Department of Radiology, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany.
EJNMMI Res. 2012 Apr 27;2(1):17. doi: 10.1186/2191-219X-2-17.
Annexin A5 (anxA5) has been found useful for molecular imaging of apoptosis and other biological processes.
Here, we report an optimised two-step synthesis of annexin A5-diethylene triamine pentaacetic acid (DTPA) (anxA5-DTPA) for positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging with a single purification step. The use of a recombinant annexin A5 (cys-anxA5) with a single thiol group allowed regionally specific coupling, without affecting the binding domain of cys-anxA5.
The metal complexing capacity of anxA5-DTPA was investigated by labelling with 111In3+ and Eu3+. Binding of modified anxA5-DTPA to apoptotic cells was tested in competition experiments with a fluorescent anxA5 derivative (anxA5-FITC) using flow cytometry and compared with that of wildtype anxA5 or non-binding anxA5-DTPA (M1234-anxA5-DTPA). The binding affinity to apoptotic cells of the anxA5-DTPA conjugate does not differ from that of wildtype anxA5.
This two-step synthesis of annexin A5-DTPA resulted in biologically active anxA5-DTPA, which can be labelled with radionuclides for use in SPECT and PET imaging.
膜联蛋白 A5（anxA5）已被发现可用于细胞凋亡和其他生物学过程的分子成像。
在这里，我们报告了一种优化的两步法合成膜联蛋白 A5-二乙烯三胺五乙酸（DTPA）（anxA5-DTPA），用于正电子发射断层扫描（PET）和单光子发射计算机断层扫描（SPECT）成像，只需进行单一纯化步骤。使用带有单个巯基的重组膜联蛋白 A5（cys-anxA5）允许区域特异性偶联，而不会影响 cys-anxA5 的结合结构域。
通过用 111In3+和 Eu3+标记来研究 anxA5-DTPA 的金属络合能力。使用流式细胞术在竞争实验中用荧光 anxA5 衍生物（anxA5-FITC）测试修饰的 anxA5-DTPA 与凋亡细胞的结合，并与野生型 anxA5 或非结合 anxA5-DTPA（M1234-anxA5-DTPA）进行比较。 anxA5-DTPA 缀合物与凋亡细胞的结合亲和力与野生型 anxA5 没有差异。
这种两步法合成膜联蛋白 A5-DTPA 产生了具有生物活性的 anxA5-DTPA，可用于 SPECT 和 PET 成像的放射性核素标记。
