Beyond the Vibrational Stark Effect: Unraveling the Large Redshifts of Alkyne C–H Bond in Solvation Environments

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 10, 2025

C-H···O hydrogen bonds are formed in systems ranging from biomolecular complexes to small-molecule structures. Previous work has focused on the blueshifts C-H stretching frequency (ν¯CH) induced by these and their chemical biological roles. Here, we show that, contrast, terminal alkyne exhibit large redshifts (50-100 cm-1) upon bonding with oxygen-containing solvents. Using spectroscopic computational approaches, elucidate compare roles of vibrational Stark effect, bond polarization, charge transfer driving redshift. We that alkyne's formation correlate Lewis basicity solvent significantly larger than those arising solely electric fields (vibrational effect), differing well-studied redshift carbonyl vibrations bonds. Through a decomposition shifts based DFT calculations using absolutely localized molecular orbitals, demonstrate including effects polarization transfer, addition results quantitative agreement between experimentally observed theoretically predicted values various Our highlight significance beyond pure electrostatics accounting for exemplify our approach quantifying contributions different physical effects.

Language: Английский

The Effect of Phosphoserine-Containing Membranes on Electrostatic Fields at the Protein–Protein Interface Measured through Vibrational Stark Effect Spectroscopy

Biochemistry, Journal Year: 2025, Volume and Issue: unknown

Published: May 9, 2025

In the cell, Ras GTPases function as membrane-bound molecular switches for a variety of cell signaling pathways. isoforms have long been interest because connection between amino acid mutations and tumorigenesis. Much research focused on has used truncated, solubilized constructs, which exclude membrane-binding domain therefore ignore effects membrane binding function. Since is highly charged surface, it could significant impact electrostatic environment at or near protein-protein interface. Here, we use thiocyanate probe chemically inserted into Ras-binding RalGDS to investigate effect active site. Changes in electric field caused by were measured vibrational energy shifts infrared (IR) spectrum. For selection mutants large this interface soluble H-Ras construct, 30% phosphatidylserine (PS)/70% phosphatidylcholine (PC) nanodisc reduced compared counterparts. Additionally, bonded wildtype (WT) construct demonstrated shift 0.7 cm-1 PC was doped from 0% PS, but introduced site show no across these PS concentrations. These results indicate that local an electrostatics needs be considered when investigating oncogenic

Language: Английский