Mutarotase that catalyzes the interconversion of beta-D-galactose and alpha-D-galactose during galactose metabolism (PubMed:12753898). Beta-D-galactose is metabolized in the liver into glucose 1-phosphate, the primary metabolic fuel, by the action of four enzymes that constitute the Leloir pathway: GALM, GALK1 (galactokinase), GALT (galactose-1-phosphate uridylyltransferase) and GALE (UDP-galactose-4′-epimerase) (PubMed:30451973). Involved in the maintenance of the equilibrium between the beta- and alpha-anomers of galactose, therefore ensuring a sufficient supply of the alpha-anomer for GALK1 (PubMed:12753898). Also active on D-glucose although shows a preference for galactose over glucose (PubMed:12753898).
