别构酶ATCase与底物分子协同结合过程的构象变化特性

利用可描述协同结合特性的动力学方法,得到了反映单个别构酶ATCase分子的结合分数与底物浓度之间的关系式.表明在确定的底物浓度条件下,单个别构酶ATCase分子处于确定的构象态,随着底物浓度的增加,别构酶ATCase分子将经历一系列中间态达到饱和构象态,S型结合分数曲线实际上显示了单个别构酶ATCase分子与底物分子的协同结合特性.利用所得模型分析了调节物分子对底物协同结合过程的影响,合理解释了结合分数曲线随调节物浓度变化而发生改变的实验结果,与别构酶ATCase分子具有的结构及所产生的生物学功能是自给的.     

Structural biology of protein tyrosine kinases

Our current understanding of the structure, mechanism of action and modes of regulation of the protein tyrosine kinase family owes a great deal to structural biology. Structures are now available for more than 20 different tyrosine kinase domains, many of these in multiple conformational states. They form the basis for the design of experiments to further investigate the role of different structural elements in the normal function and regulation of the protein and in the pathogenesis of many human diseases. Once thought to be too similar to be specifically inhibited by a small molecule, structural differences between kinases allow the design of compounds which inhibit only an acceptable few. This review gives a general overview of protein tyrosine kinase structural biology, including a discussion of the strengths and limitations of the investigative methods involved. Received 2 May 2006; received after revision 21 June 2006; accepted 9 August 2006     

中国货币政策传导的银行博弈分析

通过构建中国货币政策传导的商业银行模型、中央银行-商业银行模型,银行业市场结构模型分析了1998年至2004年中国货币政策传导的内在机制。提出政策建议:继续推进银行业市场化改革,改革监管体制,增强货币政策稳定性、连续性、科学性,鼓励银行业合理竞争。     

改进的非齐性空间反应扩散主方程的随机模拟

提出一种改进的下一子空间算法,与原先的下一子空间算法相比,可以模拟更为复杂空间结构中的生化反应,并在某些情况下还可以降低计算量。该文以一个生化反应系统为例,分别利用原始的下一子空间算法和该文的改进算法进行了模拟。结果表明,在某些条件下该文提出的改进算法可以明显地减少模拟所需的计算量。     

基因调控网络中的延滞动力学

由于基因调控网络中生物化学反应的时间多尺度性,如DNA与蛋白质结合以及蛋白质聚合等快速反应、转录翻译和降解等慢速反应,延滞现象在基因调控网络中普遍存在.文中提出一种延滞基因调控网络的随机模型,并且从矩方程和改进的Gillespie算法对模型进行探讨.还分别考虑了单基因延滞自调控网络和双基因延滞调控网络的例子,计算机模拟计算结果表明,基因调控网络中的延滞可以诱发调控产物浓度的随机振荡,这与实验结果相当吻合.     

Weibull分布下操作风险监管资本及度量精度灵敏度

根据操作风险价值不确定度的合成机理，假设操作损失强度为Weibull分布，导出高置信度下重尾性操作风险监管资本的标准差与置信区间. 进而以弹性分析方法对监管资本及其度量精度变动的灵敏度进行理论探讨后发现：随着分布特征参数的变动，监管资本及其度量精度的变动具有规律性，其灵敏度的变动仅与形状参数和频数参数有关，示例分析进一步验证了理论命题的有效性. 根据该理论命题，不仅可判别操作风险的监控参数，简化操作风险监控系统，而且可为监管资本提取方式的改进提供有价值的参考建议. 本文的研究在理论上进一步完善了损失分布法在操作风险度量与管理中的应用.     

中国食品安全监管面临的挑战及对策

通过对我国食品安全监管现状的分析,发现我国食品安全监管面临着利益主体的行为失控、食品行业发展参差不齐等传统性食品安全问题和转基因食品、环境污染影响等非传统性食品安全问题双重挑战.但目前我国分段式的食品安全监管体系、薄弱的食品安全监管基础设施、相对落后的检测手段和"被"快速老化的监管队伍均无法适应食品安全监管的要求.尽快建立全国专门食品安全监管部门、完善食品安全监管法律体系、建立行业诚信档案、实施食品质量安全追溯制度等成为应对我国食品安全监管挑战的迫切需要.     

一类新的基因调控网络的稳定性分析方法

借助M-矩阵理论分析了含时变时滞的基因调控网络的渐进稳定与指数稳定性问题.首先利用递归神经网络建立基因调控网络模型,通过选取合适的Lyapunov函数,根据M-矩阵知识推导出使网络稳定的充分条件,最后通过实例验证了此方法的有效性及简便性.     

A new method for splice site prediction based on the sequence patterns of splicing signals and regulatory elements

It is of significance for splice site prediction to develop novel algorithms that combine the sequence patterns of regulatory elements such as enhancers and silencers with the patterns of splicing signals. In this paper, a statistical model of splicing signals was built based on the entropy density profile （EDP） method, weight array method （WAM） and K test; moreover, the model of splicing regulatory elements was developed by an unsupervised self-learning method to detect motifs associated with regulatory elements. With two models incorporated, a multi-level support vector machine （SVM） system was devised to perform ab initio prediction for splice sites originating from DNA sequence in eukaryotic genome. Results of large scale tests on human genomic splice sites show that the new method achieves a comparative high performance in splice site prediction. The method is demonstrated to be with at least the same level of performance and usually better performance than the existing SpliceScan method based on modeling regulatory elements, and shown to have higher accuracies than the traditional methods with modeling splicing signals such as the GeneSplicer. In particular, the method has evident advantage over splice site prediction for the genes with lower GC content.