Agrobacterium Ti and Ri plasmids specify enzymic lactonization of mannopine to agropine.

A novel enzymic activity, responsible for the conversion of mannopine to agropine by lactonization, has been identified in Agrobacterium strains. This activity is encoded by octopine-type and agropine-type Ti or Ri plasmids, and is inducible by mannopine and agropine. In crude extracts it is stable for long periods and can be used for preparative synthesis of agropine from mannopine. The physiological role of this activity is not understood. However, it is probably involved in degradation of opines of the agropine family since it is always associated with agropine utilization in wild-type strains.