Insect Molecular Biology and Biochemistry

Cuticular Proteins (Insect Molecular Biology) Part 4

Motifs Found in Cuticular Proteins that do not Define Families The review by Andersen et al. (1995) was the first to assemble a variety of motifs found in cuticular proteins. It is now possible to distinguish among two classes of motifs. The first defines a family such as the CPR and CPF families, while the […]

Cuticular Proteins (Insect Molecular Biology) Part 5

Modeling of Cuticular Proteins CPR protein models Secondary structure prediction and experimental data summarized above (see sections 5.5.1 and 5.5.2) indicated that P-pleated sheet is most probably the underlying molecular conformation of the members of the CPR family, and that this conformation is most probably involved in P-sheet/chitin-chain interactions of the cuticular proteins with the […]

Cuticular Sclerotization and Tanning (Insect Molecular Biology) Part 1

Summary The physical properties of insect cuticles are to a large extent determined by the degree of sclerotization (stabilization). The process of sclerotization often takes place shortly after eclosion, but may also occur before ecdy-sis or in connection with puparium formation. During sclerotization the two dopamine derivatives, N-acetyldo-pamine (NADA) and N-P-alanyldopamine (NBAD), are incorporated into […]

Cuticular Sclerotization and Tanning (Insect Molecular Biology) Part 2

Cuticular Enzymes and Sclerotization The study of cuticular enzymes has to a large extent been concerned with characterization of enzymes assumed to play a role in cuticular sclerotization, mainly those involved in oxidation of catechols, and there has been a tendency to neglect the possibility that enzymes not directly involved in sclerotization may play a […]

Cuticular Sclerotization and Tanning (Insect Molecular Biology) Part 3

Various Catechol Derivatives Obtained from Sclerotized Cuticles During the process of sclerotization most of the catecho-lic material will be firmly linked to the cuticular matrix and can only be solubilized by degrading the cuticle, for instance by hydrolysis. A large variety of catecholic derivatives are released by acid hydrolysis of sclerotized cuticle; some are simple […]

Cuticular Sclerotization and Tanning (Insect Molecular Biology) Part 4

Pre-Ecdysial Sclerotization The sclerotization of some cuticular regions may start during the pharate stage before the insect has ecdysed, and after ecdysis such regions will have retained the size and shape they obtained during the pre-ecdysial deposition of cuticular materials (Cottrell, 1964). Pre-ecdysial sclero-tization may be limited to small local regions, such as mandibles and […]

Chitin Metabolism in Insects Part 1

Introduction "Chitin Metabolism in Insects" was the title of topics in both the original edition of the Comprehensive Insect Physiology, Biochemistry and Pharmacology series published in 1985 and the follow-up Comprehensive Molecular Insect Science series in 2005 (Kramer et al., 1985; Kramer and Muthukrishnan, 2005). Since 2005 substantial progress in gaining additional understanding of this […]

Chitin Metabolism in Insects Part 2

Chitin Synthases: Organization of Genes and Biochemical Properties Number and organization of CHS-encoding genes CHS genes from numerous unicellular and filamentous species of fungi have been isolated and characterized (reviewed in Roncero, 2002; Horiuchi, 2009). Genome sequencing revealed three to nine CHS genes per individual fungal species, which were categorized into seven gene classes. In […]

Chitin Metabolism in Insects Part 3

Chitin Degradation and Modification Insects must periodically replace their old cuticle with a new one because it is too rigid to allow for growth. Key to this process is the elaboration of the molting fluid with an assortment of chtitinases and proteases. Chitinases are among a group of proteins that insects use to digest the […]

Chitin Metabolism in Insects Part 4

Insect N-Acetylglucosaminidases Phylogenetic analysis of insect Af-acetylglu-cosaminidases Beta-N-acetylglucosaminidases (NAGs; EC 3.2.1.30) have been defined as enzymes that release -acetylglucosamine residues from the non-reducing end of chitooligosaccharides and from glycoproteins with terminal N-acetylglucosamines. Insect NAGs are members of the family-20 hexosaminidase super-family of the glycosylhydrolases of the Carbohydrate Active Enzymes database, CAZY (Coutinho and Henrissat, 1999; […]

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