DAz-2 is a cell-permeable sulfonic acid probe that can directly detect sulfonic acid-modified proteins in living cells [1].

DAz-2 is utilized for detecting sulfonic acids under various conditions [1]: 1. Prepare 10 μM protein, 50 μg cellular lysate, or 200 μg protein lysate. 2. Add 50 or 100 μM H2O2 and incubate at room temperature for 20 minutes; then add 1 mM Daz-2 or 5% (v/v) DMSO, and react at room temperature for 15 minutes. 3. Quench the reaction with 5 mM DTT and remove excess reagents via gel filtration. 4. Separate proteins using 4-12% SDS-PAGE, transfer to a PVDF membrane, and detect using HRP-Streptavidin Western Blotting.