Dicoumarol

β-lapachone was obtained from Southeast Pharmaceuticals, Inc. (Jiangsu, China). Propofol, N-acetyl cysteine (NAC), dicoumarol (DIC), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), glucose 6-phosphate, glucose 6-phosphate dehydrogenase, β-nicotinamide adenine dinucleotide phosphate (NADP), uridine 5’-diphosphate-glucuronic acid (UDPGA), D-saccharic acid 1,4-lactone, β-D-glucuronidase and chlorzoxazone, were all purchased from Sigma Aldrich. Diazepam was obtained from the National Institute for the Control of Pharmaceutical and Biological Products (Beijing, China).

ß-Lap was synthesized and purified by us and stock solutions prepared at 50 mM in DMSO. Methoxyamine, dicoumarol, Rucaparib and BAPTA-AM were purchased from Sigma-Aldrich (St. Louis, MO).

Human Aβ_1-42 as a click peptide was purchased from GenScript (Catalog# RP10017) and used as received. The click peptide undergoes a chemical reaction at physiological pH leading to the formation of monomeric Aβ_1-42 [19 (link)]. Thioflavin T (ThT), FAD, nicotinamide adenine dinucleotide-reduced form (NADH), and dicoumarol were purchased from Sigma-Aldrich. Aβ_1-42 covalently linked to HiLyte Fluor 647 (HF647) dye was purchased from AnaSpec (Catalog# AS-64161). Ultrapure Milli Q water was used throughout the study. Aggregation studies were performed in 100 mM potassium phosphate buffer, pH 7.4. Recombinant human WT NQO1 and the NQO1*2 variant were purified from Escherichia coli using Cibacron-blue affinity chromatography as previously described [20 (link),21 (link)]. The purified proteins resolved as single bands near 30 kDa. FAD-deficient apo NQO1 was generated by incubating WT NQO1 in two cycles of 50 mM potassium phosphate buffer, pH 7.4 containing 2 M potassium bromide as previously described [22 (link)]. Purified NQO1 proteins were stored in 50 mM potassium phosphate buffer, pH 7.4 containing 250 mM sucrose and 5 µM FAD at –80°C.