Search results for "Specificity."
showing 10 items of 2232 documents
Elucidation of Carbohydrate Molecular Interaction Mechanism of Recombinant and Native ArtinM
2013
[EN] The quartz crystal microbalance (QCM) technique has been applied for monitoring the biorecognition of ArtinM lectins at low horseradish peroxidase glycoprotein (HRP) concentrations, using a simple kinetic model based on Langmuir isotherm in previous work.(18) The latter approach was consistent with the data at dilute conditions but it fails to explain the small differences existing in the jArtinM and rArtinM due to ligand binding concentration limit. Here we extend this analysis to differentiate sugar-binding event of recombinant (rArtinM) and native (jArtinM) ArtinM lectins beyond dilute conditions. Equivalently, functionalized quartz crystal microbalance with dissipation monitoring (…
Quaternary structure of the European spiny lobster (Palinurus elephas) 1x6-mer hemocyanin from cryoEM and amino acid sequence data.
2002
Abstract Arthropod hemocyanins are large respiratory proteins that are composed of up to 48 subunits (8×6-mer) in the 75 kDa range. A 3D reconstruction of the 1×6-mer hemocyanin from the European spiny lobster Palinurus elephas has been performed from 9970 single particles using cryoelectron microscopy. An 8 A resolution of the hemocyanin 3D reconstruction has been obtained from about 600 final class averages. Visualisation of structural elements such as α-helices has been achieved. An amino acid sequence alignment shows the high sequence identity (>80%) of the hemocyanin subunits from the European spiny lobster P. elephas and the American spiny lobster Panulirus interruptus . Comparison of…
Strombine dehydrogenase in the demosponge Suberites domuncula: Characterization and kinetic properties of the enzyme crucial for anaerobic metabolism
2008
Previously, the cDNA and the respective gene for a presumed tauropine dehydrogenase (TaDH) from Suberites domuncula (GenBank accession nos. AM712888, AM712889) had been annotated. The conclusion that the sequences encode a TaDH had been inferred from the 68% identity with the TaDH protein from the marine demosponge Halichondria japonica. However, subsequent enzymatic assays shown here indicate that the presumed S. domuncula opine dehydrogenase is in fact a strombine dehydrogenase (StDH). The enzyme StDH is highly specific for glycine and is inhibited by an excess of the substrate pyruvate. Besides kinetic data, we report in this study also on the predicted tertiary and quaternary structure …
Evidence for substrate binding-induced zwitterion formation in the catalytic Cys-His dyad of the SARS-CoV main protease.
2014
The coronavirus main protease (M(pro)) represents an attractive drug target for antiviral therapy of coronavirus (CoV) infections, including severe acute respiratory syndrome (SARS). The SARS-CoV M(pro) and related CoV proteases have several distinct features, such as an uncharged Cys-His catalytic dyad embedded in a chymotrypsin-like protease fold, that clearly separate these enzymes from archetypical cysteine proteases. To further characterize the catalytic system of CoV main proteases and to obtain information about improved inhibitors, we performed comprehensive simulations of the proton-transfer reactions in the SARS-CoV M(pro) active site that lead to the Cys(-)/His(+) zwitterionic st…
Synthesis and Inhibitory Studies of Phosphonic Acid Analogues of Homophenylalanine and Phenylalanine towards Alanyl Aminopeptidases.
2020
A library of novel phosphonic acid analogues of homophenylalanine and phenylalanine, containing fluorine and bromine atoms in the phenyl ring, have been synthesized. Their inhibitory properties against two important alanine aminopeptidases, of human (hAPN, CD13) and porcine (pAPN) origin, were evaluated. Enzymatic studies and comparison with literature data indicated the higher inhibitory potential of the homophenylalanine over phenylalanine derivatives towards both enzymes. Their inhibition constants were in the submicromolar range for hAPN and the micromolar range for pAPN, with 1-amino-3-(3-fluorophenyl) propylphosphonic acid (compound 15c) being one of the best low-molecular inhibitors …
Tyrosinase/catecholoxidase activity of hemocyanins: structural basis and molecular mechanism
2000
The enzymes tyrosinase, catecholoxidase and hemocyanin all share similar active sites, although their physiological functions differ. Hemocyanins serve as oxygen carrier proteins, and tyrosinases and catecholoxidases (commonly referred to as phenoloxidases in arthropods) catalyze the hydroxylation of monophenols or the oxidation of o-diphenols to o-quinones, or both. Tyrosinases are activated in vivo by limited proteolytic cleavage, which might open up substrate access to the catalytic site. It has recently been demonstrated that if hemocyanins are subjected to similar proteolytic treatments (in vitro) they also exhibit at least catecholoxidase reactivity. On the basis of their molecular st…
Design, synthesis, and biological evaluation of novel disubstituted dibenzosuberones as highly potent and selective inhibitors of p38 mitogen activat…
2012
Synthesis, biological testing, structure-activity relationships (SARs), and selectivity of novel disubstituted dibenzosuberone derivatives as p38 MAP kinase inhibitors are described. Hydrophilic moieties were introduced at the 7-, 8-, and 9-position of the 2-phenylamino-dibenzosuberones, improving physicochemical properties as well as potency. Extremely potent inhibitors were obtained, with half-maximal inhibitory concentration (IC(50)) values in the low nM range in a whole blood assay measuring the inhibition of cytokine release. The high potency of the target compounds together with the outstanding selectivity of this novel class of compounds toward p38 mitogen activated protein (MAP) kin…
Proteomic identification of protease cleavage sites characterizes prime and non-prime specificity of cysteine cathepsins B, L, and S.
2011
Cysteine cathepsins mediate proteome homeostasis and have pivotal functions in diseases such as cancer. To better understand substrate recognition by cathepsins B, L, and S, we applied proteomic identification of protease cleavage sites (PICS) for simultaneous profiling of prime and non-prime specificity. PICS profiling of cathepsin B endopeptidase specificity highlights strong selectivity for glycine in P3' due to an occluding loop blocking access to the primed subsites. In P1', cathepsin B has a partial preference for phenylalanine, which is not found for cathepsins L and S. Occurrence of P1' phenylalanine often coincides with aromatic residues in P2. For cathepsin L, PICS identifies 845 …
Structures of Alkaloid Biosynthetic Glucosidases Decode Substrate Specificity
2011
Two similar enzymes with different biosynthetic function in one species have evolved to catalyze two distinct reactions. X-ray structures of both enzymes help reveal their most important differences. The Rauvolfia alkaloid biosynthetic network harbors two O-glucosidases: raucaffricine glucosidase (RG), which hydrolyses raucaffricine to an intermediate downstream in the ajmaline pathway, and strictosidine glucosidase (SG), which operates upstream. RG converts strictosidine, the substrate of SG, but SG does not accept raucaffricine. Now elucidation of crystal structures of RG, inactive RG-E186Q mutant, and its complexes with ligands dihydro-raucaffricine and secologanin reveals that it is the…
Design and Synthesis of 4-Substituted Indolo[3,2-e][1,2,3]triazolo[1,5-a]pyrimidine Derivatives with Antitumor Activity
2008
New derivatives of the indolo[3,2- e][1,2,3]triazolo[1,5- a]pyrimidine system, substituted in the 4 position, were designed as novel antitumor agents because of their theoretical capability to form stable complexes with DNA fragments. The calculated free energies of binding were found in the range -12.76 --> -39.68 Kcal/mol. The docking studies revealed a common binding mode with the chromophore intercalated between GC base pairs, whereas the side chain lies along the minor groove. Compounds, selected on the basis of the docking studies and suitably synthesized, showed antiproliferative activity against each type of tumor cell line investigated, generally in the low micromolar range. The mo…