G F Fabiola1, S Krishnaswamy, V Nagarajan
1Department of Crystallography and Biophysics, University of Madras, India.
This study examined the occurrence and geometry of C-H...O hydrogen bonds in beta-sheet regions of proteins. Researchers analyzed 11 high-resolution protein structures and found that these bonds are widespread. The average distances and angles of these bonds were measured, and they were found to be consistent across parallel and antiparallel beta-sheets. An inverse correlation was observed between C-H...O and N-H...O hydrogen bonds, suggesting that C-H...O bonds may contribute to structural stability. Valine and threonine residues were found to be particularly likely to form these bonds. The study also found that side-chain involvement in C-H...O hydrogen bonds is extensive. These findings suggest that C-H...O hydrogen bonds may play a supplementary role in stabilizing beta-sheets.
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Area of Science:
Background:
Understanding the structural features of proteins is central to biochemistry. While N-H...O hydrogen bonds are well-documented in beta-sheets, less is known about the role of C-H...O interactions in these regions. Prior research has established that hydrogen bonds stabilize secondary structures like beta-sheets. However, the contribution of carbon-hydrogen bonds to this stabilization remains unclear. No prior work had resolved the extent to which C-H...O hydrogen bonds occur in beta-sheets. This gap motivated a closer examination of their geometry and frequency. Existing studies typically focus on N-H...O hydrogen bonds, leaving C-H...O interactions underexplored. This uncertainty drove a detailed structural analysis of beta-sheet regions. The absence of data on C-H...O hydrogen bonds in high-resolution protein structures highlighted a need for further investigation.
Purpose Of The Study:
This study aimed to analyze the occurrence and geometry of C-H...O hydrogen bonds in beta-sheet regions of proteins. The specific problem addressed is the lack of detailed information on these interactions in protein structures. The motivation comes from the potential role of C-H...O hydrogen bonds in stabilizing beta-sheets. The goal was to determine whether these bonds are widespread and how they compare to N-H...O hydrogen bonds. The study focused on high-resolution protein structures to ensure accurate measurements. Researchers sought to identify patterns in bond distances and angles. They also aimed to assess the correlation between C-H...O and N-H...O hydrogen bonds. The study's purpose was to contribute to the understanding of beta-sheet stabilization mechanisms.
The study found that C-H...O hydrogen bonds are widespread in beta-sheets and may contribute to structural stability.
Valine and threonine residues show a higher propensity to form these bonds.
The inverse correlation suggests that C-H...O bonds may act as an additional stabilizing factor in beta-sheets.
The average C(alpha)-O distance is 3.29 Å, CH...O distance is 2.38 Å, and the C(alpha)-H...O angle is 143 degrees.
Main Methods:
The study used high-resolution protein structures with a resolution of 1.3 Å to examine beta-sheet regions. A total of 11 unique structures were analyzed for the presence of C-H...O hydrogen bonds. Researchers measured average C(alpha)-O, CH...O distances, and C(alpha)-H...O angles. The analysis included parallel and antiparallel beta-sheet regions to compare hydrogen-bond geometries. The study also assessed the correlation between C-H...O and N-H...O hydrogen bonds. Amino-acid residues were categorized based on their propensity to form C-H...O hydrogen bonds. Side-chain involvement in these interactions was also evaluated. The approach combined structural analysis with statistical evaluation of bond geometries.
Main Results:
C-H...O hydrogen bonds were found to be widespread in beta-sheet regions of proteins. The average C(alpha)-O distance was 3.29 Å, and the CH...O distance was 2.38 Å. The C(alpha)-H...O angle averaged 143 degrees. Parallel and antiparallel beta-sheets showed identical hydrogen-bond geometries. An inverse correlation was observed between C(alpha)-H...O and N(i+1)-H...O hydrogen bonds. Valine and threonine residues showed a higher propensity to form C-H...O hydrogen bonds. Side-chain involvement in these interactions was also extensive. These findings suggest that C-H...O hydrogen bonds may contribute to beta-sheet stabilization.
Conclusions:
The study concludes that C-H...O hydrogen bonds are common in beta-sheet regions of proteins. These bonds exhibit consistent geometries across parallel and antiparallel sheets. The inverse correlation with N-H...O hydrogen bonds suggests a complementary role in stabilization. Valine and threonine residues are particularly likely to form these bonds. Side-chain involvement in C-H...O hydrogen bonds is notable. The findings support the idea that these bonds may provide additional structural stability. The authors propose that C-H...O hydrogen bonds could act as supplementary stabilizing factors. These results may inform future studies on protein structure and function.
Yes, both types of beta-sheets exhibit the same hydrogen-bond geometry for C-H...O bonds.
The researchers propose that these bonds may act as an additional stabilizing factor in beta-sheets.