[1] Fluorine nuclear magnetic resonance of fluorinated ligands

This chapter discusses two types of fluorine nuclear magnetic resonance (NMR) experiments, distinguished by whether the fluorinated moiety is covalently linked to the enzyme. A variety of experiments can be designed in which a fluorinated compound interacts with a site on the protein in the same manner that a substrate, inhibitor, or product might interact. Experiments in which the fluorinated ligands is able to dissociate from the enzyme will be referred to as Type I experiments. In contrast, fluorinated molecules can be designed, which will interact with a locus on the enzyme, while bound, undergo a reaction with a group near the binding site, such that the fluorinated species becomes permanently a part of the covalent structure of the protein, and is therefore, unable to separate from the protein without breaking a chemical bond. These systems will be designated Type II systems. Application of the appropriate handling of the experimental data will produce for Type I systems two sets of data, parameters for the free (unbound) ligands and the corresponding information for the bound ligand. NMR studies of fluorinated ligands in enzyme structures offer a number of operational advantages and can produce results indicative of binding stoichiometry, ionization behavior, enzyme dynamics, and conformational changes.