Mutations in genes encoding PINK1 (PTEN-induced kinase 1) and Parkin (E3 ubiquitin ligase) are identified in familial Parkinson's disease. However, it remains unclear whether the phosphorylated Ub chains activate wildtype Parkin (w-Parkin) or phosphorylated Parkin (p-Parkin), with the consequent expulsion of the damaged mitochondria. To address this problem, we developed a chemical protein synthesis strategy that integrates hydrazide-based native chemical ligation, dehydroalanine conjugation, and chemoenzymatic modification to enable us to access the precise phosphorylated side-chain K6-linked diUbs, namely: (1) Ub P K6 Ub, which carries out phosphorylation at the distal Ub. (2) Ub K6 Ub P , which carries out phosphorylation at the proximal Ub. (3) Ub P K6 Ub P , which carries out phosphorylation at both distal and proximal Ub units. The structure of Ub P K6 Ub P was validated by X-ray crystallographic analysis at 2.2 Å resolution. Using these structurally defined phosphorylated diUbs to activate Parkin, we found that Ub K6 Ub P could activate p-Parkin but not w-Parkin. Subsequent biochemical studies showed that Ub K6 Ub P interfered with the transfer of Ub by the Ub-E2 enzyme conjugate with the thioester-linked intermediate of w-Parkin. Thus our results suggested that w-Parkin and p-Parkin are activated via two different mechanisms. Collectively, our study exemplifies the utilization of a novel synthesis strategy for the generation of structurally defined proteins bearing post-translational modifications and would be useful in elucidating ubiquitin chain signaling and pathways regulation studies in modern biochemistry and biophysics.