Department of Chemistry, New Mexico Institute of Mining and Technology, 801, Leroy Place, Socorro, New Mexico 87801, United States.
ACS Biomater Sci Eng. 2020 Apr 13;6(4):1989-1997. doi: 10.1021/acsbiomaterials.9b01720. Epub 2020 Mar 11.
Phospholipase A (PLA) is a membrane lytic enzyme that is present in many organisms. Human PLA has emerged as a potential biomarker as well as a therapeutic target for several diseases including cancer, cardiovascular diseases, and some inflammatory diseases. The current study focuses on the development of lipo-beads that are very reactive and highly sensitive to PLA. To develop the best supported lipid bilayer formulation, several lipid combinations were investigated using 10 μm porous silica beads. The reactivity of PLA was monitored via the decrease in particle fluorescence because of the release of entrapped fluorescent dye from the particle pores or the disintegration of a fluorescent lipid constituted on the bilayer upon lipid hydrolysis using flow cytometry. The enzyme binding studies indicate that lipo-beads with bulky fluorescent tags in the lipid head group and anionic lipids produce a more pronounced response. The kinetic studies suggest that these lipo-beads are very reactive with PLA and can generate a detectable signal in less than 5 min. The enzyme inhibition studies were also conducted with two known PLA inhibitors, varespladib and quercetin. We find that quercetin can hydrolyze the supported membrane, and thus inhibition of PLA is not observed; however, varespladib has shown significant PLA inhibition on lipo-beads. We have demonstrated that our lipo-bead-based approach can detect annexin-3, a known disease biomarker, as low as 10 nM within 5 min after incubation.
磷脂酶 A(PLA)是一种存在于许多生物体中的膜裂解酶。人类 PLA 已经成为几种疾病(包括癌症、心血管疾病和一些炎症性疾病)的潜在生物标志物和治疗靶点。本研究专注于开发对 PLA 具有高反应性和高灵敏度的脂球。为了开发最佳的支撑脂质双层配方,使用 10 μm 多孔硅珠研究了几种脂质组合。通过由于荧光染料从颗粒孔中释放或荧光脂质在脂质水解时在双层上崩解而导致颗粒荧光强度降低,来监测 PLA 的反应性,使用流式细胞术。酶结合研究表明,带有大体积荧光标签的脂质头部基团和阴离子脂质的脂球会产生更明显的响应。动力学研究表明,这些脂球与 PLA 反应非常迅速,在不到 5 分钟的时间内即可产生可检测的信号。还进行了两种已知的 PLA 抑制剂瓦瑞昔布和槲皮素的酶抑制研究。我们发现槲皮素可以水解支撑膜,因此不会观察到 PLA 的抑制;然而,瓦瑞昔布已显示出对脂球的显著 PLA 抑制作用。我们已经证明,我们基于脂球的方法可以在孵育后 5 分钟内检测到低至 10 nM 的已知疾病生物标志物 annexin-3。