15] Use of 31P(18O), 31P(17O), and 17O NMR methods to study enzyme mechanisms involving phosphorus

Abstract

Stimulated by the need for methodology to study the mechanism of enzyme reactions involving phosphorus, biochemists have demonstrated the 18O isotope shift effect and the 17O quadrupolar effect on 31P nuclear magnetic resonance (NMR). This chapter covers the recent developments and applications of these techniques, as well as some related new developments in magnetic resonance studies involving oxygen isotopes. The chapter emphasizes the methodology and the rationale of application, rather than the detailed insights of various mechanistic problems. There four application of 31P (18O) method are described: (1) oxygen isotope exchange, (2) phosphate exchange, (3) positional isotope exchange, and (4) stereochemistry. At least one example for each type of application is given and compared with examples of the application of the 31P (17O) NMR method. In addition, three newly developed subjects: 17O and 18O effects on 13C NMR, 17O superhyperfine splitting in ESR of metal ions, and 17O NMR of model membranes are described in the chapter.