LDN-57444 is a reversible, competitive proteasome Uch-L1 inhibitor(IC50=0.88 μM) .

UCHL1:0.88 μM

在体内,LDN-57444使突触蛋白分布和脊柱形态发生明显改变.LDN-57444导致UCH-L1活性下降,但对于cAMP水平的蛋白酶抑制没有效果.

LDN-57444（25-50 μM）以剂量依赖的方式,通过细胞凋亡途径能够通过降低泛素蛋白酶体系统的活性,并增加高度泛素化蛋白的水平,降低细胞的存活率。

HTS screen: To start an assay, 0.5 μL of 5 mg/mL test compound (about 50 μM final reaction concentration) or DMSO control is aliquoted into each well. Both enzyme and substrate are prepared in UCH reaction buffer (50 mM Tris-HCl [pH 7.6], 0.5 mM EDTA, 5 mM DTT, and 0.5 mg/mL ovalbumin). 25 μL of 0.6 nM UCH-L1 is then added to each well except substrate control wells, followed by plate shaking for 45–60 s on an automatic shaker. The enzyme/compound mixture is incubated at room temperature for 30 min before 25 μL of 200 nM Ub-AMC is added to initiate the enzyme reaction. The reaction mixture (300 pM UCH-L1, 100 nM Ubiquitin-AMC with 2.5 μg test compound) is incubated at room temperature for 30 additional minutes prior to quenching the reaction by the addition of 10 μL 500 mM acetic acid per well. The fluorescence emission intensity is measured on a LJL Analyst using a coumarin filter set (ex = 365 nm, em = 450 nm) and is subtracted by the intrinsic compound fluorescence to reveal the enzyme activity. A DMSO control (0.5 μL of DMSO, 25 μL of UCH-L1, 25 μL of ubiquitin-AMC, 10 μL of acetic acid), enzyme control (25 μL of UCH-L1, 25 μL of buffer, 10 μL of acetic acid), substrate control (25 μL of buffer, 25 μL of ubiquitin-AMC, 10 μL of acetic acid), and inhibitor control (0.5 μL of ubiquitin aldehyde [100 nM stock], 25 μL of UCH-L1, 25 μL of ubiquitin-AMC, 10 μL of acetic acid) are also performed in each assay plate to ensure quality and reproducibility. Potential UCH-L1 inhibitors are selected if the compounds demonstrated greater than 60% inhibition compared to the controls. The UCH-L1 enzymatic reactions are manually repeated twice using the same protocol to confirm the results for the hit compounds from the primary robot-assisted screen.

MTT assay(Only for Reference)