An intracellular pectinolytic enzyme, PelB (TM0437), from the hyperther-mophilic bacteriumThermotoga maritimawas functionally produced in Escherichia coliand purified to homogeneity. PelB belongs to family 28 of the glycoside hydrolases, consisting of pectin-hydrolysing enzymes. As one of the few bacterial exopolygalacturonases, it is able to remove monogalac-turonate units from the nonreducing end of polygalacturonate.