Inhibition kinetics of carba- and C-fucosyl analogues of GDP-fucose against fucosyltransferase V: implication for the reaction mechanism

Inhibition kinetics of two isosteric analogues of GDP-fucose (GDP-Fuc) were investigated against fucosyltransferase V using electrospray ionization mass spectrometry coupled to multiple reaction monitoring. The carba-Fuc analogue was found to be a competitive inhibitor with a Ki value of 67.1±9.8 μM, similar to the Km value for GDP-Fuc (50.4±5.5 μM), while the C-Fuc analogue exhibited significantly weak competitive inhibition with a Ki value of 889±93 μM.