Your protein may be glycosilated at the N-terminal. If the first four
aminoacids are glycosilated you cannot see them in the chromatograms, because
they elute outside the gradient region. In this case, the 5th residue appears
like a typical 1st cycle. The other possibility is that the first four
aminoacids are unusual, falling in uncommon regions of the chromatogram. But
this is much less probable.
Ricardo.
Amanda Hall wrote:
>
> Hi everyone,
>
> I just put a sample (short tryptic peptide on a Biobrene treated filter) on
> the protein sequencer and saw nothing for the 1st 4 residues. Then suddenly
> in the 5th residue cycles numerous AA's appeared and I am now getting
> sequence. The 5th residue looked very much like a typical 1st residue cycle
> with high levels of Glu and gly. Has anyone ever seen this before and what
> causes it?
>
> thanks a lot
>
> Amanda Hall
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Ricardo Bastos Cunha
Brazilian Center of Protein Core Facilities and Research - UnB
mailto:rbcunha@unb.br
http://www.unb.br/cbsp/CBSP.html
http://www.geocities.com/Athens/Acropolis/5221
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