Activity and Structure Changes of Arginine Kinase from Shrimp Feneropenaeus chinensis Muscle in Trifluoroethanol Solutions

Trifluoroethanol has often been used in protein folding studies. The changes in activity and unfolding of arginine kinase from shrimp Feneropenaeus Ghinensis muscle during denaturation in different concentrations of trifuoroethanol were investigated using far-ultraviolet circular dichroism and fluorescence emission spectra. Arginine kinase was inactivated in trifluoroethanol solutions. The tertiary and secondary structures of arginine kinase were also destroyed in the trifluoroethanol solutions. The unfolding and inactivation courses were measured and compared. Inactivation occurred prior to unfolding, which suggests that the arginine kinase active site is more easily damaged by the denaturant than the enzyme as a whole. The result also indicates that the arginine kinase active site is situated in a limited and flexible region of the enzymemolecule.     

Sr^2＋诱导尖吻蝮蛇毒中抗凝血因子I的结构稳定性及重新折叠

尖吻蝮蛇毒抗凝血因子I（ACFI）是活化凝血因子X（FXa）结合蛋白，具有显著的抗凝血活性．用荧光光谱研究了Sr^＋诱导ACF I的结构稳定性及重新折叠．结果表明，脱钙ACF I（apo-ACFI）可结合两个Sr^＋．ACF I与FXa的结合反应不是绝对依赖于Ca^2＋，Sr^2＋也可以诱导ACF I与FXa的结合反应．盐酸胍诱导的Sr^2＋重组ACFI（Sr^2＋-ACF I）去折叠过程是一个三态过程，有一个稳定的中间态．像Ca^2＋一样，Sr^2＋不仅能显著增加ACF I的结构稳定性，而且在不改变变性剂浓度条件下，能诱导去折叠的脱钙ACF I重新折叠成Sr^2＋-ACF I的中间态．Sr^2＋诱导apo-ACF I重新折叠过程包含快慢两步反应，Sr^2＋取代Ca^2＋只降低快折叠反应速度，而不影响慢折叠反应速度．这说明，金属离子影响快折叠过程，而慢折叠过程只决定于蛋白质本身性质．     

不同IRT模型在生活取向测验修订版中的适用性比较

为比较拓广等级展开模型、等级反应模型和拓广分部评分模型在生活取向测验修订版上的模型-数据拟合差异及项目参数估计值和标准误差的差异,选取2个学校的大一新生(3 864人)进行分析,采用单项目、两项目对和三项目组校正χ2/df检验3个模型的模型-数据的拟合,采用边际极大似然方法估计项目参数值及其标准误差.结果发现拓广等级展开模型的模型-数据拟合优于其它2个模型,但该模型的项目参数估计值及其标准误差显得并不是很合理,提示需要对该模型开展更深入的研究.     

Second-Order Auditing Practices

This paper describes the process that was followed at the Colombian National Audit Office, during 3.5 years, to develop new auditing practices, called second-order auditing. The purpose of the second-order control is to detect possible faults in the internal control mechanisms of the audited entities. General and particular models for second-order audit are presented, along with a method to carry out this type of auditing. Finally, a particular application of second-order auditing carried out in a Colombian national institution is presented.     

一类等变分歧问题在等变左右等价下的无穷小稳定开折

利用奇点理论中的方法和技巧,刻画了含两组状态变量且分歧参数带有对称性的等变分歧问题的开折的无穷小稳定性,并讨论了这类分歧问题的无穷小稳定开折的存在性.     

一类非线性磁流变阻尼系统的局部分岔

作者研究了一类非线性磁流变阻尼系统的局部分岔,运用中心流形定理讨论了系统具单零特征值时的普适开折,给出了分岔集与相图,并进一步证明了在系统内的小参数扰动下系统将发生音又分岔.     

滞后型结构缺陷对临界载荷的影响

讨论了滞后型结构临界载荷受缺陷影响的变化规律,利用普适开折理论,给出了临界载荷随缺陷变化的下界估计公式,并给出了具体的数值计算公式。     

相对映射芽的强有限决定性与通用开折

用奇点理论中横截开折的理论对相对映射芽的强有限决定性与通用开折之间的关系进行了研究．证明了相对映射芽的强有限决定性与相对映射芽的通用开折存在性之间的等价关系，即相对映射芽，是强有限决定的当且仅当，具有通用开折。