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Chitinase from barley seeds
EC number
IntEnz IntEnz view
ExPASy NiceZyme view
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum
chitinase, acidic
Symbol CHIA
Entrez 27159
HUGO 17432
OMIM 606080
RefSeq NM_001040623
UniProt Q9BZP6
Other data
Locus Chr. 1 p13.1-21.3
chitinase 1 (chitotriosidase)
Symbol CHIT1
Entrez 1118
HUGO 1936
OMIM 600031
RefSeq NM_003465
UniProt Q13231
Other data
Locus Chr. 1 q31-q32

Chitinases (EC, 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.[1]

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[2] or dissolve and digest the chitin of fungi or animals.

Species distribution[edit]

Chitinivorous organisms include many bacteria[3] (Aeromonads, Bacillus, Vibrio,[4] 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; 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.[5]

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.[6]


Like cellulose, chitin is an abundant biopolymer that is relatively resistant to degradation.[7] It is typically not digested by animals, though certain fish are able to digest chitin.[8] 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.[9] Chitinase activity can also be detected in human blood[10][11][11] and possibly cartilage.[12] As in plant chitinases this may be related to pathogen resistance.[13][14]

Clinical significance[edit]

Chitinases produced in the human body (known as "human chitinases") may be related in response to allergies, and asthma has been linked to enhanced chitinase expression levels.[15][16][17][18][19]

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[20][21][22] (worms have chitinous mouthparts to hold the intestinal wall). Finally, the link between chitinases and salicylic acid in plants is well established[further explanation needed]—but there is a hypothetical link between salicylic acid and allergies in humans.[23]

Presence in food[edit]

Chitinases occur naturally in many common foods. Bananas, chestnuts, kiwis, avocados, papaya, and tomatoes, for example, all contain significant levels of chitinase, as defense against fungal and invertebrate attack. Stress, or environmental signals like ethylene gas, may stimulate increased production of chitinase.

Some parts of chitinase molecules, almost identical in structure to hevein or other proteins in rubber latex due to their similar function in plant defense, may trigger an allergic cross-reaction known as latex-fruit syndrome.[24]


Chitinases have a wealth of applications, some of which have already been realized by industry. This includes bio-conversion of chitin to useful products such as fertilizer, the production of non-allergenic, non-toxic, biocompatible, and biodegradable materials (contact lenses, artificial skin and sutures with these qualities are already being produced) and enhancement of insecticides and fungicides.[25]

Possible future applications of chitinases are as food additives to increase shelf life, therapeutic agent for asthma and chronic rhinosinusitis, as an anti-fungal remedy, an anti-tumor drug and as a general ingredient to be used in protein engineering.[25]

See also[edit]


  1. ^ Jollès P, Muzzarelli RA (1999). Chitin and Chitinases. Basel: Birkhäuser. ISBN 3-7643-5815-7. 
  2. ^ Sámi L, Pusztahelyi T, Emri T, Varecza Z, Fekete A, Grallert A, Karanyi Z, Kiss L, Pócsi I (Aug 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. 
  3. ^ Xiao X, Yin X, Lin J, Sun L, You Z, Wang P, Wang F (Dec 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 1317360Freely accessible. PMID 16332766. 
  4. ^ Hunt DE, Gevers D, Vahora NM, Polz MF (Jan 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 2223224Freely accessible. PMID 17933912. 
  5. ^ Salzer P, Bonanomi A, Beyer K, Vögeli-Lange R, Aeschbacher RA, Lange J, Wiemken A, Kim D, Cook DR, Boller T (Jul 2000). "Differential expression of eight chitinase genes in Medicago truncatula roots during mycorrhiza formation, nodulation, and pathogen infection". Molecular Plant-Microbe Interactions. 13 (7): 763–77. doi:10.1094/MPMI.2000.13.7.763. PMID 10875337. 
  6. ^ Eurich K, Segawa M, Toei-Shimizu S, Mizoguchi E (Nov 2009). "Potential role of chitinase 3-like-1 in inflammation-associated carcinogenic changes of epithelial cells". World Journal of Gastroenterology. 15 (42): 5249–59. doi:10.3748/wjg.15.5249. PMC 2776850Freely accessible. PMID 19908331. 
  7. ^ 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. 
  8. ^ Gutowska MA, Drazen JC, Robison BH (Nov 2004). "Digestive chitinolytic activity in marine fishes of Monterey Bay, California". Comparative Biochemistry and Physiology A. 139 (3): 351–8. doi:10.1016/j.cbpb.2004.09.020. PMID 15556391. 
  9. ^ 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. 
  10. ^ Renkema GH, Boot RG, Muijsers AO, Donker-Koopman WE, Aerts JM (Feb 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. 
  11. ^ a b Escott GM, Adams DJ (Dec 1995). "Chitinase activity in human serum and leukocytes". Infection and Immunity. 63 (12): 4770–3. PMC 173683Freely accessible. PMID 7591134. 
  12. ^ Hakala BE, White C, Recklies AD (Dec 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): 25803–10. PMID 8245017. 
  13. ^ Recklies AD, White C, Ling H (Jul 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 1222662Freely accessible. PMID 12071845. 
  14. ^ van Eijk M, van Roomen CP, Renkema GH, Bussink AP, Andrews L, Blommaart EF, Sugar A, Verhoeven AJ, Boot RG, Aerts JM (Nov 2005). "Characterization of human phagocyte-derived chitotriosidase, a component of innate immunity". International Immunology. 17 (11): 1505–12. doi:10.1093/intimm/dxh328. PMID 16214810. 
  15. ^ Bierbaum S, Nickel R, Koch A, Lau S, Deichmann KA, Wahn U, Superti-Furga A, Heinzmann A (Dec 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 2718453Freely accessible. PMID 16179638. 
  16. ^ Zhao J, Zhu H, Wong CH, Leung KY, Wong WS (Jul 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. 
  17. ^ Elias JA, Homer RJ, Hamid Q, Lee CG (Sep 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. 
  18. ^ Zhu Z, Zheng T, Homer RJ, Kim YK, Chen NY, Cohn L, Hamid Q, Elias JA (Jun 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. 
  19. ^ 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 (Nov 2007). "A chitinase-like protein in the lung and circulation of patients with severe asthma". The New England Journal of Medicine. 357 (20): 2016–27. doi:10.1056/NEJMoa073600. PMID 18003958. 
  20. ^ Maizels RM (Dec 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. 
  21. ^ Hunter MM, McKay DM (Jan 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. 
  22. ^ Palmas C, Gabriele F, Conchedda M, Bortoletti G, Ecca AR (Jun 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. 
  23. ^ Feingold BF (Mar 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. 
  24. ^
  25. ^ a b Hamid R, Khan MA, Ahmad M, Ahmad MM, Abdin MZ, Musarrat J, Javed S (Jan 2013). "Chitinases: An update". Journal of Pharmacy & BioAllied Sciences. 5 (1): 21–9. doi:10.4103/0975-7406.106559. PMC 3612335Freely accessible. PMID 23559820. 

External links[edit]