There are three classification of amylase:

α - alpha-amylase
EC 3.2.1.1 / CAS# 9014-71-5
alternate names:1,4-a-D-glucan glucanohydrolase; glycogenase
The a-amylases are calcium metalloenzymes, completely unable to function in the absence of calcium. By acting at random locations along the starch chain, a-amylase breaks down long-chain carbohydrates, ultimately yielding maltotriose and maltose from amylose, or maltose, glucose and "limit dextrin" from amylopectin. Because it can act anywhere on the substrate, a-amylase tends to be faster-acting than ß-amylase. In animals, it is a major digestive enzyme.

β - beta-amylase
EC 3.2.1.2
alternate names: 1,4-a-D-glucan maltohydrolase; glycogenase; saccharogen amylase Another form of amylase, ß-amylase is also synthesized by bacteria, fungi, and plants. Working from the non-reducing end, ß-amylase catalyzes the hydrolysis of the second a-1,4 glycosidic bond, cleaving off two glucose units (maltose) at a time. During the ripening of fruit, ß-amylase breaks starch into sugar, resulting in the sweet flavor of ripe fruit. Both are present in seeds; ß-amylase is present prior to germination, whereas a-amylase and proteases appear once germination has begun. Cereal grain amylase is key to the production of malt. Many microbes also produce amylase to degrade extracellular starches. Animal tissues do not contain ß-amylase, although it may be present in microrganisms contained within the digestive tract.

γ - gluco-amylase
EC 3.2.1.3
alternative names: Glucan 1,4-a-glucosidase; amyloglucosidase; Exo-1,4-a-glucosidase;glucoamylase; lysosomal a-glucosidase; 1,4-a-D-glucan glucohydrolase.

In addition to cleaving the last a(1-4)glycosidic linkages at the nonreducing end of amylose and amylopectin, yielding glucose, α-amylase will cleave a(1-6) glycosidic linkages.