Effect of VPA on the activity of rhPE.

Abstract

<p>(<b>A</b>) Activity of 10 nM purified rhPE was measured in presence of ten doses of VPA or lithium ranging from 0.2–10 mM. Relative activity of rhPE in the presence of VPA or lithium is shown as a percentage of activity in the absence of VPA and lithium. VPA showed a <i>K_i</i> of approximately 1 mM. lithium showed no effect on PE activity. (<b>B</b>) Inhibition curves of three VPA concentrations (0.8, 1.6 and 3.5 mM) were obtained by incubating VPA with 10 nM rhPE during 90 min at 37 °0. (<b>C</b>) A Lineweaver-Burk plot was made based on the rhPE activity assays with 0.8 and 1.6 mM VPA as inhibitor. Enzyme activity was measured with increasing substrate (Suc-Gly-Pro-pNA) concentrations, ranging from 0.2–10 mM. The velocity was calculated as mM * min⁻¹ * ml⁻¹. Data are shown as the mean ± S.E.M. (n = 3 per group).</p