Hi all, Slightly off topic - but I'm having trouble solubilizing some peptides for SPR and hoped someone on the BB might have some other suggestions.
The peptides are intra-chain S-S cross-linked 12mers with pIs of ~3. 10 residues are hydrophobic and 2 are acidic. Peptides have been tested with and without N- and C-terminal modifications (amidation/acetylation). I have tried: ddH2O raising (and lowering) pH (tested up to 8.5) with different buffers Including DMF as a co-solvent (I'm avoiding DMSO because of a methionine present in the peptide) - peptide still visibly precipitates out at 100uM in 5% DMF (also a 1mM stock in 50% DMF shows significant amounts of ppt) Adding a trace amount of detergent (0.005% Tween 20) I'm guessing I could try other co-solvents such as ethanol or initially solubilizing peptide in dilute NaOH before bringing the pH down with addition of a buffer (though I'm concerned about alkaline hydrolysis). Anyway, I'd rather have some insight from people before I waste any further peptide. Thanks for any suggestions.
