Radioiodination of cyanocobalamin conjugates containing hydrophilic linkers: preparation of a radioiodinated cyanocobalamin monomer and two dimers, and assessment of their binding with transcobalamin II.
Radioiodination of cyanocobalamin conjugates containing hydrophilic linkers: preparation of a radioiodinated cyanocobalamin monomer and two dimers, and assessment of their binding with transcobalamin II.
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含有亲水性接头的氰钴胺素缀合物的放射性碘化：放射性碘化氰钴胺素单体和两个二聚体的制备，并评估它们与转钴胺素 II 的结合。
DOI：
10.1021/bc9900340
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发表时间：
1999
影响因子：
4.7
通讯作者：
Quadros,EV
中科院分区：
文献类型：
--
作者：
Wilbur,DS;Pathare,PM;Hamlin,DK;Rothenberg,SP;Quadros,EV
本报告描述了一项旨在制备具有改善的水溶性和降低的非特异性结合的放射性碘化氰钴胺素（CN-Cbl）单体和二聚体的研究。在研究中，一个单体和两个二聚体CN-Cbl衍生物的合成和放射性碘化反应进行。CN-Cbl衍生物合成的初始步骤是CN-Cbl，1的温和酸水解，然后分离所得咕啉环b-、d-和de-单羧酸酯异构体。研究仅限于制备CN-Cbl-e-羧酸盐的结合物，2因为早期研究表明，该异构体与重组人转钴胺素II（rhTCII）的结合类似于CN-Cbl。在第二个合成步骤中，将亲水性连接基部分4，7，10-三氧杂-1，13-十三烷二胺3与2缀合以形成加合物4。4与对-三-正丁基锡基苯甲酸四氟苯基酯（TFP）反应，合成了可用于放射性碘标记的单体CN-Cbl衍生物6a。还合成了两个含有芳基锡烷放射性碘标记部分的CN-Cbl二聚体。第一个二聚体8a是通过4与甲锡烷基苯甲酰基-氨基丙酸二-TFP酯7a交联而合成的。第二种二聚体11 a是通过苯三羧酸三-TFP酯10与1当量的5a和3的加合物（形成9a），然后与2当量的4以逐步方式反应而合成的。以与甲锡烷基苯甲酸酯衍生物相似的方式制备放射性碘化研究中使用的碘苯甲酸酯HPLC标准品6 b、8b和11b。在中性条件下，将6a、8a或11 a与N-氯代琥珀酰亚胺和Na[125 I]I在甲醇中反应进行放射性碘标记。放射化学产率为17 - 42%。放射性标记的CN-Cbl结合物与rhTCII的结合特性的评价表明，CN-Cbl的二聚体11b比单体6 b结合更强烈，并且二聚体的结合亲和力基本上等同于未修饰的CN-Cbl。将放射性碘标记的单体[125 I] 6 b和二聚体[125 I]11b与rhTCII孵育，然后进行分子排阻色谱分析，得到的数据表明，单体与一个rhTCII分子结合，而两个rhTCII分子与约30%的二聚体结合。
This report describes an investigation aimed at preparation of radioiodinated cyanocobalamin (CN-Cbl) monomers and dimers with improved water solubility and decreased nonspecific binding. In the investigation, synthesis and radioiodination reactions of one monomeric and two dimeric CN-Cbl derivatives were conducted. The initial step in the synthesis of the CN-Cbl derivatives was mild acid hydrolysis of CN-Cbl,1, followed by separation of the resultant corrin ringb-,d-, ande-monocarboxylate isomers. The investigation was limited to preparation of conjugates of CN-Cbl-e-carboxylate,2, as earlier studies had shown binding of that isomer with recombinant human transcobalamin II (rhTCII) was similar to CN-Cbl. In a second synthetic step, the hydrophilic linker moiety, 4,7,10-trioxa-1,13-tridecandiamine,3, was conjugated with2to form the adduct,4. The synthesis of a monomeric CN-Cbl derivative,6a, which can be used for radioiodination, was accomplished by reaction of4withp-tri-n-butylstannylbenzoate tetrafluorophenyl (TFP) ester,5a. Two CN-Cbl dimers containing the arylstannane radioiodination moiety were also synthesized. The first dimer,8a, was synthesized by cross-linking4with a stannylbenzoyl-aminoisophthalate di-TFP ester,7a. The second dimer,11a, was synthesized by reacting benzene tricarboxylate tri-TFP ester,10, in a stepwise manner with 1 equiv of the adduct of5aand3(forming9a), followed by 2 equiv of4. Iodobenzoate HPLC standards,6b,8b, and11b, used in the radioiodination studies, were prepared in a manner similar to that of the stannylbenzoate derivatives. Radioiodinations were performed by reacting6a,8a, or11awithN-chlorosuccinimide and Na[125I]I in methanol under neutral conditions. Radiochemical yields of 17−42% were obtained. Evaluation of the binding properties of radiolabeled CN-Cbl conjugates with rhTCII showed that the dimer of CN-Cbl,11b, bound more avidly than the monomer,6b, and that the binding affinity of the dimer is essentially equivalent to that of unmodified CN-Cbl. Incubation of radioiodinated monomer, [125I]6b, and dimer, [125I]11b, with rhTCII followed by size-exclusion chromatographic analysis provided data that the monomer bound one rhTCII molecule whereas two rhTCII molecules were bound to approximately 30% of the dimer.