What does beta galactosidase bind to?

Beta galactosidase is made to bind to galactose and glucose, which are the two monosaccharides of lactose. At the galactose subsite, this enzyme binds efficiently to d-galactose and is specific in recognizing this sugar. Some sugars with alterations at position 6 are able to bind, but are typically inefficient substrates. Even slight modifications at position 6 greatly reduce the efficiency of the enzyme in processing sugars. At the glucose subsite, beta galactosidase shows low specificity for d-glucose, allowing for the interchanging of different alcohols. This subsite is hydrophobic, and thus beta galactosidase with hydrophobic groups instead of glucose binds effectively. The affinity for d-glucose increases greatly after the glycosidic bond breaks.