Digestive peptidases in Tenebrio molitor and possibility of use to treat celiac disease

Abstract

Digestion in Tenebrio molitor larvae occurs in the midgut, where there is a sharp pH gradient from 5.6 in the anterior midgut (AM) to 7.9 in the posterior midgut (PM). Accordingly, digestive enzymes are compartmentalized to the AM or PM. Enzymes in the AM are soluble and have acidic or neutral pH optima, while PM enzymes have alkaline pH optima. The main peptidases in the AM are cysteine endopeptidases presented by two to six subfractions of anionic proteins. The major activity belongs to cathepsin L, which has been purified and characterized. Serine post‐proline cleaving peptidase with pH optimum 5.3 was also found in the AM. Typical serine digestive endopeptidases, trypsin‐like and chymotrypsin‐like, are compartmentalized to the PM. Trypsin‐like activity is due to one cationic and three anionic proteinases. Chymotrypsin‐like activity consists of one cationic and four anionic proteinases, four with an extended binding site. The major cationic trypsin and chymotrypsin have been purified and thoroughly characterized. The predicted amino acid sequences are available for purified cathepsin L, trypsin and chymotrypsin. Additional sequences for putative digestive cathepsins L, trypsins and chymotrypsins are available, implying multigene families for these enzymes. Exopeptidases are found in the PM and are presented by a single membrane aminopeptidase N‐like peptidase and carboxypeptidase A, although multiple cDNAs for carboxypeptidase A were found in the AM, but not in the PM. The possibility of the use of two endopeptidases from the AM – cathepsin L and post‐proline cleaving peptidase – in the treatment of celiac disease is discussed.

Digestive proteolysis organization in two closely related Tenebrionid beetles: red flour beetle (Tribolium castaneum) and confused flour beetle (Tribolium confusum)

“…Using diagnostic inhibitors and specific substrates, complex systems of digestive peptidases were described in the colorado potato beetle, Leptinotarsa decemlineata (F. Chrysomelidae) (Novillo et al, 1997), and rice water weevil, Lissorhoptrus brevirostris (F. Curculionidae) (Hernandez et al, 2003). Previously, we characterized in detail the digestive peptidase spectrum of the larvae of yellow mealworm, Tenebrio molitor (Vinokurov et al, 2006a,b;Elpidina and Goptar, 2007) with subsequent analysis of midgut cDNA transcripts encoding peptidases (Prabhakar et al, 2007). Larvae of T. molitor use a complex of digestive peptidases, including those from serine and cysteine classes, operating in a midgut with a sharp pH gradient (Terra et al, 1985;Vinokurov et al, 2006a).…”

Safety aspects of the production of foods and food ingredients from insects

“…Because insects have adapted to a variety of habitats and diets, a wide range of digestive enzymes is produced by the insect itself or by members of the gut microbiota , e.g. proteolytic enzymes , cellulases , α‐amylases , and lipases . The genomic analysis of insects and the metagenomic analysis of insect microbiota allowed to identify genes coding for enzymes with the potential to be used in food technology , but up to now no industrial applications of insect enzymes have been reported.…”

Prolidase is a critical enzyme for complete gliadin digestion in Tenebrio molitor larvae

“…The major digestive organ of T. molitor larvae is the midgut, where the pH varies from 5.6 -6.5 in the AM to 6.5 -7.9 in the PM (Elpidina & Goptar, 2007;Terra, Ferreira, & Bastos, 1985;Vinokurov et al, 2006a). This gradient determines the localization of activity of different digestive enzymes along the midgut in accordance with their pH optima (Vinokurov et al, 2006b).…”