Assay Method Information

Assay Name:  Recombinant SSAO/VAP-1 Inhibtion Assay
Description:  Briefly, HMEC cell expressing human SSAO/VAP-1 were grown in several 10 cm petri dishes, once the cells reached 100% confluency, cells were harvested and homogenates were prepared. Cells were washed twice with 5 mL of chilled HES buffer (20 mM HEPES, 1 mM EDTA, 250 mM sucrose, pH 7.4). HES buffer containing 1× protease inhibitor (Sigma Aldrich) and added and cells were incubated on ice for 3 min. Buffer was removed and cells were scraped and transferred to a centrifuge tube. Cell lysates were prepared by passing through 23 G needle for, 10 times and followed by 27 G needle for 10 times. Alternatively the cell lysates were prepared by using IKA Ultra-Turrax T 10 homogenizer for 3 min for every 10 mL of cell suspensions. Cells were then spun for 5 min at 300×g. The clear supernatant was transferred to new centrifuge tube and stored at −80 °C. until colorimetric assay was performed. Prior to the assay, 0.5 mM pargyline was added in order to inhibit any residue MAO activities. Briefly, 50 μL of cell lysate was incubated with test compounds for 30 min at 37 °C. Reaction mixtures were added and kinetic was read as described in detail in Example 5: Briefly, in a standard 96 well plate assay 50 μL of purified human SSAO/VAP-1 (0.25 μg/mL) in 0.1 M NaPO4 buffer (pH 7.4) was added into each well. Test compounds were dissolved in DMSO and tested in a Concentration Response Curve (CRC) with 4-9 data points, typically in the micromolar or nanomolar range after incubation with human SSAO/VAP-1 for 30 min at 37 °C. After 30 min incubation, 50 μL of the reaction mixture containing 600 μM benzylamine (Sigma Aldrich), 120 μM Amplex Red (Sigma Aldrich) and 1.5 U/mL horseradish peroxidase (Sigma Aldrich) prepared in 0.1 M NaPO4 buffer (pH 7.4) were added to the corresponding well. The fluorescence unit (RFU) was read every 2.5 min for 30 min at 37 °C. excitation 565 nm and emission 590 (Optima; BMG labtech). The slope of the kinetics for each well was calculated using MARS data analysis software (BMG labtech) and this value was used to deduce the IC50 value (Dotmatics).
Affinity data for this assay

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