Assay Method Information

Assay Name:  Inhibitor Assay
Description:  For inhibitor testing, the sample composition was the same as described below, except of the putative inhibitory compound added. For a rapid test of QC-inhibition, samples contained 4 mM of the respective inhibitor and a substrate concentration at 1 KM. For detailed investigations of the inhibition and determination of Ki-values, influence of the inhibitor on the auxiliary enzymes was investigated first. In every case, there was no influence on either enzyme detected, thus enabling the reliable determination of the QC inhibition. 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-°NA. The samples consisted of 0.2 mM fluorogenic substrate, 0.25 U pyroglutamyl aminopeptidase (Unizyme, H rsholm, 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 °-naphthylamine under assay conditions. One unit is defined as the amount of QC catalyzing the formation of 1 umol pGlu-°NA from H-Gln-°NA per minute under the described conditions.
Affinity data for this assay
 

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