Magnetization transfer, efficiency

A more general definition of magnetization-transfer efficiency e, , that includes only coherent effects and that is independent of structural or motional properties of a specific sample can be defined based on the idealized transfer function Lfir) ... 

The transfer efficiencies (Fig. 12) for the a-helical and (3-strand substructures are 0.036 and 0.04, respectively. Therefore, calculations suggest that the HN(CO)CANH-TROSY experiment becomes superior to the HN(CO)CA-TROSY scheme, especially on (3-sheet substructures of high molecular weight proteins at the highest magnetic field currently available. 

As can be seen by inspecting Figure 23, the coherence transfer efficiency is overwhelmingly good thanks to the very efficient 15N— -13C INEPT step employed for transferring magnetization exclusively from 15N to the sequential 13C nucleus. In addition, the possibility of an accidental resonance... 

In the spin diffusion motional regime (small molecules at low temperatures or macromolecules at all temperatures) the cross-relaxation is so efficient that it can hardly be limited to a single-step magnetization transfer. The multistep magnetization transfer is known as spin diffusion. It manifests differently in NOESY and ROESY spectra, as can be illustrated by writing eq. (29b) explicitly for the process of cross relaxation ... 

F. Du, X.-H. Zhu, H. Qiao, X. Zhang and W. Chen, Efficient in vivo P magnetization transfer approach for noninvasively determining multiple kinetic parameters and metabolic fluxes of ATP metabolism in the human brain. Magn. Reson. Med., 2007, 57, 103-114. 

These intermolecular correlation peaks mean that intermolecular cross polarization (CP) occurs between the carbon and proton of intermolecular -interacting polypeptides in blend. There may be two pathways for the observed intermolecular CP. One is that a direct transfer from proton to carbon exists, and another is that a change in the magnetization by spin diffusion (homonuclear Hartmann Hahn transfer) exists. It is thought that the former is much more efficient than the latter because the former comes from only one magnetization transfer process, but the latter comes from two... 

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