Probing interaction of melittin with lipid membranes using liquid secondary ion mass spectrometry

摘要

The membrane insertion mechanism of toxic protein is a very active domain in the study of molecular biology, and the "anchor state" of the membrane bound protein on membrane is the key problem which it is difficult to solve with traditional methods. In the present work we first studied the "anchor state" of melittin on membrane using liquid secondary ion mass spectrometry (LSIMS) in combination with proteolysis by specific enzyme. The results show that the membrane bound melittin molecules mainly take the conformation in which the axis of α helix lies parallel to the membrane surface and the side containing Lys 7, Lys 21 and Arg 22 faces the outside of the lipid membrane. This discovery is very significant to the studies of membrane insertion mechanism. The results also indicate that the combination of mass spectrometry technique with the proteolysis by specific enzyme has provided a very new and effective method for the studies of the membrane insertion mechanism.