Identification of the proteome of the midgut of silkworm, Bombyx mori L., by multidimensional liquid chromatography (MDLC) LTQ-Orbitrap MS.

The midgut is the digestive apparatus of the silkworm and its proteome was studied by using nano-LC (liquid chromatography) electrospray ionization MS/MS (tandem MS). MS data were analysed by using X!Tandem searching software using different parameters and validated by using the Poisson model. A total of 90 proteins were identified and 79 proteins were described for the first time. Among the new proteins, (i) 22 proteins were closely related to the digestive function of the midgut, including 11 proteins of digestive enzymes secreted by the epithelium, eight proteins of intestine wall muscle and mechanical digestion and three proteins of peritrophic membrane that could prevent the epithelium from being mechanically rubbed; (ii) 44 proteins were involved in metabolism of substance and energy; and (iii) 11 proteins were associated with signal transduction, substance transport and cell skeleton.