Marquis J K
Comp Biochem Physiol C Comp Pharmacol Toxicol. 1984;78(2):335-8. doi: 10.1016/0742-8413(84)90093-8.
Studies are in progress to characterize the nature of ligand interactions at peripheral anionic sites on mammalian brain AChE, including the beta-anionic or "accelerator" anionic sites where enzyme activity is increased upon Ca2+ binding. Terbium was studied as a fluorescence probe of Ca2+ binding sites in partially purified AChE from whole rat brain. Scatchard analysis of Tb3+ binding in low ionic strength (2 mM) Pipes buffer revealed at least two populations of sites: high affinity sites with Kd(app) approximately 7.6 microM and low-affinity sites with a Kd(app) approximately 49.6 microM. Low-affinity binding was selectively inhibited by 50 mM NaCl; high-affinity binding was completely inhibited by 2 mM CaCl2; and all the bound Tb3+ could be displaced by 1 mM EDTA. The heterogeneity of Tb3+ binding sites is consistent with the multiple, concentration-dependent effects of Tb3+ on enzyme activity.
目前正在进行多项研究，以表征哺乳动物脑乙酰胆碱酯酶（AChE）外周阴离子位点上配体相互作用的性质，包括β-阴离子或“促进剂”阴离子位点，在这些位点上，Ca2+结合后酶活性会增加。铽作为全大鼠脑部分纯化的AChE中Ca2+结合位点的荧光探针进行了研究。在低离子强度（2 mM）的哌嗪-1,4-二乙磺酸（Pipes）缓冲液中对Tb3+结合进行的Scatchard分析显示至少存在两类结合位点：解离常数表观值（Kd(app)）约为7.6 μM的高亲和力位点和Kd(app)约为49.6 μM的低亲和力位点。50 mM NaCl可选择性抑制低亲和力结合；2 mM CaCl2可完全抑制高亲和力结合；1 mM乙二胺四乙酸（EDTA）可置换所有结合的Tb3+。Tb3+结合位点的异质性与Tb3+对酶活性的多种浓度依赖性效应一致。
