高密度脂蛋白体外氧化修饰动力学研究

在体外ＨＤＬ在Ｃｕ＾２＋诱导下可发生氧化修饰,为了探讨体外务浆高密度脂蛋白（ＨＤＬ）氧化修饰中几种产物的动力学改变,用Ｃｕ＾２＋与ＨＤＬ保温２￣２４ｈ,分别观察了ＨＤＬ氧化修饰过程中硫代巴比妥酸反应物质（ＴＢＡＲＳ）,脂氢过氧化物（ＬＯＯＨ）、共轭二烯（ＣＤ）及相对电泳迁移率（ＲＥＭ）等的变化。结果显示,ＬＯＯＨ和ＣＤ两个指标动力学变化相似,呈现延滞期,扩增期和下降期三个时相,而ＴＢＡＲＳ和ＲＥＭ     

氧化亚铁硫杆菌氧化亚硫酸盐的动力学研究

实验用Ms培养基,利用去除铁离子的氧化亚铁硫杆菌(Thiobacillus ferrooxidans)进行了细菌亚硫酸盐的生长代谢研究。实验结果表明氧化亚铁硫杆菌对亚硫酸根具有一定的氧化能力。用Origin 7.0对实验数据进行拟合处理,表明了氧化亚铁硫杆菌催化氧化亚硫酸盐的动力学方程符合Hill方程。氧化亚铁硫杆菌催化氧化亚硫酸盐是一个底物抑制的细胞反应,其KS值随pH值和底物浓度的改变而变化。pH值对反应有很大的影响,pH值越接近中性KS就越小,反应速率就越大。     

巯基乙酸对蟾蜍血清转氨酶和钙含量的影响

以健康的中华蟾蜍为实验动物,研究皮肤染毒巯基乙酸(TGA)对血液天门冬氨酸氨基转氨酶(AST)、丙氨酸氨基转氨酶(ALT)和钙含量的影响,并对其作用机理进行初步探讨.试验结果表明,染毒巯基乙酸剂量对于血清AST、ALT和Ca含量影响效果明显.方差分析表明各试验处理组与对照组相比差异显著;染毒TGA的时间对于血清生化指标的影响呈现累积趋势,各试验处理组染毒后期与前期差异显著.表明巯基乙酸对于蟾蜍肝组织等器官具有明显的损伤作用,因此化工产品巯基乙酸对水体的污染不容忽视.     

土壤氧化还原酶催化动力学研究进展

土壤氧化还原酶是存在于土壤中的一种重要酶类,参与土壤中为数众多的重要生物化学反应,与土壤中有机物质的转化、腐殖质的形成以及土壤肥力变化密切相关.其催化反应的动力学研究常用来阐明其催化过程的特性、酶的本质属性及其对环境变化的响应等.研究土壤氧化还原酶动力学特征对探讨其来源、性质及影响因素,对进一步调控多种营养元素参与的反应过程有重要意义.文中概述了土壤氧化还原酶动力学研究的理论基础,综述了土壤氧化还原酶催化动力学研究的进展和影响因素,并对今后的研究提出了几点建议.     

HcNPV半胱氨酸蛋白酶基因的核苷酸序列研究

ＨｃＮＰＶ半胱氨酸蛋白酶基因的核苷酸序列研究贡成良１小林淳宫岛成寿金伟１吴祥甫２＊（日本三重大学分子素材工学科,三重５１４,日本;１浙江农业大学蚕学系,杭州３１００２９;２中国科学院上海生物化学研究所,上海２０００３１）关键词美国白蛾;核型多角体病毒...     

巯基乙酸对中华蟾蜍红细胞核异常的影响

试验以健康的中华蟾蜍为实验动物,研究注射巯基乙酸对红细胞核异常的影响.试验结果表明,在一定的范围内,巯基乙酸可引起蟾蜍微核细胞率和核异常细胞率遗传指标发生明显变化,随着巯基乙酸浓度的增加和作用时间的延长,蟾蜍红细胞微核和核异常率呈现先上升后下降的规律性变化.     

电渗析法分离提纯N-乙酰-L-半胱氨酸研究

使用我校由辐射法制备的高性能离子交换膜ＨＦ—１及ＨＦ—２,采用电渗析技术对合成所得的Ｎ－乙酰－Ｌ－半胱氨酸进行了分离提纯,脱盐率＞１５％,损失率＜１５％,为工业化应用提供了依据。     

歼击飞行员飞行应激对同型半胱氨酸和皮质醇的影响

目的:探讨南部战区某旅歼击飞行员血清皮质醇(COR)和同型半胱氨酸(Hcy)联合检测的意义。方法:对歼击飞行员(A组)、地方健康体检人员(B组)、部队考学战士(C组)、空军地勤人员(C组)的血清COR、Hcy水平进行两两比较,通过Kruskal-Wallis统计学方法处理分析。结果:B组人员COR水平比A组、C组、D组人员低,差异有统计学意义(P<0.05);C组人员Hcy水平比A组、B组、D组人员高,差异有统计学意义(P<0.05)。结论:经常性的飞行训练可增强飞行员分泌激素的适应性,在航空保健工作中,COR联合Hcy监测及动态观察对保障飞行员的健康和飞行安全,提高部队战斗力具有一定的意义。     

P700氧化还原动力学的测量方法及原理

P700氧化还原动力学技术可快速且无损地检测植物光系统I (PSI)的活性, 是光合研究领域中广泛使用的一种技术。该文系统归纳了P700氧化还原动力学的主要测量方法, 详细阐述其原理并探讨该技术的局限性, 旨在为深入研究光合作用机理提供技术支持。     

弱氧化醋杆菌阿拉伯糖醇脱氢酶基因克隆及其在大肠杆菌中的表达

The partial genomic library of Acetobacter suboxydans was constructed using Yeast\| E.coli shuttle plasmid YEp352 as vector.Two positive transformants,designated as DH5α(pAD91) and DH5α(pAD98),were obtained by screening the growth of transformants on the agar plate in which D\|arabitol was used as the sole carbon source.The results of Southern blot and restriction endonuclease analysis showed that the two recombinants are identical.The insert is about 2.3kb.Arabitol dehydrogenase activity assay indic…     

TGA对蟾蜍血清生理指标的影响

本试验利用生化检测方法,以健康的中华蟾蜍为实验动物,研究注射巯基乙酸对血液生理指标的影响,并对其作用机理进行了初步探讨.试验结果表明,随染毒TGA剂量增加,蟾蜍血清总蛋白、葡萄糖含量下降,胆固醇、甘油三酯含量上升;随染毒TGA时间的延长,血清总蛋白、葡萄糖含量先下降后上升但均低于对照组,胆固醇、甘油三酯含量先上升后下降但均高于对照组.因此提示化工产品对生物的影响不容忽视.     

厌氧氨氧化菌混培物生长及代谢动力学研究

研究了厌氧氨氧化菌混培物的动力学特性.测得细胞产率系数1.573mgVS(mmolNH4+)-1;细胞衰减常数0.052mgVS(g@VS@d)-1.厌氧氨氧化菌混培物的最大氨氧化速率1.320～2.761mmol(gVS@d)-1,最大亚硝酸盐转化(反硝化)速率14.497mmol(gVS@d)-1.厌氧氨氧化菌混培物利用氨的Km值1.801～4.215mmol@L-1,利用亚硝酸盐的Km值0.468mmol@L-1.氨自身的抑制常数38.018～98.465mmol@L,实际最大氨氧化速率的氨浓度16.656mmol@L-1.亚硝酸盐对厌氧氨氧化的抑制常数5.401～11.995mmol@L-1.厌氧氨氧化的最适pH7.605.厌氧氨氧化的最适温度30℃.Vmaxa、Kma、Kia和Kin的活化能依次为37.316、30.239、33.695和30.473kJ@mol-1.     

齐墩果酸氧化产物的成分研究

以齐墩果酸为原料,分别用高锰酸钾和SeO2/H2O2(30%)进行氧化。从产物中分离得到3个化合物,经1H NMR、13C NMR、2D-NMR、MS等波谱分析,分别鉴定为3,11-二羰基-12,17-二烯-28-去甲基齐墩果烷(1)、3β-羟基-11-烯-13,28-内酯-齐墩果烷(2)和3α,12β,13α-三羟基-28-羧基齐墩果烷(3),收率依次是4.5%、6.4%、2%,其中化合物1和3为新化合物。     

柠檬酸发酵过程的动力学

发酵动力学是微生物培养过程研究中的一个重要部分,它让人们从理论和定量的角度了解和分析微生物的培养过程,是过程设计和控制的基础．柠檬酸发酵过程的动力学．Chemiel^[1]、Kristiansen^〔2〕、Khan^〔3〕、Rohr^〔4〕、Vaija^〔5〕等曾作过研究。本文在考察前人工作的基础上．结合实验研究．进行如下探索。     

Cysteine and Crocin Oxidation Catalyzed by Horseradish Peroxidase

The amino acid cysteine is oxidized by horseradish peroxidase, and the water-soluble carotenoid crocin is bleached by cooxidation. The rnonophenol p-hydroxyacetophenone stimulates oxygen uptake, cysteine oxidation and crocin bleaching, whereas its concentration does not change. Superoxide dismutase significantly enhances all these oxidative reactions. Addition of H₂O₂ is not required for these peroxidase-catalyzed oxidations.     

Cysteine and Crocin Oxidation Catalyzed by Horseradish Peroxidase

The amino acid cysteine is oxidized by horseradish peroxidase, and the water-soluble carotenoid crocin is bleached by cooxidation. The rnonophenol p-hydroxyacetophenone stimulates oxygen uptake, cysteine oxidation and crocin bleaching, whereas its concentration does not change. Superoxide dismutase significantly enhances all these oxidative reactions. Addition of H₂O₂ is not required for these peroxidase-catalyzed oxidations.     

Iron (II) Ions Induced Oxidation of Ascorbic Acid and Glucose

Lipid peroxidation (LPO) of polyunsaturated fatty acids (PUFAs) is suspected to be involved in the generation of chronic diseases. A model reaction for LPO is the air oxidation of PUFAs initiated by Fe²⁺ and ascorbic acid. In the course of such model reactions glycolaldehyde (GLA) was detected as main aldehydic product. Since it is difficult to explain the generation of GLA by oxidation of PUFAs, it was suspected that GLA might be derived by oxidation of ascorbic acid. This assumption was verified by treatment of ascorbic acid with Fe²⁺.

Produced aldehydic compounds were trapped by addition of pentafluorobenzylhydroxylamine hydrochloride (PFBHA-HCl), trimethylsilylated and finally identified by gas chromatography/mass spectrometry (GC/MS). Oxidation of ascorbic acid with O₂ in presence of iron ions produced not only glycolaldehyde (GLA), but also glyceraldehyde (GA), dihydroxyacetone (DA) and formaldehyde. Glyoxal (GO) and malondialdehyde (MDA) were detected as trace compounds.

The yield of the aldehydic compounds was increased by addition of lipid hydroperoxides (LOOH) or H₂O₂. The buffer influenced the reaction considerably: Iron ions react with Tris buffer by producing dihydroxyace-tone (DA). Since ascorbic acid is present in biological systems and Fe²⁺ ions are obviously generated by cell damaging processes, the production of GLA and other aldehydic components might add to the damaging effects of LPO.

Glucose suffers also oxidation to short-chain aldehydic compounds in aqueous solution, but this reaction requires addition of equimolar amounts of Fe²⁺ together with equimolar amounts of H₂O₂ or 13-hydroperoxy-9-cis-11-trans-octadecadienoic acid (13-HPODE). Therefore this reaction, also influenced by the buffer system, seems to be not of biological relevance.     

The Viability of a Nonenzymatic Reductive Citric Acid Cycle – Kinetics and Thermochemistry

The likelihood of a functioning nonenzymatic reductive citric acid cycle, recently proposed as the precursor to biosynthesis on early Earth, is examined on the basis of the kinetics and thermochemistry of the acetate → pyruvate → oxaloacetate → malate sequence. Using data derived from studies of the Pd-catalyzed phosphinate reduction of carbonyl functions it is shown that the rate of conversion of pyruvate to malate with that system would have been much too slow to have played a role in the early chemistry of life, while naturally occurring reduction systems such as the fayalite–magnetite–quartz and pyrrhotite–pyrite–magnetite mineral assemblages would have provided even slower conversions. It is also shown that the production of pyruvate from acetate is too highly endoergic to be driven by a naturally occurring energy source such as pyrophosphate. It is thus highly doubtful that the cycle can operate at suitable rates without enzymes, and most unlikely that it could have participated in the chemistry leading to life.