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51.
本文报道了用单分子磁镊研究抗癌药顺铂导致的DNA凝聚过程.结果表明,当拉力比较小时,DNA凝聚的长度-时间曲线是连续缩短和阶跃缩短并存的复杂曲线.而当拉力较大但又不足以阻止DNA的凝聚时,凝聚曲线为连续缩短的双曲线.增加顺铂浓度只会增大凝聚速度而不会改变反应曲线的形状.实验结果与下列成环凝聚模型一致:在水溶液中顺铂能够与DNA形成双臂加合物,也能形成单臂加合物.当顺铂使DNA长链上相距较远的碱基间发生远程交联时,形成小环,导致DNA凝聚.小环间的进一步交联会引起DNA的完全凝聚.DNA凝聚产物十分稳定.
关键词:
顺铂
DNA凝聚
单分子操纵
抗癌药 相似文献
52.
During the assembly of many viruses, a powerful molecular
motor packages the genome into a preassembled capsid. The Bacillus
subtilis phage φ 29 is an excellent model system to investigate
the DNA packaging mechanism because of its highly efficient
\textitin vitro DNA packaging activity and the development of a
single-molecule packaging assay. Here we make use of structural and
biochemical experimental data to build a physical model of DNA
packaging by the φ 29 DNA packaging motor. Based on the model,
various dynamic behaviours such as the packaging rate, pause
frequency and slip frequency under different ATP concentrations, ADP
concentrations, external loads as well as capsid fillings are
studied by using Monte Carlo simulation. Good agreement is obtained
between the simulated and available experimental results. Moreover,
we make testable predictions that should guide future experiments
related to motor function. 相似文献
53.
54.
We propose a physics method to study the effect of laser field and mechanical force on the melting process of double-stranded deoxyribonucleic acid (DNA). A two-dimensional lattice model is established for DNA molecules stuck on the surface, and the stretching energy of the hydrogen bond and stacking energy for each DNA molecule are calculated by using a nonlinear potential. A real-time algorithm is employed to deal with the dynamics process of DNA melting. Numerical results explain the experimental observations. The spatial distribution of the laser field determines the sequences of DNA melting. The simulation has shown the dependence of the final number of melted DNA on the laser field and mechanical force. 相似文献
55.
Cytoplasmic Ca2+ Dynamics under the Interplay between the Different IP3R Gating Models and the Plasma Membrane Ca2+ Influx
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The cytoplasmic Ca2+ oscillations are investigated under the effect of CRAC channels in non-excitable cells (especially in T cells). The oscillatory Ca2+ signals can be modulated as the amplitude-, frequency- and mixed amplitude-frequency modulation modes dependent on the different IP3R gating models. Bifurcation analyses show that Ca2+ signals in the single positive feedback loop model is a mixed modulation mode. In contrast, Ca2+ signals in the Mak-McBride-Foskett model demonstrates approximately the frequency modulation mode only with slight amplitude shifts. 相似文献
56.
A CONTINUOUS COMPOUND FOUR-WAVE MIXING MECHANISM FOR SELF-PUMPED PHASE CONJUGATION IN BaTiO3 CRYSTALS
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A continuous compound four-wave mixing mechanism for sell-pumped phase conjugation in photorefractive crystals is presented. The coupled-beam equations of this mechanism are solved numerically when depletion of the forward going beam is neglected. The experiment in a Ce-doped BaTiO3 crystal is performed, with the stable phase conjugate reflectivity of as much as ≥80%. The curved high output phase conjugate intensity are explained using the numerical results. 相似文献
58.
Control of spiral waves and turbulent states in a cardiac model by travelling—wave perturbations 总被引:3,自引:0,他引:3
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We propose a travelling-wave perturbation method to control the spatiotemporal dynamics in a cardiac model.It is numerically demonstrated that the method can successfully suppress the wave instability(alternans in action potential duration) in the one-dimensional case and converty spiral waves and turbulent states to the normal travelling wave states in the two-dimensional case.An experimental scheme is suggested which may provide a new design for a cardiac defibrillator. 相似文献
59.
60.
A non-Markov ratchet model of molecular motors:processive movement of single-headed kinesin KIF1A
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A fluctuating ratchet model of non-Markov process is presented to describe the processive movement of molecular motors of single-headed kinesin KIF1A,where the fluctuation perturbation to the local potential is introduced and the detailed ATPase pathway of the motor is included. The theoretical results show good quantitative agreement with the previous experimental ones. 相似文献