Table 2

Effects of SK inhibitors on Michaelis-Menten parameters for ATP

Varying concentrations of ATP were incubated with purified human GST-SK, 10 μm sphingosine and DMSO (control) or 2 μm of the indicated SK inhibitor for 30 min at 37°C. The resulting Km for ATP (μm) and the Vmax (nmol S1P/min) for each condition was determined as described in “Materials and Methods.” Data represent the mean ± SD of duplicate experiments. *P < 0.001 versus DMSO as determined with unpaired t test.

CompoundKmVmax
DMSO111 ± 160.633 ± 0.024
I82 ± 50.335 ± 0.087*
II124 ± 150.114 ± 0.018*
III12 ± 30.249 ± 0.019*
IV46 ± 140.318 ± 0.021*