Catalytic properties of purified recombinant PLA derived from gene AtPLA IVA. A, Ca2+ dependence of PLA activity; inset, highlighting of low Ca2+ concentrations. B, pH dependence of activity; C, inhibition by HELSS; D, inhibition by NDGA; E, inhibition by AACOCF3; F, inhibition by ETYA; and G, inhibition by PACOCF3. Fluorescent fatty acid was quantified on a relative scale.