Findrik Zvjezdana, Vrsalović Presecki Ana, Vasić-Racki Durda
Faculty of Chemical Engineering and Technology, University of Zagreb, Savska c. 16, HR-10 000 Zagreb, Croatia.
J Biosci Bioeng. 2007 Oct;104(4):275-80. doi: 10.1263/jbb.104.275.
NADH oxidase from Lactobacillus brevis was kinetically characterized in two different buffers: Tris-HCl and glycine-sodium pyrophosphate (pH 9.0). Reaction kinetics was described using the Michaelis-Menten model with product (NAD(+)) inhibition. It was found that this type of inhibition is uncompetitive. Experiments in the continuously operated enzyme membrane reactor revealed a strong enzyme deactivation at two different residence times: 12 and 60 min. A stronger deactivation was observed at the lower residence time in the glycine-sodium pyrophosphate buffer. Enzyme deactivation was assumed to be of the first order. The developed mathematical model for the continuously operated enzyme membrane reactor described these experiments very well. The mathematical model simulations revealed that a high enzyme concentration (up to 30 g cm(-3)) is necessary to obtain and maintain the stationary NADH conversion near 100% for a longer period of time.
对来自短乳杆菌的NADH氧化酶在两种不同缓冲液（Tris-HCl和甘氨酸-焦磷酸钠，pH 9.0）中进行了动力学表征。使用具有产物（NAD(+)）抑制作用的米氏模型描述反应动力学。发现这种抑制类型是非竞争性的。在连续操作的酶膜反应器中进行的实验表明，在两个不同的停留时间（12分钟和60分钟）下酶有强烈失活。在甘氨酸-焦磷酸钠缓冲液中较低停留时间下观察到更强的失活。假定酶失活为一级反应。所建立的连续操作酶膜反应器的数学模型很好地描述了这些实验。数学模型模拟表明，为了在较长时间内获得并维持接近100%的固定NADH转化率，需要高酶浓度（高达30 g cm(-3)）。
