Abstract:
The date palm fruit stalk borer is one of the most important pests of date palm in the
world. Biochemical properties of digestive proteases in Oryctes elegans Prell larvae were
investigated in this research and optimal total proteolytic and trypsin activities were
obtained at pH 9.0 and 11.0, respectively. Activity staining of protease on SDS-PAGE
showed one isoform. Also, zymogram pattern of trypsin using nitro-cellulose membrane
revealed two isoforms. The inhibitory effect of PMSF, TLCK, TPCK, EDTA, iodoacetate
and iodoacetamide were determined on O. elegans proteolytic activity. The iodoacetamide
showed the highest inhibition on total proteolytic activity. Therefore, cysteine protease
accounted for the major proteases in the gut of O. elegans. Total proteolytic activity was
inhibited 22.3 and .15% by inhibitors extracted from Vicia faba and Lathyrus sativus,
respectively. However, the inhibitors extracted from seeds of Prosopis farcta, Panecum
miliaceum, and Alhagi maurorum showed negligible inhibitory effects on proteolytic
activities. Trypsin activity was inhibited 91.5 and 82.3% by inhibitors extracted from V.
faba and L. sativus, respectively. Electrophoretic analysis showed that inhibitors extracted
from V. faba reduced the intensity of total proteolytic and trypsin activities. The inhibitor
from V. faba was purified by ammonium sulfate precipitation and gel-filtration, also the
molecular mass of inhibitor was determined 35 kDa. This purified inhibitor was able to
inhibit trypsin activity by 72.7%. In addition, the highest inhibition of trypsin activity by
inhibitor from V. faba occurred at pH 11.0. Also, the stability of inhibitor from V. faba was
evaluated at different pHs and temperatures. This inhibitor was stable at pH 11.0 and 30 °C.
Keywords: Digestive protease type, Plant protease inhibitors, Trypsin. The date palm fruit stalk borer is one of the most important pests of date palm in the
world. Biochemical properties of digestive proteases in Oryctes elegans Prell larvae were
investigated in this research and optimal total proteolytic and trypsin activities were
obtained at pH 9.0 and 11.0, respectively. Activity staining of protease on SDS-PAGE
showed one isoform. Also, zymogram pattern of trypsin using nitro-cellulose membrane
revealed two isoforms. The inhibitory effect of PMSF, TLCK, TPCK, EDTA, iodoacetate
and iodoacetamide were determined on O. elegans proteolytic activity. The iodoacetamide
showed the highest inhibition on total proteolytic activity. Therefore, cysteine protease
accounted for the major proteases in the gut of O. elegans. Total proteolytic activity was
inhibited 22.3 and .15% by inhibitors extracted from Vicia faba and Lathyrus sativus,
respectively. However, the inhibitors extracted from seeds of Prosopis farcta, Panecum
miliaceum, and Alhagi maurorum showed negligible inhibitory effects on proteolytic
activities. Trypsin activity was inhibited 91.5 and 82.3% by inhibitors extracted from V.
faba and L. sativus, respectively. Electrophoretic analysis showed that inhibitors extracted
from V. faba reduced the intensity of total proteolytic and trypsin activities. The inhibitor
from V. faba was purified by ammonium sulfate precipitation and gel-filtration, also the
molecular mass of inhibitor was determined 35 kDa. This purified inhibitor was able to
inhibit trypsin activity by 72.7%. In addition, the highest inhibition of trypsin activity by
inhibitor from V. faba occurred at pH 11.0. Also, the stability of inhibitor from V. faba was
evaluated at different pHs and temperatures. This inhibitor was stable at pH 11.0 and 30 °C.
Keywords: Digestive protease type, Plant protease inhibitors, Trypsin.