Two Homologous Apolipoprotein AI Mimetic Peptides

Two related 18-amino acid, class A, amphipathic helical peptides termed 3F-2 and 3F14 were chosen for this study. Although they have identical amino acid compositions and many similar biophysical properties, 3F-2 is more potent than 3F14 as an apolipoprotein AI mimetic peptide. The two peptides exhibit similar gross conformational properties, forming structures of high helical content on a membrane surface. However, the thermal denaturation transition of 3F-2 is more cooperative, suggesting a higher degree of oligomerization on the membrane. Both 3F-2 and 3F14 promote the segregation of cholesterol in membranes containing phosphatidylcholine and cholesterol, but 3F-2 exhibits a greater selectivity for partitioning into cholesterol-depleted regions of the membrane. Magic angle spinning/NMR studies indicate that the aromatic residues of 3F-2 are stacked in the presence of lipid. The aromatic side chains of this peptide also penetrate more deeply into membranes of phosphatidylcholine with cholesterol compared with 3F14. Using the fluorescent probe, 1,3-dipyrenylpropane, we monitored the properties of the lipid hydrocarbon environment. 3F-2 had a greater effect in altering the properties of the hydrocarbon region of the membrane. The results are consistent with our proposed model of the effect of peptide shape on the nature of the difference in peptide insertion into the bilayer. Two related 18-amino acid, class A, amphipathic helical peptides termed 3F-2 and 3F14 were chosen for this study. Although they have identical amino acid compositions and many similar biophysical properties, 3F-2 is more potent than 3F14 as an apolipoprotein AI mimetic peptide. The two peptides exhibit similar gross conformational properties, forming structures of high helical content on a membrane surface. However, the thermal denaturation transition of 3F-2 is more cooperative, suggesting a higher degree of oligomerization on the membrane. Both 3F-2 and 3F14 promote the segregation of cholesterol in membranes containing phosphatidylcholine and cholesterol, but 3F-2 exhibits a greater selectivity for partitioning into cholesterol-depleted regions of the membrane. Magic angle spinning/NMR studies indicate that the aromatic residues of 3F-2 are stacked in the presence of lipid. The aromatic side chains of this peptide also penetrate more deeply into membranes of phosphatidylcholine with cholesterol compared with 3F14. Using the fluorescent probe, 1,3-dipyrenylpropane, we monitored the properties of the lipid hydrocarbon environment. 3F-2 had a greater effect in altering the properties of the hydrocarbon region of the membrane. The results are consistent with our proposed model of the effect of peptide shape on the nature of the difference in peptide insertion into the bilayer. There is growing evidence that certain apo 1The abbreviations used are: apo, plasma apolipoprotein; LDL, low density lipoprotein; PC, phosphatidylcholine; PO, 1-palmitoyl-2-oleoyl; SO, 1-stearoyl-2-oleoyl; PC3P, 1,3-dipyrenylpropane; MAS, magic angle spinning; NOESY, nuclear Overhauser enhancement spectroscopy; LUV, large unilamellar vesicle; DSC, differential scanning calorimetry; HPLC, high pressure liquid chromatography; PIPES, 1,4-piperazinediethanesulfonic acid; Ie, intensity of excimer emission; Im, intensity of monomer emission. A-I mimetic, class A amphipathic helical peptides can be used to inhibit atherosclerosis (1Navab M. Anantharamaiah G.M. Reddy S.T. Van Lenten B.J. Hough G. Wagner A. Nakamura K. Garber D.W. Datta G. Segrest J.P. Hama S. Fogelman A.M. Curr. Opin. Investig. Drugs. 2003; 4: 1100-1104PubMed Google Scholar). The oral administration of peptide 4F synthesized from all-D amino acids (D-4F) protects mice from diet-induced atherosclerosis without altering plasma cholesterol levels (2Garber D.W. Datta G. Chaddha M. Palgunachari M.N. Hama S.Y. Navab M. Fogelman A.M. Segrest J.P. Anantharamaiah G.M. J. Lipid Res. 2001; 42: 545-552Abstract Full Text Full Text PDF PubMed Google Scholar, 3Navab M. Anantharamaiah G.M. Hama S. Garber D.W. Chaddha M. Hough G. Lallone R. Fogelman A.M. Circulation. 2002; 105: 290-292Crossref PubMed Scopus (372) Google Scholar). Preliminary studies also suggest that oral administration of D-4F to LDL receptor null and apo E null mice causes the rapid formation and clearance of small high density lipoprotein-like particles containing peptide, cholesterol, apo A-I and paraoxonase, an enzyme capable of converting pro-inflammatory high density lipoprotein into anti-inflammatory high density lipoprotein (4Navab M. Anantharamaiah G.M. Reddy S.T. Hama S. Hough G. Grijalva V.R. Wagner A.C. Frank J.S. Datta G. Garber D. Fogelman A.M. Circulation. 2004; 109: 3215-3220Crossref PubMed Scopus (316) Google Scholar). The peptide 4F has also been tested in vitro and shown to effectively inhibit lytic peptide-induced hemolysis, inhibit oxidized phospholipid-induced monocyte chemotaxis, scavenge lipid hydroperoxides from LDL (5Datta G. Epand R.F. Epand R.M. Chaddha M. Kirksey M.A. Garber D.W. Lund-Katz S. Phillips M.C. Hama S. Navab M. Fogelman A.M. Palgunachari M.N. Segrest J.P. Anantharamaiah G.M. J. Biol. Chem. 2004; 279: 26509-26517Abstract Full Text Full Text PDF PubMed Scopus (75) Google Scholar), and maintain endothelial nitric-oxide synthetase activity in the presence of atherogenic concentrations of LDL (6Ou Z. Ou J. Ackerman A.W. Oldham K.T. Pritchard Jr., K.A. Circulation. 2003; 107: 1520-1524Crossref PubMed Scopus (92) Google Scholar). To study the relationship of peptide structure to anti-atherosclerogenic potency, we studied the properties of four related 18-amino acid, class A amphipathic helical peptides (5Datta G. Epand R.F. Epand R.M. Chaddha M. Kirksey M.A. Garber D.W. Lund-Katz S. Phillips M.C. Hama S. Navab M. Fogelman A.M. Palgunachari M.N. Segrest J.P. Anantharamaiah G.M. J. Biol. Chem. 2004; 279: 26509-26517Abstract Full Text Full Text PDF PubMed Scopus (75) Google Scholar). All of these peptides had identical amino acid compositions and very similar physical properties, yet two of these peptides, 3F-1 and 3F-2, were more potent in inhibiting lytic peptide-induced hemolysis, inhibiting oxidized phospholipid-induced monocyte chemotaxis, and scavenging lipid hydroperoxides from LDL compared with the analogs 3F3 and 3F14 (5Datta G. Epand R.F. Epand R.M. Chaddha M. Kirksey M.A. Garber D.W. Lund-Katz S. Phillips M.C. Hama S. Navab M. Fogelman A.M. Palgunachari M.N. Segrest J.P. Anantharamaiah G.M. J. Biol. Chem. 2004; 279: 26509-26517Abstract Full Text Full Text PDF PubMed Scopus (75) Google Scholar). In the present work we compare the interaction with phospholipid bilayers with and without cholesterol, of the most potent peptide of this series, 3F-2 (Ac-DKWKAVYDKFAEAFKEFL-NH2), and the least potent among these peptides, 3F14 (Ac-DWLKAFYDKVAEKFKEAF-NH2) (Fig. 1). We have previously shown that the potent analog 4F that has four, rather than three Phe, is capable of forming cholesterol-rich domains by preferentially interacting with regions of the membrane that are depleted of cholesterol (7Epand R.M. Epand R.F. Sayer B.G. Melacini G. Palgulachari M.N. Segrest J.P. Anantharamaiah G.M. Biochemistry. 2004; 43: 5073-5083Crossref PubMed Scopus (43) Google Scholar). 3F-2 exhibits similar biological potency to 4F but has somewhat less activity in inhibiting oxidized phospholipid-induced monocyte chemotaxis, about the same activity in scavenging lipid hydroperoxides from LDL and greater activity in inhibiting lytic peptide-induced hemolysis (5Datta G. Epand R.F. Epand R.M. Chaddha M. Kirksey M.A. Garber D.W. Lund-Katz S. Phillips M.C. Hama S. Navab M. Fogelman A.M. Palgunachari M.N. Segrest J.P. Anantharamaiah G.M. J. Biol. Chem. 2004; 279: 26509-26517Abstract Full Text Full Text PDF PubMed Scopus (75) Google Scholar). In contrast, although 3F14 is a class A amphipathic helical peptide with some anti-atherosclerogenic activity, it has a much weaker potency than either 3F-2 or 4F in the activities mentioned. This difference in potency is reflected in differences in the red edge effect in Trp emission from the peptide and in the quenching of 2-(3 (diphenylhexatrienyl)-propanoyl)-1-hexadecanoyl-sn-glycero-3-phosphocholine (5Datta G. Epand R.F. Epand R.M. Chaddha M. Kirksey M.A. Garber D.W. Lund-Katz S. Phillips M.C. Hama S. Navab M. Fogelman A.M. Palgunachari M.N. Segrest J.P. Anantharamaiah G.M. J. Biol. Chem. 2004; 279: 26509-26517Abstract Full Text Full Text PDF PubMed Scopus (75) Google Scholar). In this study we further evaluate the interaction of 3F-2 and 3F14 with model membranes using NMR, DSC, CD, and fluorescence. Lipids—The lipids used in this study were obtained from Avanti Polar Lipids (Alabaster, AL). The purity of the phospholipids by the and of the transition using peptides were synthesized by the with a peptide using the previously (2Garber D.W. Datta G. Chaddha M. Palgunachari M.N. Hama S.Y. Navab M. Fogelman A.M. Segrest J.P. Anantharamaiah G.M. J. Lipid Res. 2001; 42: 545-552Abstract Full Text Full Text PDF PubMed Google Scholar, G. Chaddha M. Hama S. Navab M. Fogelman A.M. Garber D.W. Epand R.M. Epand R.F. Lund-Katz S. Phillips M.C. Segrest J.P. Anantharamaiah G.M. J. Lipid Res. 2001; 42: Full Text Full Text PDF PubMed Google Scholar). The peptides were using a and the purity of the peptides by and of and concentrations of peptide in were using the and an of from the and Trp by Scopus Google Scholar). of for and and cholesterol were in containing peptide, an of a of the peptide in to the lipid in The a of with of a as to a of lipid the of the The of were by the high for least The lipid with PIPES, with and by and to for The used for were with the same in to a of The used for were to of cholesterol to the the the were in an The to a of an to the of lipid into the it were using a The and a of in a to for thermal were by using the by and with for of of peptide to the lipid three and and by the peptide by The with were for A from the and for by The of a and a for used to for In the of lipid in and by by a of the of A. J. Google Scholar). with the and to the To the or to the cholesterol acid by a of and in The were in a for to a the To for the presence of lipoprotein particles in the it by using the of PubMed Scopus Google Scholar). of the containing of peptide on a and for The with and with were on an model using a with a The in a the with The lipid by with the peptide by to of or were a of with a for thermal as a of and and to to the of were by of lipid in a of and in a to the lipid as a on the of the of were in a to a liquid for were used The were with and to of and The lipid were further by two stacked in a were on and used a of emission of the peptides in the presence and of were using an The and The emission were and for and in the physical properties of the region of the membrane and the of the peptides were monitored by the fluorescent emission of has been shown that the of the of excimer and monomer emission is to the of the membrane M. S. J. Full Text PDF PubMed Scopus Google Scholar). were containing lipids and a in were in containing of The using with in emission and were and and the of peptide. The results are as the of the intensity of excimer emission to that of monomer emission The were with two The in for with the same and but the of the and they similar with and without either of the two were using a of in a The were obtained using of and The were on to for phosphatidylcholine J. J. M.A. J. Chem. Google Scholar), cholesterol J. Full Text PDF PubMed Scopus Google Scholar), and amino acid residues Chem. 2002; PubMed Scopus Google Scholar). of containing and cholesterol were by in the presence of and 3F-2 or 3F14. we present the results from containing or of of the peptides (Fig. The are as the cholesterol as in our on 4F (7Epand R.M. Epand R.F. Sayer B.G. Melacini G. Palgulachari M.N. Segrest J.P. Anantharamaiah G.M. Biochemistry. 2004; 43: 5073-5083Crossref PubMed Scopus (43) Google Scholar). Both peptides promote the of cholesterol into domains higher of cholesterol and of peptide The cholesterol are in a and and and (Fig. This has been to a with the peptide 4F (7Epand R.M. Epand R.F. Sayer B.G. Melacini G. Palgulachari M.N. Segrest J.P. Anantharamaiah G.M. Biochemistry. 2004; 43: 5073-5083Crossref PubMed Scopus (43) Google Scholar). to can much of this R.M. Sayer B.G. Epand R.F. Biochemistry. 2003; 42: PubMed Scopus Google Scholar), but the higher are to the transition of the peptide. 3F14 causes of cholesterol of cholesterol and peptide than is with A more difference is in the the transition that is to the to liquid transition of The of this transition can be from the transition on with a transition of R.M. Sayer B.G. Epand R.F. Biochemistry. 2003; 42: PubMed Scopus Google Scholar). without cholesterol, the of 3F-2 the to and to with 3F14 of cholesterol and the of concentrations of 3F-2 this with 3F14 the of this transition is of the transition of cholesterol The are in cholesterol from the on the in in a of the transition of The are in from the the on the in in a The transition in the to that of the of the peptide. about for with 3F14 the transition is with in the of cholesterol but the transition is in with 3F-2 (Fig. The transition is on than on in of 3F-2 and 3F14 exhibit some on peptide (5Datta G. Epand R.F. Epand R.M. Chaddha M. Kirksey M.A. Garber D.W. Lund-Katz S. Phillips M.C. Hama S. Navab M. Fogelman A.M. Palgunachari M.N. Segrest J.P. Anantharamaiah G.M. J. Biol. Chem. 2004; 279: 26509-26517Abstract Full Text Full Text PDF PubMed Scopus (75) Google Scholar). The of or to 3F-2 peptide results in in the structure of 3F-2 (Fig. but the of the for 3F14 (Fig. The of the a of structure on to with 3F-2 and with 3F14 (Fig. The thermal transition is with some on and of the of 3F-2 or 3F14 in and in the presence of lipid as is a and a A, peptide in in the presence of small unilamellar of with peptide. in the presence of small unilamellar of with peptide. A used with a of of Lipid and of cholesterol, and the peptide 3F-2 or 3F14 were the In the presence of peptide, lipid is (Fig. A of cholesterol is compared with in containing by that lipoprotein particles were either a of and cholesterol a of or and also containing of 3F-2 or 3F14 for and of were (Fig. that lipoprotein particles were with The that the of lipid and peptide is in the the low concentrations used for that in the of the much higher concentrations used for NMR, the of peptide and lipid are in the and in This is in with our of a for this lipid of of of cholesterol, and peptide that had been three were on a and for The with and with with with with with emission of 3F-2 and 3F14 were in and in the presence of lipid (Fig. The emission of 3F-2 in is compared with for 3F14 in In the presence of either with or without cholesterol, the emission is to The results indicate that the Trp into the bilayer. are somewhat compared with our but in a lipid and a somewhat higher peptide In be some for of the There is an in the emission intensity of 3F-2 in the presence of without cholesterol, is in the presence of This be a of 3F-2 more deeply into bilayers containing cholesterol, but also be from or small differences in peptide (Fig. Trp emission is to the presence of cholesterol, that the of the Trp is This is similar to that with 4F (7Epand R.M. Epand R.F. Sayer B.G. Melacini G. Palgulachari M.N. Segrest J.P. Anantharamaiah G.M. Biochemistry. 2004; 43: 5073-5083Crossref PubMed Scopus (43) Google Scholar). 3F14 has identical emission intensity in the presence of either with or without cholesterol (Fig. suggesting that this peptide preferentially with cholesterol-depleted The by the of the lipid is somewhat greater with 3F14 than with 3F-2, suggesting that the Trp of the peptide is more deeply in the membrane. We have also the effect of cholesterol on the red edge In with our (5Datta G. Epand R.F. Epand R.M. Chaddha M. Kirksey M.A. Garber D.W. Lund-Katz S. Phillips M.C. Hama S. Navab M. Fogelman A.M. Palgunachari M.N. Segrest J.P. Anantharamaiah G.M. J. Biol. Chem. 2004; 279: 26509-26517Abstract Full Text Full Text PDF PubMed Scopus (75) Google Scholar), is red edge with 3F-2, but is with that Trp residues are more with 3F-2 in presence of cholesterol containing membranes compared with 3F14. be that 3F-2 has Trp the of the the of the of in 3F14. This be as a of Trp to the peptide the lipid the of the interaction with the lipid and results in a into phospholipid bilayer. has effect on this (Fig. in the of of in of and with and without the of 3F-2 or 3F14 a lipid to peptide (Fig. In with results M. S. J. Full Text PDF PubMed Scopus Google Scholar), in the present work we also that cholesterol the This is a of the and of in the presence of cholesterol the of conformational in the fluorescent The effect of the peptide is and to with higher concentrations of probe, suggesting that are and formation of This is to the presence of 3F14 but is by 3F-2, that 3F-2 has a greater effect on hydrocarbon from the of 3F-2 in the presence of a peptide to lipid are for the region of the aromatic side using or (Fig. The that the of the lipid in a although a in the of peptides in the presence of There are the aromatic and the from the of the insertion of the peptide into The of the nuclear Overhauser enhancement with is to rapid on this the peptide and lipid. In for of the in the aromatic in to that on the of the are with This that the aromatic are in as a of of the aromatic in bilayers of (Fig. as as with a of and cholesterol (Fig. The of 3F-2 with a of and cholesterol a for this The with 3F-2, for the with cholesterol, have somewhat This is for the to the in the with (Fig. from the the of the aromatic of a of containing The were and The are of the The are on the We a similar with the 3F14 peptide. The for this peptide were similar to for 3F-2 a shape with a in the of cholesterol but a in the of and The for the of 3F14 with (Fig. had of to that with In the on the in the aromatic that the aromatic are less stacked in 3F14 than in 3F-2, as be on the of the of aromatic residues in the helical of 3F-2 (Fig. 1). The the lipid and 3F14 are in the presence of cholesterol (Fig. suggesting that this peptide is from In the aromatic region of the is compared with from the the of the aromatic of a of containing 3F14. The were and The are of the In the of this the more to the aromatic The are on the of the peptide with lipid can also be by the in the of the lipid on of the peptide in from as as from in the of the environment. In the of in the of the phospholipid can be are from of cholesterol in these lipid J. J. M.A. J. Chem. Google Scholar), and the of peptide it to The of 3F-2 or 3F14 to either or results in a small in of The is to the presence of cholesterol and indicate a of the peptide in the bilayer. cholesterol are in we also The in are and is large difference 3F-2 and 3F14. In containing cholesterol the in are for and for cholesterol in of lipid by differences are in that of lipid and in the presence of peptide. A to a in the to a by the differences are in that of lipid and in the presence of peptide. A to a in the to a by the peptide in a Using in vitro to with 3F-2 and 3F14 exhibit potency (5Datta G. Epand R.F. Epand R.M. Chaddha M. Kirksey M.A. Garber D.W. Lund-Katz S. Phillips M.C. Hama S. Navab M. Fogelman A.M. Palgunachari M.N. Segrest J.P. Anantharamaiah G.M. J. Biol. Chem. 2004; 279: 26509-26517Abstract Full Text Full Text PDF PubMed Scopus (75) Google the differences in biophysical properties have been to be small work and G. Epand R.F. Epand R.M. Chaddha M. Kirksey M.A. Garber D.W. Lund-Katz S. Phillips M.C. Hama S. Navab M. Fogelman A.M. Palgunachari M.N. Segrest J.P. Anantharamaiah G.M. J. Biol. Chem. 2004; 279: 26509-26517Abstract Full Text Full Text PDF PubMed Scopus (75) Google Scholar). Both peptides are class A amphipathic and can into a helical structure amphipathic in plasma class A amphipathic G.M. Segrest J.P. Epand R.M. The Scholar). Although the of the Trp in the two peptides is the nature and of the residues on the of the helical of these two peptides are as is amino acid The and pressure indicate that the two peptides have similar but the 3F-2 is somewhat less (5Datta G. Epand R.F. Epand R.M. Chaddha M. Kirksey M.A. Garber D.W. Lund-Katz S. Phillips M.C. Hama S. Navab M. Fogelman A.M. Palgunachari M.N. Segrest J.P. Anantharamaiah G.M. J. Biol. Chem. 2004; 279: 26509-26517Abstract Full Text Full Text PDF PubMed Scopus (75) Google Scholar). Both peptides can phosphatidylcholine an of peptide and lipid (5Datta G. Epand R.F. Epand R.M. Chaddha M. Kirksey M.A. Garber D.W. Lund-Katz S. Phillips M.C. Hama S. Navab M. Fogelman A.M. Palgunachari M.N. Segrest J.P. Anantharamaiah G.M. J. Biol. Chem. 2004; 279: 26509-26517Abstract Full Text Full Text PDF PubMed Scopus (75) Google Scholar). The of the two peptides are and we in this work that the structure is of the presence of cholesterol (Fig. We also that peptides a of structure on (Fig. However, the thermal denaturation of 3F-2 is more in of 3F-2 than of 3F14 (Fig. a similar of is of the two peptides, we suggest that the transition of 3F-2 is more this peptide has a higher degree of oligomerization on the membrane compared with 3F14. We have shown that potent class A helical peptide, the formation of cholesterol-rich domains by preferentially interacting with the phospholipid of (7Epand R.M. Epand R.F. Sayer B.G. Melacini G. Palgulachari M.N. Segrest J.P. Anantharamaiah G.M. Biochemistry. 2004; 43: 5073-5083Crossref PubMed Scopus (43) Google Scholar). This an with the peptide that preferentially with cholesterol R.M. Sayer B.G. Epand R.F. Biochemistry. 2003; 42: PubMed Scopus Google Scholar). of cholesterol in membranes can from interaction of with cholesterol-rich domains as as with cholesterol-depleted domains R.M. 2004; PubMed Scopus Google Scholar). are to be to the of formation of in biological The that 3F-2 preferentially with the phospholipid in of cholesterol and This is by the that this peptide is much more potent in the transition of than is 3F14 (Fig. and 3F-2 also the formation of cholesterol of cholesterol much than are for formation in the of peptide (Fig. and The peptide 3F14 also the formation of cholesterol However, 3F14 the of the transition of in with cholesterol that it is interacting preferentially with 3F14 also the of by cholesterol, as we had shown for R.M. Sayer B.G. Epand R.F. Biochemistry. 2003; 42: PubMed Scopus Google Scholar). We suggest that a to the of cholesterol segregation in the membrane is an in the pressure of the membrane The greater of 3F-2 for cholesterol-depleted domains is also to potent peptide of this series, 4F (7Epand R.M. Epand R.F. Sayer B.G. Melacini G. Palgulachari M.N. Segrest J.P. Anantharamaiah G.M. Biochemistry. 2004; 43: 5073-5083Crossref PubMed Scopus (43) Google Scholar). This is with the less peptide 3F14. There is also a difference the two peptides in they with the membrane. The emission intensity from the Trp of 3F-2 is more by the lipid containing cholesterol (Fig. than is the of 3F14. The of the Trp of 3F-2 is similar to that of 4F (7Epand R.M. Epand R.F. Sayer B.G. Melacini G. Palgulachari M.N. Segrest J.P. Anantharamaiah G.M. Biochemistry. 2004; 43: 5073-5083Crossref PubMed Scopus (43) Google Scholar), the Trp is in for the two The similar of the Trp of two peptides, the of Trp in the helical that 3F14 more deeply into the bilayer. The greater of of the aromatic residues of 3F-2 (Fig. that side chains are stacked in the presence of lipid. In the presence of cholesterol 3F-2 exhibits with lipid from the of the The of of the that to the in the of the bilayer. This to that from red edge a of the Trp of We suggest that this difference is a of the for the two in in to in the of NMR, the the Trp and the lipid can but the Trp the is and is of the to the model we proposed (Fig. 3F-2 of of and aromatic side chains the peptide to the a in the in a in the lipid The of 3F-2 compared with 3F14 is also by the small in Trp emission by lipid (Fig. is a difference peptide into the membrane as by and by fluorescence. is that the greater by 3F-2 some of into the in a effect on Trp the indicate a greater of this peptide. In 3F14 to be from bilayers containing very the aromatic and the lipid (Fig. This is also in with the in the intensity of emission from the Trp in the presence of However, 3F14 into the it be to with the chains with less of the hydrocarbon of the as in The that we have monitored are very to the hydrocarbon or in the of the membrane. We have also studied the properties of the fluorescent that has been to in membrane properties M. S. J. Full Text PDF PubMed Scopus Google Scholar, S. PubMed Scopus Google Scholar). We to the as the for a model of the interaction of the peptide with lipid but rather as a that the more peptide, 3F-2, has a much effect on the properties of the hydrocarbon region of the compared with the less 3F14. The are consistent with the proposed model for the interaction of these peptides with bilayers on shape (Fig. In this model the 3F-2 peptide greater of the as a of and aromatic side chains the peptide to the of the in the the and excimer formation and also the for in the This is also consistent with the greater properties of 3F-2, membrane has been to be with for J. 2002; PubMed Scopus Google Scholar). In the differences in biological activity 3F-2 and the nature of the interaction of these peptides with with or without cholesterol is are differences the two peptides that our model of the difference in peptide (5Datta G. Epand R.F. Epand R.M. Chaddha M. Kirksey M.A. Garber D.W. Lund-Katz S. Phillips M.C. Hama S. Navab M. Fogelman A.M. Palgunachari M.N. Segrest J.P. Anantharamaiah G.M. J. Biol. Chem. 2004; 279: 26509-26517Abstract Full Text Full Text PDF PubMed Scopus (75) Google Scholar). Although 3F-2 is less than 3F14 by the of and pressure (5Datta G. Epand R.F. Epand R.M. Chaddha M. Kirksey M.A. Garber D.W. Lund-Katz S. Phillips M.C. Hama S. Navab M. Fogelman A.M. Palgunachari M.N. Segrest J.P. Anantharamaiah G.M. J. Biol. Chem. 2004; 279: 26509-26517Abstract Full Text Full Text PDF PubMed Scopus (75) Google Scholar), 3F-2 has with more in the of the (Fig. We suggest that this is a of a greater of the by this peptide. 3F-2 also has two that are more in with of 4F (7Epand R.M. Epand R.F. Sayer B.G. Melacini G. Palgulachari M.N. Segrest J.P. Anantharamaiah G.M. Biochemistry. 2004; 43: 5073-5083Crossref PubMed Scopus (43) Google Scholar). are a of the transition in of and cholesterol (Fig. and a more transition of the peptide. The oligomerization that also to a greater of the by insertion of a peptide The of the lipid for the of oxidized lipids from the LDL to LDL less in monocyte chemotaxis, an in the of We are to for with the

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