Partial characterization of a lipase from gypsy moth (Lymantria dispar L.) larval midgut
Abstract:
Lipase activity of the gypsy moth (Lymantria dispar L.) was studied by the spectrophotometric
method using crude homogenate of fifth-instar larval midgut tissues as the enzyme source
and p-nitrophenyl caprylate (pNPC) as substrate. A Km value of 0.310mM and a Vmax value
of 1.479U/mg prot. were obtained for this substrate. Among various p-nitrophenyl esters tested,
maximum activity was obtained for p-nitrophenyl caprylate and p-nitrophenyl caprate. The
enzyme was most active at alkaline pH, with maximum at pH 8.2. Decreased activity was
detected after preincubation in buffers of pH below 7.0 and above 8.2. The enzyme was
unstable at room temperature. The enzyme was Ca2+ independent. Its activity was inhibited
by PMSF, Fe2+, Ag+ and Pb2+, while Fe3+ inhibited enzyme activity by about 40%.
Keywords:
Lymantria dispar L.; lipase; p-nitrophenyl esters; optimal conditions; inhibitionSource:
Folia biologica (Kraków), 2008, 56, 1-2, 103-110Funding / projects:
- Fiziološki i evolucioni aspekti stresnog odgovora u prirodnim i laboratorijskim populacijama (RS-MESTD-MPN2006-2010-143033)
DOI: 10.3409/fb56_1-2.103-110
ISSN: 0015-5497
PubMed: 19055033