Levansucrase of Bacillus subtilis. Characterization of a form isolated from phenol-treated cells and activated by Triton X-100.

A macromolecular complex including an inactive and protease-sensitive form of levansucrase was isolated from phenol treatment of Bacillus subtilis. This complex has a weak affinity for hydroxyapatite. Its molecular weight is evaluated at 300 000. This levansucrase form may be activated either by Triton X-100, above its critical micellar concentration, or by phospholipase C. The enzyme form associated with the complex is quite different from the exocellular levansucrase, which is protease-insensitive and detergent-insensitive, shows high affinity for hydroxyapatite and has a molecular weight of 54 000. Triton X-100 disaggregates this complex. The active levansucrase released becomes protease-insensitive and has the same apparent sedimentation coefficient as the exocellular enzyme. Possible relationships between the existence of this trapped complex and the secretion process of levansucrase are discussed.