Purification and characterization of the invertase from Pycnoporus sanguineus

A constitutive invertase (EC 3.2.1.26) was isolated and purified by the first time from Pycnoporus sanguineus. The enzyme is a glycoprotein. Its relative molecular mass is about 84,000 and its structure is dimeric, with two identical subunits (about 41,000). The enzyme is able to attack sucrose, raffinose, stachyose, inulin and levan, being sucrose the preferred substrate (Km 4.89 +/- 0.13 mM). Fructose was a classical competitive inhibitor, but glucose was not an inhibitor of the enzyme. Lectins with specificity toward glucose are inhibitors of the enzyme. Glucose was present in invertase acid hydrolysates. Unlike higher plant invertases, bovine serum albumin is not an effector of the Pycnoporus sanguineus enzyme, and the inhibition by fructose is not suppressed by this protein. The properties of the Pycnoporus sanguineus enzyme are discussed with reference to higher plant invertases.