Background: A friend of mine does ten gallon batches of big beers, so has a lot of grain. After mashing, his technique is to fly sparge with 170 degree water. I understand this shuts-down enzymatic conversion. He'll run out of sparge water, drain maybe 2/3 of the liquid from mash tun, and then lets me do whatever I want with the mash tun in order to make a second-run (partigyle) beer.
What I do during his sparging is to create a separate small mash with two pounds of two row, and get the enzymatic activity going well there. Then, when the large mash tun becomes available, I adjust the temperature there to normal mashing temperature again (in the 150 F range), then mix in my small mash with the active enzymes (and enough appropriately heated water to mix in and come to rest at normal mashing temperature).
The Question: Will the enzymes in the small mash that are added to the large mash cause enzymatic activity in that grain that, earlier, had been "too hot"? I realize that the first large mash did most of the conversion. This question is about what is left. Will the enzymes in the small mash have a positive effect on the conversion of grains from the original mash?
Please only answer if you include references; we all likely have our ideas in the range of "probably should" or "probably shouldn't" get conversion going in the old grain, but I'm looking for something more definitive, a why it will or why it won't work, if at all possible. Also, not interested in comments or suggested changes about the background...that's just the way it is, and what I have to deal with.