ISOLATION AND CHARACTERIZATION OF ZINC-BINDING PROTEINS DISTINCT FROMMETALLOTHIONEIN FROM THE EGGS OF THE SEA-URCHIN STRONGYLOCENTROTUS-INTERMEDIUS

Two low-molecular-weight zinc-binding proteins were purified from eggs of the sea urchin Strongylocentrotus intermedius (Echinodermata: Echi noidea) by gel-permeation and anion-exchange chromatography followed b y high performance liquid chromatography. The characteristics of these proteins are distinct from those of metallothionein. Amino acid compo sitions show a low or intermediate content of cysteine and high amount s of acidic amino acids, glycine and histidine; they also contain meth ionine and aromatic residues. On the basis of these characteristics, t he S. intermedius zinc-binding proteins appear similar to other metall oproteins isolated from both vertebrates and invertebrates. No typical metallothionein was detected in the extracts from S. intel medius egg s.