重金属离子对葡萄糖氧化酶电极抑制作用的研究

采用二氧化硅溶胶-凝胶固定化酶技术制备了葡萄糖氧化酶电极,优化了酶电极的工作条件。考察了酶电极的响应性能以及Hg^2＋,Fe^3＋等重金属离子对酶电极响应的抑制影响。实验结果表明在E=0．8V,pH=5．0,θ=25℃时,Hg^2＋,Fe^3＋的存在抑制了酶电极对葡萄糖的电流响应,且抑制电流的大小和重金属离子浓度在一定范围呈线性关系,线性范围分别是0～1．5μmot／L和0～60μmol／L。将被抑制的酶电极浸入EDTA溶液中10min后,酶电极可以恢复部分响应性能。     

半乳糖苷化修饰葡萄糖氧化酶提高其热稳定性

利用一种单胺化的半乳糖衍生物,在炭化二亚胺的催化下,对葡萄糖氧化酶(COD)进行糖苷化修饰,并利用蓖麻凝集素亲和层析分离已修饰的和未修饰的酶.修饰后的酶经荧光光谱和吸收光谱分析,证实其结构发生了变化.酶活性检测证明了修饰后GOD的热稳定性增加,在较高温度如在55℃下酶活性提高了7.28倍.本研究为拓宽COD的应用奠定了基础.     

荧光素-GOD-HRP荧光淬灭法测定植物果实组织中的葡萄糖含量

植物组织中的葡萄糖在葡萄糖氧化酶的作用下产生的过氧化氢可在辣根过氧化物酶的催化作用下使荧光素褪色并使荧光淬灭,基于这一现象,笔者建立了一种选择性测定植物果实组织中葡萄糖含量的荧光分析方法,同时利用这种方法对苹果、鸭梨和酥梨组织液中的葡萄糖含量进行了测定,并与分光光度法检测的结果及文献值进行了比较,结果表明:该方法具有安全、方便、准确的优点,适合检测复杂样品尤其是植物中的葡萄糖含量.     

Mab HIM70对人Np NADPH氧化酶的调节（Ⅱ）

在发现Mab HIM70对Np NADPH氧化酶胸浆组分p47^phox、p67^phox和Rac2的表达和参与NADPH氧化酶活化均有降调节作用基础上,进一步探索了Mab HIM70对该降调节作用的机理。发现Mab HIM70可能对NADPH氧化酶上游PKC、PTK及PI3K信号传递途径的活化水平有降调节作用,该单抗对NADPH氧化酶活化有降调节的作用可能与此有关。     

牡丹不同类型总酚含量与PPO活性研究

以19个不同花型或花色的牡丹品种为试材,通过测定牡丹外植体总酚含量和多酚氧化酶(PPO)的活性,探讨了影响牡丹组培褐化的内在诱因,以期为牡丹的组织培养提供参考.     

Purification and some properties of an amine oxidase from soybean seedlings

Summary An amine oxidase was purified 447-fold from soybean seedlings and some of its properties were investigated. The molecular weight of the enzyme was estimated to be 25,000. It was most active towards putrescine, followed by spermidine and spermine. K_m-values for these substrates were relatively close. The enzyme was strongly inhibited by carbonyl reagents, such as semicarbazide and aminoguanidine.     

Administration of D-alanine did not cause increase of D-amino acid oxidase activity in mice

D-amino acid oxidase (DAAO) activity was not altered in the liver and kidney by oral administration of D-alanine to adult mice. The enzyme was apparently not induced by the enteric microflora either, since the enzyme activity in the liver and kidney of germ-free mice was not different from that of specific-pathogen-free mice. The times of appearance of DAAO activity and of free D-amino acids in the kidney were elucidated using suckling mice. DAAO activity started to increase 7 days after birth, and reached almost the adult level by 28 days. The content of free neutral D-amino acids also increased with age, in a similar fashion. A possible conclusion is that the enzyme activity normally increases during this period, to eliminate the free D-amino acids which have increased with age in the suckling mice. Consequently, the administration of D-alanine had no further effect in increasing enzyme activity.     

Biosynthesis of ascorbic acid in chick embryos

Summary Biosynthesis of ascorbic acid was found in the kidneys (mesonephros and metanephros) of the chick embryo as well as in the yolk sac membrane. The activity of L-gulonolactone oxidase in the yolk sac membrane suggested that it was the major source of ascorbic acid in the chick embryo.I am grateful to Dr R. Jenness (Univ. of Minnesota) for the generous gift of L-gulonolactone and to Dr B. Sanders (Univ. of Texas) for the chick embryo samples     

金属拟酶抗逆剂的设计与合成

磷酸酯酶(phosphatases)如紫色酸性磷酸酯酶(purpleacidphosphatase,PAP)、碱性磷酸酯酶(alkalinephosphatase,AP)和各种磷脂酶(phospholipases,PL),氧合酶和氧化酶(oxygenasesandoxidases)如脂氧合酶(lipoxygenase)、多酚氧化酶(polyphenoloxidases),及抗氧化酶,如:超氧化歧化酶(superoxidedismutase,SOD)、过氧化氢酶(catalase,CAT)、过氧化物酶(peroxidase,POD)等是植物防卫系统涉及的重要金属酶(metalloenzymes)和金属激活酶.根据金属酶活性部位结构设计、创制的拟酶化合物含植物必需的微量元素和富咪唑氮的配体,具有抗逆境胁迫(如干旱、寒冷、水渍、盐渍、高温等)和抗病原微生物(如真菌、细菌、病毒等)侵染,及抗早衰能力,提高作物产量5.1%～49.41%.这种仿生配合物性质稳定,抗性广谱,防、治作用兼备;安全、低毒(半数致死量LD50≥600～5000mg/kg);分子量小,膜透性好;高效(使用浓度4～20mg·L-1,用量小,每公顷全生长期仅用3～15g);因系化学仿生化合物,可进行规模化生产.最近,首次证明一种含铜模型化合物[Cu(EDTB)](NO3)2·EtOH和水稻稻瘟病、纹枯病病原体诱导产生的植物抗毒素(Phytoalexin,PA)一样,诱导磷脂水解产生不饱和脂肪酸及其氧化次级产物,这或许是含铜模型化合物能抗病的原因.植物免疫反应涉     

铅对河南华溪蟹主要组织细胞线粒体标志酶活性的影响

采用毒性实验方法,研究了Pb2 对河南华溪蟹心脏和肝胰腺细胞线粒体标志酶,即单胺氧化酶(MAO)、苹果酸脱氢酶(MDH)和细胞色素氧化酶(CCO)活性的影响.Pb2 处理浓度分别为0.5 mg/L、1 mg/L、5 mg/L、10 mg/L、50 mg/L,实验同时设对照组.分别在24 h、48 h、72 h、96 h进行MAO、MDH、CCO活性的测定.结果显示,随着Pb2 浓度的增加和处理时间的延长,MAO、MDH、CCO的活性基本呈先升后降的趋势,且高浓度组(50 mg/L)表现为明显的抑制作用,剂量-效应和时间-效应关系明显,同时线粒体酶活性的改变有一定的组织差异性,心脏比肝胰腺更敏感.结论:铅可以导致线粒体酶产生明显且不可逆转的损伤;线粒体酶可作为动物受逆境胁迫的生化指标.