共查询到20条相似文献,搜索用时 0 毫秒
1.
Towards More Specific Information From Isothermal Microcalorimetric Measurements on Living Systems 总被引:1,自引:0,他引:1
Calorimetry is an important thermodynamic and analytical method for investigations of living systems. The non-specific nature of calorimetry can be of advantage in such work, but will also make it difficult to interprete the results in sufficient detail. It is therefore of interest to combine calorimetry with specific analytical techniques. Work in this area is discussed with reference to the use of isothermal microcalorimetry for the characterization of living cellular systems in the pharmaceutical industry.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
2.
Water vapor sorption on morphine sulphate was studied in a twin double sorption microcalorimeter at 25°C. The vapor sorption isotherm and the differential heats of sorption were determined simultaneously from dry condition to a water activity of 0.99. Two well resolved hydration steps were obtained on the sorption isotherm at water activities of 0.01 and 0.22 corresponding to the formation of dihydrate and pentahydrate of morphine sulphate. They were accompanied by constant values of the differential heats of sorption: –24 kJ mol–1(H2O) for the dihydrate formation and –10 kJ mol–1(H2O) for the pentahydrate formation.The calorimetrically obtained sorption isotherms were compared with the results of Karl Fisher titrations of morphine sulphate samples equilibrated at different water activities. The appearance of a liquid phase in the morphine sulphate at high water activities is discussed on the basis of the obtained differential heats of sorption and measured heat capacities of morphine sulphate at different water activities.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
3.
4.
Jun YAO Yi LIU Tian Zhi WANG Jian Ben LIU Peng LIU Zi Niu YU* Key Laboratory of Microbiology of Chinese Agricultural Ministry Huazhong Agricultural University Wuhan College of Chemistry Molecular Science Wuhan University Wuhan College of Life Science Chemistry Jishou University Jishou 《中国化学快报》2003,14(6):619-622
At present, several methods are available for kinetic studies of enzyme-catalyzed reactions, but study on the reaction of Pseudomonas maltophilia tyrosiase by microcalorimetry has not been reported yet. Tyrosinase, ecoded by mel gene, is copper-containing enzyme, which can catalyze and oxidize tyrosine L-dopa to melanin. It exists in the organism of fungi, actinomycetes, bacteria, gymnosperms, angiosperms, insects, chordata, mammals, and human etc.. Tyrosinase from different source has differ… 相似文献
5.
Grell D. Grell E. Bugnon P. Dietrich B. Lehn J.-M. 《Journal of Thermal Analysis and Calorimetry》2004,77(2):483-495
The coordination of divalent and monovalent inorganic anions to synthetic polyammonium receptors is investigated in aqueous
solution around neutral pH by titration calorimetry and NMR spectroscopy. High-affinity 1:1 complexes are formed by a pyrrole
type cryptand (1) with sulfate and phosphate, characterized by association constants of almost 107 M-1. Affinities close to 105 M-1 are found for polyazacryptands (3 and 4) exhibiting F-/Cl- selectivity. The binding affinities and the anion selectivities are mainly caused by the charges of ligands and anions, which
is discussed on the basis of simple calculations of the electrostatic contribution to the anion/receptor interactions. The
binding of all investigated anions is exothermic at 298.2 K. The contribution of the large negative ΔH values to the free
energy of anion binding of the pyrrole type ligand is partially compensated by marked negative ΔS values. These unfavorable
entropic contributions are attributed to the additional inclusion of water molecules in the anion/receptor complexes.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
7.
A microcalorimetric technique was used to investigate the influence of Zn^2 on the growth metabolism of Bacillus thuringiensis .LKB-2277 Bioactivity Monitor was employed to obtain the power-time curves,from which the maximum peak-heat output power(Pmax) in the log phase,the growth rate constants(k), the inhibitory ratios(I) ,the generational time(tG) and the total heat effect (Qtotal) in 23 h for the growth metabolism of Bacillus thuringiensis at 28℃ can be evaluated,The results indicate that the concentration of Zn^2 affects its growth obviously,Low concentration (0-50μg/mL) of Zn^2 promotes the growth of Bacillus thuringiensis while high concentration (50-500μg/mL) of Zn^2 inhibits its growth .When the concentration reached up to 600μg/mL,it can not grow at all. 相似文献
8.
Several lactose samples containing various amounts of amorphicity were studied with an isothermal microcalorimetric technique,
which allow to detect the heat and the quantity of water sorption simultaneously. As interaction with vapor is characteristic
of different surfaces, the samples were easy to be discriminated from each other by studying sorption behavior. With the crystalline
lactose samples, the amount of sorbed water was too minor to be detected reliably with the technique, but differences were
found when the energy values (J g−1) were compared. In the future work, the measurement set-up will be improved so that sorption rates less than 0.1 nmol s−1 can be measured repeatably and reliably.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
极端嗜盐古生菌启动子序列缺失突变的微量热研究 总被引:2,自引:0,他引:2
用微量热方法和DNA缺失突变技术研究了来源于极端嗜盐古生菌R1上的一个推测的启动子片段(RM10)在大肠杆菌中的启动子功能. 启动子片段融合到质粒pKK232-8上无启动子的氯霉素乙酰转移酶(CAT)基因前来检测它驱动基因表达的能力, 缺失分析RM10启动子片段定位具有启动活性的重要功能区. 实验结果从热动力学角度揭示, 这个启动子片段上含有-35区和-10区特征的1382~1517 bp(碱基对)区段是它在大肠杆菌中具有启动子功能的关键部分; 在1~1382 bp区段或1571~1848 bp区段上还存在它的负调控区. 该研究为基因启动子功能研究提供了一种新的、更加灵敏便捷的、化学与生物学相结合的方法. 相似文献
10.
Metabolic thermogenic curves of mitochondria isolated from liver tissue of Carassius auratus and the effect of different concentration of NaAsO2 on it were investigated by TAM air isothermal microcalorimeter, ampoule method, at 28.00 ℃. From the thermogenic curves, activity recovery rate constants k, the maximum heat production rate (Pmax) and the total heat produced (Q) were obtained. The values of k and Pmax decline gradually with the increase of the concentration of NaAsO2, and both of the values of Pmax and k are highly correlated to the concentration of NaAsO2. When concentration of NaAsO2 reached 16.0 μg/mL, the maximum heat production rate dropped to 70.8% of the control group, and the corresponding percentage of k was 71.4% of the control group. This experimental result indicates that the addition of NaAsO2 has restrained the metabolic activities of mitochondria in vitro. 相似文献
11.
IntroductionCalorimetryhasbeenusedinmonitoringcellularmetabolismbymeansofheatmeasurements ,especiallyinstudyingmetabolismincellsandwholeorganism .1,2 Mi crocalorimetryisalsousedinmeasuringtheeffectsofvar ioussubstancesandcultureconditionsonmetabolism .Mile… 相似文献
12.
Ruan L. Liu Y. Gao Z. Shen P. Sheng Q. S. 《Journal of Thermal Analysis and Calorimetry》2002,70(2):521-525
The thermogenic curves of the aerobic metabolism of the three strains of Bacillus thuringiensis
B.t. A, B.t. B and B.t. C have been determined by using an LKB-2277 BioActivity Monitor. B.t. A was the host bacterium without foreign gene. B.t. B and B.t. C were constructed by transforming different foreign genes into the host B.t. A, respectively. B.t. B expressed erythromycin resistant gene, while B.t. C expressed both erythromycin resistant gene and tyrosinase gene. The heat flow rate of these strains is B.t. A> B.t. B >B.t. C. These results indicated that there is obvious interrelation between expression of foreign genes and heat flow rate of
B.t. strains.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
13.
14.
A microcalorimetric method was used to evaluate the action of Yb^3 ions onthe growth metabolism of Staphylococcus aureus.The power-time curves of the growth metabolism of Staphylo.coccus aureus and the action of Yb^3 ions were obtained by us-ing stopped-flow method at 37 ℃. For evaluation of the action,the growth rate constants ( k1 and k2) for the log phase 1, log phase 2, and the total heat effect (Qtotal) for Staphylococcus aureus were determined. The results show that Yb^3 ions at low concentrations have the stimnlatory effect on Staphylococcus au-reus and that Yb^3 ions at higher concentration could inhibit its growth. 相似文献
15.
X. J. Liu H. L. Zhang Z. -C. Tan K. L. Han L. X. Sun 《Journal of Thermal Analysis and Calorimetry》2007,89(3):907-911
The isoquinoline alkaloids were isolated from traditional Chinese drugs of Phellodendri Cortex, Radix Stephaniae Tetrandrae,
Corydalis Yanhusuo and Corydalis Bungeana. The power-time curves of growth of E. coli at different concentrations of isoquinoline alkaloid at 37°C were determined by a 2277 Thermal Activity Monitor. The rate
constant of bacteriostastic activity was calculated. The relationship between growth rate constant and concentration was established.
The optimum bacteriostastic concentration was determined. Experimental results have indicated that all the isoquinoline alkaloids
isolated from the four kinds of traditional Chinese drugs have bacteriostastic activity and the order is Phellodendri Cortex>Radix
Stephaniae Tetrandrae>Corydalis Yanhusuo>Corydalis Bungeana. 相似文献
16.
微量热法研究Schiff碱药物的抗菌作用 总被引:7,自引:0,他引:7
微量热法研究Schiff碱药物的抗菌作用冯英,刘义,谢昌礼,屈松生,乐芝凤,冯长建,沈昊宇,张香才(武汉大学化学系武汉430072)(华中师范大学化学系武汉)关键词Schiff碱药物,微量热法,产气杆菌Schiff碱及其金属配合物具有抗病毒抗菌等生物... 相似文献
17.
18.
J. Phillips 《Journal of Thermal Analysis and Calorimetry》1997,49(1):541-552
Microcalorimetric studies of oxygen and hydrogen chemisorption during the last decade improved the understanding of the structure and structural dynamics of supported bimetallic catalyst particles. For example, it was found that on graphitic supports two different reduced surface compositions/structures can be created for base metal/noble metal particles. Appropriate treatments switch the surface from almost pure reduced base metal to true alloy. Calorimetric studies also indicate support interactions play a major role in controlling bimetallic particle surface structure. In contrast to behaviour found on graphitic supports, iron/noble metal particles supported on refractory oxides apparently do not form alloy surfaces. The reduced surface is dominated by the noble metal. Several studies indicate the value of the models of surface composition/structure developed using microcalorimetry for predicting the activity/selectivity of bimetallic particles. 相似文献
19.
A study of the effect of drug, kanamycin, on the growth metabolism of recombinant Escherichia coli B 1 was carded out by microcalorimeter monitoring of the metabolic activity of treated cells. Power-time curves of growing recombinant Escherichia coli cell suspensions, treated with different kanamycin doses, were recorded. The extent of the effect was evaluated by changes in the slopes of the microcalorimetric curves and the kinetics of the drug action was interpreted from the time at which these changes reached their maximum values and maintained their maximum values. Experimental dose-effect relationships conform to the median-effect principle of the mass-action law: fa/(1-fa)=(D/D50)^m. A plot of y=lg[(fa)^1-1]^-1 versus x=lg D gives the slope m, D50 and R∞. The experimental results revealed that high concentration of kanamycin had an inhibitory effect on the growth of recombinant Escherichia coli B 1 in the lg phase, and had a promoting effect in the stationary period. Moreover, it was demonstrated that microcalorimetry was a reliable method for the detection of modulatory effects in biology. 相似文献
20.