Homotrimer-ONE!!! binding site?

John Kuszewski johnk at spasm.niddk.nih.gov
Fri Mar 31 15:20:05 EST 1995


In article <Pine.ULT.3.90a.950327125443.1707A-100000 at bgumail.bgu.ac.il>, aflaloc at BGUMAIL.BGU.AC.IL (Claude Aflalo) writes:
|> On Mon, 27 Mar 1995, Ralf Morgenstern wrote:
|> 
|> > Our binding studies indicate that microsomal glutathione transferase binds
|> > only one GSH per homotrimer. Are there known examples of homotrimers (or
|> > homooligomers) with one binding site only. I have a hard time envisioning
|> > this because of symmetry reasons (or lack of imagination). Perhaps three
|> > overlapping sites exist of which only one can be occupied at a time. Does
|> > anyone know of examples that describe this situation.
|> > -- 
|> > Ralf Morgenstern, IMM, Karolinska Institutet, Box 210, S-17177, SWEDEN
|> > Tlf. +46-8-7287574, Fax, +46-8-334467, E-mail: ralf.morgenstern at imm.ki.se
|> > 
|> > 
|> Have a look at the "Alternating binding change" mechanism propose by Paul 
|> D. Boyer in the 80's for the mechanism of ATP synthase (F0F1) of bacteria,
|> chloroplasts and mitochondria. The enzyme has 6 binding sites for 
|> nucleotides, 3 of them act as alternating catalytic sites. The mechanism 
|> is characterized by negative cooperativity in binding AND positive 
|> cooperativity in catalysis.
|> 
|> Claude Aflalo ###########################################################
|> Dept. of Life Sciences			Phones: Office 972-7-472118
|> Ben Gurion University of the Negev	        Lab    972-7-472119
|> P.O.Box 653				        Fax    972-7-276201
|> Beer Sheva 84105 Israel			email:  aflaloc at bgumail.bgu.ac.il
|> 

Or have a look at the GroEL structure.  It has 14 monomers, and each has a 
binding site, but only one binding site per 14mer is active at any one time.

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John Kuszewski                     ||  |/  /|  ||      
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