Petersen Frederic N R, Laursen Ib, Bohr Henrik, Nielsen Claus Hélix
Quantum Protein Center, Department of Physics, Technical University of Denmark, Kgs. Lyngby, Denmark.
Biochem Biophys Res Commun. 2009 Oct 2;387(4):760-5. doi: 10.1016/j.bbrc.2009.07.109. Epub 2009 Jul 25.
The host lipid bilayer is increasingly being recognized as an important non-specific regulator of membrane protein function. Despite considerable progress the interplay between hydrophobic coupling and lipid ordering is still elusive. We use electron spin resonance (ESR) to study the interaction between the model protein gramicidin and lipid bilayers of varying thickness. The free energy of the interaction is up to -6kJ/mol; thus not strongly favored over lipid-lipid interactions. Incorporation of gramicidin results in increased order parameters with increased protein concentration and hydrophobic mismatch. Our findings also show that at high protein:lipid ratios the lipids are motionally restricted but not completely immobilized. Both exchange on and off rate values for the lipid<-->gramicidin interaction are lowest at optimal hydrophobic matching. Hydrophobic mismatch of few A results in up to 10-fold increased exchange rates as compared to the 'optimal' match situation pointing to the regulatory role of hydrophobic coupling in lipid-protein interactions.
宿主脂质双层越来越被认为是膜蛋白功能的重要非特异性调节剂。尽管取得了相当大的进展，但疏水偶联与脂质有序化之间的相互作用仍然难以捉摸。我们使用电子自旋共振（ESR）来研究模型蛋白短杆菌肽与不同厚度脂质双层之间的相互作用。相互作用的自由能高达-6kJ/mol；因此，与脂质-脂质相互作用相比，它并不占明显优势。短杆菌肽的掺入导致随着蛋白质浓度和疏水错配的增加，序参数增加。我们的研究结果还表明，在高蛋白：脂质比时，脂质的运动受到限制，但并未完全固定。脂质<-->短杆菌肽相互作用的交换速率值在最佳疏水匹配时最低。与“最佳”匹配情况相比，几个埃的疏水错配会导致交换速率增加多达10倍，这表明疏水偶联在脂质-蛋白质相互作用中起调节作用。
