Search results for "ERAS"
showing 10 items of 4431 documents
How To Design Selective Ligands for Highly Conserved Binding Sites: A Case Study Using N-Myristoyltransferases as a Model System
2019
A model system of two related enzymes with conserved binding sites, namely N-myristoyltransferase from two different organisms, was studied to decipher the driving forces that lead to selective inhibition in such cases. Using a combination of computational and experimental tools, two different selectivity-determining features were identified. For some ligands, a change in side-chain flexibility appears to be responsible for selective inhibition. Remarkably, this was observed for residues orienting their side chains away from the ligands. For other ligands, selectivity is caused by interfering with a water molecule that binds more strongly to the off-target than to the target. On the basis o…
Presence of esterase inPinaceae pollen
1997
General esterases, like wall heterologous enzymes, may be implicated in allergenic mechanisms. We cytochemically examined the presence of these enzymes, bearing in mind thatPinus spp. is often considered a possible cause of allergies. Positive esterase results in fungus spores were found on the strip of a volumetric sampler. Data are reported here, together with the hypothesis of a possible esterase-allergenic link regarding fungus spores.
Inhibition of the herpes simplex virus-coded thymidine kinase-complex by 9-?-D-arabinofuranosyladenine 5?-monophosphate (ara-AMP) and 9-(2-hydroxyeth…
1984
The thymidine kinase-complex isolated from herpes simplex virus type 1 and type 2 (HSV-1 and HSV-2) is associated with the following enzyme activities: ATP:dThd (dCyd) deoxypyrimidine kinase, ATP:dTMP thymidylate kinase, ADP:dThd- and AMP:dThd5′-phosphotransferase. In kinetic experiments it is shown that ara-AMP inhibits AMP:dThd- and ADP:dThd phosphotransferase activity, while acyclo-GMP impairs ADP:dThd phosphotransferase reaction only; the inhibition was found to be non-compertitive. The functional subunit ATP:dThd kinase was not affected by either compound.
Semiquantitative bioluminescent assay of glutathione
1998
A novel technique has been developed for semiquantitative detection of glutathione (GSH) in small volumes of liquid samples. GSH is detected via enzymatic linkage to the NADP/NADPH + H+ redox system through glutathione reductase. Accumulated NADPH is measured via the bioluminescent FMN oxidoreductase bacterial luciferase reaction. A linear correlation is obtained between bioluminescence intensity of the luciferase reaction and the GSH content of the liquid sample. Possible applications of this procedure are discussed. © 1998 John Wiley & Sons, Ltd.
PCR-Based Site-Specific Mutagenesis
1998
The alteration of gene structure through the substitution of specific nucleotides by site-specific mutagenesis is an important tool in modern recombinant DNA technology. Nucleotide changes are necessary not only for the analysis of the structural basis of gene and corresponding protein function, but also for the generation of novel gene products. The availability of the polymerase chain reaction (PCR) in the last decade has enabled the modification of DNA for different needs to be made more rapidly and easily than was previously possible. In the course of mutagenesis the relevant sequence changes can be introduced more readily by chemically synthesized oligonucleotide primers than by manipu…
Isolierung und charakterisierung einer cholinkinase aus Phaseolus vulgaris L.-Keimlingen
1977
Summary The enzyme choline kinase (ATP: Choline phosphotransferase E.C. 2.7.1.32) was extracted and partially purified from hypocotyl hooks of Phaseolus vulgaris L. seedlings. K m -value and pH-dependence of the activity were determined. The amount of enzyme activity in extracts depended on light conditions used for plant growth. Etiolated seedlings showed much lower enzyme levels than those grown in white light. Blue and red light conditions decreased enzyme levels below dark values. The in vitro enzyme activity was influenced by inhibitors and growth regulators. The enzyme activity was stimulated by Atropine, 2-Chloroethylammoniumchloride (Cycocel) and Gibberellic acid and was inhibited b…
Isolierung und Charakterisierung einer Acetylester-Hydrolase aus Aspergillus rtiger / Isolation and Characterization of an Acetylester-Hydrolase from…
1980
Abstract The characteristic features of an acetic acid esters hydrolyzing enzyme (acetylesterase, EC 3.1.1.16) are described. The pH- and temperature optimum were 7.0 and 40 °C respectively. The stability of the enzyme regarding different pH- and temperature conditions was investigated. The molecular weight of the acetylesterase could be determined to 160000. A small acetic ester hydrolyzing activity was found too with a molecular weight of about 25000. The activity was not inhibited by addition of di-isopropylphosphorofluoridate (DFP) or physostigmine. The KM-value for glyceryl triacetate was about 90 mM. Concentration of the enzyme was done by ultrafiltration and column-chromatography. Th…
Isolation and characterization of a chlorogenic acid esterase from Aspergillus niger.
1980
Abstract The isolation and characterization of a specific chlorogenic acid esterase is described. The enzyme activity is measured by determination of the hydrolysis product caffeic acid. The enzyme had been concentrated by means of ultrafiltration and column-chromatography. The pH- and temperature optimum were 6.5 and 45 °C respectively. Divalent cations were not required for the enzyme activity. As other esterases, this enzyme is inhibited by di-isopropyl-phosphorofluoridate. The Km-value is 0.70 mᴍ chlorogenic acid, the molecular weight 240000. The described enzyme is specific for chlorogenic acid. On the other hand a typical unspecific esterase like the pig liver esterases does not split…
Poly(silicate)-metabolizing silicatein in siliceous spicules and silicasomes of demosponges comprises dual enzymatic activities (silica polymerase an…
2007
Siliceous sponges can synthesize poly(silicate) for their spicules enzymatically using silicatein. We found that silicatein exists in silica-filled cell organelles (silicasomes) that transport the enzyme to the spicules. We show for the first time that recombinant silicatein acts as a silica polymerase and also as a silica esterase. The enzymatic polymerization/polycondensation of silicic acid follows a distinct course. In addition, we show that silicatein cleaves the ester-like bond in bis(p-aminophenoxy)-dimethylsilane. Enzymatic parameters for silica esterase activity are given. The reaction is completely blocked by sodium hexafluorosilicate and E-64. We consider that the dual function o…
Species-Specific Aggregation Factor In Sponges.
1978
In dissociated single cells from the sponge Geodia cydonium, DNA synthesis is initiated after incubation with a homologous, soluble aggregation factor. During the DNA-initiation phase the cyclic AMP- and cyclic GMP levels vary drastically; the cyclic AMP content drops from 2.2 pmol/10(6) cells to 0.3 pmol/10(6) cells while the cyclic GMP content increases from 0.6 pmol to 3.7 pmol/10(6) cells. The activity of neither the adenylate cyclase nor of the guanylate cyclase isolated from cells which have been incubated for different periods of time with the aggregation factor, is changed. The soluble as well as the particulate enzyme activities were checked in vitro. The cyclic nucleotide receptor…