HETCOR spectral analysis and structural characterization of polypeptides blends

TWO-DIMENSIONAL 13C- H HETCOR SPECTRAL ANALYSIS AND STRUCTURAL CHARACTERIZATION OF POLYPEPTIDES BLENDS 

It is very important to obtain more detailed information about the relationship between the character and miscibility of polypeptide blends. For example, the PG/PLV (50/50) blend sample, the preferred conformation of the PLV is he (3-sheet which exists in the PG/PLV (50/50) blend sample. On the other hand, the 3rhelix form of PG in PG/PLV blends is almost transformed to the (3-sheet form in the PG/PLV blend sample. We have been expecting two kinds of hydrogen bonding interactions with the (3-sheet. One is a 3-sheet conformation of intermolecular HB interactions between the PG and PG, and another is a (3-sheet conformation of intermolecular HB interactions between the PG and PLV. It is important to discuss the blend mechanism. The relationships between the starting materials, the preferred conformations and the new HB interactions are shown in Fig. 17. 

it is useful to get more detailed information about the miscibility of polypeptides and to understand the polypeptide blend by using further sophisticated NMR methodology. 

Recently, the two-dimensional 13C H heteronuclear correlation (HETCOR) NMR method, using the frequency-switched Lee-Goldberg (FSLG) H decoupling sequence55 at high MAS rates, has been developed, in order to provide intermolecular and spatial distance information. The HETCOR spectrum often has multiple proton cross peaks for each carbon, and these cross peaks can be extremely helpful for assigning the spectrum. Thus, this method can be used to characterize the structure of polymers in solids.55 71 

in this section, we aim to introduce the 2D FSLG 13C-3H HETCOR NMR55 spectrum of a PG/PLV (50/50) blend sample and to elucidate the intermolecular HB interactions between PG and PLV chains. 

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