Date: Wed, 15 Jan 1997 05:06:30 -0600 (CST)
From: George Barany <barany@maroon.tc.umn.edu>
Subject: Re: pepsyn
In-Reply-To: <v02140b02af0155e95f8e@[134.197.50.216]>
To: Recipients of ABRF List <abrf@aecom.yu.edu>
David, as strange as it sounds, one can make protected derivatives of
pGlu, and i believe that they are commercially available. i can't recite
chapter and verse without spending some time looking it up, but i am quite
certain of this. i remember learning about this still in graduate school,
being puzzled, and asking someone more senior about it -- the explanation
had something to do with the resultant derivatives being more soluble.
you are quite right that the amide in pGlu will not be acylated by normal
peptide synthesis coupling reagents. Does anybody have more insights into
this? GB
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
George Barany Telephone: (612) 625-1028
Professor of Chemistry,
Laboratory Medicine & Pathology
Department of Chemistry FAX: (612) 626-7541
University of Minnesota e-mail: barany@maroon.tc.umn.edu
207 Pleasant St. S.E.
Minneapolis, MN 55455
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
>
>