Ping Pong Bi Bi机制的非稳态酶动力学分布函数图论研究

以非稳态酶动力学的布尔函数图形方法,来研究一类PingPongBiBi机制的非记酶动力学问题,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PingPongBiBi机制酶反应体系的非稳态酶动力学方程。     

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．     

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。     

双底物酶促反应动力学机制判别的优化方法

研究双底物酶促反应动力学机制的常用方法是二次作图法.本文针对二次作图法存在的问题提出了一种基于最小二乘拟合的优化算法.该算法利用最小二乘原理对顺序机制和乒乓机制下的双倒数速度方程的常系数进行拟合求解,通过比较两种拟合方程下得到的残差平方和判别酶促反应的动力学机制.通过实例计算证明该优化算法具有可靠性强、计算过程简单的特点,在双底物酶促反应动力学机制判别的准确性方面更具优势.     

酶动力学的极值原理假说

平衡态假说和稳态假说是酶动力学的基础。本文提出极值原理假说,用于完善平衡态假说和稳态假说的不足之处,扩大了酶动力学的应用范围,并以Michaelis-Menten方程为例进行了说明。     

稳态酶动力学的布尔函数图论分析

使用布尔函数图论分析稳态酶动力学过程,并提供一种简易图形算法。由简单的速率常数组合图形求得分子项中速率常数乘积项的总和。使用类似的方法也可求得分母项中速率常数乘积项的总和。此法的特点是图形鲜明,绘法简易,使用方便(不需画出支撑入树之类的图形,也不需代数运算),结果可靠(不易发生遗漏或错算)。列举无规Bi Uni、有规BiBi和无规Bi Bi酶反应体系作为此图形分析的实例。     

酶反应速率方程的普适形式

酶反应速率方程的普适形式是应用于相互关联的大规模代谢途径动力学建模的重要方法.把酶反应速率方程写成Michaelis-Menten-King-Altman方程形式可以使得动力学参数(或函数)容易与数据库中的实验数据相接轨,并可以处理任意数量的底物和产物,有利于大规模的计算.普适形式可以同时描述正、负反应方向,并能精确地用于准稳态条件.展示了在三类生物体系中广泛存在的酶反应机制中普适方程的严格推导过程,并讨论了普适方程的特点,针对不可逆反应酶反应产生的产物抑制效应可以自然消除,总结了在普适速率方程中体现调节剂的作用和协同作用.     

酶促水解大豆分离蛋白动力学模型的研究

本文对AS1.398中性蛋白酶在pH6.9和温度49℃条件下水解大豆分离蛋白的动力学机制进行了研究．结果表明：酶水解速率随水解反呈指数递减．为了解释实验结果,我们提出了如下假设：对底物而言水解反应终为零级反应,水解过程中由于游离酶攻击酶-底物中间络合物而造成的不可逆酶变性是一个二级动力学过程．在此基础上,由实验数据推导得到了描述AS1.398中性蛋白酶催化水解大豆分离蛋白的动力学方程,该方程可用于指导和优化酶解反应实验．     

Synthesis and evaluation of a bifunctional chelate for development of Bi(III)-labeled radioimmunoconjugates

A new bifunctional ligand C-DEPA was designed and synthesized as a component for antibody-targeted radiation therapy (radioimmunotherapy, RIT) of cancer. C-DEPA was conjugated to a tumor targeting antibody, trastuzumab, and the corresponding C-DEPA-trastuzumab conjugate was evaluated for radiolabeling kinetics with ^205/6Bi. C-DEPA-trastuzumab conjugate rapidly bound ^205/6Bi, and ^205/6Bi-C-DEPA-trastuzumab conjugate was stable in human serum for 72 h. The in vitro radiolabeling kinetics and serum stability data suggest that C-DEPA is a potential chelate for preclinical RIT applications using ²¹²Bi and ²¹³Bi.     

An iso-random Bi Bi mechanism for adenylate kinase.

An iso-random Bi Bi mechanism has been proposed for adenylate kinase. In this mechanism, one of the enzyme forms can bind the substrates MgATP and AMP, whereas the other form can bind the products MgADP and ADP. In a catalytic cycle, the conformational changes of the free enzyme and the ternary complexes are the rate-limiting steps. The AP(5)A inhibition equations derived from this mechanism show theoretically that AP(5)A acts as a competitive inhibitor for the forward reaction and a mixed noncompetitive inhibitor for the backward reaction.     

A pyrroloquinoline quinine-dependent membrane-bound d-sorbitol dehydrogenase from Gluconobacter oxydans exhibits an ordered Bi Bi reaction mechanism

A membrane-bound pyrroloquinoline quinine (PQQ)-dependent d-sorbitol dehydrogenase (mSLDH) in Gluconobacter oxydans participates in the oxidation of d-sorbitol to l-sorbose by transferring electrons to ubiquinone which links to the respiratory chain. To elucidate the kinetic mechanism, the enzyme purified was subjected to two-substrate steady-state kinetic analysis, product and substrate inhibition studies. These kinetic data indicate that the catalytic reaction follows an ordered Bi Bi mechanism, where the substrates bind to the enzyme in a defined order (first ubiquinone followed by d-sorbitol), while products are released in sequence (first l-sorbose followed by ubiquinol). From these findings, we proposed that the native mSLDH bears two different substrate-binding sites, one for ubiquinone and the other for d-sorbitol, in addition to PQQ-binding and Mg²⁺-binding sites in the catalytic center.     

Alcoholysis catalyzed by Candida antarctica lipase B in a gas/solid system obeys a Ping Pong Bi Bi mechanism with competitive inhibition by the alcohol substrate and water.

The kinetics of alcoholysis of methyl propionate and n-propanol catalyzed by Candida antarctica lipase B supported onto silanized Chromosorb P was studied in a continuous solid/gas reactor. In this system the solid phase is composed of a packed enzymatic sample and is percolated by nitrogen as carrier gas, which simultaneously carries substrates to the enzyme while removing reaction products. In this reactor the thermodynamic activity of substrates and effectors can be perfectly adjusted allowing kinetic studies to be performed under different operating conditions. The kinetics obtained for alcoholysis were suggested to fit a Ping Pong Bi Bi mechanism with dead-end inhibition by the alcohol. The values of all apparent kinetic parameters were calculated and the apparent dissociation constant of enzyme for gaseous ester was found very low compared with the one obtained for liquid ester in organic medium, certainly due to the more efficient diffusion in the gaseous phase. The effect of water thermodynamic activity was also investigated. Water was found to act as a competitive inhibitor, with a higher inhibition constant than n-propanol. Thus alcoholysis of gaseous methyl propionate and n-propanol catalyzed by C. antarctica lipase B was found to obey the same kinetic mechanism as in other non-conventional media such as organic liquid media and supercritical carbon dioxide, but with much higher affinity for the substrates.