Scheme 2.

Synthesis of Doubly Modified hMVP Vaults with a Fluorescent Probe and CPP^a

^a(A) Activation of Ac-Cys-(dArg)₈-NH₂ using 2,2′-dipyridyl disulfide followed by attachment of the activated Cys-r8 CPP onto FITC vaults through a disulfide exchange with MVP cysteine residues. (B) Activation of CPP octaarginine using GMBS followed by the attachment of the activated octaarginine onto FITC vaults through a thiol-maleimide linkage.