Amide Spectral Fingerprints are Hydrogen Bonding-Mediated
Sara Gómez1, Cettina Bottari2, Franco Egidi1
1Scuola Normale Superiore, Classe di Scienze, Piazza dei Cavalieri 7, 56126, Pisa, Italy.
The Journal of Physical Chemistry Letters
|June 30, 2022
Summary
Specific hydrogen bonds in aqueous solutions significantly enhance amide signals in proteins. This study uses UV Resonance Raman spectroscopy and computational modeling to reveal key interactions influencing protein structure analysis.
Area of Science:
- Biophysical Chemistry
- Computational Chemistry
- Spectroscopy
Background:
- Proteins exhibit unique spectral features in aqueous solutions.
- Understanding these features is crucial for protein structure analysis.
- Peptide molecular models are used to investigate these phenomena.
Purpose of the Study:
- To investigate the origin of amide spectral features in proteins.
- To understand the role of hydrogen bonding in spectral enhancement.
- To validate the use of UV Resonance Raman (UVRR) spectroscopy for structural analysis.
Main Methods:
- Combined theoretical and experimental approach.
- Studied UV Resonance Raman (UVRR) spectra of peptide models (NAGMA, NALMA).
- Utilized a multiscale polarizable QM/MM protocol for modeling.
Main Results:
- Demonstrated excellent agreement between theoretical modeling and experimental data.
- Identified specific hydrogen bond interactions as key to selective amide signal enhancement.
- Showcased the influence of hydration dynamics on spectral features.
Conclusions:
- Hydrogen bond interactions are critical for the observed amide spectral features.
- Vibrational spectroscopy, particularly UVRR, is a powerful tool for detailed protein structural analysis in solution.
- The findings support the use of advanced computational methods in conjunction with experimental spectroscopy.
Related Concept Videos
01:19NMR Spectroscopy Of Amines
9.3K
In proton NMR spectroscopy, primary amines and secondary amines showcase their N–H protons as a broad signal in the chemical shift range between δ 0.5 and 5 ppm. The exact position in this range depends on several factors, including sample concentration, hydrogen bonding, and the type of solvent used. Since amine protons undergo fast proton exchange in solution, the protons are labile and therefore do not participate in any splitting with adjacent protons. Thus, the observed peak is...
9.3K
01:23IR Spectrum Peak Broadening: Hydrogen Bonding
1.2K
The vibrational frequency of a bond is directly proportional to its bond strength. As a result, stronger bonds vibrate at higher frequencies, while weaker bonds vibrate at lower frequencies. The stretching vibration of the strong O–H bond in alcohols and phenols (very dilute solution or gas phase) appears as a sharp peak at 3600–3650 cm−1.
However, the extent of hydrogen bonding influences the observed stretching frequency and band broadening. Intermolecular or intramolecular...
However, the extent of hydrogen bonding influences the observed stretching frequency and band broadening. Intermolecular or intramolecular...
1.2K
01:08IR Spectrum Peak Splitting: Symmetric vs Asymmetric Vibrations
1.2K
Identical bonds within a polyatomic group can stretch symmetrically (in-phase) or asymmetrically (out-of-phase). Similar to hydrogen bonding, these vibrations also influence the shape of the IR peak. Generally, asymmetric stretching frequencies are higher than symmetric stretching frequencies. For example, primary amines exhibit two distinct IR peaks between 3300–3500 cm−1 corresponding to the symmetric and asymmetric N-H stretching, while secondary amines exhibit a single...
1.2K
01:03IR Frequency Region: Fingerprint Region
1.1K
IR spectra are divided into two main regions: the diagnostic region and the fingerprint region. The diagnostic region of the spectrum lies above 1500 cm−1. The absorptions resulting from single-bond vibrations of the N–H, C–H, and O–H stretch at higher wavenumbers and appear on the left side of the spectrum. The stretching absorptions of the C≡C and C≡N occur between 2100–2300 cm−1. In contrast, those arising from stretching absorptions of the...
1.1K
01:24IR Frequency Region: X–H Stretching
1.1K
In IR spectroscopy, signals produced by the X−H bonds (such as C−H, O−H, or N−H) can be observed in the frequency range of 2700–4000 cm–1. The C−H stretching vibration forms sharp bands in the region 2850–3000 cm–1. The presence of the O−H stretching vibration leads to the forming of an absorption band in the frequency range 3650–3200 cm−1. At the same time, N−H stretching can be confirmed by absorption bands in...
1.1K
01:15NMR Spectroscopy and Mass Spectrometry of Aldehydes and Ketones
4.3K
In aldehydes, the hydrogen atom connected to the carbonyl carbon helps distinguish aldehydes from other carbonyl compounds using ¹H NMR spectroscopy. The closeness of aldehydic hydrogen to the electrophilic carbonyl carbon highly deshields the hydrogen atom causing its signal to appear around 10 ppm in the ¹H NMR spectra. α hydrogens split the aldehydic proton signal, which helps identify the number of α hydrogens in the molecule. For instance, one α hydrogen creates a...
4.3K