[nkenton]

Hey all:

I am working with cysteine and methionine analogues with C=C bonds, and I am trying to find a selective stain for olefins that will not also stain the sulfides/thiols.  The only staining solution I've found is KMnO4, but I suspect that is too strongly oxidizing to be selective.  I have also tried iodine, but this reacts with all amino acids.  Does anyone have any suggestions?

[Honclbrif]

In my experience permanganate goes nuts over both alkenes and sulfides/thiols. You may have some luck with vanillin or anisaldehyde stains, but no guarantees.