Matioli Graciette, Zanin Gisella M, De Moraes Flávio F
Pharmacy and Pharmacology Department, State University of Maringá, PR, Brazil.
Appl Biochem Biotechnol. 2002 Spring;98-100:947-61. doi: 10.1385/abab:98-100:1-9:947.
The influence of substrate or product level on the initial velocity of cyclodextrin (CD) production by cyclodextringlycosyltransferase from a Brazilian isolate of Bacillus firmus was studied. Our results indicate that the product gamma-CD is a stronger inhibitor to the reaction than beta-CD. Small saccharides could also inhibit CD production, although to a lesser extent than the products, and maltose was the strongest inhibitor among small saccharides. Increasing substrate concentration resulted in greater reduction on enzyme activity for the formation of beta-CD than for gamma-CD. We modeled the kinetics of CD production with a set of four reversible reactions including the cyclization/coupling reaction that forms/opens CDs, and three disproportionation reactions. Our model on the initial velocity data explained well the substrate inhibition phenomenon. Kinetic parameters were determined by fitting the initial velocity data into our model.
研究了底物或产物水平对来自巴西坚强芽孢杆菌分离株的环糊精糖基转移酶生产环糊精（CD）初始速度的影响。我们的结果表明，产物γ-环糊精比β-环糊精对该反应的抑制作用更强。小糖类也能抑制CD的产生，尽管程度小于产物，且麦芽糖是小糖类中最强的抑制剂。增加底物浓度导致β-环糊精形成过程中酶活性的降低比γ-环糊精形成过程中更大。我们用一组四个可逆反应对CD生产动力学进行了建模，包括形成/打开CD的环化/偶联反应以及三个歧化反应。我们基于初始速度数据的模型很好地解释了底物抑制现象。通过将初始速度数据拟合到我们的模型中来确定动力学参数。
