Chitin: A Structural Biopolysaccharide


Chitin is a naturally occurring fibre‐forming polymer that plays a protective role in many lower eukaryotes similar to that of cellulose in plants. Chemically it is a long‐chain unbranched polysaccharide made of N‐acetylglucosamine residues; it is the second most abundant organic compound in nature, after cellulose. Taking into account the structural role played by chitin, its metabolism (synthesis and degradation) is essential for different morphogenetic events. Absent in vertebrates and plants, chitin represents a parasite‐specific target for chemotherapeutic attack and also plays a role in host immune responses. Because of its abundance in nature and its properties, biotechnological application of chitin derivatives is currently an expanding area.

Key concepts

  • Chitin is a long‐chain unbranched polysaccharide made of β‐1,4‐linked anhydro‐2‐acetamido‐2‐deoxy‐d‐glucose (GlcNAc) which forms crystalline fibrillar structures following association of adjacent chains through hydrogen bonds between the N–H and the CO groups.

  • Nascent chitin is a growing chitin chain which is being synthesized by the chitin synthase and it represents a good substrate for chitinolytic enzymes.

  • Microfibrillar chitin is a crystalline structure formed by chains of the polysaccharide which associate through hydrogen bonds between adjacent chains and it is responsible for the physico‐chemical properties of the polymer.

  • The fungal cell wall is a supramolecular network outside the plasma membrane, formed by structural polysaccharides, including chitin, and proteins and glycoproteins, that protects the fungal cell and determines morphology, similarly to cuticle (exosqueleton) in insects.

  • Insect cuticle (exosqueleton) is an extracellular matrix covering the epidermis and trachea, composed mainly by chitin (and proteins), which protects the animal and confers morphology.

  • The peritrophic membrane (matrix) is an extracellular layer that covers the midgut in most arthropods and it is made of chitin, proteins and proteoglycans, and provides protection to the underlaying digestive cells.

  • Chitin biosynthesis is a strongly regulated process, both spatially and temporally, as chitin deposition is essential for fungal growth and development (moulting) in arthropods.

  • Chitin synthases are membrane bound enzymes that incorporate the substrate (UDP‐N‐acetylglucosamine) from the cytosol to the nascent chitin chain that is extruded outside the membrane.

  • Chitinases are chitin‐hydrolysing enzymes that play important roles in the physiology of chitin‐containing eukaryotes, and chitinolytic bacteria are active in a scavenging role by degrading massive amounts of chitin in marine and soil biomass, avoiding its accumulation and favouring the utilization of chitin as a renewable source.

  • The absence of chitin in vertebrates and plants makes the chitin metabolism a potentially useful parasite‐specific target for chemotherapeutic attack.

  • Owing to their abundance in nature and properties, chitin, chitosan and their derivatives have gained potential interest for a wide range of areas, including biopharmaceutical and biomedical applications.

Keywords: polysaccharide; chitosan; chitinase; chitin synthetase; structural biopolymers

Figure 1.

Chemical structures of the repeating units of idealized chitin, chitosan and cellulose.

Figure 2.

Orientation of the molecular chains in α‐, β‐ and γ‐chitin.

Figure 3.

General pathway of chitin biosynthesis in biological systems.

Figure 4.

Electron microscopic observation of chitin microfibrils (arrowheads) synthesized in vitro after proteolytic activation with trypsin of a chitosomal (see text) zymogenic chitin synthetase preparation obtained from a fungal species (Candida albicans), bar, 100 nm.

Figure 5.

Chemical structures of some inhibitors of chitin metabolism. (a) Polyoxin D, (b) nikkomycins, (c) benzoylphenylurea derivative and (d) allosamidin.



Berkeley RCW (1979) Chitin, chitosan, and their degradative enzymes. In: Berkeley RCW, Gooday GW and Ellwood DC (eds) Microbial Polysaccharides and Polysaccharases. London: Academic Press.

Bhattacharya D, Nagpure A and Gupta RK (2007) Bacterial chitinases: properties and potential. Critical Reviews in Biotechnology 27: 21–28.

Bulawa CE (1993) Genetics and molecular biology of chitin synthesis in fungi. Annual Review of Microbiology 47: 505–534.

Chen L, Wang Q, Mao C, Shang J and Bi F (2005) Synthesis and insecticidal evaluation of propesticides of bezoylphenylureas. Journal of Agriculture and Food Chemistry 12: 38–41.

Cohen E (2001) Chitin synthesis and inhibition: a revisit. Pesticide Management Science 57: 946–950.

D'Haeze W and Holsters M (2002) Nod factors structures, responses, and perception during initiation of nodule development. Glycobiology 12: 79R–105R.

Dubinsky P, Rybos M and Turcekova L (1986) Properties and localization of chitin synthase in Ascaris suum eggs. Parasitology 92: 219–225.

Duo‐Chuan L (2006) Review of fungal chitinases. Mycopathologia 116: 345–360.

Eichinger D (1997) Encystation of Entamoeba parasites. BioEssays 19: 633–639.

Foster JM, Zang Y, Kumar S and Carlow CK (2005) Parasitic nematodes have two distinct chitin synthases. Molecular and Biochemical Parasitology 142: 126–132.

Gangishetti U, Breitenbach S, Zander SK et al. (2009) Effects of benzoylphenylurea on chitin synthesis and orientation in the cuticle of the Drosophila larva. European Journal of Cell Biology 88: 167–180.

Jarroll EL and Sener K (2003) Potential drug targets in cyst‐wall biosynthesis by intestinal protozoa. Drug Resistance Update 6: 239–246.

Kasprzewska A (2003) Plant chitinases: regulation and function. Cell and Molecular Biology Letters 8: 809–824.

Kneipp LF, Andrade AFB, de Souza W et al. (1998) Trichomonas vaginalis and Tritrichomonas foetus: expression of chitin at the cell surface. Experimental Parasitology 89: 195–204.

Kramer KJ and Muthukrishnan S (1997) Insect chitinases: molecular biology and potential use as biopesticides. Insect Biochemistry and Molecular Biology 27: 887–900.

Kumar MN, Muzzarelli RA, Muzzarelli C, Sashiwa H and Domb AJ (2004) Chitosan chemistry and pharmaceutical perspectives. Chemistry reviews 104: 6017–6084.

Kurita K (2006) Chitin and chitosan: functional biopolymers from marine crustaceans. Marine Biotechnology 8: 203–226.

Lee CG, Da Silva CA, Lee JY, Hartl D and Elias JA (2008) Chitin regulation of immune responses: an old molecule with new roles. Current Opinion in Immunology 20: 684–689.

Lessage G and Bussey H (2006) Cell wall assembly in Saccharomyces cerevisiae. Microbiology and Molecular Biology Reviews 70: 317–343.

Martínez JP and Gozalbo D (1994) Chitin synthetases in Candida albicans: a review on their subcellular distribution and biological function. Microbiologia SEM 10: 239–248.

Merzendorfer H (2006) Insect chitin syntases: a review. Journal of Comparative Physiology 176: 1–15.

Merzendorfer H and Zimoch H (2003) Chitin metabolism in insects: structure, function and regulation of chitin synthases and chitinases. Journal of Experimental Biology 206: 4393–4412.

Munro CA and Gow NA (2001) Chitin synthesis in human pathogenic fungi. Medical Mycology 39(suppl 1): 41–53.

Muzzarelli RA (1977) Chitin. Oxford: Pergamon Press.

Muzzarelli RA, Jenieux R and Gooday GW (1986) Chitin in Nature and Technology. New York: Plenum Press.

Nishimura S, Nishi N, Tokura S, Nishimura K and Azuma I (1984) Immunological activity of chitin and its derivatives. Vaccine 2: 93–99.

Prabaharan M (2008) Review paper: chitosan derivatives as promising materials for controlled drug delivery. Journal of Biomaterials Applications 23: 5–36.

Reese TA, Liang HE, Tager AM et al. (2007) Chitin induces accumulation in tissue of innate immune cells associated with allergy. Nature 447: 92–96.

Ruiz‐Herrera J (1992) Fungal Cell Wall: Structure, Synthesis and Assembly. Boca Raton, FL: CRC Press.

Ruiz‐Herrera J and San Blas G (2003) Chitin synthesis as target for antifungal drugs. Current Drug Targets: Infectious Disorders 3: 77–91.

Ruiz‐Herrera J, Gonzalez‐Prieto JM and Ruiz‐Medrano R (2002) Evolution and phylogenetic relationships of chitin synthases from yeasts and fungi. FEMS Yeast Research 1: 247–256.

Ruiz‐Herrera J, Sentandreu R and Martínez JP (1992) Chitin biosynthesis in fungi. In: Arora DK, Elander RP and Mukerji KG (eds) Handbook of Applied Mycology. Fungal Biotechnology. New York: Marcel Dekker.

Scott GM and Adams DJ (1995) Chitinase activity in human serum and leukocytes. Infection and Immunity 63: 4770–4773.

Semino CE and Allende ML (2000) Chitin oligosaccharides as candidate patterning agents in zebrafish embryogenesis. International Journal of Developmental Biology 44: 183–193.

Shakhbazov AV and Kartel’ NA (2008) Chitinases in bioengineering. Genetika 44: 1013–1022.

Spaink HP, Wijfjes AHM, van der Drift KMG et al. (1994) Structural identification of metabolites produced by the NodB and NodC proteins of Rhizobium leguminosarum. Molecular Microbiology 13: 821–831.

Spindler KD (1983) Chitin: its synthesis and degradation in arthropods. In: Scheller K (ed.) The Larval Serum Proteins of Insects. Stuttgart: Thieme.

Spindler KD, Spindler‐Barth M and Londershausen M (1990) Chitin metabolism: a target for drugs against parasites. Parasitology Research 76: 283–288.

Tellam RL (1996) The peritrophic matrix. In: Lehane MJ and Billingsley PF (eds) Biology of the Insect Midgut. London: Chapman and Hall.

Van Dellen KL, Bulik DA, Specht CA, Robbins PW and Samuelson LC (2006) Heterologous expresión of an Entamoeba histolytica chitin synthase in Saccharomyces cerevisiae. Eukaryotic Cell 5: 203–206.

Vogan CL, Powell A and Rowley AF (2008) Shell disease in crustaceans: just chitin recycling gone wrong? Environmental Microbiology 10: 826–835.

Wagner GP (1994) Evolution and multi‐functionality of the chitin system. In: Schierwater B, Streit B, Wagner GP and Desalle R (eds) Molecular Ecology and Evolution Approaches and Applications. Basel: Birkhäuser.

Wood AW and Kellogg ST (eds) (1988) Methods in Enzymology 161B: Lignin, Pectin, and Chitin. San Diego: Academic Press Inc.

Wu Y, Adam R, Williams SA and Bianco AE (1996) Chitinase genes expressed in infective larvae of the filarial nematodes, Acanthocheilonema viteae and Onchocerca volvulus. Molecular and Biochemical Parasitology 75: 207–219.

Yamamoto M and Uryu T (1998) Regioselective synthesis of sulfated polysaccharides: specific anti‐HIV activity of novel chitin sulfates. Carbohydrate Research 306: 427–433.

Yi H, Wu LQ, Bentley WE et al. (2005) Biofabrication with chitosan. Biomacromolecules 6: 2882–2884.

Yilmaz E (2004) Chitosan: a versatile biomaterial. Advaces in Experimental Medicine and Biology 553: 59–68.

Yu C, Lee AM, Bassler BL and Roseman S (1991) Chitin utilization by marine bacteria. Journal of Biological Chemistry 266: 24260–24267.

Zhang Y, Foster JM, Nelson LS, Ma D and Carlow CK (2005) The chitin synthase genes chs‐1 and chs‐2 are essential for C. elegans development and responsibly for chitin deposition in the eggshell and pharynx, respectively. Developmental Biology 15: 330–339.

Zhu Z, Zheng T, Homer RJ et al. (2004) Acidic mammalian chitinase in asthmatic Th2 inflammation and IL‐3 pathway activation. Science 304: 1678–1682.

Further Reading

Bartnicki‐Garcia S (2006) Chitosomes: past, present and future. FEMS Yeast Research 6: 957–965.

Dahiya N, Tewari R and Hoondal GS (2006) Biotechnological aspects of chitinolytic enzymes: a review. Applied Microbiology and Biotechnology 71: 773–782.

Hayes M, Carney B, Slater J and Brück W (2008) Mining marine shellfish wastes for bioactive molecules: chitin and chitosan. Part A: extraction methods. Biotechnology Journal 3: 871–877.

Hayes M, Carney B, Slater J and Brück W (2008) Mining marine shellfish wastes for bioactive molecules: chitin and chitosan. Part B: applications. Biotechnology Journal 3: 878–889.

Hegedus D, Erlandson M, Gillot C and Toprak V (2009) New inshights into perithrophic matrix synthesis, architecture and function. Annual Review of Entomology 54: 285–302.

Jayakumar R, New N, Tokura S and Tamura H (2007) Sulfated chitin and chitosan as novel biomaterials. International Journal of Biological Macromolecules 40: 175–181.

Jayakumar R, Selvamurugan N, Nair SU, Tokura S and Tamura H (2008) Preparative methods of phosphorylated chitin and chitosan, an overview. International Journal of Biological Macromolecules 43: 221–225.

Kim IY, Seo SJ, Moon HS et al. (2008) Chitosan and its derivatives for tissue engineering applications. Biotechnology Advances 26: 1–21.

Roncero C (2002) The genetic complexity of chitin synthesis in fungi. Current Genetics 41: 367–378.

Tharanathan RN and Kittur FS (2003) Chitin: the undisputed biomolecule of great potential. Critical Reviews of Food Science and Nutrition 43: 61–87.

Contact Editor close
Submit a note to the editor about this article by filling in the form below.

* Required Field

How to Cite close
Martínez, José P, Falomir, María Pilar, and Gozalbo, Daniel(Dec 2009) Chitin: A Structural Biopolysaccharide. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0000694.pub2]