β-Thiopeptides: Synthesis, NMR Solution Structure, CD Spectra, and Photochemistry

Sifferlen, Thierry; Rueping, Magnus; Gademann, Karl; Jaun, Bernhard; Seebàch, Dieter

doi:10.1002/(sici)1522-2675(19991215)82:12<2067::aid-hlca2067>3.0.co;2-5

Cited by 69 publications

(43 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Integration of the NOE cross-peak volumes, followed by calibration and classification into three distance categories, allowed their use as distance constraints 10 ) The three NOEs (NH (6) to HÀC(b) (3,4) and NH (2) to HÀC(b) (5) ) are not consistent with all other NOEs and the 10/12-helix, but indicate that other conformations must be populated, besides the 10/12-helical structure, a result previously obtained by NMR investigations and MD simulations for the deprotected b 2 /b 3 -hexapeptide 3d (see above). These NOEs were not considered in the simulated-annealing calculations.…”

mentioning

confidence: 82%

Untitled

Rueping

Schreiber

Lelais

et al. 2002

HCA

Self Cite

View full text Add to dashboard Cite

Dedicated to Professor James R. Bull on the occasion of his retirement from the Mally Chair of Organic Chemistry at the University of Cape TownThe structural properties of four mixed b-peptides with alternating b 2 /b 3 -or b 3 /b 2 -sequences have been analyzed by two-dimensional homonuclear 1 H-NMR-and CD spectroscopic measurements. All four b-peptides fold into (P)-helices with twelve-and ten-membered H-bonded rings (Figs. 3 ± 6). CD Spectra (Fig. 2) of the mixed b 3 /b 2 -hexapeptide 4a and b 3 /b 2 -nonapeptide 5a, indicating that peptides of this type also adopt the 12/10helical conformation, were confirmed by NMR structural analysis. For the deprotected b 3 /b 2 -nonapeptide 5d, NOEs not consistent with the 10/12 helix have been observed, showing that the stability of the helix decreases upon N-terminal deprotection. From the NMR structures obtained, an idealized helical-wheel representation was generated (Fig. 7), which will be used for the design of further 12/10 or 10/12 helices.

show abstract

mentioning

confidence: 82%

Untitled

Rueping

Schreiber

Lelais

et al. 2002

HCA

Self Cite

View full text Add to dashboard Cite

show abstract

“…2 So, the incorporation of thioamides to linear peptide chains may exert significant effects in their activity, specificity and/or selectivity. [3][4][5][6] Many publications have reported structural aspects of organic molecules from their mass spectra and some work has been done in regard to tautomerism studies by mass spectrometry. 7 Nevertheless, it is more common for tautomeric equilibrium commonly to be studied by nuclear magnetic resonace (NMR), infrared (IR) and other spectrometric methods.…”

Section: Introductionmentioning

confidence: 99%

Mass Spectrometry as a Tool for the Determination of Heats of Tautomerization of Thioamides in the Gas Phase

Allegretti

Milazzo

Furlong

2005

Eur J Mass Spectrom (Chichester)

View full text Add to dashboard Cite

Tautomerism of several thioamides was studied by mass spectrometry. The analysis of the corresponding mass spectra allowed some fragmentations to be assigned to specific tautomers and heats of tautomerization to be determined through temperature effects and electron energy studies. Experimental determinations were strongly supported by theoretical calculations. AM1 semi-empirical results indicate that the thioamide-thioimidol equilibrium can be studied by mass spectrometry. Also, additional evidence was obtained regarding tautomerism occurrence between neutral species.

show abstract

“…This wavelength is easily accessible for femtosecond lasers (since it is obtained by tripling the Ti:S laser wavelength), and S-O substitution may be done site-selectively. Furthermore, it has been shown that incorporation of a thioamide linkage results in only minor changes of the secondary structure of a peptide [83,84] and that secondary structure is indeed changing upon illumination of thiopeptides [85,86]. A recent combined theoretical-experimental femtosecond studies on the photoswitch itself (CH 3 -CSNH-CH 3 ) shows that the isomerization quantum yield is high (30-40%), that the molecule is stable against photodegeneration, and that the isomerization proceeds through two reaction channels, one ultrafast with a <5 ps time constant and one slower with a 200 ps time constant [87].…”

Section: Vibrational Spectroscopy Of Non-equilibrium Dynamics Of Peptmentioning

confidence: 99%

Ultrafast Peptide and Protein Dynamics by Vibrational Spectroscopy

Hamm

2008

Biological and Medical Physics, Biomedical Engineering

View full text Add to dashboard Cite

Ultrafast peptide and protein dynamics by vibrational spectroscopyHamm, P Hamm, P (2008). Ultrafast peptide and protein dynamics by vibrational spectroscopy. In: Braun, M; Gilch, P; Zinth, W. Ultrashort laser pulses in biology and medicine. Proteins are molecular machines with a well-defined 3D structure, and it is mainly the success of X-ray and NMR spectroscopic techniques that made the tremendous progress in structural biology happen. However, it is also clear that biomolecular processes generally involve conformational changes of proteins and enzymes. Mostly due to a lack of appropriate spectroscopic tools, much less is known about the dynamics of protein structures. Protein dynamics occurs on a large range of time scales, which can coarsely be related to various length scales: Dynamics of tertiary and quaternary structure extends from milliseconds to seconds and even longer, while formation of secondary structure has been observed between 50 ns and a few microseconds [1][2][3][4][5][6][7][8][9][10][11][12]. Nevertheless, several experiments have provided strong hints for the relevance of even faster processes from the observation of large instantaneous signals, which could not be time-resolved [2,7,13]. For example, Thompson et al.[5] estimated a "zipping time" for a 21-residue α-helix of 300 ps (i.e., the time for closing of subsequent hydrogen bonds, once an initial helix turn is formed), while Huang et al. [7] indirectly concluded that helix nucleation might occur on a subnanosecond time scale. Also molecular dynamics (MD) simulations suggest that peptides and proteins can undergo considerable structural changes within 1 ns or less [8-10, 14, 15]. Hummer et al. [16] found the formation of the first α-helical turn within 0.1-1 ns in work on helix nucleation in short Ala and Gly based peptides. Daura et al. [9,17] simulated equilibrium folding/unfolding of a β-heptapeptide at the melting point and above to obtain statistics on the populations of the folded and unfolded states. Several folding/unfolding events were observed in a 50 ns trajectory, where the actual transitions from unfolded to folded conformations could be as fast as 50-100ps.

show abstract

β-Thiopeptides: Synthesis, NMR Solution Structure, CD Spectra, and Photochemistry

Cited by 69 publications

References 21 publications

Untitled

Untitled

Mass Spectrometry as a Tool for the Determination of Heats of Tautomerization of Thioamides in the Gas Phase

Ultrafast Peptide and Protein Dynamics by Vibrational Spectroscopy

Contact Info

Product

Resources

About