Hydrophobic Peptide: Fragment Detection

John A. Newitt newitt at ncifcrf.gov
Thu Jul 27 17:15:56 EST 1995

In article <3v14s8$33e at newsbf02.news.aol.com>, a999999361 at aol.com
(A999999361) 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?

If you have access to a good protein chemistry facility, an N-terminus
analysis might tell you something.  If you get two or more distinct
N-terminal residues, your peptide definitely isn't pure.  A result that
only a single N-terminus exists, does NOT rule out the presence of
multiple peptides, however.


John A. Newitt, Ph.D.           |   <newitt at nih.gov>
National Institutes of Health   |   Tel: 301-402-4770
Bethesda, Maryland  USA         |   FAX: 301-402-0387

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