Lin, LinGopal, SrilaSharda, AnishPassam, FredaBowley, SherylStopa, JackXue, GuangpuYuan, CaiFurie, BarbaraFlaumenhaft, RobertHuang, MingdongFurie, Bruce2019-10-052015Lin, Lin, Srila Gopal, Anish Sharda, Freda Passam, Sheryl R. Bowley, Jack Stopa, Guangpu Xue, et al. 2015. “Quercetin-3-Rutinoside Inhibits Protein Disulfide Isomerase by Binding to Its B′x Domain.” Journal of Biological Chemistry 290 (39): 23543–52. https://doi.org/10.1074/jbc.m115.666180.0021-92581083-351Xhttp://nrs.harvard.edu/urn-3:HUL.InstRepos:41483218Quercetin-3-rutinoside inhibits thrombus formation in a mouse model by inhibiting extracellular protein disulfide isomerase (PDI), an enzyme required for platelet thrombus formation and fibrin generation. Prior studies have identified PDI as a potential target for novel antithrombotic agents. Using a fluorescence enhancement-based assay and isothermal calorimetry, we show that quercetin-3-rutinoside directly binds to the b'domain of PDI with a 1: 1 stoichiometry. The binding of quercetin-3-rutinoside to PDI induces a more compact conformation and restricts the conformational flexibility of PDI, as revealed by small angle x-ray scattering. The binding sites of quercetin-3-rutinoside to PDI were determined by studying its interaction with isolated fragments of PDI. Quercetin-3-rutinoside binds to the b'x domain of PDI. The infusion of the b'x fragment of PDI rescued thrombus formation that was inhibited by quercetin-3-rutinoside in a mouse thrombosis model. This b'x fragment does not possess reductase activity and, in the absence of quercetin-3-rutinoside, does not affect thrombus formation in vivo. The isolated b'domain of PDI has potential as an antidote to reverse the antithrombotic effect of quercetin-3-rutinoside by binding and neutralizing quercetin-3-rutinoside.en-USJournal Article2019-10-0510.1074/jbc.M115.666180