Low-temperature 15N and 13C CP/MAS (cross-polarization/magic angle spinning) NMR has been used to analyze BChl-histidine interactions and the electronic structure of histidine residues in the light-harvesting complex II (LH2) of Rhodopseudomonas acidophila. The histidines were selectively labeled at both or one of the two nitrogen sites of the imidazole ring. The resonances of histidine nitroge...

The conformation of an elastin-mimetic recombinant protein, [(VPGVG)4(VPGKG)]39, is investigated using solid-state NMR spectroscopy. The protein is extensively labeled with 13C and 15N, and two-dimensional 13C-13C and 15N-13C correlation experiments were carried out to resolve and assign the isotropic chemical shifts of the various sites. The Pro 15N, 13Calpha, and 13Cbeta isotropic shifts, and...

New methods are described that permit detailed analysis of the NMR spectra of calmodulin, an alpha-helical protein with a molecular weight of 16.7 kD. Two complementary approaches have been used: uniform labeling with 15N and labeling of specific amino acids with either 15N or 13C. It is demonstrated that uniform 15N labeling permits the recording of sensitive three-dimensional (3D) NMR spectra...

A zero-quantum/double-quantum HNCO(H) constant time experiment is presented for the quantitative evaluation of dipole-CSA cross-correlated relaxation involving the 1HN, 15N, and 13C' nuclei of the peptide plane. A simple procedure that allows the extraction of cross-correlated relaxation rate constants from intensity ratios of well-resolved doublet components along omega1 is described. The expe...

The assignment of the 1H, 15N, 13CO, and 13C resonances of recombinant human interleukin-4 (IL-4), a protein of 133 residues and molecular mass of 15.4 kDa, is presented based on a series of 11 three-dimensional (3D) double- and triple-resonance heteronuclear NMR experiments. These studies employ uniformly labeled 15N- and 15N/13C-labeled IL-4 with an isotope incorporation of greater than 95% f...

Frozen-solution conformational analysis (FrSCA) can be performed on organic compounds using REDOR spectroscopy. REDOR measurements on frozen aqueous solutions of 13C-methyl beta-15N-aminoglucoside indicate a bimodal distribution of conformations in a 68:32 ratio, with 13C-15N distances of 4.31 and 3.55 A, respectively. The high resolution and straightforward sample preparation make FrSCA an att...

We demonstrate that the SPECIFIC CP technique can be used to obtain heteronuclear correlation (HETCOR) spectra of peptide backbones with greater efficiency than conventional HETCOR methods. We show that similar design principles can be employed to achieve selective homonuclear polarization transfer mediated through dipolar or scalar couplings. Both approaches are demonstrated in a tripeptide wi...

1.Labelling plants with 15N and 13C stable isotopes usually require cultivation of plants in isotopically enriched soil and gas-tight labelling chambers - both approaches are not suitable if one aims to investigate in situ species interactions in real plant communities. 2.In this greenhouse experiment, we tested a labelling method in which dual-labelled (15N, 13C) urea solution is brushed direc...

We demonstrate the use of Lee-Goldburg cross-polarization (LG-CP) NMR under fast magic-angle spinning (MAS) to investigate the amplitude and geometry of segmental motions in biomolecular and polymeric solids. Motional geometry information was previously available only from 2H NMR, which, however, has limited site resolution and requires site-specific isotopic labeling. Using a 2D LG-CP techniqu...

Chromopeptide siderophores (azotobactin 87-I and -II) were isolated from an iron deficient culture medium of Azotobacter vinelandii ATCC 12837 (= DSM 87). Their structures were elucidated by chemical degradation studies and spectroscopic methods, especially 2D-NMR-techniques. Total assignments of 1H-, 13C-, and 15N-resonances based on 2D-HOHAHA-, 1H/13C-HMQC-, 1H/13C-HMBC-, 1H/15N-HMQC/TOCSY-, ...