Search results for "Dye"

Jararhagin-derived RKKH Peptides Induce Structural Changes in α1I Domain of Human Integrin α1β1

2003

Integrin alpha(1)beta(1) is one of four collagen-binding integrins in humans. Collagens bind to the alphaI domain and in the case of alpha(2)I collagen binding is competitively inhibited by peptides containing the RKKH sequence and derived from the metalloproteinase jararhagin of snake venom from Bothrops jararaca. In alpha(2)I, these peptides bind near the metal ion-dependent adhesion site (MIDAS), where a collagen (I)-like peptide is known to bind; magnesium is required for binding. Published structures of the ligand-bound "open" conformation of alpha(2)I differs significantly from the "closed" conformation seen in the structure of apo-alpha(2)I near MIDAS. Here we show that two peptides,…

The crystal structure of a cockroach pheromone-binding protein suggests a new ligand binding and release mechanism.

2003

Pheromone-binding proteins (PBPs) are small helical proteins found in sensorial organs, particularly in the antennae, of moth and other insect species. They were proposed to solubilize and carry the hydrophobic pheromonal compounds through the antennal lymph to receptors, participating thus in the peri-receptor events of signal transduction. The x-ray structure of Bombyx mori PBP (BmorPBP), from male antennae, revealed a six-helix fold forming a cavity that contains the pheromone bombykol. We have identified a PBP (LmaPBP) from the cockroach Leucophaea maderae in the antennae of the females, the gender attracted by pheromones in this species. Here we report the crystal structure of LmaPBP a…

Decarboxylation and alkaline colour fading reactions in presence of humic substances.

2002

Humic substances (HSs) can substantially influence velocity of reactions in the environment as shown on example of decarboxylation and alkaline colour (e.g., malachite green and crystal violet) fading reactions. In colour fading and decarboxylation reactions of 6-nitrobenzisoxazole-3-carboxylic acid HS act as inhibitors, but additions of surfactants change the pattern of reaction. The inhibitory activity of HSs much depends on their origin. The velocity of studied reactions depends also on pH, temperature and concentration of HS used. Possible micellar catalysis mechanism has been suggested.

Cyclodextrin and Adamantane Host-Guest Interactions of Modified Hyperbranched Poly(ethylene imine) as Mimetics for Biological Membranes

2011

Site-specific incorporation of perylene into an N-terminally modified light-harvesting complex II.

2010

Employing the utility of the native chemical ligation, site-specific attachment of an ultrastable perylene dye to a derivative of the major light-harvesting complex (LHCII) was demonstrated. Biochemical analysis of the conjugate indicated that the structure and function of LHCII remain largely unaffected by the N-terminal modification.

Quantum Chemical Parametrization and Spectroscopic Characterization of the Frenkel Exciton Hamiltonian for a J-Aggregate Forming Perylene Bisimide Dye

2012

Quantum chemical and quantum dynamical calculations are performed for a bay-substituted perylene bisimide dye up to its hexameric aggregate. The aggregate structure is determined by employing the self-consistent charge density functional tight-binding (SCC-DFTB) approach including dispersion corrections. It is characterized by a stabilization via two chains of hydrogen bonds facilitated by amide functionalities. Focusing on the central embedded dimer, the Coulomb coupling for this J-aggregate is determined by means of the time-dependent density functional theory (TDDFT) to be -514 cm(-1). Exciton vibrational coupling is treated within the shifted oscillator model from which five strongly co…

Calix[4]arene-functionalized naphthalene and perylene imide dyes.

2002

[reaction: see text] Calix[4]arenes bearing one, two, or four 1,8-naphthyl imide groups at the wide rim and bis-calix[4]arenes connected via perylene-bisimide dye spacers have been synthesized. The low-temperature NMR spectrum of the tetranaphthylimide suggests, in agreement with a crystal structure, a C2-symmetrical pinched cone conformation stabilized via face-to-face pi-pi interactions between opposite naphthylimide groups. UV-vis and fluorescence studies have been carried out for the perylene bis-calix[4]arene dyes.

A new culturing strategy optimises Drosophila primary cell cultures for structural and functional analyses

2004

Abstract Neurons in primary cell cultures provide important experimental possibilities complementing or substituting those in the nervous system. However, Drosophila primary cell cultures have unfortunate limitations: they lack either a range of naturally occurring cell types, or of mature physiological properties. Here, we demonstrate a strategy which supports both aspects integrated in one culture: Initial culturing in conventional serum-supplemented Schneider's medium (SM 20K ) guarantees acquisition of all properties known from 30 years of work on cell type-specific differentiation in this medium. Through subsequent shift to newly developed active Schneider's medium (SM active ), neuron…

Design of Bimodal Ligands of Neurotensin Receptor 1 for Positron Emission Tomography Imaging and Fluorescence-Guided Surgery of Pancreatic Cancer

2020

International audience; Neurotensin receptor 1 (NTSR1) is overexpressed in most human pancreatic ductal adenocarcinomas. It makes it an attractive target for the development of pancreatic cancer imaging agents. In this study, we sought to develop a bimodal PET-fluorescent imaging agent capable of specifically targeting these receptors. Starting from the structure of a known NTSR1 agonist, a series of tracers was synthesized, radiometalated with gallium-68 and evaluated in vitro and in vivo, in mice bearing an AsPC-1 xenograft. PET imaging allowed us to identify the compound [ 68 Ga]Ga-NODAGA-Lys(Cy5**)-AEEAc-[Me-Arg 8 , Tle 12 ]-NT(7-13) as the one with the most promising biodistribution pr…

A novel technique to follow fast PaO2 variations during experimental CPR

2003

An ultrafast responding fluorescent-quenching PO2 probe allows time-resolved, in vivo measurement of PO2. This study describes several validation experiments of this new device in vitro, and reports its first use during cardiopulmonary resuscitation in an animal model of cardiac arrest.The influence of CO2, temperature and motion artefacts on the signal response of the PO2 probe was analysed in vitro by systematic variation of these values. Thereafter, with approval of the Review Board for the care and use of animals, CPR was performed in four pigs. The PaO2 course was recorded continuously at time resolution of80 ms in the abdominal aorta using an uncoated fluorescence-quenching probe (Fox…