KINETIC MODELING OF HYDROLYSIS OF SUCROSE BY INVERTASE
KINETIC MODELING OF HYDROLYSIS OF SUCROSE BY INVERTASE
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DOI：
10.1002/bit.260130505
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发表时间：
1971-01-01
影响因子：
3.8
通讯作者：
VIETH, WR
中科院分区：
文献类型：
--
作者：
BOWSKI, L;SAINI, R;VIETH, WR
蔗糖转化酶水解的动力学进行了研究，特别强调高底物浓度。通过在宽范围的底物浓度（0.04 M至2.06 M）内直接跟踪葡萄糖的产生作为时间的函数来确定反应的初始速率。所得数据揭示了反应速率逐渐增加，直到蔗糖浓度达到约0.2921。3，之后反应速度随蔗糖浓度的增加而降低。以前的工作者（如Xelson和Schubertl）报道了在蔗糖浓度约为0.17 M时，通过间接偏振测量葡萄糖确定的峰值反应速度。然而，这些测量忽略了由转化酶8-lo的转移酶作用形成的中间体寡糖，并假设葡萄糖和果糖的量相等。根据安德森等人的研究，这些寡糖通过产生错误的低反应速率而干扰。这项工作的实验结果证实了安德森的观察，并显示在温度，pH值和酶浓度相同的条件下，蔗糖浓度为0.177 M和0.285 M之间的进一步反应速率增加了近20%。底物扩散，溶液粘度，水浓度，和底物抑制的影响进行了实验研究，并将结果纳入动力学模型，已被证明是令人满意的模拟实验结果。该模型考虑了主要底物的抑制作用，二级底物水的浓度作为蔗糖浓度大于0.285 M时的速率限制因素。混合的影响，在体积功率输入方面，对反应速率进行了测试。体积功率输入增加约40倍，反应速率没有增加。这些实验表明，在实验条件下，本体传质不是速率限制因素。
The kinetics of the enzymatic hydrolysis of sucrose by invertase have been examined, with particular emphasis on high substrate concentration. Initial rates of reaction were determined by following the production of glucose directly as a function of time over a wide range of substrate concentrations (0.04 M to 2.06 M). The resulting data reveal a reaction rate that increases gradually until the sucrose concentration reaches about 0.2921. 3, after which the reaction velocity decreases with increasing sucrose concentration. Previous workers (eg, Xelson and Schubertl) have reported a peak reaction velocity as determined by indirect polarimetric measurements of glucose, at a sucrose concentration of about 0.17 M. These measurements, however, neglect the intermediate oligosaccharides formed by the transferase action of invertase, 8-lo and assume equal amounts of glucose and fructose. According to Anderson et u1., Io these oligosaccharides interfere by producing an erroneously low reaction rate. Experimental results of this work confirm Anderson's observations, and show a further reaction rate increase of nearly 20% between sucrose concentrations of 0.177 M and 0.285 M under the same conditions of temperature, pH, and enzyme concentration. Effects of substrate diffusion, solution viscosity, water concentration, and substrate inhibition were experimentally studied and the results incorporated into a kinetic model that has proven satisfactory in modeling the experimental results. This model takes into account inhibition by primary substrate, with concentration of the secondary substrate water, as a rate limiting factor at sucrose concentrations greater than 0.285 M. The effects of mixing, in terms of volumetric power input, on the reaction rate have been tested. Approximately 40-fold increase in volumetric power input caused no increase in the reaction rate. These experiments have shown that bulk mass transfer is not a rate limiting factor under the experimental conditions.