Figure 1.

Strategy for tissue-specific release of Ac₃ManNAz via enzymatic activation. (A) (i) A nonmetabolizable caged azidosugar serves as a substrate for a secreted, cancer-specific protease, releasing Ac₃ManNAz. (ii) This azidosugar is then metabolized by the cell and incorporated into cell-surface glycans. (iii) The azide-labeled glycans are detected via Cu-free click chemistry using DIFO reagents. (B) Caged azidosugar used in this study (1). Cleavage of the indicated bond (dashed line) by the prostate-specific antigen (PSA) protease results in the release of a linker, the peptide, and Ac₃ManNAz.