Resonance assignment prediction

In the absence of sequence-specific protein NMR resonance assignments, the data used for NOE matching are limited to the unassigned experimental protein H and 13C chemical shifts, the predicted protein H and 13C chemical shifts, and the experimental and predicted... 

Empirical as well as ab-initio quantum mechanical calculations of chemical shifts are likely to become an important tool for resonance assignments. Specifically, the ab-initio-type calculations are likely to prove useful in predicting conformations of polymorphs by comparing the, derived from guessed 3-D molecular structure inputs, with experimental chemical shifts. 

From equation 1 it is apparent that this resonance assignment includes the model proposed by Terao for PVOH (one extreme. Figure 1 spectrum J). For ethylene rich copolymer (the other extreme) this model predicts the observation of one major resonance situated at 74 ppm. From an inspection of Figure 1 (spectrum I) this appears to be true. 

Resonance assignments are often made by empirical relationships or rules that relate structural differences to chemical shift differences. These can be based on extensive studies on model compounds as in the case of the Grant-Paul or Lindeman-Adams relationships [1-3] for predicting the chemical shifts of carbon atoms in hydrocarbons and polyhydrocarbons. These have been very valuable for assigning the resonances observed in the spectra of ethylene-propylene copolymers [4,5], propylene-butene-1 copolymers [6,7], hydrogenated polydienes [8-18], and hydrogenated... 

The hydrogen NMR spectrum of [I4]annulene consists of signals at 5 = 7.8 and -0.6 ppm. Assign the resonances and predict the relative intensities of each. 

Mode specificity has also been observed for HOCl—>Cl+OH dissociation [92, 93 and 94]- For this system, many of the states are highly mixed and unassignable (see below). However, resonance states with most of the energy in the OH bond, e.g. = 6, are assignable and have nnimolecnlar rate constants orders of magnitude smaller than the RRKM prediction [92, 93 and 94]- The lifetimes of these resonances have a very strong dependence on the J and K quantum numbers of HOCl. 

Table 7.4 lists the Q and e values for an assortment of common monomers. The extremes in the column of e values in Table 7.4—which are listed in order-quantify the range of donor-acceptor properties which is used as the basis for ranking in Fig. 7.2. The Q values perform a similar ranking with respect to resonance effects. The eight different Q-e combinations in Table 7.4 allow the estimation of ri and values for 28 different copolymers. Of course, in these systems Q and e values were assigned to give the best fit to r values which had already been measured. As an illustration of the predictive values of the Q-e scheme, consider the following example ... 

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