(ECTO)NUCLEOTIDASE KINETICS OBSERVED BY P-31-NMR SPECTROSCOPY - RESOLUTION OF SIGNALS

We used P-31-NMR to study the action of the drug ouabain, a digitalis glycoside, on the ecto-nucleotidase catalysed reaction pathway: [GRAPH ICS] Even under conditions where it was impossible to resolve all reso nances from the individual species, the rate constants for the individ ual steps may be evaluated by a chi(2) fit of equations describing the global kinetics to the NMR data. The fitted values of the reaction ra te constants show no inhibition of any step in the reaction pathway, c onfirming previous results. This improved kinetic method can be used t o evaluate the effect of different substrates, ions and drugs, both in intact or pathologically altered organs and in tissue subcellular fra ctions. (C) 1997 The Italian Pharmacological Society.