Inhibition of human glutaminyl cyclase overexpressed in HEK293 cells coexpressing amyloid precursor protein assessed as reduction in pGlu-Abeta-3(pE)-40,42 peptide formation at 1 uM relative to untreated control
Inhibition of human glutaminyl cyclase overexpressed in HEK293 cells coexpressing amyloid precursor protein assessed as reduction in pGlu-Abeta-3(pE)-40,42 peptide formation at 1 uM relative to 1-(3-(1H-imidazol-1-yl)propyl)-3-(3,4-dimethoxyphenyl)thiourea
Inhibition of human glutaminyl cyclase using L-glutamine-7-amido-4-methylcoumarin as substrate incubated for 10 mins in presence of pyroglutamyl peptidase by fluorometry analysis
Inhibition of human glutaminyl cyclase expressed in HEK293 cells using L-glutaminyl-beta-naphthylamine as substrate after 1 hr by fluorometric analysis
Inhibition of human glutaminyl cyclase expressed in Escherichia coli DH5alpha using H-Gln-AMC as substrate by fluorometric analysis in presence of pyroglutamyl aminopeptidase
Spectrophotometic Assay: Spectrophotometic Assay: This novel assay was used to determine the kinetic parameters for most of the QC substrates. QC activity was analyzed spectrophotometrically using a continuous method, that was derived by adapting a previous discontinuous assay (Bateman, R.C.J. 1989 J Neurosci Methods 30, 23-28).
Spectrophotometric Assay: This novel assay was used to determine the kinetic parameters for most of the QC substrate. QC activity was analyzed spectrophotometrically using a continuous method, that was derived by adapting a previous discontinuous assay (Bateman, R.C.J. 1989 J neurosci Methods 30, 23-28) utilizing glutamate dehydrogenase as auxiliary enzyme.
Spectrophotometric Assay: Spectrophotometric assay was used to determine the kinetic parameters for most of the QC substrates. QC activity was analyzed spectrophotometrically using a continuous method, that was derived by adapting a previous discontinuous assay (Bateman, R.C.J. 1989 J Neurosci Methods 30, 23-28) utilizing glutamate dehydrogenanse as auxiliary enzyme.
Spectrophotometric Assay: This novel assay was used to determine the kinetic parameters for most of the QC substrates. QC activity was analyzed spectrophotometrically using a continuous method, that was derived by adapting a previous discontinuous assay (Bateman, R. C. J. 1989 J Neurosci Methods 30, 23-28) utilizing glutamate dehydrogenase as auxiliary enzyme. Samples consisted of the respective QC substrate, 0.3 mM NADH, 14 mM alpha-Ketoglutaric acid and 30 U/ml glutamate dehydrogenase in a final volume of 250 ul. Reactions were started by addition of QC and persued by monitoring of the decrease in absorbance at 340 nm for 8-15 min. The initial velocities were evaluated and the enzymatic activity was determined from a standard curve of ammonia under assay conditions. All samples were measured at 30 C., using either the SPECTRAFluor Plus or the Sunrise (both from TECAN) reader for microplates. Kinetic data was evaluated using GraFit software.
Inhibition Assay: Fluorometric Assays: All measurements were performed with a BioAssay Reader HTS-7000Plus for microplates (Perkin Elmer) at 30 C. QC activity was evaluated fluorometrically using H-Gln-beta NA. The samples consisted of 0.2 mM fluorogenic substrate, 0.25 U pyroglutamyl aminopeptidase (Unizyme, Horsholm, Denmark) in 0.2 M Tris/HCl, pH 8.0 containing 20 mM EDTA and an appropriately diluted aliquot of QC in a final volume of 250 ul. Excitation/emission wavelengths were 320/410 nm. The assay reactions were initiated by addition of glutaminyl cyclase. QC activity was determined from a standard curve of beta -naphthylamine under assay conditions. One unit is defined as the amount of QC catalyzing the formation of 1 umol pGlu-beta NA from H-Gln-beta NA per minute under the described conditions.In a second fluorometric assay, QC was activity determined using H-Gln-AMC as substrate. Reactions were carried out at 30 C. utilizing the NOVOStar reader for microplates (BMG labtechnology).
Inhibition of human recombinant glutaminyl cyclase expressed in Escherichia coli at 100 uM using H-Gln-Gln-H substrate measured for 15 mins by spectrophotometry relative to control
Fluorometric Assay: All measurements were performed with a BioAssay Reader HTS-7000Plus for microplates (Perkin Elmer) at 30 C. QC activity was evaluated fluorometrically using H-Gln-beta NA. The samples consisted of 0.2 mM fluorogenic substrate, 0.25 U pyroglutamyl aminopeptidase (Unizyme, Horsholm, Denmark) in 0.2 M Tris/HCl, pH 8.0 containing 20 mM EDTA and an appropriately diluted aliquot of QC in a final volume of 250 ul. Excitation/emission wavelengths were 320/410 nm. The assay reactions were initiated by addition of glutaminyl cyclase. QC activity was determined from a standard curve of beta -naphthylamine under assay conditions. One unit is defined as the amount of QC catalyzing the formation of 1 umol pGlu-beta NA from H-Gln-beta NA per minute under the described conditions.In a second fluorometric assay, QC was activity determined using H-Gln-AMC as substrate. Reactions were carried out at 30 C. utilizing the NOVOStar reader for microplates (BMG labtechnologies).
Inhibition of human glutaminyl cyclase assessed as reduction in conversion of H-Gln-AMC hydrobromide to pGlu-AMC preincubated with substrate for 10 mins followed by enzyme addition by pGAPase coupled fluorometry
Inhibition of human N-terminal His6-tagged QC expressed in Escherichia coli BL21(DE3) at 100 uM using H-gln-gln-H as substrate in presence of NADH/H+ after 15 mins by glutamic acid dehydrogenase coupled spectrophotometric method relative to control
Inhibition of human N-terminal His6-tagged QC expressed in Escherichia coli BL21(DE3) using H-gln-gln-H as substrate in presence of NADH/H+ after 15 mins by glutamic acid dehydrogenase coupled spectrophotometric method
Inhibition of human QC expressed in HEK293T cells co-expressing APP695-A673V at 10 uM using H-gln-gln-H as substrate by glutamic acid dehydrogenase coupled spectrophotometric method
Inhibition of human QC expressed in HEK293T cells co-expressing APP695-A673V after 24 hrs using H-gln-gln-H as substrate by glutamic acid dehydrogenase coupled spectrophotometric method