Title: Calcineurin Hydrolysis of Para-Nitrophenyl Phosphorothioate
Volume: 11
Issue: 2
Author(s): Donna J. Spannaus-Martin and Bruce L. Martin
Affiliation:
Keywords:
Calcineurin,, Metal-activated enzyme,, Substrate specificity,, Substrate analog.
Abstract: para-Nitrophenyl phosphorothioate (pNPT) was hydrolyzed by calcineurin at initial rates slightly, but comparable to rates for para-nitrophenyl phosphate (pNPP). Kinetic characterization yielded higher estimates for both Km and Vmax compared to pNPP. Metal ion activation of phosphorothioate hydrolysis was more promiscuous. Unlike the hydrolysis of with pNPP, Ca2+, Mg2+, and Ba2+ activated calcineurin as well as Mn2+.