Figure 4.

Synthetic scheme of Tat-SQV bioconjugates (i) 3 equivalents Fmoc-Cys(S-Trt)-COOH in CH₂Cl₂ with DIPC/DMAP; (ii) 20% piperidine in CH₂Cl₂ ; (iii) TFA/CH₂Cl₂ (1:1); (iv) 2 equivalents Fmoc-PEG_{3.4 K}-NHS in CH₂Cl₂ with DIEA; (v) 2 equivalents 2,2'-Dithiodipyridine in DMSO; (vi) 2 equivalents. R.I.CK-Tat9 in DMSO.