glycoside hydrolase family 13

{{Infobox protein family

| Symbol = Alpha-amylase_N

| Name = Alpha amylase, N-terminal ig-like domain

| image = PDB 2d0h EBI.jpg

| width =

| caption = crystal structure of thermoactinomyces vulgaris r-47 alpha-amylase 1 (tvai) mutant d356n/e396q complexed with p2, a pullulan model oligosaccharide

| Pfam = PF02903

| Pfam_clan =

| InterPro = IPR004185

| SMART =

| PROSITE =

| MEROPS =

| SCOP = 1sma

| TCDB =

| OPM family =

| OPM protein =

| CAZy =

| CDD =

}}

{{Infobox protein family

| Symbol = Alpha-amylase

| Name = Alpha-amylase catalytic domain

| image = PDB 1cyg EBI.jpg

| width =

| caption = cyclodextrin glucanotransferase (e.c.2.4.1.19) (cgtase)

| Pfam = PF00128

| Pfam_clan = CL0058

| InterPro = IPR006047

| SMART =

| PROSITE =

| MEROPS =

| SCOP = 1ppi

| TCDB =

| OPM family =

| OPM protein =

| CAZy = GH13

| CDD =

}}

In molecular biology, glycoside hydrolase family 13 is a family of glycoside hydrolases.

Glycoside hydrolases {{EC number|3.2.1.}} are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. A classification system for glycoside hydrolases, based on sequence similarity, has led to the definition of >100 different families.{{cite journal | vauthors = Henrissat B, Callebaut I, Fabrega S, Lehn P, Mornon JP, Davies G | title = Conserved catalytic machinery and the prediction of a common fold for several families of glycosyl hydrolases | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 92 | issue = 15 | pages = 7090–4 | date = July 1995 | pmid = 7624375 | pmc = 41477 | doi = 10.1073/pnas.92.15.7090 | bibcode = 1995PNAS...92.7090H | doi-access = free }}{{cite journal | vauthors = Davies G, Henrissat B | title = Structures and mechanisms of glycosyl hydrolases | journal = Structure | volume = 3 | issue = 9 | pages = 853–9 | date = September 1995 | pmid = 8535779 | doi = 10.1016/S0969-2126(01)00220-9 | doi-access = free }}{{cite journal | vauthors = Henrissat B, Bairoch A | title = Updating the sequence-based classification of glycosyl hydrolases | journal = The Biochemical Journal | volume = 316 | issue = Pt 2 | pages = 695–6 | date = June 1996 | pmid = 8687420 | pmc = 1217404 | doi=10.1042/bj3160695}} This classification is available on the CAZy web site,{{Cite web|url=http://www.cazy.org/|title=Home|website=CAZy.org|language=en|access-date=2018-03-06}}{{cite journal | vauthors = Lombard V, Golaconda Ramulu H, Drula E, Coutinho PM, Henrissat B | title = The carbohydrate-active enzymes database (CAZy) in 2013 | journal = Nucleic Acids Research | volume = 42 | issue = Database issue | pages = D490–5 | date = January 2014 | pmid = 24270786 | pmc = 3965031 | doi = 10.1093/nar/gkt1178 | url = }} and also discussed at CAZypedia, an online encyclopedia of carbohydrate active enzymes.{{Cite web|url=http://www.cazypedia.org/index.php/Glycoside_Hydrolase_Family_13|title=Glycoside Hydrolase Family 13|website=CAZypedia.org|language=en|access-date=2018-03-06}}{{cite journal | title = Ten years of CAZypedia: a living encyclopedia of carbohydrate-active enzymes | journal = Glycobiology | volume = 28 | issue = 1 | pages = 3–8 | date = December 2018 | pmid = 29040563 | doi = 10.1093/glycob/cwx089 | author1 = CAZypedia Consortium | url = https://hal.archives-ouvertes.fr/hal-01886461/file/Hehemann_2018_01.pdf | doi-access = free }}

Enzymes containing this domain belong to family 13 ([http://www.cazypedia.org/index.php/Glycoside_Hydrolase_Family_13 CAZY GH_13]) of the glycosyl hydrolases. The maltogenic alpha-amylase is an enzyme which catalyses hydrolysis of (1-4)-alpha-D-glucosidic linkages in polysaccharides so as to remove successive alpha-maltose residues from the non-reducing ends of the chains in the conversion of starch to maltose. Other enzymes in this family include neopullulanase, which hydrolyses pullulan to panose, and cyclomaltodextrinase, which hydrolyses cyclodextrins.