Initial Methionine E Coli

ChenHA hzhen at freeuk.com
Mon Feb 14 19:43:04 EST 2000


Luc CAMOIN wrote:

> Dear Netters,
>
> I purified a recombinant protein from E Coli. The N-terminal sequence and
> Mass spectrometry experiments show that the initial methionine is eliminated
> in 90% of the purified protein.
>
> Does anyone have any explanation about this phenomenon?
>

It's the effect of the second residue.  See

Hirel et al, (89) PNAS 86, 8247-8251

Briefly, small uncharged second residues (e.g. glycine, alanine) result in
efficient removal of N-terminal methionine, while large, charged or aromatic
residues result in inefficient removal of methionine.  For those in-between the
effectiveness of removal may depends on fermentation conditions.

>
> Thanks in advance
>
> Luc CAMOIN
>
> --
> Luc CAMOIN
> Tel:+33 1 40 51 64 98
> Fax:+33 1 40 51 72 10
> Institut Cochin de Génétique Moléculaire / Groupe Chimie des Protéines
> Laboratoire d'Immuno-Pharmacologie Moleculaire / CNRS UPR 415
> 22 rue Méchain
> 75014 Paris France
> Internet:    http://www.cochin.inserm.fr/upr415/UPR415E2.htm
>





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