Novel inhibition mechanism of Bacillus cereus sphingomyelinase by beryllium fluoride

Phosphate analogs have been known to inhibit competitively various phosphatases and phospholipase C and D. We found for the first time that only beryllium fluoride (BeFx) among the phosphate analogs studied inhibits Bacillus cereus sphingomyelinase (SMase) activity. The active inhibitory species proved to be not BeF3− but BeF2 by the measurement of SMase activity and of 19F NMR spectroscopy in the presence of a fixed concentration of BeCl2 and different concentrations of NaF, although both the species have been reported for other kinds of enzymes. The result of kinetic experiment also indicated that the BeFx binds in the vicinity of the essential binding site for the substrate and that the Mg2+ binding to SMase is essential for the binding of BeFx to the enzyme.