title: The synthesis of deuterium-substituted, spin-labeled analogues of AMP and NAD+ and their use in ESR studies of lactate dehydrogenase.
abstract: Two spin-labeled analogues of AMP and NAD+ were synthesized, in which a perdeuterated nitroxide radical (4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, TEMPAMINE) was attached to C-6 or C-8 position of the adenine ring. The ESR spectra of these derivatives exhibit a 4-fold increase in sensitivity and a concomitant decrease in line-width as compared to the corresponding protonated analogues. The improved resolution of composite spectra consisting of freely tumbling and immobilized components is demonstrated in ternary complexes of the spin-labeled NAD+ derivatives with lactate dehydrogenase (L-lactate:NAD+ oxidoreductase, EC 1.1.1.27) and oxalate.
mesh_terms: D000249:Adenosine Monophosphate / Q000031:analogs & derivatives*; D003497:Cyclic N-Oxides; D003903:Deuterium; D004578:Electron Spin Resonance Spectroscopy; D007770:L-Lactate Dehydrogenase; D009243:NAD / Q000031:analogs & derivatives*; D013113:Spin Labels / Q000138:chemical synthesis*
chemical_list: D003497:Cyclic N-Oxides; D013113:Spin Labels; D009243:NAD; C015527:4-amino-TEMPO; D000249:Adenosine Monophosphate; D003903:Deuterium; D007770:L-Lactate Dehydrogenase