Enzymatic Assemblies of Thiophosphopeptides Instantly Target Golgi Apparatus and Selectively Kill Cancer Cells**

Abstract

Changing an oxygen atom of the phosphoester bond in phosphopeptides by a sulfur atom enables instantly targeting Golgi apparatus (GA) and selectively killing cancer cells by enzymatic self-assembly. Specifically, conjugating cysteamine S-phosphate to the C-terminal of a self-assembling peptide generates a thiophosphopeptide. Being a substrate of alkaline phosphatase (ALP), the thiophosphopeptide undergoes rapid ALP-catalyzed dephosphorylation to form a thiopeptide that self-assembles. The thiophosphopeptide enters cells via caveolin-mediated endocytosis and macropinocytosis and instantly accumulates in GA because of dephosphorylation and formation of disulfide bonds in Golgi by themselves and with Golgi proteins. Moreover, the thiophosphopeptide potently and selectively inhibits cancer cells (HeLa) with the IC50 (about 3 μM), which is an order of magnitude more potent than that of the parent phosphopeptide.