along the stem were obtained with thinning equation, 5th degree polynomial, adjusted to the stand. The observed estimates for the 95% confidence interval showed that the Fixed Area Method presented a total commercial volume of 766.0 m³/ha (± 64.2 m³/ha) and 18% sampling error. The Prodan Method resulted in a total commercial volume of 606.1 m³/ha (±33.8 m³/ha) and 11% sampling error. The Fixed Area Method presented a 0.87 relative efficiency while the Prodan Method presented a 0.70 relative efficiency in the commercial volume estimate per hectare. It can be concluded that the Fixed Area Method was more efficient since it presented lower variation coefficient between the stands despite of taking more time in the execution of the inventory, and the Prodan Method was more precise since it presented the sampling smallest errors to estimate the dendrometric variables
PRODAN Dual Emission Feature To Monitor BHDC Interfacial Properties Changes with the External Organic Solvent Composition
No full textWe
have investigated the water/benzyl-n-hexadecyldimethylammonium
chloride (BHDC)/n-heptane:benzene reverse micelles
(RMs) interfaces properties using 6-propionyl-2-(N,N-dimethyl)aminonaphthalene, PRODAN, as molecular probe. We have used
absorption and emission (steady-state and time-resolved) spectroscopy
of PRODAN to monitor the changes in the RMs interface functionalities
upon changing the external organic solvent blend. We demonstrate that
PRODAN is a useful probe to investigate how the external solvent composition
affects the micelle interface properties. Our results show that changes
in the organic solvent composition in water/BHDC/n-heptane:benzene RMs have a dramatic effect on the photophysics of
PRODAN. Thus, increasing the aliphatic solvent content over the aromatic
one produces PRODAN partition and PRODAN intramolecular electron transfer
(ICT) processes. Additionally, the water presence in these RMs makes
the PRODAN ICT process favored with the consequent decreases in the
LE emission intensity and a better definition of the charge transfer
(CT) band. All this evidence suggests that the benzene molecules are
expelled out of the interface, and the water–BHDC interactions
are stronger with more presence of water molecules in the polar part
of the interface. Thus, we demonstrate that a simple change in the
composition of the external phase promotes remarkable changes in the
RMs interface. Finally, the results obtained with PRODAN together
with those reported in a previous work in our lab reveal that the
external phase is important when trying to control the properties
of RMs interface. It should be noted that the external phase itself,
besides the surfactant and the polar solvent sequestrated, is a very
important control variable that can play a key role if we consider
smart application of these RMs systems
- …
