Franquinet R, Le Moigne A, Hanoune J
Biochim Biophys Acta. 1978 Feb 13;539(1):88-97. doi: 10.1016/0304-4165(78)90124-1.
The particulate fraction prepared after homogenization of planaria Polycelis tenuis in a buffer containing 3 mM EDTA and 15 mM 2-mercaptoethanol possesses an adenylate cyclase activity which was enhanced two-fold by serotonin and 20-fold by the nucleotide analog guanosine 5'-(beta-gamma-imino)triphosphate, Gpp(NH)p; when present together, the two activators exhibited a marked synergistic effect. The effect of serotonin was dose dependent, with a KA of 2 micrometer and a Hill coefficient of 0.4. In the presence of 10 micrometer Gpp(NH)p, these values became 45 nM and 1.5, respectively. The effect of serotonin was due to an increase in the maximal velocity of the enzyme and was specifically inhibited by methiotepin. The effect of methiotepin was half-maximal at 0.2 micrometer in the absence of Gpp(NH)p and at 5.0 micrometer in its presence. Planaria thus appear to be the lowest organisms in which guanine nucleotides are active upon adenylate cyclase. As serotonin is normally present in planaria, it is postulated that a serotonin-dependent regulation of adenylate cyclase activity plays a physiological role in this species.
将真涡虫（Polycelis tenuis）在含有3 mM乙二胺四乙酸（EDTA）和15 mM 2-巯基乙醇的缓冲液中匀浆后制备的颗粒部分具有腺苷酸环化酶活性，该活性可被血清素增强两倍，被核苷酸类似物鸟苷5'-（β-γ-亚氨基）三磷酸（Gpp(NH)p）增强20倍；当两者同时存在时，这两种激活剂表现出明显的协同效应。血清素的作用呈剂量依赖性，其解离常数（KA）为2微摩尔，希尔系数为0.4。在存在10微摩尔Gpp(NH)p的情况下，这些值分别变为45 nM和1.5。血清素的作用是由于酶的最大反应速度增加，且被美替拉酮特异性抑制。在不存在Gpp(NH)p时，美替拉酮的半数最大效应浓度为0.2微摩尔，在存在Gpp(NH)p时为5.0微摩尔。因此，真涡虫似乎是鸟嘌呤核苷酸对腺苷酸环化酶有活性作用的最低等生物。由于血清素通常存在于真涡虫中，推测腺苷酸环化酶活性的血清素依赖性调节在该物种中发挥生理作用。
