gst pull down assay - (Nov/18/2005 )

Hello
I have recently read about GST pull down assay for protein purification.
What is the chemical reaction occurring between GST fusion protein and the glutathione that's attached to the beads?
None of the protocols I have read mentioned it.
Thank you.

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enzyme-substrate binding

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So the GST is the enzyme and the glutathione is the substrate and when a donor’s presence the GST transfers S to the glutathione?
To which glutathione’s atom does the enzyme attach the S?

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