Signal multiplicity determination

Population transfer experiments may be selective or nonselective. Selective population transfer experiments have found only limited use for signal multiplicity assignments (SSrensen et al, 1974) or for determining signs of coupling constants (Chalmers et al., 1974 Pachler and Wessels, 1973), since this is better done by employing distortionless enhancement by polarization transfer (DEPT) or Correlated Spectroscopy (COSY) experiments. However, nonselective population transfer experiments, such as INEPT or DEPT (presented later) have found wide application. 

Determination of the elemental composition should be started with the M + 2 peak. Chlorine, bromine, sulfur, and silicone are easily detected due to characteristic signal multiplicity for each of these elements. There is a simple mle to check the presence of the main A + 2 elements. If the intensity of the M + 2 peak constitutes less than 3% of the intensity of the M peak, the compound does not contain chlorine, bromine, sulfur, or silicon atoms. This rule is valid for the fragment ions as well, while its applicability is confirmed by the data summarized in Table 5.4. 

Wahlberg, J., and Spiess, M. (1997). Multiple determinants direct the orientation of signal-anchor proteins the topogenic role of the hydrophobic signal domain./ Cell... 

Note As each pair of signals delivers an independent mass value for the hypothetical singly charged ion, mass accuracy can greatly be enhanced in ESI by multiple determination of this value and subsequent calculation of the average. 

As can be seen in Table 3.1 for commonly used deuterated solvents, deviations of Jcu/Jcd from the ratio yH/yD are rare and small, so that only J(H or JCD need be determined experimentally. To conclude, all relations found for JCH can also be derived for JCD. The signal multiplicities, however, are different (3 for CD, 5 for CD2 and 7 for CD3, respectively) because of different spin quantum numbers (/D = 1 /H = ). 

The 13C signal multiplicities were determined by DEPT experiments and shown in Fig. 8.8. 

The structures in solution of these amides were established based on the observed scalar 6Li,15N NMR coupling constants. 6Li is a spin 1 nucleus and 15N is a spin nucleus. Thus, the multiplicity, N, of the 15N signal is determined by N = 2n + 1 and the multiplicity of the 6Li signal is correspondingly determined by N = n + 1, where n is the number of attached spin-coupled nuclei17,19,34. For a monomer of a doubly (6Li,15N) labelled lithium amide, the 6 Li signal would become a doublet and the 15N signal a triplet. The... 

The maximum multiplicity (number of lines, L) in a given NMR signal is determined by the number (n) of neighboring coupled nuclei according the Eq. (8.3), L... 

Specihc membrane and membrane-associated proteins also control the organelle traffic and fusion events that are associated with the movement of proteins between different intracellular compartments. Membrane proteins of the secretory and endocytic pathways depend on sorting signals that reside in their cytoplasmic domains. Many proteins exhibit multiple signals that determine their passage along these diverse pathways. Therefore, the steady-state distribution of any given membrane... 

Neurons, particularly those in the brain, receive multiple excitatory and Inhibitory signals. What Is the name of the extension of the neuron at which such signals are received How does the neuron integrate these signals to determine whether or not to generate an action potential ... 

STEP 2 If each compound is expected to produce the same number of signals, then determine the chemical shift, multiplicity, and integration of each signal in both compounds. 

When two different sets of protons split a signal, the multiplicity of the signal is determined by using the A + 1 mle separately (N +l)(Ni,+l) for each set of protons when the coupling constants for the two sets are different. When the coupling constants are similar, the iV +1 mle is applied to both sets at the same time. 

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