NMR spectra of macromolecules

With TROSY, CRIPT and CRINEPT, high-resolution NMR spectra of macromolecules with masses of one to several hundred thousand Daltons can be recorded [3, 26, 35] (Figs. 10.1 and 10.6). Sequence-specific NMR assignments for large structures have already been obtained (Fig. 10.5), and TROSY-based NOESY experiments [12, 16, 31, 32] for the collection of structural constraints are also available. Practical applications for... 

Figure 12.14. Schematic illustration of the effects of slow, intermediate, and fast exchange on the appearance of peaks in NMR spectra of macromolecule-ligand complexes. In the slow exchange case separate peaks are seen for free and bound forms. Note the broader peak for the bound ligand because it now adopts the correlation time of the macromolecule. In the fast...

Johnson BA (2004) Using NMR view to visualize and analyze the NMR spectra of macromolecules. Methods Mol Biol 278 313-352... 

Following the characterization of the human genome sequence and the identification of specific proteins coded for by the genes, this has led to a resurgence of interest in protein structure determination, or structural genomics as it is sometimes called. There are a number of important 3D NMR experiments that are used for assigning the peaks in NMR spectra of macromolecules such as proteins, which have been obtained fully labeled with and N. Additionally, 3D NMR spectroscopy has been used to investigate the structures of synthetic polymers. 

A Swiss NMR technique makes it possible to obtain high-resolution solution NMR spectra of macromolecules and supramolecular structures with masses up to several... 

The same influences which determine the dependence of carbon-13 shifts on chain microstructure in the solution NMR spectra of macromolecules appear to be operative also in the solid state. — L.A. Belfiore et al. [6]... 

Fig. 5. H-NMR. spectra of oligomers C4Dg(C4HtD4)aLi formed from 1,1,3,4-tetradeu-terobutadiene in benzene at room temperature DP in ascending order. 1, 2.1, and 3.2. (X.Y) Signals from (predominantly) 1,4- and 1,2-units in nonterminal monomer (a, /3, y, 8) those from terminal (Li) units. Reprinted with permission from S. By water, D. J. Worsfold, and G. Hollingsworth, Macromolecules S, 389 (1972). Copyright by the American Chemical Society.

The two reasons for extending NMR studies beyond three dimensions are the same as those for going from one to two dimensions (1) to spread out crowded resonances and (2) to correlate resonances. 3D and 4D experiments have been carried out almost exclusively to interpret the spectra of macromolecules, principally large proteins. We return in Chapter 13 to a discussion of these applications, but here we give a brief description of some types of 3D and 4D experiments. 

FIGURE 7-37 60 MHz H NMR spectra of PMMA [redrawn from an original figure by F. A. Bovey, High Resolution NMR of Macromolecules, Academic Press (1972)]. 

To estimate the conformations of (I) and (II) at the enzyme active site of fungi or plants, IR and H-NMR spectra of the azole compounds in solutions were measured. From the results of mode of action and binding assay, (I) and (II) are considered to locate in the close proximity to the prosthetic porphyrin group of cytochrome P-450 enzymes. The polarity of macromolecules close to the porphyrin moiety of apohemog1obin has been determined by fluorescence study to be similar to that of n-octanol (1 0)> In our study, carbon tetrachloride and deuterioch1 oroform of which polarities were similar to that of n-octanol were used. 

Fig. 2. Observed CP/MAS C NMR spectra of PMAA, PVAc, and the PMAA/PVAc blends (A) carboxyl regions of PMAA and carbonyl regions of PVAc. (B) Aliphatic region. The sum of the C NMR spectra of pure PMAA and pure PVAc at the respective molar unit ratio is also depicted on the right of the observed spectra. (Figure 1 in the original literature A. Asano, M. Eguchi, M. Shimizu and T. Kurotsu, Macromolecules, 2003, 25, 8819.)...

During the period of this review, the NMR spectra of most elements have received at least some chemical biological or physical investigation. Due to the space limitation, structure determination and related studies of natural products or macromolecules will be excluded, and the review articles are given for... 

Figure 7. Solid state deuterium NMR spectra of labelled poly(butylene terephthalate). Calculated spectra are for a two-site hopping model between two orientations of the C-D bond differing by 103° (Jelinski, L. W. Dumais, J. J. Engel, A. K. Macromolecules, 1983, 1 6, 492).

Figure 13.3-2. NMR spectra of rat serum illustrating the various NMR responses that are possible through the use of different pulse sequences, which edit the spectral intensities (a) standard water suppressed spectrum, showing all metabolites (b) CPMG spin-echo spectrum, with attenuation of peaks from fast relaxing components such as macromolecules and lipoproteins (c) diffusion-edited spectrum, with attenuation of peaks from fast diffusing components such as small molecules and (d) a projection of a 2D J-resolved spectrum on to the chemical shift axis, showing removal of all spin-spin coupling and peaks from fast relaxing species.

H NMR spectra of blood plasma suffer from the same problem of signal overlapping as the spectra of urine. Again, the already mentioned JRES technique can help to simplify the spectra in order to assign the intact fluid. This is especially necessary because broad resonances caused by macromolecules such as lipids and proteins (in particular albumin and immunoglobulins) can hide minor metabolites of drugs. 

FIGURE 10.5 Selection of protons with characteristic signals in the H-250 MHz NMR spectra of partially ozonized polybutadiene macromolecules. 

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