排序方式: 共有66条查询结果,搜索用时 203 毫秒
51.
52.
53.
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
54.
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
56.
Cytoplasmic Ca2+ Dynamics under the Interplay between the Different IP3R Gating Models and the Plasma Membrane Ca2+ Influx 下载免费PDF全文
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
57.
We study the effects of the strength of coupling between neurons on the spiking regularity and coherence in a complex network with randomly connected Hodgkin-Huxley neurons driven by colored noise. It is found that for the given topology realization and colored noise correlation time, there exists an optimal strength of coupling, at which the spiking regularity of the network reaches the best level, Moreover, when the temporal regularity reaches the best level, the spatial coherence of the system has already increased to a relatively high level. In addition, for the given number of neurons and noise correlation time, the values of average regularity and spatial coherence at the optimal strength of coupling are nearly independent of the topology realization. Furthermore, there exists an optimal value of colored noise correlation time at which the spiking regularity can reach its best level. These results may be helpful for understanding of the real neuron world. 相似文献
58.
Brownian dynamics simulation of the cross-talking effect among modified histones on conformations of nucleosomes 下载免费PDF全文
Using Brownian dynamics simulation,we studied the effect of histone modifications on conformations of an array of nucleosomes in a segment of chromatin.The simulation demonstrated that the segment of chromatin shows the dynamic behaviour that its conformation can switch between a state with nearly all of the histones being wrapped by DNA and a state with nearly all of the histones being unwrapped by DNA,thus involving the "cross-talking" interactions among the histones.Each state can stay for a sufficiently long time.These conformational states are essential for gene expression or gene silence.The simulation also shows that these conformational states can be inherited by the daughter DNAs during DNA replication,giving a theoretical explanation of the epigenetic phenomenon. 相似文献
59.
We present an analytical solution for fluid velocity field distribution of polyelectrolyte DNA. Both the electric field force and the viscous force in the DNA solution are considered under a suitable boundary condition. The solution of electric potential is analytically obtained by using the linearized Poisson-Boltzmann equation. The fluid velocity along the electric field is dependent on the cylindrical radius and concentration. It is shown that the electric field-induced fluid velocity will be increased with the increasing cylindrical radius, whose distribution also varies with the concentration 相似文献