Briggs R W, Hinton J F
Biochemistry. 1978 Dec 12;17(25):5576-82. doi: 10.1021/bi00618a038.
A thallium-205 and proton nuclear magnetic resonance study of the ionophores monensin and nigericin is reported. Evidence is presented for the simultaneous existence of two forms of monensin free acid in chloroform solution, one containing a water molecule in the central cavity and one with a water molecule on the periphery, linking the ends of the monensin molecule by hydrogen bonding. There appear to be three structurally different monensin complexes of thallium, two in the salt form and one in the acid form. In free nigericin acid, both terminal hydroxyl moieties hydrogen bond to the terminal carboxylic acid oxygens; in the Na+ salt, the binding of one of the carboxylate oxygens to the metal ion allows but one of the terminal OH's to hydrogen bond strongly. Thallium-205 chemical shifts and spin-lattice relaxation times in the title complexes are discussed and compared to those in ionophores studied previously.
报道了对离子载体莫能菌素和尼日利亚菌素进行的铊-205与质子核磁共振研究。有证据表明，莫能菌素游离酸在氯仿溶液中同时存在两种形式，一种在中心腔中含有一个水分子，另一种在外围含有一个水分子，通过氢键连接莫能菌素分子的两端。似乎存在三种结构不同的铊的莫能菌素配合物，两种为盐形式，一种为酸形式。在游离的尼日利亚菌素酸中，两个末端羟基部分都与末端羧酸氧原子形成氢键；在钠盐中，一个羧酸根氧原子与金属离子的结合使得只有一个末端羟基能强烈地形成氢键。讨论了标题配合物中的铊-205化学位移和自旋晶格弛豫时间，并与之前研究的离子载体中的进行了比较。
