Date: Wed, 22 Jan 1997 10:30:20 -0800
Message-Id: <199701221830.KAA12808@leonardo.ls.huji.ac.il>
From: "assaf friedler" <fasaf@leonardo.ls.huji.ac.il>
Subject: Re: HPLC
To: Recipients of ABRF List <abrf@aecom.yu.edu>
In message <9701211732.AA07061@uts.univ.trieste.it> writes:
>
> --zyxwvutsrqponmlkjihgfedcba
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>
> Hello everybody,
>
> We have a synthetic amidated peptide which is giving us a problems in HPLC.
> The
> crude material gave a fairly broad band with shoulders. We identified the
> correct fraction and isolated it. The purified material now shows an odd
> saw-tooth like background preceding a central peak with lots of shoulders.
> The
> peptide also seems to ionize poorly in ES-MS, giving weak signals. The only
> unusual aspect of this peptide for us is the presence of Cys at the
> C-terminal.
Hello
I had many problems with peptides that have Cys at the C-terminus. They were
very difficult to purify. One of the reasons is that the Cys in C-terminus
undergoes racemization very easily. I also had problems of oxidation of cys
during the cleavage from the resin.
Assaf Friedler
Dept. of Organic Chemistry
The Hebrew University of Jerusalem
Israel