الفهرس 
Insect lipidsOnly 14 pages are availabe for public view
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Abstract
The present study has been conducted to purify intracellular fat
body lipase and midgut lipase, for the first time, from last larval
instar of Galleria mellonella. Purification methods by
combination of ammonium sulfate precipitation and gel filtration
using Sephadex G-100, yielded a 98.9 and 49.15- fold purity and
recovery of 50.81% and 18.3% for fat body lipase and midgut
lipase, respectively. SDS-PAGE and zymogram revealed that the
molecular weight of midgut lipase was 104.23 kDa, while fat
body lipase showed two monomers with molecular weights of
178.8 and 62.6 kDa. Furthermore biochemical characterization of,
fat body lipase and midgut lipase, was carried out through testing
their activities against several factors such as; different
temperatures, pHs, metal ions and inhibitors ending by
determination of their kinetic parameters with the use of p-
Nitrophenyl butyrate (PNPB) as a substrate. The highest activities
of enzyme were determined at the temperature ranges of 35-37°C
and 37-40°C and pH ranges of 7-9 and 7–10 for midgut and fat
body lipase, respectively. The partially purified enzymes showed
significant stimulation by Ca2+, K+ and Na+ metal ions indicating
that both enzymes are metalloproteinases. Also, lipase activity
was strongly inhibited by some inhibitors; phenylmethylsulfony
fluoride(PMSF), ethylene-diaminetetractic acid (EDTA) and
ethylene glycoltetraacetic acid (EGTA) providing an evidence of
presence of serine residue and activation of enzymes by metal
ions.Kinetic parameters were 301.95mM Km and 0.361Umg-1 Vmax
for fat body lipase and 381.46 mM Km and 0.7893Umg-1 Vmax for
midgut lipase.
Key words: Galleria mellonella, purification, characterization,
digestive lipase, midgut lipase, intracellular lipase and fat body
lipase.