An enzyme that normally digests a disaccharide into two monosaccharides is most likely able to digest other similar disaccharides.

Enzymes are very specific in the substrates they bind to due to their unique three-dimensional structures and the specific active site where the substrate fits. An enzyme that digests a disaccharide into two monosaccharides is most likely specialized for this particular reaction. However, if there is another substrate this enzyme could digest, it would most likely be a substrate with a similar structure to the disaccharide it normally acts upon.

For instance, if the enzyme in question is lactase, which specifically breaks lactose (a disaccharide made of glucose and galactose) into its monosaccharide components, the enzyme may not have the ability to digest a significantly different disaccharide like sucrose—which is composed of glucose and fructose—since the bond and the shape of the sucrose molecule are different. However, in the event that other similar disaccharides are compatible with the enzyme's active site and can be accommodated without significant alteration to the shape and chemistry of the active site or substrate, then the enzyme might act upon them. This scenario is less common since enzymes generally demonstrate a high degree of specificity.