Ca2+ and peroxidase derived from cultured peanut cells

A 5% increase of Ca²⁺ content of the incubation medium for cultured peanut ( Arachis hypogaea L.) cells caused a rise of peroxidase (EC 1.11.1.7) activity in the medium, which could be abolished by the addition of the chelator EGTA [eth-yleneglycol-bis-(β-aminoethyl ether)-N,N,N',N'-tetraacetic acid]. However, the determination of in vivo peroxidase synthesis in these cells showed that Ca²⁺ had a direct effect on the biosynthesis rather than on transport alone. This concept was re-enforced by the lack of effect by the ionophore A23187 on the transport. The Ca²⁺ content was 2 and 5 mol (mol protein⁻¹) for the cationic and anionic peanut peroxidase, respectively. The latter is different from the value reported for the anionic peroxidase from horseradish.