Message-Id: <9701151216.AA19716@ibch.siobc.ras.ru>
From: "Vladimir Titov" <titov@ibch>
Date: Wed, 15 Jan 1997 15:17:48 +0300
Subject: Re: pepsyn
In-Reply-To: <v02140b02af0155e95f8e@[134.197.50.216]>
To: Recipients of ABRF List <abrf@aecom.yu.edu>
> True pyroglutamic acid (such as Aldrich P7,520-2,
> (S)-2-pyrrolidinone-5-carboxylic acid, CANNOT be converted to a Z, T-Boc,
> or FMOC derivative, as it has no amino group- that becomes an amide on
> conversion to pGlu. Sounds like you may have started with Z-glutamic
> acid?? What you may be seeing is some of the peptide with N-terminal Glu,
> some with N-terminal pyroGlu (same as N-terminal Glu -water in molecular
> weight), and some that is still protected???? Or did you start with
> Z-glutamine? The latter will spontaneously form pyroGlu under basic
> conditions, Z-Glu will not.
>
You are not correct. There is still a proton which may be substituted
(nobody wanders about Z-Pro). Both Boc- and Z-pGlu are commercially
available and rumoured to give more reliable couplings than unprotected
pGlu.
Vladimir Titov
MailTo:titov@ibch.siobc.ras.ru
http://titov.siobc.ras.ru