Table 1: The effects of bee venom melittin (mel) on thermodynamic parameters ( and ) and on PLA2 esterase activity measured in DMPC large unilamellar liposomes treated with either acidic (aPLA2) or basic (bPLA2) phospholipase A2 enzymes from Cmm rattlesnake venom. In rows 4, 5, 7, 8 the melittin-treated liposomes were post-treated (row 4, 7) or pre-treated (row 5, 8) with enzymes. Each data point is a mean of three experiments with the ± SD of the means. and are respectively the values for the enthalpy change and the width of main transition peak at its half-height in control DMPC liposomes (in absence of melittin and PLA2 enzymes).
|
Liposome systems |
(kJ/mol) |
( °C) |
µmoles fatty acid/ 10-11 moles PLA2 |
DMPC/fatty acid molar ratio |
1 |
DMPC |
1.00 ± 0.012 |
1.00 ± 0.011 |
0.000 |
– |
2 |
DMPC + melittin |
0.91 ± 0.012 |
2.51 ± 0.035 |
0.000 |
– |
3 |
DMPC + aPLA2 |
0.85 ± 0.011 |
2.75 ± 0.038 |
0.091 ± 0.0020 |
33 |
4 |
DMPC + mel + aPLA2 |
0.73 ± 0.010 |
3.51 ± 0.049 |
0.193 ± 0.0044 |
16 |
5 |
DMPC + aPLA2 + mel |
0.80 ± 0.011 |
2.79 ± 0.039 |
0.115 ± 0.0026 |
26 |
6 |
DMPC + bPLA2 |
0.79 ± 0.011 |
2.81 ± 0.039 |
0.124 ± 0.0028 |
24 |
7 |
DMPC + mel + bPLA2 |
0.86 ± 0.012 |
2.71 ± 0.037 |
0.084 ± 0.0019 |
36 |
8 |
DMPC + bPLA2 + mel |
0.84 ± 0.011 |
2.76 ± 0.038 |
0.085 ± 0.0019 |
35 |