New methodologies for site-specifically radiolabeling proteins with the PET isotope [18F] are required to generate high quality radiotracers for imaging in both the preclinical and clinical settings. The enzymatic radiofluorination overcomes many of the limitations encountered to date with purely chemical approaches. The bacterial enzyme lipoic acid ligase was used to conjugate [18F]-fluorooctanoic acid to both a small peptide and a Fab antibody fragment. Labeling was site-specific and highly efficient under mild aqueous conditions using small amounts of peptide/protein (1-10 nmol). The labeled construct retained full epitope binding affinity and was stable in mouse serum. Using an optimized reaction scheme, mCi quantities of [18F]-Fab were generated, an amount sufficient for human imaging.
用PET同位素[18F]对蛋白质进行特异性标记的新方法对于在临床前和临床环境中生成高质量放射示踪剂是必需的。酶促放
氟反应克服了迄今为止纯
化学方法所遇到的许多限制。细菌酶
硫辛酸连接酶被用于将[18F]-
氟辛酸与小肽和Fab
抗体片段结合。在温和
水性条件下,使用少量的肽/蛋白质(1-10 nmol),标记是特异性的且高效的。标记的构建物保留了完整的抗原结合亲和力,并在小鼠血清中稳定。使用优化的反应方案,产生了足够进行人体成像的mCi数量的[18F]-Fab。