N-Methylacetamide and Its Hydrogen-Bonded Water Molecules Are Vibrationally Coupled

Chen, X. G.; Schweitzer‐Stenner, Reinhard; Krimm, Samuel; Mirkin, Noemi G.; Asher, Sanford A.

doi:10.1021/ja00103a033

Cited by 116 publications

(124 citation statements)

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“…Variations in background buffer spectra due to solute concentration may be important as indicated by several works in the literature (37,47,57). Infrared spectra of deuterated water in the presence of denaturants and small amides resulted in significant shifts in the O-D stretching vibrations (58).…”

Section: Figmentioning

confidence: 99%

A Holistic Approach for Protein Secondary Structure Estimation from Infrared Spectra in H2O Solutions

Vedantham

Sparks

Sane

et al. 2000

Analytical Biochemistry

113

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Section: Figmentioning

confidence: 99%

A Holistic Approach for Protein Secondary Structure Estimation from Infrared Spectra in H2O Solutions

Vedantham

Sparks

Sane

et al. 2000

Analytical Biochemistry

113

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“…1 Among those functional groups possessed in proteins, which strongly interact with water, the peptide linkage -CdO-NH-builds the backbone chain of a protein molecule and is considered to have a major contribution to its hydration property. 2 Many authors reported on interactions of water with an amide group as a model of the peptide linkage in experimental [3][4][5][6][7][8][9][10][11][12][13][14] and theoretical [15][16][17][18][19][20][21][22][23][24][25] studies. A number of infrared spectroscopic studies were carried out to elucidate intermolecular interactions associated with hydration of N-methyl amide in aqueous solution.…”

Section: Introductionmentioning

confidence: 99%

Infrared and Near-Infrared Study of the Interaction of Amide C═O with Water in Ideally Inert Medium

Iwamoto¹

2010

J. Phys. Chem. A

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Hydration property of amide C=O was investigated from the OH stretching fundamentals and the first combinations of the water in the hydrate, formed in hydrophobic solution of an N,N-dialkyl amide ((CH(3)CH(2))(2)NCO(CH(2))(10)CH(3)) in heptane. The property was also examined for ester C=O of an alkyl ester (CH(3)(CH(2))(8)COOCH(3)) for comparison. The hydrates of C=O...H-O-H (I) and C=O...H-O-H...O=C (II) occur, the latter emerging above 5% concentration only and increasing in relative population with increasing concentration. The free OH of the water in I shows a sharp stretching band (nu(1)(OH(f))) at about 3690 cm(-1) and the bonded OH shows a much broader stretching band (nu(1)(OH(b))) of a significantly lower frequency. The difference Deltanu(fb) (= nu(1)(OH(f))-nu(1)(OH(b))), which is used as an indicator of hydration ability, is much larger for amide C=O (205 cm(-1)) than for ester C=O (134 cm(-1)). Equilibrium constant k(H) for the hydration process [C=O + (H(2)O) <--> C=O...H-O-H] is larger by about ten times for amide C=O than for ester C=O. Factors Deltanu(fb) and k(H) demonstrate that amide C=O has a strong hydration ability, implying that amide C=O of peptide linkage has an important contribution to high hydration ability of proteins.

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“…Their broad absorption spectra provide little information about the underlying excited states. UVRR excitation profiles and Raman depolarization ratios are utilized here to examine the underlying amide electronic transitions25,26,29. The present consensus is that predominantly three electronic transitions occur in simple amides in the 130 to 230 nm range.…”

Section: Introductionmentioning

confidence: 99%

UV Resonance Raman Investigation of Electronic Transitions in α-Helical and Polyproline II-Like Conformations

2008

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UV resonance Raman (UVRR) excitation profiles and Raman depolarization ratios were measured for a 21-residue predominantly alanine peptide, AAAAA(AAARA) 3 A (AP), excited between 194 and 218 nm. Excitation within the π→π* electronic transitions of the amide group results in UVRR spectra dominated by amide vibrations. The Raman cross sections and excitation profiles provide information about the nature of the electronic transitions of the α-helix and PPII-like peptide conformations. AP is known to be predominantly α-helical at low temperatures and takes on a polyproline II (PPII) helix-like conformation at high temperatures. The PPII-like and α-helix conformations show distinctly different Raman excitation profiles. The PPII-like conformation cross sections are approximately twice those of the α-helix. This is due to hypochromism that results from excitonic interactions between the NV 1 transition of one amide group with the higher energy electronic transitions of other amide groups, which decreases the α-helical NV 1 (π→π*) oscillator strengths. Excitation profiles of the α-helix and PPII-like conformations indicate that highest signalto-noise Raman spectra of α-helix and PPII-like conformations are obtained at excitation wavelengths of 194 and 198 nm, respectively. We also see evidence of at least two electronic transitions underlying the Raman excitation profiles of both the α-helical and PPII-like conformations. In addition to the well known ∼190 nm π→π* transitions, the Raman excitation profiles and Raman depolarization ratio measurements show features between 205-207 nm, which in the α-helix likely results from the parallel excitonic component. The PPII-like helix appears to also undergo excitonic splitting of its π→ π* transition which leads to a 207 nm feature.

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N-Methylacetamide and Its Hydrogen-Bonded Water Molecules Are Vibrationally Coupled

Cited by 116 publications

References 0 publications

A Holistic Approach for Protein Secondary Structure Estimation from Infrared Spectra in H2O Solutions

A Holistic Approach for Protein Secondary Structure Estimation from Infrared Spectra in H2O Solutions

Infrared and Near-Infrared Study of the Interaction of Amide C═O with Water in Ideally Inert Medium

UV Resonance Raman Investigation of Electronic Transitions in α-Helical and Polyproline II-Like Conformations

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