[agodzilla]

I am looking for a way to change the amine functional group on a lysine to either an epoxide, thiol or a benzamide functional group. I am specific reactions to amine group on lysine and does not interact with guanidine functional group on arginine. I have been looking through the literature and cannot find anything. If you can find anything sources would be nice but any help would be much appreciated.
Another thing that would be useful is any guides or links to protein engineering. I am looking to link two proteins and any information on different methodologies tips or tricks would be fantastic.

[Babcock_Hall]

Are you talking about modifying free lysine or a lysine residue in a protein?  When you say link, do you mean crosslinking?  What is the purpose of the crosslinking?  Your questions are somewhat broad.

[opsomath]

Run, do not walk, to request from your library a copy of Hermanson's "Bioconjugate Techniques." It is pretty nearly the Bible of modifying biomolecules.

I know how to do the opposite of the reaction you want, if that helps. Phenylglyoxal derivatives will condense and cyclize with arginine's guanidinium group. I used this reaction to specifically label arginines in an antibody with azides, using azidophenylglyoxal.

[Babcock_Hall]

There are several old or even older books on protein modification that deserve a place on anyone's shelf who does this kind of work.  Means and Feeney wrote one (Chemical Modification of Proteins), and Roger Lundblad wrote more than one.

[molecular-world]

"Methods and Strategies of Peptide Ligation" (Tam JP, Xu J, Eom KD; 2001) might be a helpful review in terms of your work on linking proteins. Good luck!