FIG 4.

Substrate specificity of LpGH32 and release of breakdown products during conversion of different β-(2-1)-fructans. (A) Products formed by purified LpGH32 enzyme (0.9 μg/ml) incubated with fructan [β-(2-1) and β-(2-6)] substrates: native inulin [from chicory, β-(2-1)], oligofructose [β-(2-1)], levan [β-(2-6), bacterial origin], and sucrose [α-(1-2)]. St, standard containing fructose (Fruc), sucrose (Suc), 1-kestose (GF2), and nystose (GF3). Incubation was at pH 4.0 (lane 3) and pH 5.0 (lane 4) for 40 h; lane 2, substrate control. Accumulation of intermediate breakdown products liberated by LpGH32 (excess, 0.9 μg/ml, and minimal, 0.15 μg/ml, amounts) during incubations with GF-type fructan native inulin (B) and FF-type fructan oligofructose (also contains GF-type fructans) (C) and stopping reactions after 40 h. Main product released was fructose; accumulation of intermediate breakdown products is highlighted with arrowheads.