| abstract |
Amino-sulfhydryl cross-linking reagents (6) that are cleavable under mildly acidic conditions. Also disclosed are methods of making the cross-linkers (4, 5, 6) as well as methods of using the cross-linkers, e.g., to deliver a biologically active substance (8) across the membranes of selected cells in a heterogeneous cell population; once inside the cell the active substance is released, intact, by the transient, mild acidity of certain cell structures. Finally, a method of characterizing complex multi-chain protein structures is disclosed. |