Heme-independent soluble and membrane-associated peroxidase activity of a<i>Zea mays</i>annexin preparation

Abstract

Annexins are cytosolic proteins capable of reversible, Ca2+-dependent membrane binding or insertion. Animal annexins form and regulate Ca2+-permeable ion channels and may therefore participate in signaling. Zea mays (maize) annexins (ZmANN33 and ZmANN35) have recently been shown to form a Ca2+-permeable conductance in planar lipid bilayers and also exhibit in vitro peroxidase activity. Peroxidases form a superfamily of intra- or extracellular heme-containing enzymes that use H2O2 as the electron acceptor in a number of oxidative reactions. Maize annexin peroxidase activity appears independent of heme and persists after membrane association, the latter suggesting a role in reactive oxygen species signaling.