Search

Ancylostoma caninum anticoagulant peptide 5 (AcAP5) is a potent inhibitor for coagulation factor Xa (FXa). Previous studies show that AcAP5 binds to FXa at the active site, and/or the exosite. The active site-binding contributes to direct blocking of FXa catalytic activity, but the effect of exosite-binding and the underlying mechanism remain unknown. To investigate whether and how the exosite-binding affects FXa function, we prepared several AcAP5 mutants with modifications to the active site-binding or exosite-binding region. Their FXa-inhibiting and anticoagulant activities were examined both in vitro and in rabbit plasma, and the interactions with FXa were analyzed using in silico molecular modeling, docking, and molecular dynamics simulation. Mutants abolishing either active site- or exosite-binding resulted in a dramatic decrease in their anti-FXa and anticoagulant activities. Elongation of AcAP5 exosite-binding region also impaired the FXa-inhibiting activity. Computational analysis demonstrated that the conformation of FXa becomes more rigid due to exosite-binding with AcAP5, which consequently affects its catalytic activity. Our results suggest that both active site- and exosite-binding contribute to the FXa inhibitory activity of AcAP5. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) nanophotocatalyst is a promising candidate for degrading organic pollutants but has an extremely low photocatalytic activity under nature sunlight. In this work, flower-like MoS 2 quantum dots/ZnO (MQ/ZnO) nanospheres with the size of approximately 1.26 μm are prepared at low temperature. The resultant flower-like MQ/ZnO nanospheres displayed higher photocatalytic activity than pure ZnO nanospheres under natural sunlight and without stirring, with the decomposition rate of the MQ/ZnO composites approximately 3.3 times higher than that of the pure ZnO nanospheres. Furthermore, the introduction of MoS 2 QDs endowed ZnO nanospheres with optical memory ability. The enhanced sunlight-driven photocatalytic activity is dependent on the unique electrical properties of MoS 2 QDs and the synergistic effect between ZnO and MoS 2 QDs. [ABSTRACT FROM AUTHOR]

Catalytic hydrogenation of CO 2 to methane was investigated over Ru/rutile TiO 2 , focusing on the influence of the pretreatment temperature on the activity. Rutile TiO 2 stabilized Ru nanoparticles even after pretreatment at 800 °C; therefore it was possible to establish the structure–activity relationship without considering the particle size effect. The CO 2 turnover frequency initially increased with increasing pretreatment temperature from 300 to 800 °C, and reached a maximum value of 1.59 s −1 on Ru/rutile TiO 2 pretreated at 600 °C; it decreased to 1.16 s −1 for the sample pretreated at 800 °C. The characterization results indicated that the activity depended on both the extent of encapsulation of Ru particles by TiO x layers and the number of hydroxyl groups on the TiO x surface. The mechanism of CO 2 methanation was discussed based on in situ diffuse-reflectance infrared Fourier-transform spectroscopy results. [ABSTRACT FROM AUTHOR]