Hydrophobic Peptide: Fragment Detection

[Rick Neubig]

newitt at ncifcrf.gov (John A. Newitt) wrote:

>> We are working with a 25 amino acid peptide ... extremely hydrophobic ...
>> which was synthesized solid phase using Fmoc chemistry. After HPLC
>> (reverse phase), Mass Spec indicated the presence of fragments. Further
>> Mass Spec experiments indicate that laser desorption will cause these same
>> fragments, but do not rule out the presence of the fragments *prior* to
>> Mass Spec. The components differ by  approximately 500 MW.
>> 
>> Question: What is the best (and preferably quickest) method to determine
>> the presence of fragments, assuming the sample is supposed to contain only
>> pure peptide?


You could try an analytical HPLC to see if there are multiple
peaks. As with the N terminal analysis, negative results aren't
definitive but would make you feel more comfortable about
the integrity of your sample.

_________________________________________________________
Rick Neubig                             RNeubig at umich.edu
University of Michigan               Phone (313) 763-3650
http://www.umich.edu/~rneubig        FAX   (313) 763-4450