B-amylase
| Beta-amylase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 | |||||||||
| Identifiers | |||||||||
| EC number | 3.2.1.2 | ||||||||
| CAS number | 9000-91-3 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / EGO | ||||||||
| |||||||||
Beta-amylase (EC 3.2.1.2, saccharogen amylase, glycogenase, beta amylase, 1,4-alpha-D-glucan maltohydrolase) is an enzyme with systematic name 4-alpha-D-glucan maltohydrolase.[2][3][4] This enzyme catalyses the following chemical reaction
- Hydrolysis of (1->4)-alpha-D-glucosidic linkages in polysaccharides so as to remove successive maltose units from the non-reducing ends of the chains
This enzyme acts on starch, glycogen and related polysaccharides and oligosaccharides producing beta-maltose by an inversion. Alpha-amylase is found in bacteria, fungi, and plants and bacteria and cereal sources are the most heat stable. Working from the non-reducing end, β-amylase catalyzes the hydrolysis of the second α-1,4 glycosidic bond, cleaving off two glucose units (maltose) at a time. During the ripening of fruit, β-amylase breaks starch into maltose, resulting in the sweet flavor of ripe fruit.
β-amylase is present in an inactive form prior to seed germination. Many microbes also produce amylase to degrade extracellular starches. Animal tissues do not contain β-amylase, although it may be present in microorganisms contained within the digestive tract. The optimum pH for β-amylase is 4.0–5.0[5]
See also
References
- ↑ Rejzek, M.; Stevenson, C. E.; Southard, A. M.; Stanley, D.; Denyer, K.; Smith, A. M.; Naldrett, M. J.; Lawson, D. M.; Field, R. A. (2011). "Chemical genetics and cereal starch metabolism: Structural basis of the non-covalent and covalent inhibition of barley β-amylase". Molecular BioSystems. 7 (3): 718–730. doi:10.1039/c0mb00204f. PMID 21085740.
- ↑ Balls, A.K.; Walden, M.K.; Thompson, R.R. (1948). "A crystalline β-amylase from sweet potatoes". J. Biol. Chem. 173: 9–19.
- ↑ French, D. (1960). "β-Amylases". In Boyer, P.D.; Lardy, H.; Myrbaumlck, K. The Enzymes. 4 (2nd ed.). New York: Academic Press. pp. 345–368.
- ↑ Manners, D.J. (1962). "Enzymic synthesis and degradation of starch and glycogen". Adv. Carbohydr. Chem. 17: 371–430. doi:10.1016/s0096-5332(08)60139-3.
- ↑ "Amylase, Alpha" , I.U.B.: 3.2.1.11,4-α-D-Glucan glucanohydrolase.
External links
- Beta-amylase at the US National Library of Medicine Medical Subject Headings (MeSH)