A rapid and high-yielding cysteine labelling of peptides has been observed with the specific labelling agent for amines, N-succinimidyl 4-[18F]fluorobenzoate ([18F]SFB). Interestingly, conjugation of the 4-fluorobenzoyl (FB) moiety is selectively achieved through a cysteine (Cys) thiol of the peptides with high yield (>80%) in short time (<5 min), while for a Cys amino acid derivative, a slow process has been observed. The large reactivity of these peptides for the conjugation reaction is rationalised on the basis of electrostatic interactions between the sulfhydril and the guanidinium groups of the amino acid side chains. Moreover, the stability of these novel conjugates and the biodistribution of the radiolabelled dodecapeptide by positron emission tomography (PET) in rats has been examined.
                                    已经观察到使用特定的胺标记试剂,N-琥珀
酰亚胺基 
4-[18F]氟苯甲酸酯 ([18F]SFB) 对肽进行快速且高产率的半胱
氨酸标记。有趣的是,4-
氟苯甲酰 (FB) 基团通过肽的半胱
氨酸 (Cys) 巯基选择性偶联,在短时间内(<5 分钟)达到高产率(>80%),而对于半胱
氨酸
氨基酸衍
生物,则观察到一个缓慢的过程。这些肽在偶联反应中具有高反应性,可以基于巯基和
氨基酸侧链
胍基之间的静电相互作用来合理化。此外,还考察了这些新型偶联物的稳定性以及正电子发射断层扫描 (PET) 在小鼠中放射性标记十二肽的
生物分布。