Qualitative aspects of hydrogen-deuterium exchange in the proton, carbon-13, and nitrogen-15 nuclear magnetic resonance spectra of viomycin in aqueous solution

Abstract

The 1H, 13C, and 15N high field nuclear magnetic resonance spectra of the cyclic peptide viomycin have been fully assigned using homo- and heteronuclear double resonance experiments and pH effects. In addition it is shown how the two- and three-bond H-D isotope effects upon carbonyl resonances may assist in their assignment. The resistance to exchange with solvent water of the amide proton involved in the transannular hydrogen bond is observed directly in the 1H spectra, via the isotope effect on a carbonyl resonance in the 13C spectra, and via the one-bond 1H couppling in the 15N spectra.

Secondary structure of the Arg‐Gly‐Asp recognition site in proteins involved in cell‐surface adhesion

“…Increasing conformational mobility of Ser 6,,y at higher temperature will lessen the deshielding (downfield shifting) influence of the Ser carboxyl without affecting the Ser NH exchange rate. It should be noted that a detailed study of the cyclic pentapeptide viomycin [33] revealed that at pH 7 -7.5 the only N H that showed a resolved coupling to Ha was the one known to form a stable intramolecular hydrogen bond. The only other detectable NH was directed toward the center of the peptide ring and was thus also protected from solvent.…”

Tautomerism and isotopic multiplets in the 13C NMR spectra of partially deuterated 3‐arylpyrimido[4,5‐c]pyridazine‐5,7(6H,8H)‐diones and their sulfur analogs—evidence for elucidation of the structure backbone and tautomeric forms

“…The 1 H NMR and 13 C NMR spectra were recorded on Bruker 300 FT-NMR spectrometer (300 MHz for 1 H, 75 MHz for 13 C) in DMSO-d 6 at ambient temperature (26 • C), using 5-mm direct detection broadband probes and deuterium lock. The center of the solvent signal was used as an internal standard, which was related to tetramethylsilane with δ = 2.49 ppm ( 1 H) and δ = 39.5 ppm ( 13 C).…”

“…[10 -21] The slow exchange of amide hydrogens has led to the observation of isotopic multiplets in the spectra of amides. [10,12,13] . Recently, we reported the β-isotope effect on 13 C NMR spectra of some azo dyes based on pyrimidine(1H,3H,5H)2,4,6-triones and 2-thioxopyrimidine(1H,3H,5H)4,6-diones for elucidation of predominant tautomeric forms.…”

Four‐bond deuterium isotope effects on the chemical shifts of amide nitrogens in proteins

“…[9][10][11][12][13][14] The development of multidimensional NMR [15,16] has had an impact on the number and accuracy of the measurements of a variety of deuterium isotope effects on chemical shifts. The effects of proton-to-deuterium ( 1 H-to-D) substitution on the chemical shifts of 13 C α , 13 C β , and methyl 13 C nuclei 1-to-3 bonds away [17][18][19][20][21][22][23][24][25][26] and, more recently, 1-to-3-bond effects on the chemical shifts of the backbone 15 N, 13 CO, 13 C α , 13 C β , 1 H N and 1 H α , [27][28][29] Tyr 13 C ζ [30] and Cys 13 C β nuclei [31] have been quantified.…”