Search results for "binding"

8-NH2-Boldine, an Antagonist of α1Aand α1BAdrenoceptors without Affinity for the α1DSubtype: Structural Requirements for Aporphines at α1-Adrenocepto…

2005

Structure-activity analysis of 21 aporphine derivatives was performed by examining their affinities for cloned human alpha (1A), alpha (1B) and alpha (1D) adrenoceptors (AR) using membranes prepared from rat-1 fibroblasts stably expressing each alpha (1)-AR subtype. All the compounds tested competed for [ (125)I]-HEAT binding with steep and monophasic curves. The most interesting compound was 8-NH (2)-boldine, which retains the selective affinity for alpha(1A)-AR (pKi = 6.37 +/- 0.21) vs. alpha(1B)-AR (pKi = 5.53 +/- 0.11) exhibited by 1,2,9,10-tetraoxygenated aporphines, but shows low affinity for alpha(1D)-AR (pKi < 2.5). Binding studies on native adrenoceptors present in rat cerebral cor…

Relationships between structure and vascular activity in a series of benzylisoquinolines

1997

1 1In the present work, the properties of 3-methyl isoquinoline, 3,4-dihydropapaverine, tetrahydropapaverine and tetrahydropapaveroline were compared with those of papaverine and laudanosine. The work includes functional studies on rat isolated aorta contracted with noradrenaline, caffeine or KC1, and a determination of the affinity of the compounds for α1-adrenoceptors and calcium channel binding sites, with [#H]-prazosin, [#H]-nitrendipine and [#H]-(+)-cis-diltiazem binding to rat cerebral cortical membranes. The effects of papaverine derivatives on the different molecular forms of cyclic nucleotide phosphodiesterases (PDE) isolated from bovine aorta were also determined. 2 2The three pap…

Hydrolytic action of phospholipase A2 in monolayers in the phase transition region: direct observation of enzyme domain formation using fluorescence …

1990

Phospholipase A2, a ubiquitous lipolytic enzyme highly active in the hydrolysis of organized phospholipid substrates, has been characterized optically in its action against a variety of phospholipid monolayers using fluorescence microscopy. By labeling the enzyme with a fluorescent marker and introducing it into the subphase of a Langmuir film balance, the hydrolysis of lipid monolayers in their liquid-solid phase transition region could be directly observed with the assistance of an epifluorescence microscope. Visual observation of hydrolysis of different phospholipid monolayers in the phase transition region in real-time could differentiate various mechanisms of hydrolytic action against …

No Label Required: Protein Binding at Membrane Interfaces Visualized through Colloid Phase Transitions

2004

Molecular dynamics study of high-pressure alumina polymorphs with a tight-binding variable-charge model

2016

Abstract A tight-binding variable-charge model aimed at performing large-scale realistic simulations of bulk, surfaces and interfaces of aluminum oxides have been developed. This model is based on the charge equilibration (QEq) method and explicitly takes into account the mixed iono–covalent character of the metal–oxygen bond by means of a tight-binding analytical approach in the second-moment approximation of the electronic structure. The parameters of the model were optimized to reproduce structural and energetic properties of the α-Al2O3 corundum structure at room temperature and pressure. The model exhibits a good transferability between five alumina polymorphs: corundum, Rh2O3(II)-type…

Recombinant water-soluble chlorophyll protein from Brassica oleracea var. Botrys binds various chlorophyll derivatives.

2003

A gene coding for water-soluble chlorophyll-binding protein (WSCP) from Brassica oleracea var. Botrys has been used to express the protein, extended by a hexahistidyl tag, in Escherichia coli. The protein has been refolded in vitro to study its pigment binding behavior. Recombinant WSCP was found to bind two chlorophylls (Chls) per tetrameric protein complex but no carotenoids in accordance with previous observations with the native protein [Satoh, H., Nakayama, K., Okada, M. (1998) J. Biol. Chem. 273, 30568-30575]. WSCP binds Chl a, Chl b, bacteriochlorophyll a, and the Zn derivative of Chl a but not pheophytin a, indicating that the central metal ion in Chl is essential for binding. WSCP …

Ab initio simulations on the atomic and electronic structure of single-walled BN nanotubes and nanoarches

2009

To simulate the perfect single-walled boron nitride nanotubes and nanoarches with armchair- and zigzag-type chiralities and uniform diameter of � 5 nm, we have constructed their one-dimensional (1D) periodic models. In this study, we have compared the calculated properties of nanotubes with those for both hexagonal and cubic phases of bulk: bond lengths, binding energies per B–N bond, effective atomic charges as well as parameters of total and projected one-electron densities of states. For both phases of BN bulk, we have additionally verified their lattice constants. In the density functional theory (DFT), calculations performed using formalism of the localized Gaussian-type atomic functio…

In Vitro Analysis of the Two-Component System MtrB-MtrA from Corynebacterium glutamicum▿ †

2007

ABSTRACT The two-component system MtrBA is involved in the osmostress response of Corynebacterium glutamicum . MtrB was reconstituted in a functionally active form in liposomes and showed autophosphorylation and phosphatase activity. In proteoliposomes, MtrB activity was stimulated by monovalent cations used by many osmosensors for the detection of hypertonicity. Although MtrB was activated by monovalent cations, they lead in vitro to a general stabilization of histidine kinases and do not represent the stimulus for MtrB to sense hyperosmotic stress.

A supramolecular complex in the environmental stress signalling pathway of Bacillus subtilis

2003

SigmaB, an alternative sigma-factor of Bacillus subtilis, mediates the response of the cell to a variety of physical insults. Within the environmental stress signalling pathway RsbU, a protein phosphatase, is stimulated by its interaction with the protein kinase RsbT. In the absence of stress RsbT is expected to be trapped by an alternative binding partner, RsbS. Here, we have demonstrated that RsbS alone cannot act as an alternative partner for RsbT, but instead requires the presence of RsbR to create a high molecular mass RsbR:RsbS complex (approximately 1 MDa) able to capture RsbT. In this complex the phosphorylation state of RsbS, and not that of RsbR, controlled the binding to RsbT, wh…

Tyrosine-phosphorylation-dependent and Rho-protein-mediated control of cellular phosphatidylinositol 4,5-bisphosphate levels

1998

The polyphosphoinositide PtdIns(4,5)P2, best known as a substrate for phospholipase C isozymes, has recently been recognized to be involved in a variety of other cellular processes. The aim of this study was to examine whether the cellular levels of this versatile phospholipid are controlled by tyrosine phosphorylation. The studies were performed in human embryonic kidney (HEK)-293 cells stably expressing the M3 muscarinic acetylcholine receptor. Inhibition of tyrosine phosphatases by pervanadate induced an up-to-approx.-2.5-fold increase in the total cellular level of PtdIns(4,5)P2, which was both time- and concentration-dependent. In contrast, the tyrosine kinase inhibitors, genistein and…