Purification and characterization of invertase from Lactobacillus reuteri CRL 1100.

The invertase of Lactobacillus reuteri CRL 1100 is a glycoprotein composed by a single subunit with a molecular weight of 58 kDa. The enzyme was stable below 45 degrees C over a wide pH range (4.5-7.0) with maximum activity at pH 6.0 and 37 degrees C. The invertase activity was significantly inhibited by bivalent metal ions (Ca(++), Cu(++), Cd(++), and Hg(++)), beta-mercaptoethanol, and dithiothreitol and partially improved by ethylenediaminetetraacetic acid. The enzyme was purified 32 times over the crude extract by gel filtration and ion-exchange chromatography with a recovery of 17%. The K(m) and V(max) values for sucrose were 6.66 mM and 0.028 micromol/min, respectively. An invertase is purified and characterized for the first time in Lactobacillus, and it proved to be a beta-fructofuranosidase.