From: benoiton@aix1.uottawa.ca
Date: Wed, 15 Jan 1997 10:05:44 -0500 (EST)
Subject: Re: pepsyn
In-Reply-To: <v02140b02af0155e95f8e@[134.197.50.216]>
Message-Id: <Pine.A41.3.95.970115100045.39636A-100000@aix1.uottawa.ca>
To: Recipients of ABRF List <abrf@aecom.yu.edu>
Dear David Schooley:
I am sorry to advise that I submit you really did put your foot in it, as
the expression goes.
All Boc-, Z and Fmoc-pyroglutamic acid derivatives indeed do exist, and
can be used for peptide synthesis. They are not prepared by direct
acylation of pyroglutamic acid, but some cylization approach. I can
readily provide a reference for the BOc and Fmoc-derivatives if somone
wants them.
Leo Benoiton
benoiton@aix1.uottawa.ca
On Tue, 14 Jan 1997, David A. Schooley wrote:
> Pat-
> 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.
>
> >We are doing small molecule organic synthesis in our cominatorial
> >lab. We recently made some compounds which involve amide bond
> >formation using N-Z-Pyroglutamate as an acid monomer coupled with
> >various amines. Analytical HPLC of these samples exhibit high purity
> >(generally >90%). However, after having run these samples on HPLC, I
> >did ESI-MS on them the following day and some of them have 6, 8, 10
> >major ions that show up. My question is this. Is it possible that
>
> David
>
> David A. Schooley
> Dept. of Biochemistry/330
> Univ. of Nevada
> Reno, NV 89557
> schooley@med.unr.edu
> tel: (702) 784-4136; fax (702) 784-1419
>
>
>