E or 'early' set domains are associated with the catalytic domain of galactose oxidase at the C-terminal end. Galactose oxidase is an extracellular monomeric enzyme which catalyzes the stereospecific oxidation of a broad range of primary alcohol subs ...
E or 'early' set domains are associated with the catalytic domain of galactose oxidase at the C-terminal end. Galactose oxidase is an extracellular monomeric enzyme which catalyzes the stereospecific oxidation of a broad range of primary alcohol substrates, and possesses a unique mononuclear copper site essential for catalysing a two-electron transfer reaction during the oxidation of primary alcohols to corresponding aldehydes. The second redox active centre necessary for the reaction was found to be situated at a tyrosine residue. The C-terminal domain of galactose oxidase may be related to the immunoglobulin and/or fibronectin type III superfamilies. These domains are associated with different types of catalytic domains at either the N-terminal or C-terminal end, and may be involved in homodimeric/tetrameric/dodecameric interactions. Members of this family adopt a secondary structure consisting of a bundle of seven, mostly antiparallel, beta-strands surrounding a hydrophobic core. The 7 strands are arranged in 2 sheets, in a Greek-key topology [1]. This domain is found in sugar-utilising enzymes, such as galactose oxidase or chitinase [2-6].
Galactose oxidase is a copper containing enzyme which oxidises primary alcohols to aldehydes by the reduction of molecular oxygen to hydrogen peroxide. The enzyme catalyses the oxidation of many substrates, including dihydroxyacetone, small molecules and olysaccharides by use of a protein radical cofactor, a novel metalloradical complex, formed by a unique structural feature at the copper site with a novel thioether bond linking Cys 228 and Tyr 272 formed from a post-translational modification, which is in a stacking interaction with Trp 290. Galactose oxidase is remarkable in the extent to which free radicals are involved in all aspects of the enzyme function: serving as a key feature of the active site structure, defining the characteristic reactivity of the complex, and directing the biogenesis of the Tyr-Cys cofactor during protein maturation.
Defined by 6 residues: CYS:A-228TYR:A-272TRP:A-290TYR:A-495HIS:A-496HIS:A-581
