期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2014
卷号：111
期号：23
页码：8607-8612
DOI：10.1073/pnas.1407379111
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Use of the highly toxic and easily prepared rodenticide tetramethylenedisulfotetramine (TETS) was banned after thousands of accidental or intentional human poisonings, but it is of continued concern as a chemical threat agent. TETS is a noncompetitive blocker of the GABA type A receptor (GABAAR), but its molecular interaction has not been directly established for lack of a suitable radioligand to localize the binding site. We synthesized [14C]TETS (14 mCi/mmol, radiochemical purity >99%) by reacting sulfamide with H14CHO and s-trioxane then completion of the sequential cyclization with excess HCHO. The outstanding radiocarbon sensitivity of accelerator mass spectrometry (AMS) allowed the use of [14C]TETS in neuroreceptor binding studies with rat brain membranes in comparison with the standard GABAAR radioligand 4'-ethynyl-4-n-[3H]propylbicycloorthobenzoate ([3H]EBOB) (46 Ci/mmol), illustrating the use of AMS for characterizing the binding sites of high-affinity 14C radioligands. Fourteen noncompetitive antagonists of widely diverse chemotypes assayed at 1 or 10 {micro}M inhibited [14C]TETS and [3H]EBOB binding to a similar extent (r2 = 0.71). Molecular dynamics simulations of these 14 toxicants in the pore region of the 1{beta}2{gamma}2 GABAAR predict unique and significant polar interactions for TETS with 1T1' and {gamma}2S2', which are not observed for EBOB or the GABAergic insecticides. Several GABAAR modulators similarly inhibited [14C]TETS and [3H]EBOB binding, including midazolam, flurazepam, avermectin Ba1, baclofen, isoguvacine, and propofol, at 1 or 10 M, providing an in vitro system for recognizing candidate antidotes.
