Direct electron transfer reactions between human ceruloplasmin and electrodes

In an effort to find conditions favouring bioelectrocatalytic reduction of oxygen by surface-immobilised human ceruloplasmin (Cp), direct electron transfer (DET) reactions between Cp and an extended range of surfaces were considered. Exploiting advances in surface nanotechnology, bare and carbon-nanotube-modified spectrographic graphite electrodes as well as bare, thiol- and gold-nanoparticle-modified gold electrodes were considered, and ellipsometry provided clues as to the amount and form of adsorbed Cp. DET was studied under different conditions by cyclic voltammetry and chronoamperometry. Two Faradaic processes with midpoint potentials of about 400 mV and 700 mV vs. NHE, corresponding to the redox transformation of copper sites of Cp, were clearly observed. In spite of the significant amount of Cp adsorbed on the electrode surfaces, as well as the quite fast DET reactions between the redox enzyme and electrodes, bioelectrocatalytic reduction of oxygen by immobilised Cp was never registered. The bioelectrocatalytic inertness of this complex multi-functional redox enzyme interacting with a variety of surfaces might be associated with a very complex mechanism of intramolecular electron transfer involving a kinetic trapping behaviour.     

Comparative Spectroelectrochemical Studies of Lyophilized and Nonlyophilized Laccases from Cerrena unicolor Basidiomycete

The electrochemical, spectroelectrochemical, and kinetic investigations of two preparations of Cerrena unicolor laccase, lyophilized (LLAC) and nonlyophilized frozen enzymes (FLAC), were performed. It was found that the value of the redox potential of the T1 site of C. unicolor laccase is ca. 750 vs. NHE. It was also shown that one of the redox potentials of the T2/T3 cluster of C. unicolor laccase is close to 400 mV, as was previously confirmed for other blue multicopper oxidases, such as trees and fungal laccases, ascorbate oxidase, and bilirubin oxidase. Furthermore, the poor stability of both preparations, but especially of LLAC, in their reduced state was confirmed using mediated and mediatorless spectroelectrochemical studies. DET‐based biocatalytic reduction of O₂ by C. unicolor laccase was only obtained, when FLAC was directly adsorbed on a spectrographic graphite electrode. Moreover, only low values of the steady‐state potentials of gold and graphite electrodes modified by C. unicolor laccase were also found. Heterogeneity of the 3‐D structures of laccase molecules, conformational changes, and partial denaturation of the enzyme, which appeared after enzyme isolation, purification, and especially lyophilization, were found to be the reasons for the low bioelectrocatalytic current, the high K_M‐value towards O₂, and the unusual electrochemical behavior of C. unicolor laccase used in the present study. In spite of the comparable specific activity and long‐term stability of both preparations in homogeneous solution, the stability of immobilized LLAC was found to be inadmissibly low for both fundamental studies and possible electrochemical applications. Indeed, FLAC is a much better source of enzyme than its lyophilized counterpart.     

离子液体中聚对苯二甲酰己二胺的合成与表征

以咪唑类离子液体为溶剂、亚磷酸三苯酯(TPP)为活化剂合成了聚对苯二甲酰己二胺(PA6T),考察了反应时间、反应温度、TPP用量和单体浓度对分子量的影响,得到特性黏数[η]为0.49～1.68dL/g的聚合物.与以水为介质在高压釜中(温度220℃、压力1.8MPa、反应5h)合成的预聚物(prePA6T)及再固相缩聚8h的产物(PA6T-SSP-8h)相比,离子液体中容易获得特性黏数[η]高的聚合物(PA6T-IL)、聚合时间明显缩短且反应温度降低.     

A proposed bioactive conformation of Peptide T

The conformational profiles of Peptide T, (5–8)Peptide T, [Abu⁵](4–8)Peptide T and (4–8)Peptide T were computed independently to assess the geometrical characteristics of the bioactive conformation of Peptide T. The conformational profiles of the peptides were computed within the molecular mechanics framework using an effective dielectric constant of 80. The conformational space was thoroughly sampled using an iterative simulated annealing protocol. The bioactive conformation was assessed by pairwise cross comparisons of each of the unique low energy conformations found for each of the different analogs studied. After a putative bioactive conformation was selected, in order to further validate our hypothesis the conformational profile of the potent compound cyclo(Thr-Thr-Asn-Tyr-Thr-Asp) was computed and the putative bioactive conformation was found. The conformation exhibits a pseudo -turn involving the side chain of Thr⁵ and the carbonyl oxygen of Tyr⁷ forming a C12 ring.     

辐射交联顺1,4-聚丁二烯的NMR研究

用１３ＣＮＭＲ方法,测定了辐射交联顺１,４聚丁二烯在室温下的自旋晶格弛豫时间（Ｔ１）,核Ｏｖｅｒｈａｕｓｅｒ因子（ＮＯＥ）,和１３ＣＮＭＲ线宽．以及凝胶本体１ＨＮＭＲ的Ｔ１和Ｔ２弛豫时间,结果表明,辐射交联顺１,４聚丁二烯体系中,随着凝胶含量的增加各碳核质子的Ｔ１值变化很小,而—ＣＨ２—核的ＮＯＥ因子明显降低和１３ＣＮＭＲ线宽增宽．以及１ＨＮＭＲ的Ｔ１和Ｔ２表现的双指数弛豫特性反映了交联体系中大分子链段长程运动受阻以及饱和交联叔碳核—ＣＨ对链段运动的影响．     

High-Modulus Wholly Aromatic Fibers. II. Partially Ordered Polyamide-Hydrazides

Partially ordered polyarnide-hydrazides were produced by the poly condensation of diacid chlorides with aminobenz-hydrazides, the order that results being a consequence of the considerably more rapid reaction of a diacid chloride with the hydrazide group in competition with the aromatic amine group of the aminobenzhydrazide. Fibers were produced from a series of such polymers containing from 50 mole % meta-oriented phenylene rings to 100 mole % para-oriented ones. Fiber from the wholly para-oriented type of polymer exhibited very high strength and modulus: 12.5 and 468 g/den, respectively, at 4.3% elongation-to-break. Although the crystallinity and density observed for hot-drawn fibers of partially ordered completely para-oriented polyarnide-hydrazides were comparable to the crystallinity and density of fibers of the isomeric wholly ordered polymer, the partially ordered polymers were more readily spun to the ultra-high strength and high modulus type fibers, probably because their greater solubility made them easier to spin.     

CH4-nFn(n=1～3)与CH3氢抽提反应微观动力学的理论研究

采用量子化学的QCISD(T)/6-311 G(d,p)//BHandHLYP/6-311G(d,p)方法研究了氟代甲烷CH4-nFn(n=1~3)与CH3自由基氢抽提反应的微观动力学性质.并利用Polyrate程序分别计算了3个反应在200~3000K范围内的速率常数.计算结果表明,R1a,R2a和R3三个反应路径的反应能量分别为-12.7,-9.5和11.8kJ/mol,相应的能垒依次为67.0,62.2和67.5kJ/mol.在437K时,kCVT/SCT分别为6.72×10-19,8.01×10-18和8.82×10-20cm3/(molecule.s).计算结果还表明,在低温段反应的量子隧道效应显著,在计算温度范围内变分效应对反应速率常数的影响可以忽略.     

天然气制取液体燃料工艺技术进展

简要介绍了国内外天然气制取液体燃料工艺技术新进展, 包括SMDS、SSPD、SAS、MTG、AGC221、Syntroleum、Gas Cat 工艺以及我国在这方面的研究状况, 并对我国天然气的开发利用提出建议。     

Hydrogels Incorporating GdDOTA: Towards Highly Efficient Dual T(1) /T(2) MRI Contrast Agents

Do not tumble dry: Gadolinium-DOTA encapsulated into polysaccharide nanoparticles (GdDOTA?NPs) exhibited high relaxivity (r(1) =101.7?s(-1) mM(-1) per Gd(3+) ion at 37?°C and 20?MHz). This high relaxation rate is due to efficient Gd loading, reduced tumbling of the Gd complex, and the hydrogel nature of the nanoparticles. The efficacy of the nanoparticles as a T(1) /T(2) dual-mode contrast agent was studied in C6 cells.     

T3P-Promoted Synthesis of a Series of 2-Aryl-3-phenyl-2,3-dihydro-4H-pyrido[3,2-e][1,3]thiazin-4-ones and Their Activity against the Kinetoplastid Parasite Trypanosoma brucei

A series of fourteen 2-aryl-3-phenyl-2,3-dihydro-4H-pyrido[3,2-e][1,3]thiazin-4-ones was prepared at room temperature by T3P-mediated cyclization of N-phenyl-C-aryl imines with thionicotinic acid, two difficult substrates. The reactions were operationally simple, did not require specialized equipment or anhydrous solvents, could be performed as either two or three component reactions, and gave moderate–good yields as high as 63%. This provides ready access to N-phenyl compounds in this family, which have been generally difficult to prepare. As part of the study, the first crystal structure of neutral thionicotinic acid is also reported, and showed the molecule to be in the form of the thione tautomer. Additionally, the synthesized compounds were tested against T. brucei, the causative agent of Human African Sleeping Sickness. Screening at 50 µM concentration showed that five of the compounds strongly inhibited growth and killed parasites.     

Development of Novel Isoindolone-Based Compounds against Trypanosoma brucei rhodesiense

This study identified the isoindolone ring as a scaffold for novel agents against Trypanosoma brucei rhodesiense and explored the structure-activity relationships of various aromatic ring substitutions. The compounds were evaluated in an integrated in vitro screen. Eight compounds exhibited selective activity against T. b. rhodesiense (IC₅₀<2.2 μm ) with no detectable side activity against T. cruzi and Leishmania infantum. Compound 20 showed low nanomolar potency against T. b. rhodesiense (IC₅₀=40 nm ) and no toxicity against MRC-5 and PMM cell lines and may be regarded as a new lead template for agents against T. b. rhodesiense. The isoindolone-based compounds have the potential to progress into lead optimization in view of their highly selective in vitro potency, absence of cytotoxicity and acceptable metabolic stability. However, the solubility of the compounds represents a limiting factor that should be addressed to improve the physicochemical properties that are required to proceed further in the development of in vivo-active derivatives.     

高级从头计算法精确研究基态He和Li原子间的相互作用势

高级从头计算法精确研究基态Ｈｅ和Ｌｉ原子间的相互作用势王一波（贵州大学化学系,贵阳,５５００２５）关键词ＨｅＬｉ,弱相互作用势,ＭＰ４ＳＤＴＱ,ＱＣＩＳＤ（Ｔ）,ＣＣＳＤ（Ｔ）基态Ｈｅ和Ｌｉ原子之间的ｖａｎｄｅｒＷａａｌｓ作用势处于１０－６ａ,ｕ．数...     

藏红T褪色分光光度法测定微量肝素

在pH 5.02的Britton-Robinson缓冲溶液中,肝素与碱性吩嗪染料藏红T形成离子缔合物,染料发生明显的褪色,体系吸光度的降低与肝素钠质量浓度成正比,0~2μg/mL范围内符合比耳定律,比吸光系数为0.36×103L.g-1.cm-1。研究了表面活性剂和共存物质的影响,表明方法选择性好。用于肝素钠注射液效价的测定。     

A New Efficient Commercial Iron Mediated Debromination of Aryl Substituted Vic-Dibromide

Debromination of vic-dibromides with commercially available metallic iron in a methanolic medium affords alkenes and alkynes in excellent yields.     

ASCOPYRONE P: CHEMICAL SYNTHESIS FROM d-GLUCOSE

The pyranone, 1,5-anhydro-4-deoxy-d-glycero-hex-1-en-3-ulose (1) (ascopyrone P), has been synthesised in eight steps from d-glucose. The key steps were deacetylation of 3,6-di-O-acetyl-1,5-anhydro-d-glycero-hex-3-en-2-ulose (8) to give isomers and hydrates of 1,5-anhydro-4-deoxy-d-glycero-hex-3-en-2-ulose (9). Isomerisation of this mixture afforded 1,5-anhydro-4-deoxy-d-glycero-hex-1-en-3-ulose (1) (ascopyrone P) in a moderate yield.     

An electrochemical gene detection assay utilising T7 exonuclease activity on complementary probe–target oligonucleotide sequences

This communication describes the synthesis of an electrochemically active oligonucleotide probe and its application in sensing complementary oligonucleotides sequences using a T7 exonuclease enzyme. Target oligonucleotides are detected by hybridisation with a ferrocene labelled probe oligonucleotide followed by addition of T7 exonuclease. The T7 enzyme is a double strand specific exonuclease that removes the terminal 5′ nucleotide of the probe sequence. The 5′ nucleotide is attached to a ferrocene label, which is subsequently detected at an electrode using differential pulse voltammetry. Time and temperature resolved measurements were performed and an associated study using dual labelled fluorophore–quencher labelled probes was performed to confirm the validity of the electrochemical assay.     

催化荧光法测定痕量硒

基于稀硝酸介质中溴酸钾氧化藏红T,使其荧光猝灭,硒(Ⅳ)对此反应具有阻抑作用,使荧光强度增大,建立了催化荧光法测定痕量硒(Ⅳ)的新方法。方法检出限为0.12μg L,线性范围为0.5～10μg L。方法可用于测定水样中的硒(Ⅳ)。