W. Niu et al., Orientation of membrane-bound melittin studied by a combination of HPLC and liquid secondary ion mass spectrometry (LSIMS), IUBMB LIFE, 50(3), 2000, pp. 215-219
Combining two analytical techniques, HPLC and liquid secondary ion mass spe
ctrometry, the orientation of liposomal membrane-hound melittin was analyze
d through its trypsin-digested products. We found that trypsin can access a
ll proteolytic sites of the membrane-bound melittin when the liposomes have
no transmembrane potential, whereas the proteolytic site near the N termin
us of melittin is blocked when the liposomes have a negative transmembrane
potential. The results suggest that the negative transmembrane potential ma
y induce the melittin molecules to insert into the membrane perpendicularly
, whereas melittin lies flat on the membrane surface in the absence of a ne
gative potential.