Chitin binding domain.

Chitin recognition protein.

Hevein or Type 1 chitin binding domain subfamily co-occuring with family 19 glycosyl hydrolases or with barwin domains. This subfamily includes Hevein, a major IgE-binding allergen in natural rubber latex. ChtBD1 is a lectin domain found in proteins from plants and fungi that bind N-acetylglucosamine, plant endochitinases, wound-induced proteins, and the alpha subunit of Kluyveromyces lactis killer toxin. This domain is involved in the recognition and/or binding of chitin subunits; it typically occurs N-terminal to glycosyl hydrolase domains in chitinases, together with other carbohydrate-binding domains, or by itself in tandem-repeat arrangements.

Glycoside hydrolase family 19 chitinase domain. Chitinases are enzymes that catalyze the hydrolysis of the beta-1,4-N-acetyl-D-glucosamine linkages in chitin polymers. Family 19 chitinases are found primarily in plants (classes I, III, and IV), but some are found in bacteria. Class I and II chitinases are similar in their catalytic domains. Class I chitinases have an N-terminal cysteine-rich, chitin-binding domain which is separated from the catalytic domain by a proline and glycine-rich hinge region. Class II chitinases lack both the chitin-binding domain and the hinge region. Class IV chitinases are similar to class I chitinases but they are smaller in size due to certain deletions. Despite any significant sequence homology with lysozymes, structural analysis reveals that family 19 chitinases, together with family 46 chitosanases, are similar to several lysozymes including those from T4-phage and from goose. The structures reveal that the different enzyme groups arose from a common ancestor glycohydrolase antecedent to the procaryotic/eucaryotic divergence.

Chitinase class I.