Glycoside hydrolase family 19

Short description: Enzyme

Glycosyl hydrolases family 19

the refined crystal structure of an endochitinase from hordeum vulgare l. seeds to 1.8 angstroms resolution

Identifiers
Symbol| Glyco_hydro_19
Pfam| PF00182
Pfam clan| CL0037
InterPro| IPR000726
PROSITE| PDOC00620
SCOP2| 2baa / SCOPe / SUPFAM
CAZy| GH19
CDD| cd00325
| Available protein structures:

Pfam | structures / ECOD
PDB| RCSB PDB; PDBe; PDBj
PDBsum| structure summary

In molecular biology, Glycoside hydrolase family 19 is a family of glycoside hydrolases EC 3.2.1., which 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.[1][2][3] This classification is available on the CAZy web site,[4][5] and also discussed at CAZypedia, an online encyclopedia of carbohydrate active enzymes.[6][7] y[ _]9

Glycoside hydrolase family 19 CAZY GH_19 comprises enzymes with only one known activity; chitinase (EC 3.2.1.14).

Chitinases[8] are enzymes that catalyze the hydrolysis of the beta-1,4-N-acetyl-D-glucosamine linkages in chitin polymers. Chitinases belong to glycoside hydrolase families 18 or 19.[9] Chitinases of family 19 (also known as classes IA or I and IB or II) are enzymes from plants that function in the defence against fungal and insect pathogens by destroying their chitin-containing cell wall. Class IA/I and IB/II enzymes differ in the presence (IA/I) or absence (IB/II) of a N-terminal chitin-binding domain. The catalytic domain of these enzymes consist of about 220 to 230 amino acid residues.

## Active site

Active site of gycoside hydrolase family 19 papaya chitinase (PDB: 3cql​).[10] Conserved residues are shown surrounding the catalytic acid, Glu67. A GlcNAc2 unit binding in the -1 and +1 subsites is shown in narrow stick representation and an arrow indicates the position of the glycosidic oxygen.

GH19 enzymes has a conserved sequence motif ([FHY]-G-R-G-[AP]-ζ-Q-[IL]-[ST]-[FHYW]-[HN]-[FY]-[NY], ζ= hydrophilic amino acid) in its active site.[11]

## References

1. ↑ "Conserved catalytic machinery and the prediction of a common fold for several families of glycosyl hydrolases". Proceedings of the National Academy of Sciences of the United States of America 92 (15): 7090–4. July 1995. doi:10.1073/pnas.92.15.7090. PMID 7624375. Bibcode: 1995PNAS...92.7090H.
2. ↑ "Structures and mechanisms of glycosyl hydrolases". Structure 3 (9): 853–9. September 1995. doi:10.1016/S0969-2126(01)00220-9. PMID 8535779.
3. ↑ "Updating the sequence-based classification of glycosyl hydrolases". The Biochemical Journal 316 ( Pt 2) (Pt 2): 695–6. June 1996. doi:10.1042/bj3160695. PMID 8687420.
4. ↑ "Home" (in en). http://www.cazy.org/.
5. ↑ "The carbohydrate-active enzymes database (CAZy) in 2013". Nucleic Acids Research 42 (Database issue): D490-5. January 2014. doi:10.1093/nar/gkt1178. PMID 24270786.
6. ↑ "Glycoside Hydrolase Family 19" (in en). http://www.cazypedia.org/index.php/Glycoside_Hydrolase_Family_19.
7. ↑ CAZypedia Consortium (December 2018). "Ten years of CAZypedia: a living encyclopedia of carbohydrate-active enzymes". Glycobiology 28 (1): 3–8. doi:10.1093/glycob/cwx089. PMID 29040563. https://hal.archives-ouvertes.fr/hal-01886461/file/Hehemann_2018_01.pdf.
8. ↑ "What's new in chitinase research?". Experientia 48 (8): 701–16. August 1992. doi:10.1007/BF02124285. PMID 1516675.
9. ↑ "A classification of glycosyl hydrolases based on amino acid sequence similarities". The Biochemical Journal 280 ( Pt 2) (2): 309–16. December 1991. doi:10.1042/bj2800309. PMID 1747104.
10. ↑ "Structure and function of enzymes acting on chitin and chitosan". Biotechnology & Genetic Engineering Reviews 27 (1): 331–66. 2010-01-01. doi:10.1080/02648725.2010.10648156. PMID 21415904.
11. ↑ "Evolution, homology conservation, and identification of unique sequence signatures in GH19 family chitinases". Journal of Molecular Evolution 70 (5): 466–78. May 2010. doi:10.1007/s00239-010-9345-z. PMID 20480157. Bibcode: 2010JMolE..70..466U.

This article incorporates text from the public domain Pfam and InterPro: IPR000726

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Hydrolase: sugar hydrolases (EC 3.2)

3.2.1: Glycoside hydrolases|

| Disaccharidase|

* Sucrase/Sucrase-isomaltase]]/Invertase
* Maltase
* Trehalase
* Lactase

|

Glucosidases|

* Cellulase
* Alpha-glucosidase
* Acid
* Neutral AB
* Neutral C
* Beta-glucosidase
* cytosolic
* Debranching enzyme

Other|

* Amylase
* Alpha-amylase
* Chitinase
* Lysozyme
* Neuraminidase
* NEU1
* NEU2
* NEU3
* NEU4
* Bacterial neuraminidase
* Viral neuraminidase
* Galactosidases
* Alpha
* Beta
* alpha-Mannosidase
* Glucuronidase
* Klotho
* Hyaluronidase
* Pullulanase
* Glucosylceramidase
* lysosomal
* non-lysosomal
* Galactosylceramidase
* Alpha-N-acetylgalactosaminidase
* NAGA
* Alpha-N-acetylglucosaminidase
* Fucosidase
* Hexosaminidase
* HEXA
* HEXB
* Iduronidase
* Maltase-glucoamylase
* Heparanase
* HPSE2

3.2.2: Hydrolysing
N-Glycosyl compounds|

* DNA glycosylases: Oxoguanine glycosylase

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Enzymes

Activity|

* Active site
* Binding site
* Catalytic triad
* Oxyanion hole
* Enzyme promiscuity
* Catalytically perfect enzyme
* Coenzyme
* Cofactor
* Enzyme catalysis

Regulation|

* Allosteric regulation
* Cooperativity
* Enzyme inhibitor
* Enzyme activator

Classification|

* EC number
* Enzyme superfamily
* Enzyme family
* List of enzymes

Kinetics|

* Enzyme kinetics
* Eadie–Hofstee diagram
* Hanes–Woolf plot
* Lineweaver–Burk plot
* Michaelis–Menten kinetics

Types|

* EC1 Oxidoreductases (list)
* EC2 Transferases (list)
* EC3 Hydrolases (list)
* EC4 Lyases (list)
* EC5 Isomerases (list)
* EC6 Ligases (list)
* EC7 Translocases (list)

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