کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1982772 | 1062315 | 2009 | 9 صفحه PDF | دانلود رایگان |
Laccase is a multi-copper enzyme found in variety of organisms including plants, fungi and bacteria. In insects, laccase is thought to play an important role in cuticle sclerotization with its ability to catalyze the oxidation of phenolic compounds to their corresponding quinones. From the newly ecdysed pupae of the silkworm, Bombyx mori, we purified a dimer form of cuticular laccase with 70-kDa polypeptides. Mass spectrometric analysis of the tryptic fragments and cDNA sequence analysis revealed that the gene for the purified laccase (BmLaccase2) is an ortholog of laccase2, one of the multiple laccase genes found in insect genomes. BmLaccase2 is highly expressed in the epidermis prior to ecdysis, suggesting that the BmLaccase2 protein accumulates before ecdysis. However, the cuticle of newly ecdysed pupa does not have laccase activity, and the activity only becomes detectable several hours after ecdysis. These data suggest that cuticle laccase is synthesized as an inactive precursor, which is later activated after ecdysis. We also found that urea-solubilized cuticle protein extract contains an inactive form of laccase that can be activated by trypsin treatment.
Journal: Insect Biochemistry and Molecular Biology - Volume 39, Issue 4, April 2009, Pages 254–262