Want to minimize the complex sugars that can't be consumed by yeast, or are creating a mash that uses a high percentage of fermentables that are lacking in enzymes (e.g. not base malts)? This will help get the most starches converted possible, giving you a dry beer / higher alcohol spirit wash. This bacterially-derived, powdered α-amylase enzyme will break down gelatinised starch to yield short chain dextrins and simple sugars that your yeast can then convert into alcohol.
 
Note: If you're trying to mash raw grains that haven't been malted, you'll need to boil the grains first to gelatanize the starches (otherwise the enzymes won't have anything they can convert into sugars).
 
Optimal Conditions for Conversion:
pH: 5.3-5.7
Temperature: 70°C