Amylosucrase from Neisseria polysaccharea: novel catalytic properties

Amylosucrase is a glucosyltransferance that synthesises an insoluble alpha- glucan from sucrose, The catalytic properties of the highly purified amylos ucrase from Neisseria polysaccharea were characterised. Contrary to previou sly published results, it was demonstrated that in the presence of sucrose alone, scleral reactions are catalysed, in addition to polymer synthesis: s ucrose hydrolgysis, maltose and maltotriose synthesis by successive transfe rs of the glucosyl moiety of sucrose onto the released glucose, and finally turanose and trehalulose synthesis - these tao sucrose isomers being obtai ned by glucosyl transfer onto fructose. The effect of initial sucrose conce ntration on initial activity demonstrated a non-Michaelian profile never pr eviously described. (C) 2000 Federation of European Biochcmical Societies.