Are enzymes used up in the conversion process?

[InspectorJon]

I did a Google search on this question and could not find an answer. The answer may have bee buried in one of the long technical papers I could not really understand. I understand that the amylase enzymes are denatured by high temperatures and work slower at lower temperatures but are they actually used up? The application question is this: If the enzyme level is low, will the enzymes keep working until all the starches they are capable of converting are converted but just take a long time or do they get broken down or wear out at some point?

 

[AlexKay]

The enzymes do not wear out from use; they bind reagents, unbind products, and are left unchanged. In theory, low enzyme levels could be used in a cool mash for a long time to get complete or near-complete conversion.

But there are practical limits. Denaturation slows down at lower temperatures but does not stop completely; you'll get more turnovers per enzyme, but you'll still eventually lose the enzyme. (I suspect the denaturation rate versus temperature is complex, so how much improvement you get may be hard to predict.) And you can't keep dropping the temperature and extending the time: a days-long mash at 100 F is only going to get you lactobacillus growth.