Re: Pepsyn, +14 adduct of N-terminal Cys

FranÁoise Baleux (baleux@pasteur.fr)
Thu, 28 Oct 1999 11:35:22 +0100

Messages sorted by: [ date ][ thread ][ subject ][ author ]
Next message: Steven Johnson: "Re: HPLC of protected peptide fragments"
Previous message: John Wade: "Nin-formyl tryptophan"
Maybe in reply to: FranÁoise Baleux: "Pepsyn, +14 adduct of N-terminal Cys"

>Date: Wed, 27 Oct 1999 14:00:17 +0100
>To: "Singleton, David H" <david_h_singleton@groton.pfizer.com>
>From: FranÁoise Baleux <baleux@pasteur.fr>
>Subject: Re: Pepsyn, +14 adduct of N-terminal Cys
>Cc:
>Bcc:
>X-Attachments:
>
>Dear David,
>
>Recently, PE Biosystems recommended us to use IsoPrOH for final wash
>instead of MeOH. According to them, "there is evidence that a side
>reaction can occur when synthesizing peptides on PEG_PS resin that have
>the first AA attached and when using methanol as final wash. The major
>side product (60/40 by HPLC in their example)has a molecular weight 14
>mass units (methyl adduct from MeOH) higher than the desired peptide .
>Some resins, such as Fmoc-Gly-PEG-PS are much prone to this side
>reaction". Using IsoPrOH eliminate this side reaction (you must only
>increase the drying time of your resin-peptide).
>
>We have never seen this side product (may be we extensively dry our
>peptide-resin) for 3 years of peptide synthesis using Fmoc chemistry on
>our Pioneer instrument (PE Biosystems), using MeOH as final wash.
>We saw this adduct a long time before with Boc chemistry with
>Boc-His(BOM)OH and a N-ter Cys residu .This was of course, the
>well-documented N-ter thiazolidone formation, as you write.
>
>FranÁoise BALEUX
>
>
>

FranÁoise Baleux
Institut Pasteur
UnitÈ de Chimie Organique
28 rue du Dr Roux
75724 Paris cedex 15

Tel: (33) 145 68 83 96
Fax: (33) 145 68 84 04
e.mail: baleux@pasteur.fr

Next message: Steven Johnson: "Re: HPLC of protected peptide fragments"
Previous message: John Wade: "Nin-formyl tryptophan"
Maybe in reply to: FranÁoise Baleux: "Pepsyn, +14 adduct of N-terminal Cys"