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Tryptophan Chemical Shift in Peptides and Proteins: A Solid State Carbon-13 Nuclear Magnetic Resonance Spectroscopic and Quantum Chemical Investigation
- Source :
- Journal of the American Chemical Society. 126:4726-4734
- Publication Year :
- 2004
- Publisher :
- American Chemical Society (ACS), 2004.
-
Abstract
- We have obtained the carbon-13 nuclear magnetic resonance spectra of a series of tryptophan-containing peptides and model systems, together with their X-ray crystallographic structures, and used quantum chemical methods to predict the (13)C NMR shifts (or shieldings) of all nonprotonated aromatic carbons (C(gamma), C(delta 2) and C(epsilon 2). Overall, there is generally good accord between theory and experiment. The chemical shifts of Trp C(gamma) in several proteins, hen egg white lysozyme, horse myoglobin, horse heart cytochrome c, and four carbonmonoxyhemoglobins, are also well predicted. The overall Trp C(gamma) shift range seen in the peptides and proteins is 11.4 ppm, and individual shifts (or shieldings) are predicted with an rms error of approximately 1.4 ppm (R value = 0.86). Unlike C(alpha) and N(H) chemical shifts, which are primarily a function of the backbone phi,psi torsion angles, the Trp C(gamma) shifts are shown to be correlated with the side-chain torsion angles chi(1) and chi(2) and appear to arise, at least in part, from gamma-gauche interactions with the backbone C' and N(H) atoms. This work helps solve the problem of the chemical shift nonequivalences of nonprotonated aromatic carbons in proteins first identified over 30 years ago and opens up the possibility of using aromatic carbon chemical shift information in structure determination.
- Subjects :
- Models, Molecular
Hartree–Fock method
Biochemistry
Catalysis
Spectral line
chemistry.chemical_compound
Colloid and Surface Chemistry
Nuclear magnetic resonance
Animals
Horses
Nuclear Magnetic Resonance, Biomolecular
Carbon Isotopes
Myoglobin
Chemical shift
Egg Proteins
Carbon-13
Tryptophan
Cytochromes c
Proteins
General Chemistry
Carbon-13 NMR
Delta II
Carboxyhemoglobin
chemistry
Quantum Theory
Muramidase
Chickens
Subjects
Details
- ISSN :
- 15205126 and 00027863
- Volume :
- 126
- Database :
- OpenAIRE
- Journal :
- Journal of the American Chemical Society
- Accession number :
- edsair.doi.dedup.....93833ff66a2a6fa961e90c8b789e9496