Benishin C G, Carroll P T
J Neurochem. 1981 Feb;36(2):732-40. doi: 10.1111/j.1471-4159.1981.tb01649.x.
The choline analog homocholine is not acetylated in vitro by choline-O-acetyltransferase (ChAT, EC 2.3.1.6), which is solubilized by 100 mM-sodium phosphate buffer washes of a crude vesicular fraction of mouse forebrain. However, both homocholine and choline are acetylated by a form of ChAT which is nonionically associated with a subcellular fraction of mouse forebrain containing membrane-associated organelles and occluded acetylcholine (P4). Acetylation of homocholine by membrane-associated ChAT is saturable. 4-(1-Naphthylvinyl)pyridine (NVP) inhibits the acetylation of both choline (60%) and homocholine (40%) by membrane-associated ChAT but reduces the acetylation of choline alone by soluble ChAT (76%). Choline and homocholine serve as competitive alternative substrates for the same membrane-associated ChAT, whereas homocholine acts only as a competitive inhibitor of choline acetylation by soluble ChAT. Acetylhomocholine competitively inhibits the acetylation of choline by both soluble and membrane-associated ChAT more dramatically than does the natural end product, acetylcholine.
胆碱类似物高胆碱在体外不能被胆碱-O-乙酰转移酶（ChAT，EC 2.3.1.6）乙酰化，该酶可通过用100 mM磷酸钠缓冲液洗涤小鼠前脑粗囊泡部分来溶解。然而，高胆碱和胆碱都能被一种与含有膜相关细胞器和封闭乙酰胆碱的小鼠前脑亚细胞部分（P4）非离子结合的ChAT形式乙酰化。膜相关ChAT对高胆碱的乙酰化是可饱和的。4-(1-萘基乙烯基)吡啶（NVP）抑制膜相关ChAT对胆碱（60%）和高胆碱（40%）的乙酰化，但仅降低可溶性ChAT对胆碱的乙酰化（76%）。胆碱和高胆碱作为同一膜相关ChAT的竞争性替代底物，而高胆碱仅作为可溶性ChAT对胆碱乙酰化的竞争性抑制剂。乙酰高胆碱比天然终产物乙酰胆碱更显著地竞争性抑制可溶性和膜相关ChAT对胆碱的乙酰化。
