The adsorptive immobilization of phospholipids D mediated by calcium ions

Immobilization of phospholipase D from cabbage was studied with the aim of stabilizing the enzyme for its use in synthesis of phospholipids. It was shown that phospholipase D can be immobilized by adsorption to polymeric carriers containing long chain anchor groups such as octadecyl, octyl, or other alkyl residues. Starting from the crude enzyme, phospholipase D activity is preferentially bound (up to 100%) in competition with contaminating proteins. A prerequisite of high binding rates is the presence of calcium ions, which play a mediating role in the adsorption process. The maximum activity of the carrier‐enzyme complexes depends upon the calcium concentration in the immobilization process and the carrier material (≥10m M CaCl 2 with octadecyl‐Si40, ≥40 m M CaCl 2 with octyl‐sepharose and butyl‐fractogel). Immobilization of phospholipase D to octyl‐sepharose was shown to result in a distinctly increased storage stability and an enlarged pH‐optimum range for the catalytic activity. Operational stability of different phospholipase D‐carrier complexes was compared. © 1993 Wiley & Sons, Inc.