Homotrimer-ONE!!! binding site?

Claude Aflalo aflaloc at BGUMAIL.BGU.AC.IL
Mon Mar 27 06:05:30 EST 1995


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




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