Chemical Research in Chinese Universities最新文献

Preparation and characterization of the hapten-protein conjugates are fundamental to developing environmental immunoassays. As a hapten, 1-pyrenebutyric acid(PBA) was conjugated to the carrier protein of bovine serum albumin(BSA) or ovalbumin(OVA) by active ester method. Infrared spectra(IR) showed that PBA-BSA and PBA-OVA conjugates were successfully prepared. The number of the haptens conjugated to the carrier protein was determined by ultraviolet spectra(UV) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry(MALDI-TOF-MS). The calculated average binding ratios of PBA/BSA and PBA/OVA were 18:1 and 10:1 by UV, and 31:1 and 22:1 by MALDI-TOF-MS, respectively. Although there was a discrepancy between the results determined by the two methods, both of them were useful for the characterization of the hapten-protein conjugates. The antibody was produced against the antigen of PBA-BSA, and the affinity was tested by the double agar diffusion method. The conjugates and the antibody could be used for developing a sensitive and selective immunoassay of polycyclic aromatic hydrocarbons(PAHs).

0.5%Pt-K/γ-Al₂O₃ catalysts for the synthesis of o-phenylphenol(OPP) from o-cyclohexenyl-cyclohexanone (dimer) dehydrogenation were prepared by means of a two subsequent impregnation method. The effects of catalyst preparation parameters, such as K promoters, calcination, and reduction conditions, were investigated. The results showed that the addition of K₂SO₄ to Pt/γ-Al₂O₃ catalyst notably promoted the selectivity of OPP, and its optimum content was found to be 6% in mass fraction. The higher activity was obtained when Pt/γ-Al₂O₃ catalyst was calcined in nitrogen atmosphere at 400—500 °C and then reduced at the same temperature for 3 h in hydrogen atmosphere. The conversion of the dimer and the selectivity of OPP were always above 99% and 90%, respectively, over 0.5%Pt-6% K₂SO₄/γ-Al₂O₃ catalyst during the pilot scale test of 8000 h.

The twisted aromatics, functional dibenzo[d,f][1,3]dioxepine derivatives were synthesized in high yields from reactions of 5,5′-dibromo-2,2′-biphenol with corresponding ketal or ketone compounds under acid catalysis. The structures of these compounds were characterized by ¹H NMR, elemental analysis, UV-Vis absorption spectrum and X-ray diffraction analysis. The conformation of O—C—O bridged biphenyl derivatives with varied substitute groups on 6,6′-position was studied by X-ray crystallography and force-field simulation. The result of calculations by UNIVERSAL 1.02 force field in Cerius² package(4.6) indicates that dibenzo[d,f][1,3]dioxepine derivatives show twisted conformations and the twisted angle between the phenyl rings is about 40°, which is accordant with the result from crystal structure determination, though the obtained angles in the crystal of dibenzo[d,f][1,3]dioxepine derivatives with the varied substitute groups on 6,6′-position are shown to be slightly shifted to 40° owing to intermolecular interactions in crystal stacking. DSC studies exhibit that the substitute groups on 6,6′-position can induce a large variation of endothermic peaks ranging from 80 to 135 °C. The conjugated polymers based on dibenzo[d,f][1,3]dioxepine derivatives, which have ultraviolet emitting with a quantum efficiency of 10%, were obtained by Yamamoto coupling.

The influences of magnesium and ferric ions in their different ratios on the rate of gypsum crystallization were studied under the conditions similar to those of wet flue-gas desulfurization(WFGD). The results show that addition of both Mg²⁺ and Fe³⁺ increased induction time and decreased the growth efficiency up to 50% compared with the baseline(without impurities) depending on the concentration and the type of impurity. The effects of Mg²⁺ and Fe³⁺ on the surface energy and the rate of nucleation were estimated by employing the classical nucleation theory. The surface energy decreased by 8% and 14% with the addition of 0.02 mol/L magnesium or ferric ions, respectively, compared to the baseline. Mg²⁺ and Fe³⁺ made the growth rate of the (020), (021) and (040) faces of gypsum crystal a much greater reduction, which leads to the formation of needle crystals compared to the baseline which favors the formation of plate or flakes. Furthermore, an edge detection program was developed to quantify the effects of impurities on the filtration rate of gypsum product. The results show that the inhibition efficiency of the presence of 0.02 mol/L Mg²⁺ and Fe³⁺ on the filtration rate of gypsum crystal ranges from 22% to 39%.

The interaction of bromothymol blue(BB) with human serum albumin(HSA) was studied by electrochemical techniques and a sensitive method for proteins assay was developed. When BB interacted with HSA, the voltammetric peak current value of BB decreased linearly with the concentration of HSA in a range of 1.0—40.0 mg/L, and the peak potential shifted negatively. Based on the results, a sensitive assay method for proteins, such as HSA, bovine serum albumin(BSA), and egg albumin etc. was established. This method was further applied to determining the HSA in healthy human blood samples, and the results are not significantly different from those obtained by the classic Coomassie Brilliant Blue G-250 spectrophotometic method. The detecting conditions of this method were optimized and the interaction mechanism was discussed. The results show that the electrochemical parameters(formal potential E⁰, standard rate constant of the electrode reaction k_s, parameter of kinetic nα) of BB have no obvious changes before and after the interaction, which indicate that BB can interact with HSA, forming an electrochemical non-active complex. The equilibrium constant(β_s) and the binding ratio(m) for this complex were calculated. The m is 4 and β_s is 1.41×10¹⁹. This method is fast, simple, highly sensitive, and has good selectivity, which can be used in clinical measurements.

Ginsenosides Rg₁, Re, Rb₁, Rc, Rb₂, Rb₃, and Rd in different parts of the American ginseng plant were investigated. The extraction process was a pressurized microwave-assisted extraction(PMAE). The seven ginsenosides were separated and determined by high-performance liquid chromatography(HPLC) with a ultraviolet(UV) detector, at 203 nm. The experiment results showed significant variations in the individual ginsenoside contents of the American ginseng in different parts and ages of the plant. The results demonstrated that the leaves, root hairs, and rhizomes of Panax quinquefolius L. contained higher ginsenoside contents, followed by the main roots and stems. The leaves contained dramatically higher levels of ginsenoside Rg₁, Rb₃, and Rd than the other four parts. Higher contents of Rb₁ and Re were present in the main roots, root hairs, and rhizomes. The amount of ginsenoside content in the stems was the lowest. The total content of the seven ginsenosides in main roots, root hairs and rhizomes increased with the age of the plant. In contrast, the ginsenoside contents in the leaves and stems decreased with a year of growth.

The entire gene of carboxyltransferase(CT) domain of acetyl-CoA carboxylase(ACCase) from Chinese Spring wheat(CSW) plastid was cloned firstly, and the 2.3 kb gene was inserted into PET28a⁺ vector and expressed in E. coil in a soluble state. The (His)₆ fusion protein was identified by SDS-PAGE and Western blot. The recombinant protein was purified by affinity chromatography, and the calculated molecular mass(M_r) was 88000. The results of the sequence analysis indicate that the cloned gene(GeneBank accession No. EU124675) was a supplement and revision of the reported ACCase CT partial cDNA from Chinese Spring wheat plastid. The recombinant protein will be significant for us to investigate the recognizing mechanism between ACCase and herbicides, and further to screen new herbicides.

To explore the functional mechanism of Resveratrol against colon cancer cells Is174t and the growth of colon cancer tissue of tumor-bearing mice, MTT method was used to observe the functions of resveratrol for inhibition against cells Is174t in vitro. Transmission electron microscope was used to observe the cell apoptosis. FCM assay was performed to measure the change of the cell apoptosis rate and of cell cycle. RT-PCR method was used to detect the expressions of bcl-2 and bax mRNA. Western blot method was used to detect the expressions of bcl-2 and bax protein. Cells Is174t were transplanted subcutaneously to nude mice to observe the effect of resveratrol on the growth of subcutaneously transplanted tumor. RT-PCR method was used to detect the expressions of bcl-2 and bax mRNA in the tumor tissue. Western blot method was used to detect the expressions of bcl-2 and bax protein in the tumor tissue. Resveratrol has an effect of inhibiting proliferation of cells Is174t in vitro(P<0.01). It is able to induce the apoptosis of cells Is174t, causing the decrease in the expression of bcl-2 and the increase in the expression of bax. Resveratrol could inhibit the growth of subcutaneously transplanted tumor of nude mice(P<0.05), causing the decrease in the expression of bcl-2 and the increase in the expression of bax. Resveratrol can inhibit the growth of cells 174t and the growth of subcutaneously transplanted tumor. The mechanism is possibly related to the induction of the cell apoptosis and the regulation of bcl-2/bax expression.

Survivin, a novel member of inhibitor of apoptosis(IAP) protein family, is aberrantly expressed in cancer but undetectable in normal, differentiated adult tissues. The cancer-specific expression of survivin, coupled with its importance in inhibiting cell death and in regulating cell division makes it a useful diagnostic marker of cancer and a potential target for cancer treatment. Survivin cDNA amplified from the total RNA of 293 cells through RT-PCR was cloned into prokaryotic expression vector pRSET-B. The recombinant plasmid pRSET-B-Surv was expressed in E.coli BL21, and the relative molecule mass(M_r) of expressed fusion protein was approximately 21000. The recombinant protein was purified through Ni²⁺ affinity chromatography column and characterized by SDS-PAGE and Western blot. The purified recombinant protein was then injected into rabbits, and antisurvivin polyclonal antibody with a high titer was obtained.

The reaction mechanisms of intermolecular cleavage reaction of N-(2-hydroxyphenyl)-phthalamic acid were studied via the density functional theory(DFT). All geometries of the reactant, transition states, and products were optimized at the B3LYP/6-31G(d, p) level. Vibration analysis was carried out to confirm its identity as transitions' structure, and the intrinsic reaction coordinate method(IRC) was used to search the minimum energy path. Two possible reaction channels are reported in this article. The calculated results indicate that O-cyclization reaction channel has the lower activation barrier, and therefore, it occurs more easier than the other.