| Assay Method Information | |
| | LOX Inhibition Assay |
| Description: | Lysyl oxidase (LOX) is an extracellular copper dependent enzyme which oxidizes peptidyl lysine and hydroxylysine residues in collagen and lysine residues in elastin to produce peptidyl alpha-aminoadipic-delta-semialdehydes. This catalytic reaction can be irreversibly inhibited by β-aminopropionitrile (BAPN) that binds to the active site of LOX (Tang S. S., Trackman P C and Kagan H. M., Reaction of aortic lysyl oxidase with beta-aminoproprionitrile. J Biol Chem 1983; 258: 4331-4338). There are five LOX family members; these are LOX, LOXL1, LOXL2, LOXL3 and LOXL4. LOX and LOXL family members can be acquired as recombinant active proteins from commercial sources, or extracted from animal tissues like bovine aorta, tendons, pig skin; or prepared from cell cultures. The inhibitory effects of the compounds of the present invention were tested against the given LOX-LOXL preparation using a method based on the detection of hydrogen peroxide with an Amplex Red oxidation assay (Zhou et al. A stable nonfluorescent derivative of resorufin for the fluorometric determination of trace hydrogen peroxide: applications in detecting the activity of phagocyte NADPH oxidase and other oxidases. Anal. Biochem. 1997; 253, 162-168). The assay was developed using either 384 or 96 well format. Briefly, in a standard black, clear bottom 384 well plate assay 25 μL of a dilution of any of the isoenzymes and orthologues in 1.2 M urea, 50 mM sodium borate buffer (pH 8.2) were added into each well in the presence of 1 μM mofegiline and 0.5 mM pargyline (to inhibit SSAO and MAO-B and MAO-A, respectively; not necessary if the enzyme is from a recombinant or purified form). Test compounds were dissolved in DMSO and tested in a Concentration Response Curve (CRC) with 11 data points, typically in the micromolar or nanomolar range after incubation with the enzyme for 30 min at 37° C. Twenty five μL of a reaction mixture containing twice the KM concentration of putrescine (Sigma Aldrich, e.g. 20 mM for LOX, or 10 mM for LOXL2 and LOXL3), 120 μM Amplex Red (Sigma Aldrich) and 1.5 U/mL horseradish peroxidase (Sigma Aldrich) prepared in 1.2 M urea, 50 mM sodium borate buffer (pH 8.2) were then added to the corresponding wells. The above volumes were doubled in the case of 96 wells plate. The fluorescence (RFU) was read every 2.5 min for 30 min at a range of temperatures from 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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