羰基毒害在糖尿病晚期并发症中的作用

动物机体组织的氧化紧张损伤和老化交联是糖尿病晚期并发症中神经病变、动脉粥样硬化、风湿性关节炎、肾病变、白内障等老化慢性疾病的共同特征.对氧化紧张到底是糖尿病晚期并发症的初始原因还是糖尿病组织衰变的次级诱因提出了探讨.结果表明糖尿病患者机体和血浆中的糖氧化产物及脂类过氧化物的增多表明病患者体内氧化紧张的加强;然而,它们中的某些产物与氧化紧张并不相关;此外,其它一些氧化紧张的直接指标,如氨基酸的氧化,在糖尿病患者的皮肤胶原中也并没有增多.因此,对于糖尿病患者中蛋白质化学修饰的现象,用活性羰基的毒化超过其系统解毒能力的观点来解释更合适.这种在氧化或非氧化反应中形成的不饱和羰基化合物在体内总是以相对恒定的浓度存在,因而在糖尿病中,由羰基毒害引起组织中糖类和脂类衍生物的增长可以被认为是生物化学动力学的一种必然结果.     

白内障形成过程中晶状体细胞膜上脂类与蛋白质氧化的时间差异性

用马来酰亚胺和５恶唑氮氧自由基硬脂酸分别标记晶状体细胞膜中蛋白质及脂类,以电子自旋共振方法研究在三硝基甲苯、亚硒酸钠,半乳糖、平阳霉素及紫外线等白内障诱发剂作用下,晶状体细胞膜的氧化损伤变化。结果发现当晶状体细胞暴露于空气中时,晶状体细胞膜脂类氧化早于蛋白质氧化;在五种白内障诱发剂作用下,均是如此。这说明白内障的形成首先是由膜中脂类氧化所引起。     

超快过程激光生物学的内容、方法和意义 Ⅱ.超快过程激光生物学的研究领域

首先,讨论了用超短光脉冲对高等植物和细菌光合作用研究,从瞬态吸收研究推出了电子转移步骤。分析了对其他植物色素研究激光应用的可能性;其次,讨论在动物色素研究中的激光应用,它包括：黑色素的研究;视觉的原初过程;卟啉和它的衍生物（血红蛋白）研究及生物发光。进一步指出了紫外激光在蛋白质、核酸、糖类和脂类中的应用。     

超快过程激光生物学的内容,方法和意义：II.超快过程激光生物学的研究领域

首先,讨论了用超短光脉冲对高等植物和细菌光合作用研究,从瞬态吸收研究推出了电子转移步骤。分析了对其他植物色素研究激光应用的可能性;其次,讨论在动物色素研究中的激光应用,它包括：黑色素的研究;视觉的原初过程;卟啉和它的衍生物（血红蛋白）研究及生物发光。进一步指出了紫外激光在蛋白质、核酸、糖类和脂类中的应用。     

白内障形成过程中晶状体细胞膜上脂类与蛋白质氧化的时间差异性

用马来酰亚胺及５恶唑氮氧自由基硬脂酸分别标记晶状体细胞膜中蛋白质及脂类,以电子自旋共振方法研究在三硝基甲苯、亚硒酸钠、半乳糖、平阳霉素及紫外线等白内障诱发剂作用下,晶状体细胞膜的氧化损伤变化。结果发现当晶状体细胞暴露于空气中时,晶状体细胞膜脂类氧化早于蛋白质的氧化;在五种白内障诱发剂作用下,均是如此．这说明白内障的形成首先是由膜中脂类氧化所引起。     

氧化甾醇结合蛋白相关蛋白家族的研究进展

膜脂是细胞膜的主要组分, 也是参与信号转导的重要信号分子。不同脂质分子在细胞膜上的不均等分布需要特殊类型的通道蛋白和运输蛋白来实现。氧化甾醇结合蛋白相关蛋白(ORPs)是一类非常保守的蛋白分子, 能够对磷脂酰肌醇和固醇等脂类分子进行识别并转运, 参与细胞中的许多生理过程, 包括信号转导、囊泡运输、脂类代谢和非囊泡运输等...     

白内障形成过程中晶状体细胞膜上脂类与蛋白质氧化的时间差异性

用马来酰亚胺及５恶唑氮氧自由基硬脂酸分别标记晶状体细胞膜中蛋白质及脂类,以电子 自旋共振方法研究在三硝基甲苯、亚硒酸钠、半乳糖、平阳霉素及紫外线等白内障诱发剂作用下,晶状体细胞膜氧化损伤变化,结果发现当晶状体细胞暴露于空气中时,晶状体细胞膜脂类氧化早于蛋白质的氧化;在五种白内障诱发剂作用下,均是如此,这说明白内障的形成首先是由膜中脂类氧化所引起。     

核受体LXRs与骨骼肌糖脂代谢相关基因的关系

肝X受体(liver X receptors,LXRs)属孤核受体家族,LXRs参与机体的多种生理活动的调节,包括胆固醇的代谢和转运,脂肪的形成,糖类的代谢和炎症等过程.LXRs除在肝脏中大量表达外,在占成人体重40%的骨骼肌也有表达,并在机体的糖类代谢和脂类氧化方面发挥重要作用.目前LXRs参与骨骼肌糖脂代谢的作用和与此相关的基因已成为研究的热点,本文将对LXRs对骨骼肌代谢相关基因的表达调控作一综述.     

嗜酸硫杆菌属硫氧化系统研究进展

硫化矿的酸溶解和化学氧化过程中(H 和Fe3 作用下,金属硫化矿中分解),伴随着硫元素转变成多聚硫S8或硫代硫酸盐的过程。对嗜酸硫杆菌属硫氧化过程的研究表明,胞外环状多聚硫S8可能通过细胞外膜蛋白巯基活化成线状-SnH后,被转运到细胞周质区域,进而被硫加双氧酶氧化成SO32-,活化过程中同时生成少量H2S;这些酶促反应不需要辅助因子参与,不释放电子。胞外硫代硫酸盐通过未知途径进入细胞周质。细胞周质中的SO32-主要经由亚硫酸-受体氧化还原酶氧化成SO42-,S2O32-可能经由硫代硫酸盐-辅酶Q氧化还原酶、硫代硫酸盐脱氢酶、连四硫酸盐水解酶等氧化为硫酸,少量H2S则经由硫化物-辅酶Q氧化还原酶氧化为多聚硫,后者再经由SO32-和S2O32-氧化生成最后产物SO42-。这些生物氧化过程释放的电子进入呼吸链参与产生细菌生长代谢所需的能量。然而,关于A.ferrooxidans硫氧化系统中各种硫化合物的酶催化氧化机制的研究仍很缺乏,胞内外硫化合物的转运机制、是否存在胞外酶催化氧化等仍然有待解决。另外,硫的型态和价态、酶催化反应的细胞微区域以及硫氧化系统中一些关键酶的分离及其表达基因的鉴定等问题都还有待进一步研究。基于对这些事实的分析,提出了一个嗜酸硫杆菌属硫氧化系统的模型。     

酿酒酵母氧化胁迫应答反应机制

氧化胁迫是生物体面对逆境时的重要反应。在与逆境和活性氧做斗争的过程中,细胞进化出一套完整的应答调控机制,通过调节体内活性氧的代谢平衡,来保护DNA、脂质和蛋白质等免受氧化攻击。本文以酿酒酵母为例,根据近年来国内外研究的进展,围绕其在氧化胁迫应答过程中的三道保护屏障,即抗氧化物质和防御酶系统、转录调节和氧化物降解以及细胞器自噬,综述了其抗氧化代谢机理,为深入认识细胞的抗氧化应答机制奠定基础。     

Anaerobic ammonium oxidation in constructed wetlands with bio-contact oxidation as pretreatment

Anaerobic ammonium oxidation (ANAMMOX) may provide an effective nitrogen removal pathway for constructed wetlands with low C/N influent. In a study of domestic sewage treatment, anaerobic ammonium oxidation process was identified in the pilot-scale constructed wetland of a bio-ecological process which was composed of a bio-contact oxidation reactor and a horizontal subsurface flow constructed wetland (CW). To investigate the ANAMMOX establishment in the bio-ecological process, two new CWs (planted and unplanted) were developed to be a control for the pre-existing CW. Under operational conditions of DO 2-3 mg/l, HRT 3.5 h for the bio-contact oxidation reactor, HRT 3 days for CWs, and domestic sewage as influent, the process achieved more than 90% TN removal rate after the ANAMMOX was established. The ANAMMOX bacteria on the media of the constructed wetlands were analyzed by specific polymerase chain reaction (PCR) with ANAMMOX specific primer set AMX818F-AMX1066R. The result of the genetic sequencing showed that the PCR product was related to Candidatus B. anammoxidans (AF375994.1) with 98% sequence similarity. Copy numbers of 16S rRNA gene of ANAMMOX bacteria in the pre-existing CW, the new planted CW and new unplanted CW were 3.47 × 10⁵, 3.02 × 10⁵ and 1.30 × 10⁵, respectively. These results demonstrated that the ANAMMOX process was successfully established and operated consistently in the constructed wetlands with a bio-contact oxidation reactor as a pretreatment, and that vegetation positively affected the growth and enrichment of ANAMMOX bacteria.     

Study on TEMPO-mediated selective oxidation of hyaluronan and the effects of salt on the reaction kinetics

2,2,6,6-Tetramethyl-1-piperidinyloxy radical (TEMPO)-mediated oxidation of hyaluronan was studied at pH 10.2 and temperature of 0 degrees C with NaOCl as the primary oxidant. As with other polysaccharides, a high selectivity of oxidation was observed. The degradation of the polymer was essentially caused by the oxidation process. The primary oxidant and the pH of the reaction mixture did not alter the molecular weight of hyaluronan during oxidation. The kinetics of the oxidation process was investigated at different concentrations of reactants and the inorganic salts, NaBr, NaCl, and Na2SO4. An increase in the salt concentration in the mixture causes a major decrease in the rate of the oxidation, and this decrease is independent of the nature of the salt.     

Dissecting the pattern of proton release from partial process involved in ubihydroquinone oxidation in the Q-cycle

A key feature of the modified Q-cycle of the cytochrome bc₁ and related complexes is a bifurcation of QH₂ oxidation involving electron transfer to two different acceptor chains, each coupled to proton release. We have studied the kinetics of proton release in chromatophore vesicles from Rhodobacter sphaeroides, using the pH-sensitive dye neutral red to follow pH changes inside on activation of the photosynthetic chain, focusing on the bifurcated reaction, in which 4H⁺are released on complete turnover of the Q-cycle (2H⁺/ubiquinol (QH₂) oxidized). We identified different partial processes of the Q_o-site reaction, isolated through use of specific inhibitors, and correlated proton release with electron transfer processes by spectrophotometric measurement of cytochromes or electrochromic response. In the presence of myxothiazol or azoxystrobin, the proton release observed reflected oxidation of the Rieske iron?sulfur protein. In the absence of Q_o-site inhibitors, the pH change measured represented the convolution of this proton release with release of protons on turnover of the Q_o-site, involving formation of the ES-complex and oxidation of the semiquinone intermediate. Turnover also regenerated the reduced iron-sulfur protein, available for further oxidation on a second turnover. Proton release was well-matched with the rate limiting step on oxidation of QH₂ on both turnovers. However, a minor lag in proton release found at pH?7 but not at pH?8 might suggest that a process linked to rapid proton release on oxidation of the intermediate semiquinone involves a group with a pK in that range.     

Treatment of oilfield wastewater containing polymer by the batch activated sludge reactor combined with a zerovalent iron/EDTA/air system

Laboratory-scale experiments were conducted in order to evaluate the performance of a novel treatment process for oilfield wastewater based on combining chemical oxidation, performed by a zerovalent iron (ZVI), ethylenediamine tetraacetic acid (EDTA) and air process, with biological degradation, carried out in a batch activated sludge reactor. The influence of some operating variables was studied. The results showed that the optimum pretreatment conditions were 150 mg/L EDTA, 20 g/L ZVI, and a 180-min reaction time, respectively. Under these conditions, removal efficiencies for hydrolyzed polyacrylamide (HPAM), total petroleum hydrocarbons (TPH), and chemical oxygen demand (COD) were 66%, 59%, and 45%, respectively. During the subsequent 40 h of bioremediation, the concentrations of HPAM, TPH, and COD were decreased to 10, 2 and 85 mg/L, respectively. At the end of experiments, the total removal efficiencies of HPAM, TPH, and COD were 96%, 97% and 92%, respectively.     

The emitting species formed by the oxidation of hydrazides with hypohalites or N-halosuccinimides.

The chemiluminescence accompanying the oxidation of salicylic hydrazide (2-hydroxybenzoic acid hydrazide) with hypochlorite, hypobromite, N-chlorosuccinimide, N-bromosuccinimide or hydrogen peroxide with cobalt(II) matched the photoluminescence emission of salicylic acid. In a related reaction, the oxidation of a mixture of isoniazid and ammonia, a synergistic effect was observed. The chemiluminescence spectrum for this reaction matches that accompanying the oxidation of the hydrazide, rather than the oxidation of ammonia. These results were used to assess mechanisms proposed by previous authors.     

Primary oxidation of organic matter in the soil

Summary The course of respiration rate during glucose decomposition in a soil sample was studied. The whole process of oxidation (mineralization) is divided into two principal parts: the primary oxidation which occurs while the substrate is still present and the secondary oxidation after the disappearance of the substrate. The primary oxidation brought about by two different components: the oxidative component represents the sum of enzyme activity present originally in the soil sample, and the assimilative component is built up during the process by synthesis of microbial enzymes. The size of the oxidative component is correlated with the biological potency of soil. Sometimes, an intermediary stage can be observed at the beginning of the secondary oxidation. A method is given for enumeration of the proportions of the two components involved in primary oxidation. The biochemical and pedological meaning of these data is discussed.     

Development of biofuel cells based on gold nanoparticle decorated multi-walled carbon nanotubes

This study focused on developing the synthesis of Au nanoparticle-decorated functionalized multi-walled carbon nanotubes (Au-NPs/f-MWCNTs) for monosaccharide (bio-fuel) oxidation reactions and practical application in air-biofuel cells. We developed a scalable and straightforward method to synthesize Au-NPs/f-MWCNTs which allow us to control the loading and size of the Au-NPs. The Au-NPs/f-MWCNTs exhibited better catalytic activities and stability than the Au sheet and subsequently resulted in a threefold increase in the power density of the air-glucose fuel cell with an exceptionally high open circuit voltage (∼1.3 V). The catalytic efficiency was confirmed by high performance liquid chromatography with the superior of the Au-NPs/f-MWCNTs over a bare gold electrode. In addition, the application of this advanced catalyst to other monosaccharide oxidation reactions figured out that the configuration of –OH groups at C₂ and C₃ of the reactants plays an important role in the initial adsorption process, and thus, affects the required activation energy for further oxidation. The different monosaccharides lead to significantly different fuel cell performances in terms of power density, which coherently corresponds to the difference in the configuration of C₂ and C₃. Because two small air-glucose fuel cells using Au-NPs/f-MWCNTs can run a LED lamp, further applications of other monosaccharides as fuel in biofuel cells for equivalent required power devices may be possible.     

The autocatalytic step is an integral part of the hydrogenase cycle

We earlier proved the involvement of an autocatalytic step in the oxidation of H₂ by HynSL hydrogenase from Thiocapsa roseopersicina, and demonstrated that two enzyme forms interact in this step. Using a modified thin-layer reaction chamber which permits quantitative analysis of the concentration of the reaction product (reduced benzyl viologen) in the reaction volume during the oxidation of H₂, we now show that the steady-state concentration of the product displays a strong enzyme concentration dependence. This experimental fact can be explained only if the previously detected autocatalytic step occurs inside the catalytic enzyme-cycle and not in the enzyme activation process. Consequently, both interacting enzyme forms should participate in the catalytic cycle of the enzyme. As far as we are aware, this is the first experimental observation of such a phenomenon resulting in an apparent inhibition of the enzyme. It is additionally concluded that the interaction of the two enzyme forms should result in a conformational change in the enzyme–substrate form. This scheme is very similar to that of prion reactions. Since merely a few molecules are involved at some point of the reaction, this process is entirely stochastic in nature. We have therefore developed a stochastic calculation method, calculations with which lent support to the conclusion drawn from the experiment.     

Mineralogical controls on the bacterial oxidation of refractory Barberton gold ores

Abstract: The effect of mineralogical characteristics of gold ore minerals on the nature of sulphide oxidation during a bacterial leaching process was investigated. Three different ore types from the South African goldmines were used, i.e. an arsenopyritic-pyritic ore (Sheba goldmine), a pyritic ore (Agnes goldmine) and a loellingitic-arsenopyritic ore (New Consort goldmine). Detailed mineralogical characterization of each ore was performed. Thereafter, polished sections of the sulphides were suspended in a bacterial leach pulp in an air-stirred vessel for various periods of time. The effect of bacterial oxidation on the sulphides was monitored. Different types of gold-bearing arsenopyrite exist, each type having its own characteristic behaviour during the bacterial oxidation process. The rate of oxidation is controlled by the amount of defects in the crystal structure, and the amount of defects is again controlled by the composition of the arsenopyrite crystal. The distribution of refractory gold in the sulphide minerals can be correlated with the presence of compositional zones and structural deviations. These same mineralogical features also control the sites and rates of bacterial oxidation. Thus. refractory gold occurs at sites which are preferentially leached by the bacteria. The rate of gold liberation from sulphides is therefore being enhanced during the early stages of bacterial oxidation. Defects in a crystal structure influence the rate of bio-oxidation, and can be related directly to the crystal structure of the sulphide mineral, the crystallographic orientation of the exposed surfaces, and differences in chemical compositional and mechanical deviations in the crytals. A combination of all of these mineralogical factors influences the bacterial oxidation process. To optimize and to understand the leaching of an individual ore it is important to establish its controlling factors.