Hydrolysis of (1→4)-α-D-glucosidic linkages in polysaccharides so as to remove successive maltose units from thenon-reducing ends of the chains
This enzyme acts onstarch,glycogen and relatedpolysaccharides andoligosaccharides producing beta-maltose by an inversion. Beta-amylase is found inbacteria,fungi, andplants; bacteria and cereal sources are the most heat stable. Working from the non-reducing end, β-amylase catalyzes the hydrolysis of the second α-1,4glycosidic bond, cleaving off two glucose units (maltose) at a time. During theripening offruit, β-amylase breaks starch into maltose, resulting in the sweet flavor of ripe fruit.
β-amylase is present in an inactive form prior to seedgermination. Manymicrobes also produce amylase to degrade extracellular starches. Animal tissues do not contain β-amylase, although it may be present in microorganisms contained within thedigestive tract. The optimum pH for β-amylase is 4.0–5.0[5] They belong toglycoside hydrolase family 14.
^Rejzek M, Stevenson CE, Southard AM, Stanley D, Denyer K, Smith AM, Naldrett MJ, Lawson DM, Field RA (March 2011). "Chemical genetics and cereal starch metabolism: structural basis of the non-covalent and covalent inhibition of barley β-amylase".Molecular BioSystems.7 (3):718–30.doi:10.1039/c0mb00204f.PMID21085740.
