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PROSITE documentation PDOC00839 [for PROSITE entry PS01095]

Chitinases family 18 active site


Chitinases (EC [1] are enzymes that catalyze the hydrolysis of the β-1,4-N-acetyl-D-glucosamine linkages in chitin polymers. From the view point of sequence similarity chitinases belong to either family 18 or 19 in the classification of glycosyl hydrolases [2,E1]. Chitinases of family 18 (also known as classes III or V) groups a variety of proteins:

 a) Chitinases from:

 - Prokaryotes such as Alteromonas, Bacillus, Serratia, Streptomyces, etc.
 - Plants such as Arabidopsis, cucumber, bean, tobacco, etc.
 - Fungi such as Aphanocladium, Rhizopus, Saccharomyces, etc.
 - Nematode (Brugia malayi).
 - Insects (Manduca sexta).
 - Baculoviruses (Autographa Californica Nuclear Polyhedrosis virus).

 b) Other proteins:

 - Hevamine, a rubber tree protein with chitinase and lysozyme activities.
 - Kluyveromyces lactis killer toxin alpha subunit, which acts as a chitinase.
 - Flavobacterium and Streptomyces endo-beta-N-acetylglucosaminidases (EC 3.2.
 - Mammalian  di-N-acetylchitobiase  which  is  involved in the degradation of
   asparagine-linked glycoproteins.
 - Human cartilage glycoprotein Gp-39.
 - Jack  bean  concanavalin  B  (conB),  a protein that has lost its catalytic

Site directed mutagenesis experiments [3] and crystallographic data [4,5] have shown that a conserved glutamate is involved in the catalytic mechanism and probably acts as a proton donor. This glutamate is at the extremity of the best conserved region in these proteins.

Expert(s) to contact by email:

Neuhaus J.-M.
Henrissat B.

Last update:

November 1997 / Text revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

CHITINASE_18, PS01095; Chitinases family 18 active site  (PATTERN)


1AuthorsFlach J. Pilet P.-E. Jolles P.
TitleWhat's new in chitinase research?
SourceExperientia 48:701-716(1992).
PubMed ID1516675

2AuthorsHenrissat B.
TitleA classification of glycosyl hydrolases based on amino acid sequence similarities.
SourceBiochem. J. 280:309-316(1991).
PubMed ID1747104

3AuthorsManya H. Aoki J. Watanabe M. Adachi T. Asou H. Inoue Y. Arai H. Inoue K.
TitleSwitching of platelet-activating factor acetylhydrolase catalytic subunits in developing rat brain.
SourceJ. Biol. Chem. 273:18567-18572(1998).
PubMed ID9660828

4AuthorsPerrakis A. Tews I. Dauter Z. Oppenheim A.B. Chet I. Wilson K.S. Vorgias C.E.
TitleCrystal structure of a bacterial chitinase at 2.3 A resolution.
SourceStructure 2:1169-1180(1994).
PubMed ID7704527

5Authorsvan Scheltinga A.C.T. Kalk K.H. Beintema J.J. Dijkstra B.W.
SourceStructure 2:1181-1189(1994).


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