Figure 2

The response of hLPYK activity to changing concentrations of Cd²⁺ and V²⁺. Both Cd²⁺ and V²⁺ support low levels of hLPYK activity. For this initial screen, hLPYK purified with Mg²⁺ present was diluted into the assay cocktail, giving rise to an expected background activity due to the carryover of some small level of Mg²⁺. Error bars for Cd²⁺ data are the standard deviation for three replicate reads and when they are not visible, they are smaller than data points. The V²⁺ data was only collected once, so no error bars are included. Lines are to show data trends only. Other divalent cations that supported activity were further evaluated using a buffer containing the respective divalent cations (Mg²⁺, Mn²⁺, Co²⁺, Ni²⁺, and Zn²⁺). Cu²⁺, Pb²⁺ and Fe²⁺ supported activity but also caused a precipitate to form which precluded them from the study. Ca²⁺, Ba²⁺, Be²⁺, Cr²⁺, Hg²⁺ and Sr²⁺ did not support activity in this initial divalent cation screen.