Random Bi Bi机制的非稳态酶动力学布尔函数图论研究

本文以非稳态酶动力学的布尔函数图形方法^[1],来研究一类Random Bi Bi机制的非稳态酶动力学问题,推导同此类反应的非稳态酶动力学方程,并对此动力学方程进行了讨论,分析了此类Random Bi Bi机制酶反应体系的非稳态酶动力学方程。     

竞争性抑制的非稳态酶动力学布尔函数图论研究

以非稳戊酶动力学的布尔函数图形方法,来研究一类竞争性抑制的非稳态酶动力学问题,推导出此类反应的百稳态酶动力学方程,并对此动力学方程进行了讨论,分析了此类竞争性抑制酶反应体系的非稳态酶动力学问题。     

一类非竞争性抑制的非稳态酶动力学布尔函数图解研究

本文以非稳态酶动力学的布尔函数图形方法^[1],来研究一类非竞争性抑制的非稳态酶动力学问题,推导出此类反应的非稳态酶动力学方程,并对此动力学方程进行了讨论,分析了此类非竞争性抑制的非稳态酶动力学的动力学过程。     

反竞争性抑制的非稳态酶动力学布尔函数图解研究

以非稳态酶动力学的布尔函数图形方法,来研究一类反竞争性抑制的非稳态酶动力学问题,推导出此类反应的非稳态酶动力学方程,并对此动力学方程进行了讨论,分析了此类反竞争性制酶反应体系的非稳态酶动力学问题。     

非稳态酶活化动力学的布尔函数图论分析

以非稳态酶动力学的布尔函数图形方法研究非稳态酶活化动力学问题,推导出此类反应的非稳态酶动力学方程,并对此动力学方程进行了讨论,分析了酶活化反应体系的非稳态酶动力学过程．     

非均匀人群SIR模型的稳态分布

文章利用测度论的方法研究非均匀人群中疾病传播的SIR模型,建立了动态模型中感染人群的演化方程,在此基础上我们得到了非均匀SIR模型的稳态分布.     

过氧化物酶体的稳态维持机制与膜接触位点

过氧化物酶体是保守存在于真核生物中的一种细胞器,参与多种生化代谢过程,包括脂肪酸β氧化反应、活性氧的产生和降解等。过氧化物酶体在生物发生和应对环境胁迫过程中,通过数量和时空分布的规律性动态变化,实现质量控制,以维持其生化代谢的稳态,从而保持机体的正常生命活动。同时,作为真核细胞的代谢枢纽,过氧化物酶体功能的正常发挥与稳态维持需要与其他细胞器相互协作。过氧化物酶体膜接触位点在过氧化物酶体与各细胞器相互连接和交流中发挥着重要作用。近年来,过氧化物酶体稳态维持机制和膜接触位点的组成和功能成为国内外相关研究的热点,本文对相关研究的进展进行了综述。     

非受体酪氨酸激酶ARG与过氧化氢酶相互作用机制的初步研究

通过体外结合实验,发现Arg蛋白与过氧化氢酶之间有相互作用,且这种作用是通过Arg蛋白的SH3结构域和过氧化氢酶的P290FNP介导的。利用体外激酶分析和Western印迹证明Arg蛋白可以使过氧化氢酶磷酸化。本研究为过氧化氢酶的活性调控研究奠定了基础。     

落叶松幼苗过氧化氢酶动力学的初步研究

采用碘量法对4种落叶松幼苗的过氧化氢酶（CAT）动力学进行了研究。结果表明：在25℃、pH 7.0下,落叶松幼苗CAT活性为48.8～77.9 U·g^-1 FW;Km值为8.3×10-2～2.38×10^-1 mol·L^-1;Vmax为0.071～0.200 μmol·min^-1;CAT最适温度15～25℃,对温度的适应范围华北落叶松和兴安落叶松宽,长白落叶松和太白落叶松的窄;CAT最适pH值为7.0。太白落叶松对pH适应范围最窄,其可能是退化的物种。     

蛇毒纤溶酶的药物代谢动力学研究

目的研究蛇毒纤溶酶在体内过程及药代动力学.方法以125I-蛇毒纤溶酶作示踪剂进行研究.结果静脉注射后,体内血药浓度时程曲线为二房室模型,大鼠体内T1/2β分别为6.1h(低剂量)、6.3h(中剂量)、5.6h(高剂量)、小鼠尾静脉注射后3h,各脏器中放射性活性达到峰值,其值(%)大小顺序为肾(1.34)＞肺(1.09)＞肝(0.90)=脾(0.90)＞心(0.51)＞肌肉(0.45)＞脑(0.29),125I-蛇毒纤溶酶静脉注射后72h内,尿排泄率为85.6%,粪排泄率为5.4%,胆汗排泄率为12%.结论蛇毒纤溶酶静脉注射后,体内血药浓度时程曲线为二房室模型,主要从尿排泄.     

pH modulation of transient state kinetics of enzymes. I. Simple theoretical models

The effect of proton concentration on pre-steady-state kinetics has been investigated theoretically for enzyme reactions involving the breaking of one substrate into two products. Even for the simple double-intermediate mechanism the approach to the steady state may exhibit a rather complex kinetics, which is pH-dependent. This process may even exhibit damped oscillations. A change of pH may completely change this transient kinetics and even suppresses the oscillatory regime. A simple method is presented which allows estimation of the values of the rate and ionization constants. This procedure allows one to distinguish the simple double-intermediate mechanism from a more complex process where the 'fast' binding of the substrate induces a 'slow' conformation change of the enzyme.     

Comparison of two-phase lipase-catalyzed esterification on micro and bench scale

Lipase type B from Candida antarctica was used to catalyze the esterification of propionic acid and 1-butanol in a water/n-decane two-phase system on micro and on bench scale. The reaction was described by a Ping Pong Bi Bi mechanism with alcohol inhibition. The kinetic parameters on micro and bench scale were compared; no significant differences were found. Furthermore, effects of temperature on activation and inactivation of the enzyme were found to be similar on micro and bench scale. Therefore, parameters found on either scale can be used for the other scale. Enzyme kinetic parameters can be determined on a micro scale, with very low consumption of reagents and catalyst, and then be applied to bench scale. This can reduce the cost of optimizing enzyme processes by downscaling.     

Deep Enzymology Studies on DNA Methyltransferases Reveal Novel Connections between Flanking Sequences and Enzyme Activity

DNA interacting enzymes recognize their target sequences embedded in variable flanking sequence context. The influence of flanking sequences on enzymatic activities of DNA methyltransferases (DNMTs) can be systematically studied with “deep enzymology” approaches using pools of double-stranded DNA substrates, which contain target sites in random flanking sequence context. After incubation with DNMTs and bisulfite conversion, the methylation states and flanking sequences of individual DNA molecules are determined by NGS. Deep enzymology studies with different human and mouse DNMTs revealed strong influences of flanking sequences on their CpG and non-CpG methylation activity and the structures of DNMT-DNA complexes. Differences in flanking sequence preferences of DNMT3A and DNMT3B were shown to be related to the prominent role of DNMT3B in the methylation of human SATII repeat elements. Mutational studies in DNMT3B discovered alternative interaction networks between the enzyme and the DNA leading to a partial equalization of the effects of different flanking sequences. Structural studies in DNMT1 revealed striking correlations between enzymatic activities and flanking sequence dependent conformational changes upon DNA binding. Correlation of the biochemical data with cellular methylation patterns demonstrated that flanking sequence preferences are an important parameter that influences genomic DNA methylation patterns together with other mechanisms targeting DNMTs to genomic sites.