Thermostable α-galactosidase from Thermotoga neapolitana: cloning, sequencing and expression

Abstract A gene encoding a thermostable α-galactosidase from the hyperthermophile Thermotoga neapolitana was cloned and sequenced. Sequence analysis showed that the 552-amino acid protein is similar to Escherichia coli Raf type α-galactosidase and belongs to Family 36 of the glycosyl hydrolases. Recombinant α-galactosidase expressed in E. coli has a molecular mass of ca. 61 kDa, and an optimum activity at 93°C at pH 7.0. The enzyme is highly thermostable and retains 75% of activity after heating to 80°C for 4 h. The potential application of the enzyme to high temperature processing of soy molasses has been demonstrated.