Does the presence of a GST tag have influence on docking and binding interactions of the substrate with the tagged enzyme? If not, can any one suggest some reference?
It mainly depends on the PDB structure you are going to use. You may remove GST tag from structure before preparing it for docking. Alternatively If the GST tag is not adjacent to active site of the molecules it can be left like that. I suggest looking for structure without GST tag in PDB...
It should not affect if you are using a good docking program. GST and other fusion tags are generally easy to identify computationally. However, just to be sure you can run the Docking both with and without the GST and see if the result converges. If they do not, I would suggest trying what Arvind said