Re: hydrophobic peptides

Marcus Macht (Marcus.Macht@uni-koeln.de)
Fri, 09 Jul 1999 09:58:31 +0100

At 11:59 08.07.99 -0700, you wrote:
>
>
>I have a glycoprotein with a highly hydrophobic peptide backbone that remains
>soluable when glycosylated. However, when I digest and deglycosylate,
>the hydrophobic peptides precipitate from solution. By holding the
solution in
>guanidine, I am able to arrest any visible precipitation however, my
recovery of
>2 peptides is only 50%. These peptides have ~30% leucine or isoleucine
residues.
>Ugh. The remaining peptide peices are not very hydrophobic and are recovered
>well. At present I am using a Jupiter C4 column with water/acetonitrile/tfa
>mobile phase.
>
>Are there any ideas about how to increase my recoveries for these 2
peptides? I
>am guessing that they're lost in the tube but perhaps they are lost once
they're
>injected. Has anyone put guanidine in their mobile phase?
>
>Thanks for your help.
>Shawn Novick
>
Dear Shawn,

you can try to modify your organic mobile phase. In the group where I did
my PhD, some people worked on an extremly hydrophobic protein which
consisted of around 65% of Leu, Ile and Val and was additionally
palmitoylated. They made the HPLC using isopropanol as organic phase
because it has a higher solvent strength than acetonitrile. If you want to
have more details, you can have a look into: P. Mayer-Fligge et al.,
Synthesis and structural characterization of human-identical lung
surfactant SP-C protein, J. Pept. Sci.. 1998 Aug;4(5):355-63.

Yours sincerely,
Marcus Macht
******************************************************************
Dr. Marcus Macht
ZMMK-Servicelabor
Joseph-Stelzmann-Str. 52
50931 Koeln
Tel.: +49 221 478-6995
Fax: +49 221 478-6977
e-mail: Marcus.Macht@uni-koeln.de
******************************************************************