Description
PTAD-Azide (4-(4-(2-Azidoethoxy)phenyl)-1,2,4-triazolidine-3,5-dione) is a 1,2,4-triazolidine-3,5-dione derivative. It can be prepared from ethyl hydrazinecarboxylate. NotePTAD-Azide must be first activated by stirring in a 1:0.98 molar ratio with 1,3-dibromo-5,5-dimethylhydantoin (product # 157902). Activation is evident upon solution color change from colorless to deep red and the activated reagent should be used immediately.General Procedure for Protein Modification with PTAD.Part 1: PTAD activationMix together 1:0.98 molar equivalents of unactivated PTAD to 1,3-dibromo-5,5-dimethylhydantoin (product # 157902) in organic solvent (preferred solvents are DMF or acetonitrile, avoid using DMSO)Color change is observed from colorless/pale yellow to deep red (approximately 5 min of mixing).After the solution turns red, store the now activated reagent on ice and use for protein modification within 30 min.Part 2: Protein modificationAdd protein solution in mixed phosphate/Tris buffer or Tris buffer (pH should be 6 - 9) to the eppendorf tube (or other vial) containing the activated PTAD reagent prepared above and mix gently at room temperature for up to 30 min. Preferably use 10-fold molar excess of reagent relative to protein. Use protein at a minimum concentration of 1 mg/ml (higher concentrations are preferred for enhanced labeling).Remove excess unreacted PTAD by gel filtration.PTAD-Azide may be used in the preparation of 4-(4-(2-azidoethoxy)phenyl)-3H-1,2,4-triazole-3,5(4H)-dione and aplaviroc-urazole.This urazole was recently demonstrated in the traceless, chemoselective labeling of peptides and proteins through electrochemical tyrosine-click (e-Y-CLICK) chemistry