Hi Safaa my main question is why do you want to do it?

Protein thiols are already the most reactive protein residues, you want to make them less reactive by attaching a polymeric residue?

Thank you Steingrimur Stefansson for your answer. I want to photo-crosslink it with a hydrogel by uv.

Hi Safaa, my main concerns is that 1) hydrogel is very non reactive, 2) uv crosslinking is very inefficient and indiscriminate and you will crosslink other proteins as well. 3) You will have to isolate your  thiol  protein from other crap that is also crosslinked to the hydrogel.

Thanks again Steingrimur Stefansson! I know but I want to explore it then decide. Just looking for an efficient reaction... Best