ABSTRACT
Galactose oxidase (GOase, EC 1 .1.3.9) is an extracellular enzyme produced by fungi of the Fusarium genera [20,40]. It catalyzes the oxidation of primary alcohols to alde hydes by molecular oxygen, producing hydrogen peroxide as a byproduct (equation 1 ):
been determined to 1.7 A resolution [42,43]. The polypeptide chain is divided into three predominantly (3-structural domains. Domain 1 (residues 1-155) has a P-sandwich structure, which is linked to domain 2 by a well-ordered stretch of the polypep tide chain. Domain 2 (residues 156-532) has pseudo-sevenfold symmetry with the overall appearance of a seven-bladed propeller wherein each blade consists of a four-stranded antiparallel P sheet. The copper ion, which is part of the active site, is located on the solvent-accessible surface of this domain close to the sevenfold axis. Domain 3 (residues 533-639) lies on the opposite side of domain 2 from the copper center. Two of the seven P strands in domain 3 form a hairpin loop that extends through the pore in the middle of domain 2 , providing a histidine ligand (His581) for the copper ion. The space between the hairpin and the pore walls in domain 3 is filled with well-ordered water molecules.
