We switched from the OPFp esters to HATU activation after some
much-improved results on a peptide that we were having trouble with.
That might help. This sequence actually doesn't look particularly
hydrophobic. I've synthesized much more hydrophobic peptides without
any special problems.
> I am having a problem synthesizing a peptide with the sequence
> PITKYIMTCMSADLEVVT. I am using std FMOC chemsitry with OPfp esters,
> 20% Pip as the deblock, DMA as the solvent and PEG-PS as the starting
> resin. I am using a 9050 instrument. I dried the resin and cleaved in
> 92.5 % TFA, 2.5% TIS, 2.5% ethanethiol for 2 hrs. I precipitated the
> peptide in fresh ether and washed it 3x. The pellet was dried on a
> lyophilizer. The resulting pellet was very granular. I tested the
> crude peptide using RPHPLC, 5-60% ACN and saw no clear peak. I sent
> the crude out for ES MS analysis and the tracing showed alot of noise
> but no target peptide. I know this sequence is very hydrophobic and I
> may have to change my purification strategy but I don't feel like I
> even have the peptide on the resin yet. Any sugesstions would be
> appreciated.
-- Michael Pereckas // msp@mcw.edu // Michael.Pereckas@mixcom.com Protein and Nucleic Acid Shared Facility, Medical College of Wisconsin Research Technologist and sysadmin/webmaster of www.biochem.mcw.edu