Synthesis and conformational analysis of N-glycopeptides. II. CD, molecular dynamics, and NMR spectroscopic studies on linear N-glycopeptides

A. Perczel, E. Kollat, M. Hollos, G. D. Fasman

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

The comprehensive structural analysis reported herein of eight N-glycopeptides, in three different solvents, is based on quantitative CD experiments, homonuclear nuclear Overhauser effect measurements, and molecular dynamics (MD) calculations. Although several orientations of the two amide planes attached to the carbohydrate pyranose ring are possible, according to NOE, CD data, and MD simulations, of all of the glycopeptide models, regardless of the type of the carrier peptide, only one dominant conformer population was found. This conformer is characterized by a nearly trans orientation of the CH and NH hydrogens of both acetamido groups. This finding is in perfect agreement with x-ray crystallographic data on the solid state conformation of the 1-N-acetyl- and 1-N (β-aspartoyl) -2-acetamido-2-deoxy-β-D-glucopyranosylamine. The precise identification of this dominant conformer of N-glycopeptides in solution was the major question addressed herein by the structural analyses. A 'CD additivity' experiment was carried out using an equimolar solution of Boc-Pro-Asp-NHCH3 and 1-N-acetyl-3,4,6-tri-O-acetyl-2-acetamido-2-deoxy-β-D-glucopyranosylamine at ambient temperature in acetonitrile. The CD spectrum obtained from the equimolar solution of the above two molecules (the 'spectroscopic sum') was identical with the CD curve obtained from the algebraic summation of the individually recorded CD spectra of the peptide and the carbohydrate moiety ('mathematical sum'). The global picture of the CD spectral analyses of the eight parent peptides with the eight N-glycopeptides revealed that in trifluoroethanol and acetonitrile, the side-chain modification of the Asn models (natural N-glycopeptide analogues) by N-glycosylation has a significant effect on the conformation of the carrier peptide, resulting in a decrease in the original type I β-turn content. Simultaneously, the type II β-turn conformational percentage increased to ≃ 20%. Such a conformational ratio change seems to be larger than the expected errors arising from the CD analyses, and agrees with the results of MD calculations. N-glycosylation of Asn residues causes perturbations, not only through the covalent bond, but also through specific hydrogen bonds between the backbone and side chain atoms. CD spectroscopy, augmented by efficient CD curve deconvolution techniques, has proved to be a useful tool for studying multicomponent conformer mixtures of small linear peptides in solution and changes of conformational equilibria caused by N-glycosylation.

Original languageEnglish
Pages (from-to)665-685
Number of pages21
JournalBiopolymers - Peptide Science Section
Volume33
Issue number4
Publication statusPublished - Apr 1993

Fingerprint

Glycopeptides
Molecular Dynamics Simulation
Peptides
Molecular dynamics
Glycosylation
Nuclear magnetic resonance
Carbohydrates
Acetonitrile
Conformations
Hydrogen
Trifluoroethanol
Covalent bonds
Deconvolution
Amides
Structural analysis
Spectrum Analysis
Hydrogen bonds
Experiments
X-Rays
Spectroscopy

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Biophysics

Cite this

Synthesis and conformational analysis of N-glycopeptides. II. CD, molecular dynamics, and NMR spectroscopic studies on linear N-glycopeptides. / Perczel, A.; Kollat, E.; Hollos, M.; Fasman, G. D.

In: Biopolymers - Peptide Science Section, Vol. 33, No. 4, 04.1993, p. 665-685.

Research output: Contribution to journalArticle

@article{6f72d1f126f74131bde2fa74f1264816,
title = "Synthesis and conformational analysis of N-glycopeptides. II. CD, molecular dynamics, and NMR spectroscopic studies on linear N-glycopeptides",
abstract = "The comprehensive structural analysis reported herein of eight N-glycopeptides, in three different solvents, is based on quantitative CD experiments, homonuclear nuclear Overhauser effect measurements, and molecular dynamics (MD) calculations. Although several orientations of the two amide planes attached to the carbohydrate pyranose ring are possible, according to NOE, CD data, and MD simulations, of all of the glycopeptide models, regardless of the type of the carrier peptide, only one dominant conformer population was found. This conformer is characterized by a nearly trans orientation of the CH and NH hydrogens of both acetamido groups. This finding is in perfect agreement with x-ray crystallographic data on the solid state conformation of the 1-N-acetyl- and 1-N (β-aspartoyl) -2-acetamido-2-deoxy-β-D-glucopyranosylamine. The precise identification of this dominant conformer of N-glycopeptides in solution was the major question addressed herein by the structural analyses. A 'CD additivity' experiment was carried out using an equimolar solution of Boc-Pro-Asp-NHCH3 and 1-N-acetyl-3,4,6-tri-O-acetyl-2-acetamido-2-deoxy-β-D-glucopyranosylamine at ambient temperature in acetonitrile. The CD spectrum obtained from the equimolar solution of the above two molecules (the 'spectroscopic sum') was identical with the CD curve obtained from the algebraic summation of the individually recorded CD spectra of the peptide and the carbohydrate moiety ('mathematical sum'). The global picture of the CD spectral analyses of the eight parent peptides with the eight N-glycopeptides revealed that in trifluoroethanol and acetonitrile, the side-chain modification of the Asn models (natural N-glycopeptide analogues) by N-glycosylation has a significant effect on the conformation of the carrier peptide, resulting in a decrease in the original type I β-turn content. Simultaneously, the type II β-turn conformational percentage increased to ≃ 20{\%}. Such a conformational ratio change seems to be larger than the expected errors arising from the CD analyses, and agrees with the results of MD calculations. N-glycosylation of Asn residues causes perturbations, not only through the covalent bond, but also through specific hydrogen bonds between the backbone and side chain atoms. CD spectroscopy, augmented by efficient CD curve deconvolution techniques, has proved to be a useful tool for studying multicomponent conformer mixtures of small linear peptides in solution and changes of conformational equilibria caused by N-glycosylation.",
author = "A. Perczel and E. Kollat and M. Hollos and Fasman, {G. D.}",
year = "1993",
month = "4",
language = "English",
volume = "33",
pages = "665--685",
journal = "Biopolymers",
issn = "0006-3525",
publisher = "John Wiley and Sons Inc.",
number = "4",

}

TY - JOUR

T1 - Synthesis and conformational analysis of N-glycopeptides. II. CD, molecular dynamics, and NMR spectroscopic studies on linear N-glycopeptides

AU - Perczel, A.

AU - Kollat, E.

AU - Hollos, M.

AU - Fasman, G. D.

PY - 1993/4

Y1 - 1993/4

N2 - The comprehensive structural analysis reported herein of eight N-glycopeptides, in three different solvents, is based on quantitative CD experiments, homonuclear nuclear Overhauser effect measurements, and molecular dynamics (MD) calculations. Although several orientations of the two amide planes attached to the carbohydrate pyranose ring are possible, according to NOE, CD data, and MD simulations, of all of the glycopeptide models, regardless of the type of the carrier peptide, only one dominant conformer population was found. This conformer is characterized by a nearly trans orientation of the CH and NH hydrogens of both acetamido groups. This finding is in perfect agreement with x-ray crystallographic data on the solid state conformation of the 1-N-acetyl- and 1-N (β-aspartoyl) -2-acetamido-2-deoxy-β-D-glucopyranosylamine. The precise identification of this dominant conformer of N-glycopeptides in solution was the major question addressed herein by the structural analyses. A 'CD additivity' experiment was carried out using an equimolar solution of Boc-Pro-Asp-NHCH3 and 1-N-acetyl-3,4,6-tri-O-acetyl-2-acetamido-2-deoxy-β-D-glucopyranosylamine at ambient temperature in acetonitrile. The CD spectrum obtained from the equimolar solution of the above two molecules (the 'spectroscopic sum') was identical with the CD curve obtained from the algebraic summation of the individually recorded CD spectra of the peptide and the carbohydrate moiety ('mathematical sum'). The global picture of the CD spectral analyses of the eight parent peptides with the eight N-glycopeptides revealed that in trifluoroethanol and acetonitrile, the side-chain modification of the Asn models (natural N-glycopeptide analogues) by N-glycosylation has a significant effect on the conformation of the carrier peptide, resulting in a decrease in the original type I β-turn content. Simultaneously, the type II β-turn conformational percentage increased to ≃ 20%. Such a conformational ratio change seems to be larger than the expected errors arising from the CD analyses, and agrees with the results of MD calculations. N-glycosylation of Asn residues causes perturbations, not only through the covalent bond, but also through specific hydrogen bonds between the backbone and side chain atoms. CD spectroscopy, augmented by efficient CD curve deconvolution techniques, has proved to be a useful tool for studying multicomponent conformer mixtures of small linear peptides in solution and changes of conformational equilibria caused by N-glycosylation.

AB - The comprehensive structural analysis reported herein of eight N-glycopeptides, in three different solvents, is based on quantitative CD experiments, homonuclear nuclear Overhauser effect measurements, and molecular dynamics (MD) calculations. Although several orientations of the two amide planes attached to the carbohydrate pyranose ring are possible, according to NOE, CD data, and MD simulations, of all of the glycopeptide models, regardless of the type of the carrier peptide, only one dominant conformer population was found. This conformer is characterized by a nearly trans orientation of the CH and NH hydrogens of both acetamido groups. This finding is in perfect agreement with x-ray crystallographic data on the solid state conformation of the 1-N-acetyl- and 1-N (β-aspartoyl) -2-acetamido-2-deoxy-β-D-glucopyranosylamine. The precise identification of this dominant conformer of N-glycopeptides in solution was the major question addressed herein by the structural analyses. A 'CD additivity' experiment was carried out using an equimolar solution of Boc-Pro-Asp-NHCH3 and 1-N-acetyl-3,4,6-tri-O-acetyl-2-acetamido-2-deoxy-β-D-glucopyranosylamine at ambient temperature in acetonitrile. The CD spectrum obtained from the equimolar solution of the above two molecules (the 'spectroscopic sum') was identical with the CD curve obtained from the algebraic summation of the individually recorded CD spectra of the peptide and the carbohydrate moiety ('mathematical sum'). The global picture of the CD spectral analyses of the eight parent peptides with the eight N-glycopeptides revealed that in trifluoroethanol and acetonitrile, the side-chain modification of the Asn models (natural N-glycopeptide analogues) by N-glycosylation has a significant effect on the conformation of the carrier peptide, resulting in a decrease in the original type I β-turn content. Simultaneously, the type II β-turn conformational percentage increased to ≃ 20%. Such a conformational ratio change seems to be larger than the expected errors arising from the CD analyses, and agrees with the results of MD calculations. N-glycosylation of Asn residues causes perturbations, not only through the covalent bond, but also through specific hydrogen bonds between the backbone and side chain atoms. CD spectroscopy, augmented by efficient CD curve deconvolution techniques, has proved to be a useful tool for studying multicomponent conformer mixtures of small linear peptides in solution and changes of conformational equilibria caused by N-glycosylation.

UR - http://www.scopus.com/inward/record.url?scp=0027574907&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0027574907&partnerID=8YFLogxK

M3 - Article

C2 - 8467070

AN - SCOPUS:0027574907

VL - 33

SP - 665

EP - 685

JO - Biopolymers

JF - Biopolymers

SN - 0006-3525

IS - 4

ER -