α-1,4-葡聚糖裂解酶的动力学性质研究

Investigation on Kinetic Properties of α-1,4- Glucan Lyase in the Red Seaweed G. lemaneiformis

红藻中的α-1,4-葡聚糖裂解酶是红藻淀粉的降解酶，除了 红藻淀粉外，它还可以作用于多种底物。文中分别以PNPG和可溶性淀粉作底物，以龙须菜的 几个品系作为材料，研究了该酶促反应的动力学方面的性质。以 PNPG作为底物，该酶在60m in内酶促反应速度与保温时间成线性关系；在野生型龙须菜品系中该酶的最适反应温度是50 ℃，在两种突变型品系中是40℃；最适pH范围在4.4～5.5；底物浓度是4mmol/L时达到最大反 应速度；葡萄糖对该酶促反应有明显的抑制作用。以可溶性淀粉作为底物，在反应60 min内 酶反应速度与保温时间成线性关系；最适反应温度为50℃；最适pH范围在5.0～5.8；底物浓 度是8mg/mL时达到最大反应速度；葡萄糖对可溶性淀粉的抑制作用比对PNPG的弱。

α-1,4-Glucan lyase is the degrading enzyme of flo ridean starch in red algae. It can act on many substrates besides floridean star ch. Its kinetic properties acting on PNPG and soluble starch, in several species of Gracilaria lemaneiformis, were investigated. When PNPG was used as subst rate, the relationship between reaction velocity and reaction time was linear wi thin 60 minutes; the optimum temperature was 50℃ in wild type and 40℃ in two o ther mutant types of G. lemaneiformis; the range of optimum pH was between 4.4～5.5; the reaction velocity reached the maximum when PNPG concentrati on was 4 mmol/L; glucose showed a dramatic inhibition to this reaction. When sol uble starch was used as substrate, the relationship between its reaction velocit y and reaction time was linear within 60 minutes; the optimum temperature was 50 ℃ in three species of G. lemaneiformis; the range of optimum pH was between 5.0～5.8; the reaction velocity reached the maximum when soluble starch concentr ation was 8 mg/mL; glucose showed a slighter inhibition to this reaction compare d with the PNPG reaction.