Hydrolytic Reactions of Guanosyl-(3‘,3‘)-uridine and Guanosyl-(3‘,3‘)-(2‘,5‘-di-<i>O</i>-methyluridine)
作者:Anu Kiviniemi、Tuomas Lönnberg、Mikko Ora
DOI:10.1021/ja047568i
日期:2004.9.1
Hydrolytic reactions of guanosyl-(3',3')-uridine and guanosyl-(3',3')-(2',5'-di-O-methyluridine) have been followed by RP HPLC over a wide pH range at 363.2 K in order to elucidate the role of the 2'-hydroxyl group as a hydrogen-bond donor upon departure of the 3'-uridine moiety. Under neutral and basic conditions, guanosyl-(3',3')-uridine undergoes hydroxide ion-catalyzed cleavage (first order in
鸟苷-(3',3')-尿苷和鸟苷-(3',3')-(2',5'-二-O-甲基尿苷)的水解反应在很宽的pH范围内被RP HPLC跟踪363.2 K 以阐明 2'-羟基在 3'-尿苷部分离开时作为氢键供体的作用。在中性和碱性条件下,鸟苷基-(3',3')-尿苷经历氢氧根离子催化的 P-O3' 键裂解([OH(-)] 中的一级),得到尿苷和鸟苷 2',3 '-环状单磷酸酯,随后水解成 2'- 和 3'-单磷酸酯的混合物。这种键断裂的速度是鸟苷-(3',3')-(2',5'-二-O-甲基尿苷) P-O3' 键相应断裂生成 2',5' 的 23 倍-O-二甲基尿苷和鸟苷 2',3' -环磷酸盐。在酸性条件下,反应性差异较小,脱嘌呤和异构化与裂解竞争。Zn(2+) 对鸟苷-(3',3')-尿苷 P-O3' 键断裂的影响不大:在 [Zn(2+)] = 5 处观察到约 6 倍的加速mmol L(-)(1)