Search results for "binding site"
showing 10 items of 856 documents
Fumarate respiration of Wolinella succinogenes: enzymology, energetics and coupling mechanism.
2002
Wolinella succinogenes performs oxidative phosphorylation with fumarate instead of O2 as terminal electron acceptor and H2 or formate as electron donors. Fumarate reduction by these donors ('fumarate respiration') is catalyzed by an electron transport chain in the bacterial membrane, and is coupled to the generation of an electrochemical proton potential (Deltap) across the bacterial membrane. The experimental evidence concerning the electron transport and its coupling to Deltap generation is reviewed in this article. The electron transport chain consists of fumarate reductase, menaquinone (MK) and either hydrogenase or formate dehydrogenase. Measurements indicate that the Deltap is generat…
Anti-Idiotypic Antibodies Against the Kinin Receptor
1992
Three sets of monoclonal antibodies against bradykinin (MBK1, MBK2, MBK3) were generated by somatic cell fusion, characterized by their peptide specificity and compared to the known ligand specificity of the kinin receptor subtypes. By these criteria the paratope of MBK3 resembled the B2 receptor binding site whereas MBK1 shared principal binding characteristics with the B1 recrptor. Anti-idiotypic antibodies against MBK1, MBK2 and MBK3 were raised in rabbit and sheep. Specificity of the network components was verified by inhibition experiments on the level of peptide, idiotype and anti-idiotype. Anti-idiotypic antibodies against MBK3 recognized a conformation-dependent epitope which was bi…
Structural Determinants for the Mode of Action of Imidazopyridine DS2 at δ-Containing γ-Aminobutyric Acid Type A Receptors
2021
Despite the therapeutic relevance of δ-containing γ-aminobutyric acid type A receptors (GABAARs) and the need for δ-selective compounds, the structural determinants for the mode and molecular site of action of δ-selective positive allosteric modulator imidazo[1,2-a]pyridine DS2 remain elusive. To guide the quest for insight, we synthesized a series of DS2 analogues guided by a structural receptor model. Using a fluorescence-based fluorometric imaging plate reader membrane potential assay, we found that the δ-selectivity and the pharmacological profile are severely affected by substituents in the 5-position of the imidazopyridine core scaffold. Interestingly, the 5-methyl, 5-bromo, and 5-chl…
Inhibition of the Cysteine Protease Human Cathepsin L by Triazine Nitriles: Amide⋅⋅⋅Heteroarene π-Stacking Interactions and Chalcogen Bonding in the …
2016
We report an extensive "heteroarene scan" of triazine nitrile ligands of the cysteine protease human cathepsin L (hCatL) to investigate π-stacking on the peptide amide bond Gly67-Gly68 at the entrance of the S3 pocket. This heteroarene⋅⋅⋅peptide bond stacking was supported by a co-crystal structure of an imidazopyridine ligand with hCatL. Inhibitory constants (Ki ) are strongly influenced by the diverse nature of the heterocycles and specific interactions with the local environment of the S3 pocket. Binding affinities vary by three orders of magnitude. All heteroaromatic ligands feature enhanced binding by comparison with hydrocarbon analogues. Predicted energetic contributions from the ori…
Sodium Solute Symporter and Cadherin Proteins Act as Bacillus thuringiensis Cry3Ba Toxin Functional Receptors in Tribolium castaneum*
2013
Understanding how Bacillus thuringiensis (Bt) toxins interact with proteins in the midgut of susceptible coleopteran insects is crucial to fully explain the molecular bases of Bt specificity and insecticidal action. In this work, aminopeptidase N (TcAPN-I), E-cadherin (TcCad1), and sodium solute symporter (TcSSS) have been identified by ligand blot as putative Cry3Ba toxin-binding proteins in Tribolium castaneum (Tc) larvae. RNA interference knockdown of TcCad1 or TcSSS proteins resulted in decreased susceptibility to Cry3Ba toxin, demonstrating the Cry toxin receptor functionality for these proteins. In contrast, TcAPN-I silencing had no effect on Cry3Ba larval toxicity, suggesting that th…
Human conglutinin-like protein inhibits infection by the human immunodeficiency virus-1 in vitro.
1992
In summary the lectin-like protein analogous to bovine conglutinin was purified from human serum. Using a lectin-based ELISA system, it was demonstrated that conglutinin-like protein binds to human immunodeficiency virus-1 (HIV1) glycoprotein 120 (gp 120) via its carbohydrate binding site. In vitro experiments with T-lymphoblastoid CEM cells revealed that conglutinin-like protein abolishes infection by HIV1; a 50 % cytoprotective concentration of 23.9 μg/ml was measured.
Binding of human fibronectin to Aspergillus fumigatus conidia.
1996
Aspergillus fumigatus conidia exhibited the ability to bind purified human fibronectin, whereas mycelial forms did not bind the ligand, as detected by an indirect immunofluorescence assay with an antifibronectin polyclonal antibody after incubation of the cells with fibronectin. Flow cytometry confirmed that binding of the ligand to conidia was dose dependent and saturable. Pretreatment of the cells with trypsin markedly reduced binding, which suggested a protein nature for the binding sites present at the surface of conidia. Intact conidia were also able to adhere to fibronectin or antifibronectin antibodies, a significant reduction (from 88 to 92%) in the binding of conidia was noticed, t…
Binding of extracellular matrix proteins to Aspergillus fumigatus conidia
1996
As detected by confocal immunofluorescence microscopy, binding of fibronectin and laminin appeared to be associated with the protrusions present on the outer cell wall layer of resting Aspergillus fumigatus conidia. Flow cytometry confirmed that binding of laminin to conidia was dose dependent and saturable. Laminin binding was virtually eliminated in trypsin-treated organisms, thus suggesting the protein nature of the binding site. Conidia were also able to specifically adhere to laminin immobilized on microtiter plates. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting (immunoblotting) with laminin and antilaminin antibody of whole conidial homogenates allowed…
Molecular basis of filamin a-filGAP interaction and its impairment in congenital disorders associated with filamin a mutations
2008
Background Mutations in filamin A (FLNa), an essential cytoskeletal protein with multiple binding partners, cause developmental anomalies in humans. Methodology/Principal Findings We determined the structure of the 23rd Ig repeat of FLNa (IgFLNa23) that interacts with FilGAP, a Rac-specific GTPase-activating protein and regulator of cell polarity and movement, and the effect of the three disease-related mutations on this interaction. A combination of NMR structural analysis and in silico modeling revealed the structural interface details between the C and D β-strands of the IgFLNa23 and the C-terminal 32 residues of FilGAP. Mutagenesis of the predicted key interface residues confirmed the b…
Low Density Lipoprotein Receptor-related Protein (LRP) Interacts with Presenilin 1 and Is a Competitive Substrate of the Amyloid Precursor Protein (A…
2005
Presenilin 1 (PS1) is a critical component of the gamma-secretase complex, which is involved in the cleavage of several substrates including the amyloid precursor protein (APP) and the Notch receptor. Recently, the low density receptor-related protein (LRP) has been shown to be cleaved by a gamma-secretase-like activity. We postulated that LRP may interact with PS1 and tested its role as a competitive substrate for gamma-secretase. In this report we show that LRP colocalizes and interacts with endogenous PS1 using coimmunoprecipitation and fluorescence lifetime imaging microscopy. In addition, we found that gamma-secretase active site inhibitors do not disrupt the interaction between LRP an…