Skip to main content
. Author manuscript; available in PMC: 2012 Jun 6.
Published in final edited form as: Mol Pharm. 2011 May 3;8(3):901–912. doi: 10.1021/mp200007b

Figure 1.

Figure 1

(A) Structure of the peptide-drug conjugate KCC-TGX. KCC-TGX contains a HER2-targeting peptide, a GGG spacer, a PSA cleavable substrate, a self-cyclizing linker and the parent drug TGX-D1. (B) The activation mechanism of KCC-TGX. KCC-TGX is expected to be cleaved at the Gln-Ser site by PSA to release NH2-SL-TGX. The free amino group of Ser (S) in NH2-SL-TGX attacks the ester carbonyl group and releases the parent drug TGX-D1. The dipeptide Ser-Leu self-cyclizes to form diketopiperazines (DKP).