<Tr> <Th> PDBsum </Th> <Td> structure summary </Td> </Tr> <P> α - Amylase is a protein enzyme EC 3.2. 1.1 that hydrolyses alpha bonds of large, alpha - linked polysaccharides, such as starch and glycogen, yielding glucose and maltose . It is the major form of amylase found in humans and other mammals . It is also present in seeds containing starch as a food reserve, and is secreted by many fungi . </P> <P> Although found in many tissues, amylase is most prominent in pancreatic juice and saliva, each of which has its own isoform of human α - amylase . They behave differently on isoelectric focusing, and can also be separated in testing by using specific monoclonal antibodies . In humans, all amylase isoforms link to chromosome 1p 21 (see AMY1A). </P> <P> Amylase is found in saliva and breaks starch into maltose and dextrin . This form of amylase is also called "ptyalin" / ˈtaɪəlɪn / It will break large, insoluble starch molecules into soluble starches (amylodextrin, erythrodextrin, and achrodextrin) producing successively smaller starches and ultimately maltose . Ptyalin acts on linear α (1, 4) glycosidic linkages, but compound hydrolysis requires an enzyme that acts on branched products . Salivary amylase is inactivated in the stomach by gastric acid . In gastric juice adjusted to pH 3.3, ptyalin was totally inactivated in 20 minutes at 37 ° C. In contrast, 50% of amylase activity remained after 150 minutes of exposure to gastric juice at pH 4.3 . Both starch, the substrate for ptyalin, and the product (short chains of glucose) are able to partially protect it against inactivation by gastric acid . Ptyalin added to buffer at pH 3.0 underwent complete inactivation in 120 minutes; however, addition of starch at a 0.1% level resulted in 10% of the activity remaining, and similar addition of starch to a 1.0% level resulted in about 40% of the activity remaining at 120 minutes . </P>

Where is alpha amylase found in the body