Enrico,
+48 in a cysteine peptide generally indicates oxidation to the sulfeic
(sulfonic) acid (R = -CH2-SO3H)
As far as I know it's pretty much irreversible at this point. As for
minimizing this reaction in the future, I generally prefer trityl blocking
on Cys, with reagent K or R for cleavage.
Mark
-----Original Message-----
From: Enrico Millo [mailto:millo@vega.cba.unige.it]
Sent: Saturday, March 24, 2001 5:36 AM
To: Recipients of ABRF List
Subject: PEP synt
Dear ABRF,
I made a peptide with spps Fmoc strategy, in ESI-MS I see a m/z + 48(about
40%) with respect of molecular weight. What 's happen? Is there someone that
can help me?
The sequence is:
KTVKQPHVQACVDNSIVHLDVCQLKKPTLF
The mix of cleavage:
TFA-TIS-EDT-H2O
Thank a lot
Enrico Millo
Dr Enrico Millo
Department of Experimental Medicine, Biochemistry section
University of Genoa
CBA Largo R. Benzi 10
16132 Genoa
Italy
39 10 5737452
39 10 5737270 FAX
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