Chromatography Forum

Derivatization of methionine.

Any one knows of a way to modify methionine, hopefully selectively, preferably on the S atom.

Thank you, noam

There are some fluorescence derivatization reagents which allow highly selective analysis of -SH amino acids and small peptides. We did homocysteine here in this lab, some 10 years ago. Thus a literature search on your part may dig up some newer methods and will most likely take less time than me digging into our old stuff. If you run into problems it might make sense to compare experience, though.
Note that fluorescence derivatized substances can be detected in the absorption mode (UV detector), you may just loose some sensitivity and selectivity.

Thank you, the thing is, I think that Cys (-SH group) should have different chemical reactivity from that of Met (-SCH3 group).

I was wondering if there is a way to selectively modify them differently.

Sorry, forgot about the methyl. -SH and -SCH3 certainly are completely different, chemically.

Just a thought: there is an enzyme, which react specifically with Met producing SAM (SAM=S-adenosyl-L-methionine - a cofactor in methylation reactions); so I wonder if it can be of any use. Well, sounds crazy, but still...

Regards.
Serg.

Noam,

Is this modification to be performed on MET in an intact peptide/protein or on free MET (either as a single free AA, or as part of a post-hydrolysis reaction) ??

JMB