Β-Amylase

β-Amylase (EC 3.2.1.2, saccharogen amylase, glycogenase) is an enzyme with the systematic name 4-α-D-glucan maltohydrolase.^[2][3][4] It catalyses the following reaction:

Hydrolysis of (1→4)-α-D-glucosidic linkages in polysaccharides so as to remove successive maltose units from the non-reducing ends of the chains

β-amylase
Structure of barley beta-amylase. PDB 2xfr[1]
Identifiers
EC no.	3.2.1.2
CAS no.	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 / QuickGO
Search PMC articles PubMed articles NCBI proteins

This enzyme acts on starch, glycogen and related polysaccharides and oligosaccharides producing beta-maltose by an inversion. Beta-amylase is found in bacteria, fungi, and plants; 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] They belong to Glycoside hydrolase family 14.

See also

• Amylase
• Alpha-amylase

References

1. 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. PMID 21085740.
2. Balls AK, Walden MK, Thompson RR (March 1948). "A crystalline β-amylase from sweet potatoes". The Journal of Biological Chemistry. 173 (1): 9–19. doi:10.1016/S0021-9258(18)35550-9. PMID 18902365.
3. French D (1960). "β-Amylases". In Boyer PD, Lardy H, Myrbaumlck K (eds.). The Enzymes. Vol. 4 (2nd ed.). New York: Academic Press. pp. 345–368.
4. Manners DJ (1962). "Enzymic synthesis and degradation of starch and glycogen". Advances in Carbohydrate Chemistry. 17: 371–430. doi:10.1016/s0096-5332(08)60139-3. ISBN 9780120072170.
5. "Amylase, Alpha", I.U.B.: 3.2.1.11,4-α-D-Glucan glucanohydrolase.

Further reading

• Friedberg F, Rhodes C (March 1986). "Cloning and characterization of the β-amylase gene from Bacillus polymyxa". Journal of Bacteriology. 165 (3): 819–24. doi:10.1128/JB.165.3.819-824.1986. PMC 214501. PMID 2419310.
• Rhodes C, Strasser J, Friedberg F (May 1987). "Sequence of an active fragment of B. polymyxa β amylase". Nucleic Acids Research. 15 (9): 3934. doi:10.1093/nar/15.9.3934. PMC 340808. PMID 2438660.

External links

• "Amylase, Alpha", I.U.B.: 3.2.1.11,4-α-D-Glucan glucanohydrolase. "Amylase, Alpha", I.U.B.: 3.2.1.11,4-α-D-Glucan glucanohydrolase.

External links

• Beta-amylase at the U.S. National Library of Medicine Medical Subject Headings (MeSH)