The Contribution of C-H···O Hydrogen Bonds to Membrane Protein Stability Depends on the Position of the Am
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- 作者：Madhusoodanan Mottamal and Themis Lazaridis
- 刊名：Biochemistry
- 出版年：2005
- 出版时间：February 8, 2005
- 年：2005
- 卷：44
- 期：5
- 页码：1607 - 1613
- 全文大小：124K
- 年卷期：v.44,no.5(February 8, 2005)
- ISSN：1520-4995
文摘
Structural analyses of membrane proteins reveal a large number of C
-H···O contacts betweentransmembrane helices, presumed to be hydrogen bonds. Recent experiments produced conflicting resultsfor the contribution of such hydrogen bonds to membrane protein stability. An FTIR study estimated anenergy of -0.88 kcal/mol for the G79-C-H···I76-O hydrogen bond in glycophorin A, whereas amutagenesis study showed that the A51-C-H···T24-O
hydrogen bond does not stabilize bacteriorhodopsin. Here, we reconcile these results using molecular mechanics calculations and an implicit membranemodel (IMM1). With explicit hydrogen atoms, the potential energy of the G79-C-H···I76-O interactionin GpA ranges from -0.54 to -0.9 kcal/mol and its contribution to stability (effective energy) from-0.49 to -0.83 kcal/mol, depending on the structural model used. The average values of these quantitiesin GpA-like motifs are similar. In bR, the corresponding numbers for the A51-C-H···T24-O interactionare +0.15 and +0.32 kcal/mol. The difference results from the different arrangement of the interactinggroups and specifically the position of the acceptor with respect to the C and N atoms. This conclusionlikely applies to soluble proteins as well.
-H···O contacts betweentransmembrane helices, presumed to be hydrogen bonds. Recent experiments produced conflicting resultsfor the contribution of such hydrogen bonds to membrane protein stability. An FTIR study estimated anenergy of -0.88 kcal/mol for the G79-C-H···I76-O hydrogen bond in glycophorin A, whereas amutagenesis study showed that the A51-C-H···T24-O hydrogen bond does not stabilize bacteriorhodopsin. Here, we reconcile these results using molecular mechanics calculations and an implicit membranemodel (IMM1). With explicit hydrogen atoms, the potential energy of the G79-C-H···I76-O interactionin GpA ranges from -0.54 to -0.9 kcal/mol and its contribution to stability (effective energy) from-0.49 to -0.83 kcal/mol, depending on the structural model used. The average values of these quantitiesin GpA-like motifs are similar. In bR, the corresponding numbers for the A51-C-H···T24-O interactionare +0.15 and +0.32 kcal/mol. The difference results from the different arrangement of the interactinggroups and specifically the position of the acceptor with respect to the C and N atoms. This conclusionlikely applies to soluble proteins as well.