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 T 1 2 o 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

ΔH Δ H 0 (kJ/mol)

( T 1 2 T 1 2 0 °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