You can find more information about different enzymes and their functionality on this page:
As to sources for smaller usage quantities, you might want to ask the enzyme producer which ingredient distributors they work with. Corbion for example may have what you need in a smaller quantity, or can direct you to a distributor who sells their ingredients. I use UL Prospector often to search for suppliers of certain ingredients. http://www.ulprospector.com
Please do let us know how you make out!