Studies on the structure and function of hemeproteins that use advantage of introduction of fluoroalkyl groups

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Functional regulation of hemeprotein is thought to be achieved through electronic structure of heme, and heme environment furnished by nearby amino acid residues. In this study, I have performed substitution of electron-withdrawing fluoro (F) and perfluoromethyl (CF_3) group(s) as pyrrole, porphyrin and heme side chain(s) to obtain large alteration of the heme electronic structure in order to elucidate the relationship between the structure and function. I have measured the ^<19>F-NMR, and the equilibrium constant (pKa) of the "acid-alkaline transition" in metmyoglobin in order to quantitatively assess the effects of the F and CF_3 substitutions for the electron density of heme Fe atom of the hemeprotein. I have confirmed that the introduction of F or CF_3 group(s) to the heme side chain(s) leads to a decrease in the electron density of the heme Fe atom, which in turn decreases the O_2 affinity of hemeprotein.