Assay Method Information

Assay Name:  Spectrophotometrical In Vitro Assay
Description:  The activity of compounds 1-19 and 21-23 as inhibitors of ACMSD1 was determined by measuring the conversion of 3OH-Anthranilic Acid into product (i.e., ACMS) in a spectrophotometrical in vitro assay.The pre-assay mixture consisting of 3-hydroxyanthranilic acid (3OH-HA), 3-hydroxyanthranilic acid, 3,4-diOxygenase (HAO), and a dialyzed crude extract of E. coli BL21 (DE3) cells expressing the recombinant enzyme, was incubated at 25° C. with monitoring of the increase in absorbance at 360 nm due to the formation of ACMS from 3OH-HA. After the reaction was completed within 2 mins, an aliquot of ACMSD1 solution (prepared and purified from Pichia Pastoris overexpressing the recombinant enzyme) was added, and the decrease in absorbance at 360 nm was followed at 15 second intervals. The effect of ACMS concentration on the enzyme activity was investigated by varying 3OH-HA concentration from 2 to 20 μM. Kinetic parameters were calculated from the initial velocity data by using the Lineweaver-Burk plot.The rate of the decrease in absorbance caused by ACMSD1 was calculated by subtracting that of the control reaction mixture without ACMSD from that described above. One unit of ACMSD activity was indicated as the amount of enzyme that converts 1 mmol of ACMS per minute at 25° C. The absence or a reduction of ACMSD1 activity (e.g., by using ACMSD inhibitors) results in a slow ACMS-spontaneous degradation (i.e., cyclization to form quinolic acid).
Affinity data for this assay
 

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