Proline C–H bonds as loci for proline assembly via C–H/O interactions
Daniecki, Noah J.
Bhatt, Megh R.
Yap, Glenn P. A.
Zondlo, Neal Joseph
Proline residues within proteins lack a traditional hydrogen bond donor. However, the hydrogens of proline are all sterically accessible, with polarized C–H bonds that can be sites for molecular recognition. C–H/O interactions, between proline C–H bonds and oxygen lone pairs, have been previously identified as modes of recognition in proteins. A series of proline derivatives was synthesized, including 4R-hydroxyproline nitrobenzoate methyl ester, acylated on the proline nitrogen with bromoacetyl and glycolyl groups, and Boc-4S-(4-iodophenyl)hydroxyproline methyl amide. All three derivatives exhibited multiple close intermolecular C–H/O interactions in the crystallographic state, with H•••O distances as close as 2.3 Å. These observed distances are well below the 2.72 Å sum of the van der Waals radii of H and O. We further analyzed the role of C–H/O interactions in all previously crystallized derivatives of these amino acids, and found that all 26 structures exhibited close intermolecular C–H/O interactions. Finally, we analyzed all proline residues in the Cambridge Structural Database. The majority of these structures exhibited intermolecular C–H/O interactions at proline C–H bonds, suggesting that C–H/O interactions are an inherent and important mode for recognition of and higher-order assembly at proline residues. Due to steric accessibility and multiple polarized C–H bonds, proline residues are uniquely positioned as sites for binding and recognition via C–H/O interactions.
This is the peer reviewed version of the following article: Daniecki, N..J., Bhatt, M..R., Yap, G..P.A. and Zondlo, N..J. (2022), Proline C–H bonds as loci for proline assembly via C–H/O interactions. ChemBioChem. Accepted Author Manuscript. https://doi.org/10.1002/cbic.202200409, which has been published in final form at https://doi.org/10.1002/cbic.202200409. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited. This article will be embargoed until 09/21/2023.
hydrogen bonds , noncovalent interactions , protein structure , self-assembly , stereoelectronic effects
Daniecki, N..J., Bhatt, M..R., Yap, G..P.A. and Zondlo, N..J. (2022), Proline C–H bonds as loci for proline assembly via C–H/O interactions. ChemBioChem. Accepted Author Manuscript. https://doi.org/10.1002/cbic.202200409