Trifluoroacetyl-HYNIC peptides: Synthesis and Tc-99m radiolabeling

摘要

Fmoc-lys(HYNIC-Boc)-OH, a precursor for solid-phase synthesis of Tc-99m-labeled peptides, was synthesized efficiently without HPLC purification. HPLC-ESMS showed that deprotection and decoupling of peptide from the resin with trifluoroacetic acid gave initially HYNIC-peptide, which was trifluoroacetylated upon prolonged incubation. The trifluoroacetyl-HYNIC group was hydrolyzed during Tc-99m labeling, rendering deprotection unnecessary. Trifluoroacetyl-HYNIC peptide was Tc-99m-labeled as efficiently, producing the same product, as HYNIC-peptide. These modifications enhance the versatility of HYNIC for Tc-99m peptide labeling.