Purification and properties of ι-carrageenase from a marine bacterium

Abstract

An ι-carrageenase has been purified from the cell-free culture medium of a marine bacterium grown in ι-carrageenan. The enzyme hydrolyzes the β1 → 4 linkages in ι-carrageenan; the major end products, as identified by 13C nuclear magnetic resonance spectroscopy, are ι-neocarratetraose sulfate and ι-neocarrahexaose sulfate. The enzyme was purified by fractionation on Sephacryl S-200 in 2.0 M NaCl and hydrophobic interaction chromatography on Phenyl-Sepharose CL-4B. The purified enzyme had an apparent molecular weight of 57 000, and optimum activity was expressed at pH 8.0, 40 °C, in 0.1 M Na+. The enzyme was stable for at least 6 months at 4 °C in 1.0 M NaCl. Removal of the salt, freezing, or lyophilization destroyed enzyme activity. Membrane fractions, prepared by discontinuous sucrose density gradient centrifugation, also exhibited ι-carrageenase activity. Properties of ι-carrageenase suggest an association with cell wall components.