Date: Tue, 14 Jan 1997 23:28:54 GMT
Message-Id: <v02140b02af0155e95f8e@[134.197.50.216]>
From: schooley@unr.edu (David A. Schooley)
Subject: Re: pepsyn
To: Recipients of ABRF List <abrf@aecom.yu.edu>
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