Alpha-amylase
class of enzymes
α-Amylase is an enzyme. It breaks down (hydrolyses) the bonds of large α-linked polysaccharides, such as starch and glycogen. This gives shorter chains of dextrin and maltose.
It is the main form of amylase in humans and other mammals. It is also present in seeds containing starch as a food reserve, and is secreted by many fungi.
Many people have more than one α-Amylase because they have tandem repeats of the gene. That shows how important the gene became to humans in their relatively recent evolution..
A diastase is any enzyme which breaks down starch.