5.3.99.2 Ba2+ increase in activity 653299 5.3.99.2 Ca2+ half maximal effective concentration at 0.4 mM, 1.5fold increase in activity 653299 5.3.99.2 Mg2+ - 704977 5.3.99.2 Mg2+ half maximal effective concentration at 0.05 mM, 1.5fold increase in activity, Mg2+ increases the affinity for glutathione 653299 5.3.99.2 Sr2+ increase in activity 653299