ABSTRACT
Aim To study the effect of tetrandrine derivative HL-49 on the conformation and biological ac-tivity of Bloom helicase ( BLM ) , and to explore its antitumor mechanism.Methods The effect of HL-49 on the conformation of BLM helicase was studied by ultra- violet spectroscopy.The effects of HL-49 on DNA binding activity, DNA chain dissociation activity and ATPase activity of HL-49 on BLM DNA helicase were analyzed by fluorescence polarization and malachite green-ammonium phosphomolybdate colorimetric method.Results HL-49, a tetrandrine derivative, indirectly inhibited the ATPase activity of BLM DNA heli- case and DNA unwinding activity by reversible binding with DNA.The results of fluorescence polarization experiments showed that HL-49 could not affect the bind ing activity of BLM DNA helicase to DNA (dsDNA/ss- DNA) , but could bind to DNA in a concentration-de- pendent manner (P < 0.01).With the increase of HL- 49 concentration, the DNA unwinding ability of BLM DNA helicase decreased, and the Kobs value decreased gradually.The results of malachite green-ammonium phosphomolybdate colorimetry showed that HL-49 could significantly inhibit the ATPase activity of BLM DNA helicase.Conclusions HL49 can inhibit the ATPase activity and DNA unwinding activity of BLM DNA helicase by the reversible binding with DNA.
ABSTRACT
Aim To investigate the effects of bisbenzyl-isoquinoline alkaloid tetrandrine derivative HL-27 on the biological properties of the BLM642-1290 helicase. Methods Fluorescence polarization technique was used to investigate the effects of bisbenzylisoquinoline alkaloid tetrandrine derivative HL-27 on the DNA bind-ing activity and unwinding activity of the BLM642-1290 helicase. Malachite green-phosphate ammonium molyb-date colorimetry was used to investigate the effects of HL-27 on the ATPase activity of the BLM642-1290 heli-case. Ultraviolet spectral scanning was used to investi-gate the effects of HL-27 on the conformation of the BLM642-1290 helicase. Results When the concentra-tion of HL-27 reached 33.34 μmol·L-1, the inhibi-tion ratio of dsDNA and ssDNA binding activity of the BLM642-1290 helicase was 41.35% and 59.54% , re-spectively. When the concentration of HL-27 reached 50 μmol·L-1, the inhibition ratio of DNA unwinding activity of the BLM642-1290 helicase was 78.68% . When the concentration of HL-27 reached 100 μmol· L-1, the inhibition ratio of ATPase activity of the BLM642-1290 helicase was 43.8% . Conclusion The DNA binding activity, ATPase activity and unwinding activity of the BLM642-1290 helicase can be inhibited by bisbenzylisoquinoline alkaloid tetrandrine derivative HL-27.
ABSTRACT
Objective To build a 3D finite element model of the whole cervical spine by using Simpleware software, as well as validate and analyze the model, so as to provide a reliable model for exploring the mechanism of cervical spine injury. Methods The 3D entity model of the whole cervical spine C1-7 was established based on CT tomography images, medical image processing software Simpleware, reverse engineering software Geomagic, which was imported to Hypermesh for meshing, adding ligaments and introducing facet joint contact relation, etc., thus to establish the finite element model of the whole cervical spine C1-7. Biomechanical properties of the cervical spine under flexion, extension, lateral bending and torsion were simulated by ANSYS. Results The established model was proved to be accurate and reliable, and its range of motion (ROM) under flexion, extension, lateral bending and axial rotation was similar to in vitro experiment and finite element analysis results in related literatures. The stress of intervertebral disc was concentrated on the compression side of the vertebral body, and the cervical spine C4/5 was more prone to have a stress concentration. Conclusions The finite element model of the whole cervical spine C1-7 can effectively simulate the biomechanical characteristics of the cervical vertebra, which establishes a good foundation for the follow-up studies on whiplash injury of the cervical spine.