水溶性金属卟啉与DNA相互作用的微量热法研究

叶琳化合物以其对肿瘤组织的特殊亲和性和光动力学效应受到广泛的重视，国内外研究报导甚多·自D79年nel等人山证实水溶性四一K甲基毗陡基）叶咐及其金属配合物能嵌入＊＊A的碱基之间后，人们以这类水溶性叶琳为模型利用各种物理和化学手段研究它们与＊NA相互作用［2，3］．但用微量热法进行研究尚未见报导．我们曾报导用共振拉曼光谱研究图1所示的二个水溶性金属叶琳ru（＊A仰）」和卜i（N＊＊刊I同＊＊A的作用＊‘］，本文进一步报导用微量热法和紫外可见光谱研究的结果．1实验部分1．1试剂将小牛胸腺DN以华美生物工程公司产品）直接…     

线粒体体外代谢热动力学模型及其演化优化研究

导出了线粒体体外代谢的热动力学方程，探讨了它和指数模型的关系，将演化计算技术引入生物热化学领域，用ＭＴＤ方程和演化计算技术，对文献报导的八种鱼肝线粒体体外代谢的热动力学参数进行了全局优化。     

Studies on interaction between gatifloxacin and human serum albumin as well as effect of copper(II) on the reaction

The binding characteristics of gatifloxacin (GTFX) and human serum albumin (HSA) have been studied by fluorescence spectroscopy in aqueous solution, and the interaction influenced by copper(II) was also explored in the paper. The results show that the two-reaction equilibrium constant and the number of binding sites were K = 1.16 x 10(5) l mol(-1), n = 1.27 for GTFX and K = 1.62 x 10(5) l mol(-1), n = 1.74 for GTFX-Cu2+, respectively. The quenching mechanism of fluorescence of HSA by GTFX is a static quenching procedure. The binding distance between GTFX and HSA and the energy transfer efficiency are obtained based on the theory of Fōrster spectroscopy energy transfer. The effect of GTFX on the conformation of HSA was also been analyzed by using synchronous fluorescence spectroscopy. The interaction of GTFX and HSA has been studied by flow-mixed microcalorimetry in the absence and presence of copper(II) and their thermodynamic parameters were obtained. The enthalpy changes and the entropy changes were calculated to be DeltaH approximately 0, DeltaS > 0 in the absence of copper(II),which indicated that static forces played major role in the interaction of GTFX and HSA, and to be DeltaH approximately 0, DeltaS > 0 in the presence of copper(II),which indicated that the static forces also played major role on the reaction. The molar free energy changes of the two reactions are identical with each other because the entropy-enthalpy compensation happened between the two reactions.     

Imprinting unique motifs formed from protein-protein associations

Lysozyme and cytochrome c were imprinted in aqueous media, both as individual proteins and in combination, together with the functional monomer 3-aminophenylboronic acid (APBA) using ammonium persulphate as the initiator. The polymers were formed as films on the gold surfaces of quartz crystal microbalance (QCM) electrodes. It was shown that the lysozyme imprinted polymer was capable of selective template recognition. Micro-calorimetry measurements were used to determine the ratio of lysozyme and cytochrome c giving rise to the maximum enthalpy change when combined in the presence of the functional monomer. Using this procedure a maximum enthalpic change was found when the two proteins were present in an equimolar ratio. A polymer, formed by jointly imprinting the proteins in this ratio, exhibited minimal recognition for the individual template proteins, but was however able to recognise them in combination, suggesting that the proteins when imprinted together interact to form a ‘new’ imprintable motif.The introduction of a series of protein solutions, comprising the imprint proteins in various ratios, to the lysozyme/cytochrome c imprinted films, showed that the films exhibit maximum affinity towards the proteins when they are presented in approximately the same mole ratio (57% cytochrome c and 43% lysozyme) as was used to form the original imprint (equimolar ratio).Frequency response profiles of the QCM electrodes carrying the films, as a function of time, showed the establishment of a new stable baseline (−4.3 Hz) after the electrode was challenged with template protein (1.39 × 10⁻⁹ mol) in less than 3 min.     

Synthesis and characterization of acidic properties of Al-HMS materials of varying Si/Al ratios

HMS and Al-HMS materials with Si/Al ratio in the range 5-45 were synthesized by neutral templating pathway. The as synthesized as well as calcined samples were examined for pore size distribution, surface area and XRD. These investigations confirmed the hexagonal mesoporous structure formation at all Si/Al ratios. The TGA measurements indicated that two types of template species interacting with Si or Al could be distinguished. The acidity and acid strength distribution studies using microcalorimetric NH₃ adsorption indicated that the acidity increases with Al content in the mesoporous structure. The presence of Al in the structure creates a wide variety of acid sites of varying strengths. The heterogeneity of the sites also increases with Al content of the catalysts. The activities for cumene cracking reaction to test acidity of the materials supported the trend obtained from microcalorimetric NH₃ adsorption results.     

微量热法测定细菌的临界生长温度

In this paper, we have determined the multiplication rate constanis (k) of Shigella flexneri and E. coli. at different temperatures and in different culture media by means of a microcalorimeter. From these results a linear equation as k~(1/2)=a+bT can be established for the bacterial growth. The corresponding linear equation for S. flexneri is k~(1/2)=-1.2823+0.0047122 T(r=0.971), so its eritica lgrowth temperature T_0 is equal to 272.1 K. The linear equation for E coli is k~(1/2)=-1.6390+0.005948 T (r=0.994), T_0=275.5 K. The experimental results indicate that the critial growth temperature of E. coli. is nearly a constant (T_0=273.9 K) in different culture media, which is very informative for the study on microorganism growth.     

嗜盐古菌染色体DNA片段在大肠杆菌中的启动子功能

以启动子探针质粒pKK232-8为载体, 用微量量热法研究了源自盐生盐杆菌R1染色体的RM13 DNA片段在大肠杆菌HB101中的真细菌启动子功能, 该启动子RM13 DNA片段的大小为1000bp(碱基对), 它能启动探针质粒pKK232-8上的氯霉素乙酰水解酶基因(即:氯霉素抗性基因Cmr), 氯霉素抗性水平可达到150 mg•L－1, 抗性水平较高, 启动活性较大.研究结果表明, 在盐生盐杆菌染色体上可能存在具有双功能或多功能的启动子DNA片段, 这对系统发育、微生物遗传学和生物热化学等均有重要的意义.     

Kinetics and thermodynamics of the attack of a phosphate ore by acid solutions at different temperatures

A calorimetric study of the kinetics and thermodynamics of the attack of a phosphate ore from Gafsa region (Tunisia) by phosphoric acid and by a mixture of phosphoric acid and sulfuric acids is undertaken at different temperatures. Two samples of the same ore having different grain size have been used. At 25 °C, the dissolution enthalpy in phosphoric acid solution equals −233.6 ± 2.2 J/g for both of the samples. Attack by the mixture of acids is strongly dependent on the solid granulometry. Interpretation of the calorimetric results by Avrami model shows the existence of three domains attributed to phosphate ore dissolution/H₂PO₄⁻ neutralisation, hemihydrate (HH) precipitation and hemihydrate/dihydrate (DH) transformation. The attack by the acid mixture was performed at higher temperatures and showed in addition the transitional formation of the anhydrous sulfate (AH) at T ≥ 55 °C, which transforms into dihydrate after the HH/DH transformation.     

微量热法研究头孢菌素对大肠杆菌微生物活性的影响

用微量热法测定了两种头孢菌素头孢哌酮钠(CFZ)和头孢哌酮钠舒巴坦钠(CFZ-SBT)在37 ℃时对大肠杆菌DH5α代谢作用的影响. 根据产热曲线分别获得了大肠杆菌DH5α在不同浓度的头孢哌酮钠和头孢哌酮钠舒巴坦钠作用下的生长速率常数(k)、抑制率(I)、最大产热功率(Pm)以及最大产热功率所对应的时间tm等热动力学参数. 研究结果表明, 头孢哌酮钠和头孢哌酮钠舒巴坦钠对大肠杆菌的致死量分别为0.1和0.25 μg/mL. 通过研究k, I, Pm, tm和浓度(c)间的关系发现, 舒巴坦钠的加入没有增加头孢哌酮钠对大肠杆菌DH5α的抑制作用.     

微量热法研究碱土金属离子与18-冠-6结合的热力学常数

通过微量热法研究了18-冠-6与碱土金属离子结合过程. 根据反应后的平衡关系, 求出反应平衡常数、焓、熵和吉布斯自由能变化. 金属离子由原来溶剂化的游离态变为与18-冠-6以静电力结合, 体系的能量降低, 放出了热量;同时由原来的自由运动变为被限制在冠醚孔穴内, 自由度减小, 熵值减少. 冠醚内的氧原子能够紧紧地围绕着半径为138 pm的Ba2+, 而离子半径较小的其它离子, 围绕得不够紧密, 与氧原子之间的作用力变小. 从Be2+、Mg2+、Ca2+、Sr2+到Ba2+, 与冠醚结合的放热增加, 平衡常数也逐渐增大.