取代苯甲酸、取代苯酚酸性PKa和取代苯胺碱性PKb的分子拓扑研究

基于元素的Pauling电负性,原子成σ键的电子数,原子直接键连的氢原子数目和原子形成离域键时所提供的PZ电子数,建立了一种分子连接性指数(4X),它与19种取代苯酚酸性Pka的线性方程为:Pka=14.1127-1.63754X,它与22种取代苯胺碱性Pkb的线性方程为:Pkb=4.5524 2.08464X.它与30种取代苯甲酸酸性Pka的线性方程为:Pka=7.1000-0.72034X.结果表明,4X具有良好的结构选择性和性质相关性,可用于预测其它取代苯甲酸、取代苯酚酸性Pka值和取代苯胺碱性Pkb值.     

水杨醛β-丙氨酸希夫碱复合双金属配合物催化分子氧氧化环己烯的性能研究

合成了水杨醛β-丙氨酸希夫碱复合双金属配合物(SACo/Cu、SACo/Mn、SACo/Fe),并用FT-IR,ICP,XPS进行了结构表征.以分子氧做氧化剂,考察了复合双金属配合物对环己烯选择性氧化催化性能,探论了温度、时间、催化剂用量与底物比、溶剂及添加剂等因素对该反应的影响.     

Membrane protein folding on the example of outer membrane protein A of <Emphasis Type="Italic">Escherichia coli</Emphasis>

The biophysical principles and mechanisms by which membrane proteins insert and fold into a biomembrane have mostly been studied with bacteriorhodopsin and outer membrane protein A (OmpA). This review describes the assembly process of the monomeric outer membrane proteins of Gram-negative bacteria, for which OmpA has served as an example. OmpA is a two-domain outer membrane protein composed of a 171-residue eight-stranded -barrel transmembrane domain and a 154-residue periplasmic domain. OmpA is translocated in an unstructured form across the cytoplasmic membrane into the periplasm. In the periplasm, unfolded OmpA is kept in solution in complex with the molecular chaperone Skp. After binding of periplasmic lipopolysaccharide, OmpA insertion and folding occur spontaneously upon interaction of the complex with the phospholipid bilayer. Insertion and folding of the -barrel transmembrane domain into the lipid bilayer are highly synchronized, i.e. the formation of large amounts of -sheet secondary structure and -barrel tertiary structure take place in parallel with the same rate constants, while OmpA inserts into the hydrophobic core of the membrane. In vitro, OmpA can successfully fold into a range of model membranes of very different phospholipid compositions, i.e. into bilayers of lipids of different headgroup structures and hydrophobic chain lengths. Three membrane-bound folding intermediates of OmpA were discovered in folding studies with dioleoylphosphatidylcholine bilayers. Their formation was monitored by time-resolved distance determinations by fluorescence quenching, and they were structurally distinguished by the relative positions of the five tryptophan residues of OmpA in projection to the membrane normal. Recent studies indicate a chaperone-assisted, highly synchronized mechanism of secondary and tertiary structure formation upon membrane insertion of -barrel membrane proteins such as OmpA that involves at least three structurally distinct folding intermediates.     

铝锗酸盐分子筛KAlGe3O8的合成与结构

在KOH-GeO2-Al2O3-H2O-有机胺(二正丁胺、环己胺、二异丙胺、正丙胺、三正丁胺、哌啶、1,3-丙二胺、三乙烯四胺和溴化四丙基铵)体系中,采用水热法合成了一种新的锗铝酸盐分子筛KAlGe3O8,X射线单晶结构分析表明其结构与硅铝酸盐矿物paracelsian的类似,是由四元环带组成的4,6,8的空间网络结构,钾离子占据其八元环孔道中,KAlGe3O8的结晶学参数：Mτ=411．85,正交晶系,Pnmα,α=9．437(3)A,b=8．707(2)A,c=9．825(3)A,V=807．3(4)A^3,Z=4,R(F)=3．92％,wR(F^2)=8．57％。     

Gene cloning and molecular breeding to improve fiber qualities in cotton

Cotton fiber is one of known natural resources comprising the highest purity cellulose. It plays an important role world wide in the textile industry. With the acceleration of spinning speeds and the improvement of the people‘s living level, the demand of improving cotton fiber qualities is getting stronger and stronger. So, making clear the developmental model of fiber cell and elucidating systematically the molecular mechanisms of cotton fiber development and regulation will produce a great significance to make full use of cotton gene resources, raise cotton yield and improve fiber quality, and even develop man-made fiber. In the paper, the status of the gene cloning and the molecular breeding to improve cotton fiber quality were reviewed, the importance and potential of gene cloning related with cotton fiber quality were put forward and the proposal and prospect on fiber quality improvement were made. Using national resources available and through the creative exploration in corresponding research, some international leading patents in genes or markers linked with cotton fiber development having Chinese own intellectual property should be licensed quickly. And they can be used to improve cotton fiber quality in cotton breeding practice.     

DNA microarray synthesis by using PDMS molecular stamps (Ⅲ)—— Optimization for the reaction conditions

Optimization for the technological processes of fabricating oligonucleotide microarray by the molecular stamping method is studied in this note. Three factors that affect the pressing coupling reactions of the nucleosides are focused on: the stability of the chemical activities of the reaction solutions, the contamination of the remain of the reactive nucleotides among the different spots on the chip, and the influence of the capping reaction on the hybridization result. The experiments show that the acetonitrile solution of tetrazole and nucleoside monomer could maintain sufficient reactive activity for more than 10 h. An effective method has been used and proved to eliminate the residual reactive nucleosides on chip with small molecules containing hydroxyl group. Finally, the capping step—a regular step in the conventional DNA chemical synthesis can be neglected in our on-chip DNA synthetic process, which would not affect its hybridization results.     

Modulating multidrug resistance through inhibiting of protein kinase C activity by phenothiazines

In the present study, actions of phenothiazines(PTZ) in reversing multidrug resistance(MDR) and inhibiting PKC activity were investigated. It was found that the three PTZs caused 2.49, 36.58 and 75.78 fold reversal of K562/AO2 MDR cells resistant to adriamycin, respectively, while the chemosensitizer verapamil caused 40 fold reversal in the same condition, indicating that PTZ11 is a novel reversal agent of MDR and a potential chemotherapeutic reagent for tumor therapy. PKC activity analysis in the presence of PTZs showd that PTZ6 and PTZ11 inhibited rat brain protein kinase C activity in a manner of dose_dependent. The IC 50 values were (489.77±31.4) and (113±9.64) μmol/L, respectively. PTZ7 had no inhibition on PKC activity. Further study showed that PTZ11 could reduce PMA_mediated activation of PKC in a manner of dose_dependent, suggesting that PTZ11 might compete for the high_affinity phorbol ester binding site within PKC molecule. Recently, an X_ray structure of PMA in complex with PKC Cys2 activator_binding domain was solved. We therefore decided to explore the possible binding model of PTZ11 with PKC molecule using SYBYL 6.02 program. It was shown that the binding site of PTZ11 with PKC molecule partially overlapped with that of PMA, providing for the first time new data for designing PKC inhibitors and MDR reversal drugs.     

Molecular mechanism of the inhibitory effect of methylation outside the recognition sequence of restriction endonuclease Pvu Π on its cleavage activity

In 1991, we found that methylation outside the PvuⅡ recognition sequence could partially inhibit its cleavage activity. To clarify the molecular mechanism, three plasmids with different methylation states were constructed. Then, together with the original one, four plasmids were digested with different amounts of PvuⅡ. Results show that methylation on both sites results in 90% inhibition; moving the methylated site one base further away decreases the inhibitory effect to about 30%; with the adjacent dam methylation site eliminated, the inhibitory effect disappears. The data suggest that the inhibition of cleavage activity caused by outside methylation is not "all or none", and the degree of inhibition is dependent on the position and the number of methylated bases.     

结核分枝杆菌单克隆抗体与自身抗原组蛋自的免疫交叉反应研究

WesternBlot实验证实了结核分枝杆菌（Mycobacteriumtuberculosis）H37Ra的单克隆抗体与自身抗原组蛋白发生免疫交叉反应．利用计算机软件对交叉反应的分子生物学基础进行了分析,发现结核分枝杆菌H37Ra的蛋白与组蛋白H1,H2A,H2B,H3,H4各有一个包含3个或4个氨基酸的序列同源区域．     

聚丙烯酰胺在油砂岩芯中的不可及孔隙体积

采用ＫＳＣＮ作示踪剂,测定了高分子量聚丙烯酰胺（ＨＰＡＭ）５８℃时在辽河油田油砂岩芯中的不可及孔隙体积．分析结果表明,随着ＨＰＡＭ浓度的增加,不可及孔隙体积也增加;油砂的孔隙率越高,不可及孔隙体积越小．表明ＨＰＡＭ在油砂中将有更高的驱油效率．