¹³C and ¹H NMR Studies of PQQ and Selected Derivatives

Abstract

The ortho-quinone structure of PQQ is famous for its reactivity with nucleophilic species of carbon, nitrogen, and oxygen(Duine et. al. 1987). In fact, the crystal structure of PQQ was solved in the form of the C-5 acetone adduct(Salisbury et. al 1979). The propensity of the ortho-quinone to accept nucleophiles is the chemical basis of the function of PQQ at enzyme active sites. The present study focuses on the NMR of PQQ and various derivatives formed with oxygen and nitrogen nucleophiles. Our goals are to assign the ^lH, ¹³C, and ¹⁵N NMR spectra and to rigorously confirm the structures of the adducts. Once the NMR data of the relevant adducts are well defined, we will use ¹³C-and ¹⁵N-labeled substrates to probe the active sites of PQQ-containing enzymes.