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Activity and sequence characterization of two cysteine proteases in the digestive tract of the reduviid bug Triatoma infestans
Author(s) -
Kollien A. H.,
Waniek P. J.,
Nisbet A. J.,
Billingsley P. F.,
Schaub G. A.
Publication year - 2004
Publication title -
insect molecular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.955
H-Index - 93
eISSN - 1365-2583
pISSN - 0962-1075
DOI - 10.1111/j.0962-1075.2004.00504.x
Subject(s) - triatoma infestans , biology , reduviidae , triatoma , proteases , digestive tract , cysteine , genetics , computational biology , zoology , biochemistry , parasite hosting , hemiptera , medicine , enzyme , trypanosoma cruzi , world wide web , computer science
Cathepsin B‐ and cathepsin L‐like activities were identified in gut extracts of the blood‐sucking bug Triatoma infestans using specific substrates and inhibitors. Activities decreased during the first 2 days after feeding but increased to a maximum value at 5 and 10 days post feeding. The deduced 332 and 328 amino acid sequences showed high levels of identity (50–60%) to other insect cathepsin B‐ and L‐like proteases, respectively. The three amino acid residues of the catalytic domain, CHN, and the GCNGG motif were conserved in both cathepsins, but the occluding loop, characterizing B‐like cathepsins, was present only in one. ERFNIN and GNFD motifs occurred in the other sequence, defining it as cathepsin L‐like. The cathepsin B‐like gene was expressed at low, constitutive levels in unfed and fed T. infestans .