Purification and properties of an invertase with sucrose: sucrose fructosyltransferase (SST) activity from the roots of Cichorium intybus L.

SUMMARY An invertase was purified From Cichorium intyhbus L. roots by a combination of ammonium sulphate precipitation. Concanavalimn A affinity chromatography, anion exchange chromatography and gel filtration. A 230–fold purification and a final specific activity of 2.7U per mg protein was obtained. The enzyme has a M, of 93000 as estimated by gel filtration ans after SDS‐PAGE a single bannd with a M, of 50000 was found. Optima activity was found between pH 5 and pH 5.5.At low substrate concentrations equal amounts of fructose and glucose were produced (apperant Kw 55 mm). At higher sucrose concentrations progressively more isokestose was produced and fructose synthesis was inhibited. The high sucrose concentrations needed for isokestose systhesis do not support a physiological role for the enzyme in fructan biosynthesis.