کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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2829092 | 1162784 | 2008 | 7 صفحه PDF | دانلود رایگان |

Fourier transform infrared spectroscopy (FTIR) was used to study the secondary structure of peptides which imitate the amino acid sequences of the C-terminal domain of the pro-apoptotic protein Bax (Bax-C) when incorporated into different lipid vesicles with or without negatively charged phospholipids. The infrared spectroscopy results showed that while the β-sheet components are predominant in the membrane-free Bax-C secondary structure as well as in the presence of phosphatidylcholine vesicles, the peptide changes its secondary structure in the presence of negatively charged membranes, including phospholipids such as phosphatidylglycerol or phosphatidylinositol, depending on both the lipid composition and their molar ratio. The negative charges in the model membrane surface caused a marked change from β-sheet to α-helix structure. Moreover, using attenuated total reflection infrared spectroscopy (ATR-FTIR), we investigated the orientation of Bax-C α-helical structures with respect to the normal to the internal reflection element. The orientation of Bax-C in membranes was also affected by negatively charged lipids, the presence of phosphatidylglycerol reduced the angle it forms with the normal to the germanium plate from 45° in phosphatidylcholine to 27° in phosphatidylglycerol vesicles. These results highlight the importance of lipid-protein interaction for the correct folding of membrane proteins and they suggest that the C-terminal domain of Bax will only span membranes with a net negative charge in their surface.
Journal: Journal of Structural Biology - Volume 164, Issue 1, October 2008, Pages 146–152