A thioredoxin peroxidase (TPx) gene was cloned from the bumblebee, Bumbus ignitus. The B. ignitus TPx (BiTPx) contains an open reading frame of 585 bp encoding 195 amino acid residues and possesses two cysteine residues that are characteristic of 2-Cys subgroup of peroxiredoxin family. The deduced amino acid sequence of the BiTPx cDNA showed 90% identity to Apis melifera (AmTPx-1), 80% to Aedes aegypti (AaTPx), and 78% - 47% to other insect 2-Cys TPx. Northern blot analysis revealed the presence of BiTPx transcripts in all tissues examined. Western blot analysis showed the presence of the BiTPx in the fat body, midgut, muscle and epidermis, but not in the hemolymph, suggesting the BiTPx is not secretable. The cDNA encoding BiTPx was expressed as a 27-kDa polypeptide in baculovirus-infected insect Sf9 cells. The purified recombinant BiTPx was shown to reduce H2O2 in the presence of electrons donated by dithiothreitol and shown to be active in the presence of thioredoxin as electron donor.

A thoredoxin (CTRX) gene was cloned and characterized from a full length cDNA library prepared from taproot of three-year old Codonopsis lanceolata. A CTRX was 666 nucleotides long and has an open reading frame of 372 bp with 124 amino acid residues (pI = 4.92). The deduced amino acid sequence of the CTRX matched to the previously reported plant thioredoxin h genes. The deduced amino acid sequence of CTRX exhibited the similarity of 33-67% among previously registered thioredoxin genes. The expression of CTRX in leaves of Codonopsis lanceolata was increased by wounding and 1 mM H2O2, but decreased by 0.1 mM cadmium.