Determination of the stability of the noncovalent phospholipid transfer protein-lipid complex by electrospray time-of-flight mass spectrometry.
Phosphatidylcholine transfer protein (PC-TP) containing different molecular species of PC and phosphatidylinositol transfer protein alpha (PI-TPalpha) containing either a PI, PC, or PG molecule were identified as intact complexes by nano-electrospray ionization time-of-flight mass spectrometry. The stability of these complexes in the gas phase was determined by elevating the cone voltage (cv) resulting in the appearance of the protein void of lipid. PC-TP containing a PC species carrying an sn-1 palmitoyl chain was less stable than PC-TP containing a PC species carrying an sn-1 stearoyl chain given that these complexes were dissociated for 50% at a cv of roughly 30 and 45 V, respectively. Different acyl chains on the sn-2 position did not lead to significant changes in stability of the complex. In the case of PI-TPalpha, the complexes containing PI and PG were dissociated for 50% at a cv of 100 V as compared to a cv of 40 V for the complex containing PC. We propose that this difference in stability is due to hydrogen bonds between the polar headgroup of PI and PG and the lipid-binding site of PI-TPalpha. This may explain why PI-TPalpha preferentially binds PI from a membrane interface.
de Brouwer
A P M
AP
Department of Biochemistry of Lipids, Institute of Biomembranes, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Versluis
C
C
Westerman
J
J
Roelofsen
B
B
Heck
A J R
AJ
Wirtz
K W A
KW
D000727:Androgen-Binding Protein; D000818:Animals; D002352:Carrier Proteins / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D002417:Cattle; D006860:Hydrogen Bonding; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D051379:Mice; D036103:Nanotechnology / Q000379:methods; D010713:Phosphatidylcholines / Q000378:metabolism; D010716:Phosphatidylinositols / Q000032:analysis / Q000378:metabolism; D049294:Phospholipid Transfer Proteins; D010743:Phospholipids / Q000378:metabolism*; D011994:Recombinant Proteins / Q000032:analysis; D029701:Saccharomyces cerevisiae Proteins; D021241:Spectrometry, Mass, Electrospray Ionization; D016339:Spectrometry, Mass, Fast Atom Bombardment
D000727:Androgen-Binding Protein; D002352:Carrier Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D010713:Phosphatidylcholines; D010716:Phosphatidylinositols; D049294:Phospholipid Transfer Proteins; D010743:Phospholipids; D011994:Recombinant Proteins; C118289:SEC24 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins