β-amylase (EC 3.2.1.2) [1,2] is an enzyme that hydrolyzes 1,4-α-glucosidic linkages in starch-type polysaccharide substrates so as to remove successive maltose units from the non-reducing ends of the chains. β-amylase is present in certain bacteria as well as in plants.

Three highly conserved sequence regions are found in all known β-amylases. The first of these regions is located in the N-terminal section of the enzymes and contains an aspartate which is known [3] to be involved in the catalytic mechanism. The second, located in a more central location, is centered around a glutamate which is also involved [4] in the catalytic mechanism. We use both regions as signature patterns.