Glutathione sequence

Chris Penington chrisp at rschp1.anu.edu.au
Sun Mar 5 23:29:35 EST 1995


In article   writes:
>fdn.fr!jussieu.fr!univ-lyon1.fr!ghost.dsi.unimi.it!ictpsp10.ictp.trieste.it!genes.icgeb.trieste.it!buratti
>From: buratti at genes.icgeb.trieste.it (Emanuele Buratti)
>Newsgroups: bionet.molbio.proteins
>Subject: Glutathione sequence
>Date: 1 Mar 1995 12:20:52 GMT
>Organization: ICGEB
>Lines: 15
>Message-ID: <3j1or4$ke5 at ictpsp10.ictp.trieste.it>
>NNTP-Posting-Host: base.icgeb.trieste.it
>X-Newsreader: TIN [version 1.2 PL2]
>
>Hi all,
>	my question is:  the glutathione that is used to elute any GST
>fusion protein from the glutathine-derivatized affinity column has the
>sequence (GAMMA)Glu-Cys-Gly.  
>	Does anybody know whether the sequence (BETA)Glu-Cys-Gly present
>in the primary structure of a protein can also interact in the active site
>of the enzyme?. I seem to remember that it is the -SH part of the 
>tripeptide that does most of the docking, does the way the glutamic acid 
>is bound to the cysteine affect this interaction?.

I think this is fairly unlikely.  In the various structures of
vertebrate GSTs that have been published there are about 15 contacts
between enzyme and substrate.  The cysteine thiol is important for
conjugation reactions, but is not critical for binding of GSH to GST (
you can substitute it with a hydroxyl group and still get quite good
binding).  Adang's group has published a series of papers looking at a
variety of GSH analogs and found that the gamma glutamyl group is the
least tolerant to substitution and appears to play a critical role in
binding of GSH to the enzyme.  The crystallographic data supports this
conclusion: the enzymes make numerous contacts with the gamma-glutamyl
group.

	Chris


	
-- 
Chris Penington			       The opinions expressed are mine. NOT
Research School of Chemistry,          those of the school *or* the  university
Australian National University,
Canberra, ACT 0200			chrisp at rschp1.anu.edu.au



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