Assay Method Information

Assay Name:  Inhibition Assay
Description:  LOX and LOXL2: 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 high-throughput coupled colorimetric method (Holt A. and Palcic M., A peroxidase-coupled continuous absorbance plate-reader assay for flavin monoamine oxidases, copper-containing amine oxidases and related enzymes. Nat. Protoc. 2006; 1: 2498-2505). The assay was developed using either 384 or 96 well format. Briefly, in a standard 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). 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 L 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.
Affinity data for this assay
 

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