|PDB structures||RCSB PDB PDBe PDBsum|
|Locus||Chr. 1 p13.1-21.3|
|chitinase 1 (chitotriosidase)|
|Locus||Chr. 1 q31-q32|
Chitinases (EC 22.214.171.124, chitodextrinase, 1,4-beta-poly-N-acetylglucosaminidase, poly-beta-glucosaminidase, beta-1,4-poly-N-acetyl glucosamidinase, poly[1,4-(N-acetyl-beta-D-glucosaminide)] glycanohydrolase, (1->4)-2-acetamido-2-deoxy-beta-D-glucan glycanohydrolase) are hydrolytic enzymes that break down glycosidic bonds in chitin. As chitin is a component of the cell walls of fungi and exoskeletal elements of some animals (including worms and arthropods), chitinases are generally found in organisms that either need to reshape their own chitin or dissolve and digest the chitin of fungi or animals.
Species distribution 
Chitinivorous organisms include many bacteria (Aeromonads, Bacillus, Vibrio, among others), which may be pathogenic or detritivorous. They attack living arthropods, zooplankton or fungi or they may degrade the remains of these organisms.
Fungi, such as Coccidioides immitis, also possess degradative chitinases related to their role as detritivores and also to their potential as arthropod pathogens.
Chitinases are also present in plants (barley seed chitinase: PDB 1CNS, EC 126.96.36.199); some of these are pathogenesis related (PR) proteins that are induced as part of systemic acquired resistance. Expression is mediated by the NPR1 gene and the salicylic acid pathway, both involved in resistance to fungal and insect attack. Other plant chitinases may be required for creating fungal symbioses.
Although mammals do not produce chitin, they have two functional chitinases (Chitotriosidase - CHIT1 and acidic mammalian chitinase - AMCase) as well as chitinase-like proteins (such as YKL-40) that have high sequence similarity but lack chitinase activity.
Like cellulose, chitin is an abundant biopolymer that is relatively resistant to degradation. It is typically not digested by animal, though certain fish are able to digest chitin. It is currently assumed that chitin digestion by animals requires bacterial symbionts and lengthy fermentations, similar to cellulase digestion by ruminants. Nevertheless, chitinases have been isolated from the stomachs of certain mammals, including humans. Chitinase activity can also be detected in human blood and possibly cartilage. As in plant chitinases this may be related to pathogen resistance.
Clinical significance 
Human chitinases may explain the link between some of the most common allergies (dust mites, mold spores - both of which contain chitin) and worm (helminth) infections, as part of one version of the hygiene hypothesis (worms have chitinous mouthparts to hold the intestinal wall). Finally, the link between chitinases and salicylic acid in plants is well established - but there is a hypothetical link between salicylic acid and allergies in humans.
Presence in food 
Chitinase occurs naturally in many common foods. This is at least one cause of the cross-reaction phenomenon in latex-fruit syndrome. Bananas, chestnuts, kiwis, avocados, papaya, and tomatoes, for example, all contain significant levels of chitinase.
See also 
- Jollès P, Muzzarelli RAA (1999). Chitin and Chitinases. Basel: Birkhäuser. ISBN 3-7643-5815-7.
- Sámi L, Pusztahelyi T, Emri T, Varecza Z, Fekete A, Grallert A, Karanyi Z, Kiss L, Pócsi I (August 2001). "Autolysis and aging of Penicillium chrysogenum cultures under carbon starvation: Chitinase production and antifungal effect of allosamidin". The Journal of General and Applied Microbiology 47 (4): 201–211. doi:10.2323/jgam.47.201. PMID 12483620.
- Xiao X, Yin X, Lin J, Sun L, You Z, Wang P, Wang F (December 2005). "Chitinase Genes in Lake Sediments of Ardley Island, Antarctica". Applied and Environmental Microbiology 71 (12): 7904–9. doi:10.1128/AEM.71.12.7904-7909.2005. PMC 1317360. PMID 16332766.
- Hunt DE, Gevers D, Vahora NM, Polz MF (January 2008). "Conservation of the Chitin Utilization Pathway in the Vibrionaceae". Applied and Environmental Microbiology 74 (1): 44–51. doi:10.1128/AEM.01412-07. PMC 2223224. PMID 17933912.
- Salzer P, Bonanomi A, Beyer K, Vögeli-Lange R, Aeschbacher RA, Lange J, Wiemken A, Kim D, Cook DR, Boller T (July 2000). "Differential expression of eight chitinase genes in Medicago truncatula roots during mycorrhiza formation, nodulation, and pathogen infection". Molecular Plant-Microbe Interactions : MPMI 13 (7): 763–77. doi:10.1094/MPMI.2000.13.7.763. PMID 10875337.
- Eurich, K; et al. (2009 Nov). "Potential role of chitinase 3-like-1 in inflammation-associated carcinogenic changes of epithelial cells.". World J Gastroenterol 15 (42): 5249–5259. PMC 2776850. PMID 19908331.
- Akaki C, Duke GE (2005). "Apparent chitin digestibilities in the Eastern screech owl (Otus asio) and the American kestrel (Falco sparverius)". Journal of Experimental Zoology 283 (4–5): 387–393. doi:10.1002/(SICI)1097-010X(19990301/01)283:4/5<387::AID-JEZ8>3.0.CO;2-W.
- Gutowska MA, Drazen JC, Robison BH (November 2004). "Digestive chitinolytic activity in marine fishes of Monterey Bay, California". Comparative biochemistry and physiology. Part A, Molecular & Integrative Physiology 139 (3): 351–8. doi:10.1016/j.cbpb.2004.09.020. PMID 15556391.
- Paoletti MG, Norberto L, Damini R, Musumeci S (2007). "Human gastric juice contains chitinase that can degrade chitin". Annals of Nutrition & Metabolism 51 (3): 244–51. doi:10.1159/000104144. PMID 17587796.
- Renkema GH, Boot RG, Muijsers AO, Donker-Koopman WE, Aerts JM (February 1995). "Purification and Characterization of Human Chitotriosidase, a Novel Member of the Chitinase Family of Proteins". The Journal of Biological Chemistry 270 (5): 2198–202. doi:10.1074/jbc.270.5.2198. PMID 7836450.
- Escott GM, Adams DJ (December 1995). "Chitinase activity in human serum and leukocytes". Infection and Immunity 63 (12): 4770–3. PMC 173683. PMID 7591134.
- Hakala BE, White C, Recklies AD (1993). "Human cartilage gp-39, a major secretory product of articular chondrocytes and synovial cells, is a mammalian member of a chitinase protein family". The Journal of Biological Chemistry 268 (34): 25803–25810. PMID 8245017.
- Recklies AD, White C, Ling H (July 2002). "The chitinase 3-like protein human cartilage glycoprotein 39 (HC-gp39) stimulates proliferation of human connective-tissue cells and activates both extracellular signal-regulated kinase- and protein kinase B-mediated signalling pathways". The Biochemical Journal 365 (Pt 1): 119–26. doi:10.1042/BJ20020075. PMC 1222662. PMID 12071845.
- van Eijk M, van Roomen CPAA, Renkema GH, Bussink AP, Andrews L, Blommaart EFC, Sugar A, Verhoeven AJ, Boot RG, Aerts JMFG (2005). "Characterization of human phagocyte-derived chitotriosidase, a component of innate immunity". International Immunology 17 (11): 1505–1512. doi:10.1093/intimm/dxh328. PMID 16214810.
- Bierbaum S, Nickel R, Koch A, Lau S, Deichmann KA, Wahn U, Superti-Furga A, Heinzmann A (December 2005). "Polymorphisms and Haplotypes of Acid Mammalian Chitinase Are Associated with Bronchial Asthma". American Journal of Respiratory and Critical Care Medicine 172 (12): 1505–9. doi:10.1164/rccm.200506-890OC. PMC 2718453. PMID 16179638.
- Zhao J, Zhu H, Wong CH, Leung KY, Wong WS (July 2005). "Increased lungkine and chitinase levels in allergic airway inflammation: a proteomics approach". Proteomics 5 (11): 2799–807. doi:10.1002/pmic.200401169. PMID 15996009.
- Elias JA, Homer RJ, Hamid Q, Lee CG (September 2005). "Chitinases and chitinase-like proteins in T(H)2 inflammation and asthma". The Journal of Allergy and Clinical Immunology 116 (3): 497–500. doi:10.1016/j.jaci.2005.06.028. PMID 16159614.
- Zhu Z, Zheng T, Homer RJ, Kim YK, Chen NY, Cohn L, Hamid Q, Elias JA (June 2004). "Acidic mammalian chitinase in asthmatic Th2 inflammation and IL-13 pathway activation". Science 304 (5677): 1678–82. doi:10.1126/science.1095336. PMID 15192232.
- Chupp GL, Lee CG, Jarjour N, Shim YM, Holm CT, He S, Dziura JD, Reed J, Coyle AJ, Kiener P, Cullen M, Grandsaigne M, Dombret MC, Aubier M, Pretolani M, Elias JA (2005). "A Chitinase-like Protein in the Lung and Circulation of Patients with Severe Asthma". The New England Journal of Medicine 357 (20): 2016–2027. doi:10.1056/NEJMoa073600. PMID 18003958.
- Maizels RM (December 2005). "Infections and allergy — helminths, hygiene and host immune regulation". Current Opinion in Immunology 17 (6): 656–61. doi:10.1016/j.coi.2005.09.001. PMID 16202576.
- Hunter MM, McKay DM (January 2004). "Review article: helminths as therapeutic agents for inflammatory bowel disease". Alimentary Pharmacology & Therapeutics 19 (2): 167–77. doi:10.1111/j.0269-2813.2004.01803.x. PMID 14723608.
- Palmas C, Gabriele F, Conchedda M, Bortoletti G, Ecca AR (June 2003). "Causality or coincidence: may the slow disappearance of helminths be responsible for the imbalances in immune control mechanisms?". Journal of Helminthology 77 (2): 147–53. doi:10.1079/JOH2003176. PMID 12756068.
- Feingold BF (March 1975). "Food additives in clinical medicine". International Journal of Dermatology 14 (2): 112–4. doi:10.1111/j.1365-4362.1975.tb01426.x. PMID 1123257.
- Chitinase at the US National Library of Medicine Medical Subject Headings (MeSH)
- X-ray structure of a chitinase from the pathogenic fungus Coccidioides immitis