Figure 6.

Biotechnological preparation of the six trimeric paCOS DAA, ADA, AAD, DDA, DAD, and ADD. DAA and ADA can be prepared from chitotriose AAA by the action of the CDA NodB from Rhizobium and VcCDA from Vibrio, respectively. DDA can then be produced by subsequent treatment with the other enzyme. Similarly, ADD and DAD can be prepared from DDD by the action of these two enzymes acting in reverse mode in the presence of excess amounts of acetate, and AAD can then be produced by subsequent reverse action of the other enzyme. The substrates for these reactions, AAA and DDD, can be prepared from polymeric chitin or polyglucosamine by the action of a chitinase or chitosanase, respectively. Alternatively, chitotriose can be produced by an E. coli cell factory strain expressing NodC from Rhizobium, yielding chitin pentaose which can then be cleaved, in vivo or in vitro, by a chitinase, yielding chitobiose and chitotriose. In each case, the trimeric product has to be purified using liquid chromatography.