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 amylosucrase from Neisseria polysaccharea were characterised. Contrary to previously published results, it was demonstrated that in the presence of sucrose alone, scleral reactions are catalysed, in addition to polymer synthesis: sucrose hydrolgysis, maltose and maltotriose synthesis by successive transfers of the glucosyl moiety of sucrose onto the released glucose, and finally turanose and trehalulose synthesis - these tao sucrose isomers being obtained by glucosyl transfer onto fructose. The effect of initial sucrose concentration on initial activity demonstrated a non-Michaelian profile never previously described. (C) 2000 Federation of European Biochcmical Societies.