title: Solution conformation of lactate dehydrogenase as studied by saturation transfer ESR spectroscopy.
abstract: Several binary and ternary inhibitor and 'dead end' complexes of pig heart lactate dehydrogenase (L-lactate:NAD+ oxidoreductase, EC 1.1.1.27) were studied by saturation transfer ESR spectroscopy by means of an active NAD analog, spin-labeled at N6. The mobility of the spin-label depends on the nature of small molecules bound at the remote catalytic end of the coenzyme. The spin-label was found to serve as a reporter group monitoring the conformation of the peptide loop that is folded down over the active cleft in crystals of ternary complexes. The data suggest a fluctuation of the loop between open and closed forms in solution. The structure of the inhibitor molecules has been correlated with their ability to stabilize a more closed conformation of the loop.
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D007770:L-Lactate Dehydrogenase; D008968:Molecular Conformation; D009243:NAD; D012996:Solutions; D013113:Spin Labels
chemical_list: D012996:Solutions; D013113:Spin Labels; D009243:NAD; D007770:L-Lactate Dehydrogenase