图1 NA-P-甲苯磺酰-L-精氨酸甲酯盐酸盐合成反应式
将L-精氨酸26.25g(0.25mol)、4mol/L氢氧化钠溶液62.5mL(0.25mol)加入装有机械搅拌、温度计、酸度计、滴加瓶的500mL四口烧瓶中，在冷阱中开启搅拌，使精氨酸和氢氧化钠反应完全，向四口烧瓶中加入2.7g四丁基硫酸氢铵和50mL水及甲醇搅拌使相转移催化剂溶解，0℃以下缓慢滴加对甲基苯磺酰氯42.5mL(0.3mol)，后期不断滴加pH=9的硼酸缓冲溶液调节pH保持在9左右。对甲基苯磺酰氯滴完后将温度升至15℃，继续搅拌反应3h，TLC检测反应完全。用乙醚洗涤(2×20mL)，醚层弃去。不断搅拌下缓慢滴加6mol/L盐酸，调节水相pH=2，继续搅拌20min，析出白色固体。乙酸乙酯萃取(3×30mL)，分出乙酸乙酯有机层。用质量分数为5%氯化钠溶液和水洗至中性，无水硫酸钠干燥，旋蒸除乙酸乙酯，得油状液体。置于冰箱冷冻过夜，油状液体析出大量白色固体，加入大量石油醚，搅拌得白色粉末状固体。抽滤，用石油醚洗涤、干燥，得NA-P-甲苯磺酰-L-精氨酸甲酯盐酸盐。
Anaphase-promoting complex (APC)
The absence of APC substrates, TAME hydrochloride ejects Cdc20 from the APC by promoting Cdc20 auto-ubiquitination in its N-terminal region. Cyclin B1 antagonizes TAME hydrochloride's effect by promoting binding of free Cdc20 to the APC and suppressing Cdc20 auto-ubiquitination. TAME hydrochloride stabilizes cyclin B1 in Xenopus extract by two mechanisms. First, it reduces the k cat of the APC Cdc20 /cyclin B1 complex without affecting the K m , slowing the initial ubiquitination of unmodified cyclin B1. Second, as cyclin B1 becomes ubiquitinated, it loses its ability to promote Cdc20 binding to the APC in the presence of TAME hydrochloride. As a result, cyclin B1 ubiquitination terminates before reaching the threshold necessary for proteolysis.