Conjugated Polyelectrolyte Based Real-Time Fluorescence Assay for Phospholipase C
作者:Yan Liu、Katsu Ogawa、Kirk S. Schanze
DOI:10.1021/ac701672g
日期:2008.1.1
A fluorescence turnoff assay for phospholipase C (PLC) from Clostridium perfringens is developed based on the reversible interaction between the natural substrate, phosphatidylcholine, and a fluorescent, water-soluble conjugated polyelectrolyte (CPE). The fluorescence intensity of the CPE in water is increased substantially by the addition of the phospholipid due to the formation of a CPE−lipid complex. Incubation of the CPE−lipid complex with the enzyme PLC causes the fluorescence intensity to decrease (turnoff sensor); the response arises due to PLC-catalyzed hydrolysis of the phosphatidylcholine, which effectively disrupts the CPE−lipid complex. The PLC assay operates with phospholipid substrate concentrations in the micromolar range, and the analytical detection limit for PLC is <1 nM. The optimized assay provides a convenient, rapid, and real-time sensor for PLC activity. The real-time fluorescence intensity from the CPE can be converted to substrate concentration by using an ex situ calibration curve, allowing PLC-catalyzed reaction rates and kinetic parameters to be determined. PLC activation by Ca2+ and inhibition by EDTA and fluoride ion are demonstrated using the optimized sensor.
根据天然底物磷脂酰胆碱与荧光水溶性共轭聚电解质(CPE)之间的可逆相互作用,开发了一种产气荚膜梭状芽孢杆菌磷脂酶 C(PLC)的荧光关闭测定法。由于形成了 CPE-脂质复合物,加入磷脂后,CPE 在水中的荧光强度大大增加。将 CPE-脂质复合物与 PLC 酶孵育,会导致荧光强度降低(关闭传感器);这种反应是由于 PLC 催化水解磷脂酰胆碱,从而有效地破坏了 CPE-脂质复合物。PLC 检测法的磷脂底物浓度在微摩尔范围内均可操作,PLC 的分析检测限小于 1 nM。优化后的检测方法提供了一种方便、快速和实时的 PLC 活性传感器。CPE 的实时荧光强度可通过使用原位校准曲线转换为底物浓度,从而确定 PLC 催化反应的速率和动力学参数。使用优化的传感器证明了 Ca2+ 对 PLC 的激活作用以及 EDTA 和氟离子对 PLC 的抑制作用。