The influence of Glu44 and Glu56 of cytochrome b5 on the protein structure and interaction with cytochrome c

The gene encoding trypsin-solubilized bovine liver microsomalcytochrome b₅ (82 residues in length) has been mutated, in whichthe codons of Glu44 and Glu56 were changed to those of Ala.The mutated genes were expressed in Escherichia coli successfullyand three mutant proteins (E44A, E56A and E44/56A) were obtained.The UV-visible, CD and ¹H NMR spectra of proteins have beenstudied. The results show that the mutagenesis at surface residuesdoes not alter the secondary and tertiary structures of cytochromeb₅ significantly. The interactions between recombinant cytochromeb₅ and its mutants with cytochrome c were studied by using opticaldifference spectra. The results demonstrated that both Glu44and Glu56 of cytochrome b₅ participate in the formation of acomplex between cytochrome b₅ and cytochrome c.     

成色剂COY—5中主要杂质的分析研究

应用高效液相色谱、薄层色谱、质谱及核磁共振谱等仪器分析手段，提出了成色剂ＣＯＹ—５中主要杂质的分子结构，指出了该杂质的产生原因和机理，以及降低该杂质含量的最佳途径     

In situ synchrotron X-ray studies on copper-nickel 5 V Mn oxide spinel cathodes for Li-ion batteries

Partial substitution of Mn in lithium manganese oxide spinel materials by Cu and Ni greatly affects the electrochemistry and the cycle life characteristics of the cathode. Substitution with either metal or a combination of both metals in the spinel lattice structure reduces the 3.9-4.2 V potential plateaus associated with the conversion of Mn³⁺ to Mn⁴⁺. Higher potential plateau associated with oxidation of the substituted transition elements is also observed. These substituents also significantly alter the onset of Jahn-Teller distortions in the 3 V potential plateau. Synchrotron based in situ X-ray absorption (XAS) was used to determine the exact nature of the oxidation state changes in order to explain the overall observed capacities at different potential plateaus. The studies on LiCu_0.5Mn_1.5O₄ show single phase behavior in the 4-5 V potential region with a good cycle life. Lower cycle life characteristic observed in cycling LiNi_0.5Mn_1.5O₄ and LiNi_0.25Cu_0.25Mn_1.5O₄ versus Li metal are ascribed to coexistence of several phases in this potential region. However, LiCu_0.5Mn_1.5O₄ shows onset of Jahn-Teller distortions in the 3 V potential plateau, in contrast to LiNi_0.5Mn_1.5O₄ and LiNi_0.25Cu_0.25Mn_1.5O₄ cathode materials.     

5—烃基—2,3—二甲基吡嗪的合成

2,3-二基-5,6-二氢吡嗪与醛或酮在氢氧化钠的乙醇溶液中反应制得16种5-烃基-2,3-二甲基吡嗪。产率66%～90%。其中6种为新合成的化合物。产率17%～87.9%。     

化工节能思索与“九五”目标

指出节约能源是化学工业实现可持续发展的重要条件，评述了“九五”期间化学工业在重点耗能行业合成氨、烧碱、电石等生产过程采取的节能措施及应达到的能耗目标。     

6-甲氧基-2-[5-甲氧基-2-(4-甲基苯磺酰氨基)]苯基-4-苯并噁嗪酮的合成及荧光性能

以3 羟基苯甲醛为原料,通过硝化、醚化、氧化、还原等过程,找出制备中间体5 甲氧基邻氨基苯甲酸的较佳条件。在吡啶中,5 甲氧基邻氨基苯甲酸和对甲苯磺酰氯反应,得到荧光发射波长为590nm的荧光剂6 甲氧基 2 [5 甲氧基 2 (4 甲苯磺酰氨基)]苯基 4 苯并口恶嗪酮,并配制油墨:黏度54 3Pa·s,黏性4 71,细度11μm。适应于轮转胶印印刷。     

Electrosyntheses and characterization of poly(5‐bromoindole) in boron trifluoride diethyl etherate

Poly(5‐bromoindole) (PBrI) films were synthesized electrochemically by direct oxidation of 5‐bromoindole in pure boron trifluoride diethyl etherate. The oxidation potential of 5‐bromoindole in this medium was measured to be only 0.97 V vs. saturated calomel electrode, which was lower than that determined in acetonitrile + 0.1 mol L^?1 Bu₄NBF₄ (1.08 V). PBrI films obtained from this medium showed good electrochemical behavior and good thermal stability. Structural studies showed that the polymerization of 5‐bromoindole ring occurred at 2,3 position. As‐formed PBrI films were thoroughly soluble in strong polar solvent dimethylsulfoxide and partly soluble in tetrahydrofuran. Fluorescent spectral studies indicated that PBrI was a good blue‐light emitter. The excitation and emission spectra of PBrI showed a significant shift to longer wavelength compared with that of the monomer, consistent with the greater extent of electron delocalization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 539–547, 2006     

从假性紫罗兰酮合成β-紫罗兰酮中主要副产物(I)的分离鉴定

假性紫罗兰酮在浓硫酸及 - 2 0°C低温条件下反应 ,主要生成 β-紫罗兰酮 ,少量的 α-及 γ-紫罗兰酮 ,同时生成副产物 ( I)及 ( II)。用 IR、1H NMR及 MS光谱分析方法 ,对副产物 ( I)进行了结构鉴定 ,结构为 3,4,4a,5 ,8,8a-六氢 - 2 ,5 ,5 ,8a-四甲基 - 2 H - 1 -苯并吡喃     

Isobutane/2-butene alkylation on MCM-22 catalyst. Influence of zeolite structure and acidity on activity and selectivity

The catalytic behavior of the novel MCM-22 zeolite for the continuous alkylation of isobutane with 2-butene has been investigated at a temperature of 50°C, 2.5 MPa total pressure, and a variety of olefin space velocities. At high olefin conversions the MCM-22 zeolite showed a very high initial cracking activity attributable to strong Brønsted acid sites, as well as to the existence of strong diffusional restrictions of the TMP's (formed inside the zeolite) to exit through the channels. At short times on stream (TOS), TMP's account for ca. 40% of the C₈ fraction. The olefin conversion and the cracking activity rapidly decline with TOS, while the alkylate product became richer in dimethylhexenes, indicating a predominance of 2-butene dimerization and a loss of hydrogen transfer activity as the catalyst aged. Moreover, MCM-22 gives less TMP's than large-pore zeolites (USY, beta, mordenite), but more than the mediumpore ZSM-5 at similar 2-butene conversion. The latter catalyst was much more selective for olefin dimerization than for isobutane alkylation, presumably because formation of the bulkier TMP's was strongly impeded in its smaller pores.     

Chemisorption of alkenes on copper-exchanged ZSM-5 zeolite

On Cu-ZSM-5 zeolite at room temperature, propane is physisorbed, while propene shows characteristics of chemisorption. The chemisorption mode has certain advantages for the catalytic control of automotive emissions. Alkane and alkene adsorption equilibria and kinetics are compared on Cu-ZSM-5 and on ZSM-5 free of alumina. The results are discussed in terms of the Langmuir adsorption isotherm.