I am looking for a reagent (and vendor) that will irreversible put a raher bulky substituent on a free SH group and that does not react with free amines (or other potential reactive groups present on a protein surface). The connection with crystallography is that it is required for an experiment asked by a referee necessary to confirms or reject a hypothesis that results from a crystal structure. For this experiment it is essential that the reaction is not reversible (so no S-S bond formation).
Any maleimide-based fluorescent dye will be bulky, irreversible and when done right will only go for thiols. Also easy to quantify extent of modification.
Dima
Remy Loris Vrije Universiteit Brussel
