The trefoil protein TFF1 is bound to MUC5AC in humangastric mucosa

The trefoil protein TFF1 is expressed principally in the superficial cells of the gastric mucosa. It is a small protein and forms homo- and hetero-dimers via a disulphide bond through Cys58 which is located three amino acids from the C terminus. TFF1 is co-expressed with the secreted mucin MUC5AC in superficial cells of the gastric mucosa suggesting that it could be involved in the packaging or function of gastric mucus. We have previously shown that TFF1 co-sediments with mucin glycoproteins on caesium chloride gradients. To extend this observation we have now used gel filtration under physiological conditions, immunoprecipitation and Western transfer analysis to characterise the interaction of TFF1 with gastric mucin glycoproteins. We show that TFF1 co-elutes with MUC5AC but not MUC6 on gel filtration and that immunoprecipitation and Western transfer analysis confirms that TFF1 interacts with MUC5AC. We also demonstrate that the TFF1 dimer is the predominant molecular form bound to MUC5AC. Salt and chelators of divalent cations such as EDTA and EGTA disrupted the TFF1- MUC5AC interaction and increased the degradation of MUC5AC, whereas calcium increased the amount of TFF1 bound to MUC5AC. These data support the contention that TFF1 is pivotal in the packaging and function of human gastric mucusa.Received 24 March 2004; received after revision 14 May 2004; accepted 7 June 2004     

Study on the DME-cytochrome<Emphasis Type="Italic">b</Emphasis><Subscript>5</Subscript> and its mutants at site of F58

Phenylalanine-58 is one of the conservative residues in the hydrophobic pocket of Cyt bs, which forms aromatic stacking with the heme b. Previous study showed that both the stacking and the property of the aromatic residue affect hydrophobicity of the heme pocket, leading to change of protein‘s property. In order to further reveal the essence we esterify the heme propionate of Cyt bs, F58Y and F58W, and eliminate the hydrogen bond between heme propionate and Ser64 in examining the effect of hydrogen net on the π-π interaction. In this paper thermal denaturation of DME-Cyt b5 and its F58Y and F58W mutants has been studied by UV-visible and CD spectra. The heme transfer reactions between these proteins and apo-myoglobin have been studied as well. The results demonstrate that esterification did not destroy the aromatic stacking; however, it affects the stability of the proteins due to different volumes, hydropho-bicities and hydrogen bonds forming ability of these substituents.     

混合表面活性剂3,5-二溴-4-氨基苯基荧光酮分光光度法测定微量锌

研究了在阳离子溴化十六烷基三甲铵(CTMAB)及非离子(Tween80)表面活性剂存在下,3,5二溴4氨基苯基荧光酮(DBAPF)与锌的显色反应及光度性质.DBAPF与锌及CTMAB+Tween80形成多元配合物,Zn∶DBAPF=1∶2,其最大吸收峰在578nm波长处,表观摩尔吸光系数ε为4.20×104L·mol-1·cm-1,锌含量在0～8μg/10mL范围内符合比尔定律,拟定方法用于大米中锌含量的测定,结果满意.     

预先知道最大请求的两条线路带宽分派问题

研究两条线路带宽问题,利用“预先知道所有请求中最大的那一个请求的大小”这一部分信息来设计算法,该算法比可能有的最好的在线算法在性能上要好得多,同时在某些情况下,该算法是可能有的最好的半在线算法.     

基于Delphi的大型MIS用户权限设置策略

结合一个石油化工管理系统实例提出了一种基于Delphi的通用大型MIS权限设置的策略，并给出了按模块和用户角色的设置用户权限的具体方法。     

一类广义多边形树的色唯一性

讨论了5-桥图F（a,a,a,a,b）（2≤a＜b）的色性,并证明了此类图是色唯一的.     

利用Delphi实现数据库的备份与恢复

随着计算机技术的不断发展,数据库及网络安全越来越重要,因此安全有效的数据库备份成为计算机技术研究的一项重要课题.编写Delphi数据库处理方面程序,实现一系列进行数据库备份与恢复的方法和技巧.使得用户不需要掌握太多的数据库知识,在客户端即可对数据库进行备份和恢复.这样在系统遭到破坏时,就可以安全高效地恢复数据,从而避免重大损失的发生.     

SF5CF3几何构型及红外振动光谱的量子化学研究

采用8种密度泛函方法BHLYP,BLYP,B3LYP,BP86,B3P86,B3PW91,BPW91和KMLYP,以及DZP 基组,对新的温室气体SF5CF3进行了几何构型优化和红外谐振光谱计算.该分子为Cs构型.通过计算值与实验值比较,用KMLYP和BHLYP方法所得几何构型参数与实验值最接近.采用8种方法对SF5CF3进行了红外谐振频率计算,通过与实验值对比,用B3LYP,B3P86和B3PW91方法得出了比较满意的结果.其平均绝对误差分别为29 cm-1,22 cm-1和24 cm-1.红外吸收强度预测表明,SF5CF3是一种威胁性很大的温室气体.     

基于Delphi 6的串口通信程序实现方法研究

串口是计算机最重要的外设接口之一，因此对其通信程序实现方法进行研究有着重要的意义．叙述了在Delphi 6环境下串口通信程序的四种实现方法：采用直接嵌入汇编、利用Windows的API通信函数、利用Activex控件MSComm、利用第三方控件SPComm．同时对各种实现方法进行了比较，并给出了编程实例．     

用户满意度指数测评系统设计

用户满意度指数已经成为许多国家衡量经济产出质量的重要指标,为宏观经济管理提供了有效的决策参考依据.本文以青海省"名牌产品"用户满意度调查为背景,以相应的指数模型为框架,通过Delphi工具,建立了计算机测评系统.