Nucleic acid molecules which encode a branching enzyme from a bacterium of the genus Neisseria, vectors, host cell, plant cells and plants containing said nucleic acid molecules as well as starch obtainable from the plants described are described. Furthermore, an in-vitro method for producing .alpha.-1,6-branched .alpha.-1,4-glucans on the basis of sucrose and a combination of enzymes of an amylosucrase and a branching enzyme as well as the .alpha.-1,6-branched .alpha.-1,4-glucans obtainable by said method are described.