Chitin in insect cuticle

Chitin, a linear structural polysaccharide is a major constituent of insect procuticle. Chitin is embedded in a complex matrix of proteins, which contributes significantly to the physicochemical and physiological properties of the cuticle. The wide range of properties of individual cuticles at specific anatomical locations and developmental stages is attributable to difference in chitin/protein ratio, protein composition of the matrix, cross-linking, presence of minerals and the degree of dehydration. The epidermal cells that underlie the cuticle orchestrate the timing of appearance of individual layers of the cuticle and its composition and organization. This process is particularly important during molting, when the old cuticle is replaced by a new one. Molting fluid contains an assortment of enzymes that deproteinize the cuticular matrix to expose the chitin crystallites to chitinolytic enzymes. A variety of enzymes of chitin metabolism participate in the synthesis, modification, and turnover of cuticular components and in cross-linking and tanning of proteins. Chemical inhibitors and RNA interference strategies targeted against the chitin metabolic enzymes and cuticular proteins represent specific and effective strategies for insect control.