Probing Protein Structure by Solvent Perturbation of NMR Spectra

A Comparison with Photochemically Induced Dynamic Nuclear Polarization Techniques Applied to Native α-Lactalbumin

Authors


Correspondence to S. Improta, European Molecular Biology Laboratory, Meyerhofstr. 1, D-69012 Heidelberg, Germany

Abstract

We have suggested elsewhere the use of surface mapping by spin label probes (Esposito et al., 1992). According to this approach, soluble nitroxides are added to a protein solution. Resonances of protons that are accessible to the nitroxide are broadened and bleached out of the spectrum, while resonances in the protein interior remain unaffected. This approach is, in principle, complementary to another technique, photochemically induced dynamic nuclear polarization, which maps the position of aromatic protons on the protein surface. A detailed comparison between the two techniques is necessary for a confident use of the more recent suggested nitroxide perturbation approach. In the present study, we show that the results obtained by the two techniques for the native state of bovine α-lactalbumin are fully consistent and may therefore be combined for the study of protein surfaces.

Abbreviations
Photo-CIDNP

photochemically induced dynamic nuclear polarization

CPMG

Carr-Purcell-Meiboom-Gill

TOCSY

total correlation spectroscopy

NOESY

two-dimensional nuclear Overhauser effect spectroscopy

DQF-COSY

double quantum filtered correlated spectroscopy

R

protein/TEMPOL concentration ratio

TEMPOL

4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl

Ancillary