Metalloproteins proton exchange

Two-dimensional NMR methods that yield a two-dimensional frequency spectrum have not yet been attempted successfully to study metal interactions with HS, although instances of successful applications of these approaches can be found in the study of metalloproteins (Kingery et al., 2001). Mononuclear ( H) two-dimensional NMR experiments, such as total correlation spectroscopy (TOCSY), can show H- H coupling throughout the complete spin system, and exchange protons can provide information on sites to which metal attach. For example, N-containing units in HS that bind the metal can be identified since the amido protons from these structures will exchange and disappear from the spectrum. 

Proton ENDOR. Ligands to metalloproteins often can be identified by the characteristic hyperfine behavior observed in the proton ENDOR spectrum. Further information is gained by determining whether the proton can be exchanged with deuterium. 

A terminal water or hydroxyl ligand is another source of proton hyperfine couplings in metalloproteins. Characteristically, these protons can usually be exchanged in deuterated media (unlike the constitutive protons discussed above), allowing for complementary H ENDOR studies on the exchanged samples. For example, ENDOR resonances from exchangeable... 

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