BETA-FRUCTOSIDASES - A NEW SUPERFAMILY OF GLYCOSYL HYDROLASES

Enzymes with beta-fructosidase activity are classified in two families , basing on their amino acid sequences: one (glycosyl hydrolase family 32) including pro- and eukaryotic sucrases and fructanases, and the o ther including bacterial levansucrases. We have compared the sequences of several representatives of the two families. Nine regions similar to previously known highly consented regions of sucrases and fructanas es have been found in levansucrases, indicating that the two families have evolved from a common precursor and should be grouped into a supe rfamily. It has also been shown that the Aspergillus niger invertase, previously considered not to be homologous to the above proteins, is a ctually a divergent member of the glycosyl hydrolase family 32.